GameTime/lib/application/use_cases.dart

import 'dart:convert';

import '../domain/domain.dart';
import 'ports.dart';

const Object _useCaseUnchanged = Object();

final class AuthUseCases {
  const AuthUseCases({
    required this.tokenStore,
    required this.accountRepository,
    required this.remoteAuthApi,
    required this.clock,
    required this.ids,
  });

  final AuthTokenStore tokenStore;
  final OnlineAccountRepository accountRepository;
  final RemoteAuthApi remoteAuthApi;
  final Clock clock;
  final IdGenerator ids;

  Future<UserAccountSession> register({
    required String email,
    required String password,
    String? displayName,
  }) async {
    _validateAuthInput(email: email, password: password);
    final result = await remoteAuthApi.register(
      email: email.trim(),
      password: password,
      displayName: displayName,
    );
    return _persistAuthenticatedSession(result, displayName: displayName);
  }

  Future<UserAccountSession> login({
    required String email,
    required String password,
  }) async {
    _validateAuthInput(email: email, password: password);
    final result = await remoteAuthApi.login(
      email: email.trim(),
      password: password,
    );
    return _persistAuthenticatedSession(result);
  }

  Future<void> logout() async {
    final token = await tokenStore.readToken();
    if (token != null) {
      try {
        await remoteAuthApi.logout(token);
      } on RemoteAuthException {
        // Local logout must not depend on remote reachability.
      }
    }
    await tokenStore.clearToken();
    final session = await accountRepository.currentSession();
    if (session != null) {
      final now = clock.now();
      await accountRepository.saveSession(
        session.copyWith(isLoggedIn: false, updatedAt: now),
      );
    }
  }

  Future<UserAccountSession?> currentSession() async {
    final session = await accountRepository.currentSession();
    if (session == null) {
      return null;
    }
    final token = await tokenStore.readToken();
    if (token != null || !session.isLoggedIn) {
      return session;
    }
    final updated = session.copyWith(isLoggedIn: false, updatedAt: clock.now());
    await accountRepository.saveSession(updated);
    return updated;
  }

  Future<UserAccountSession> _persistAuthenticatedSession(
    RemoteAuthResult result, {
    String? displayName,
  }) async {
    await tokenStore.saveToken(result.token, result.expiresAt);
    final now = clock.now();
    final existing = await accountRepository.currentSession();
    final session = UserAccountSession(
      id: existing?.id ?? ids.newId(),
      serverUserId:
          existing != null &&
              existing.email.trim().toLowerCase() ==
                  result.email.trim().toLowerCase()
          ? existing.serverUserId
          : result.userId,
      email: result.email,
      displayName: displayName ?? existing?.displayName,
      isLoggedIn: true,
      createdAt: existing?.createdAt ?? now,
      updatedAt: now,
      lastAuthenticatedAt: now,
    );
    await accountRepository.saveSession(session);
    return session;
  }
}

final class SyncUseCases {
  const SyncUseCases({
    required this.tokenStore,
    required this.remoteSyncApi,
    required this.metadataRepository,
    required this.mappingRepository,
    required this.localChanges,
    required this.clock,
    required this.deviceId,
  });

  final AuthTokenStore tokenStore;
  final RemoteSyncApi remoteSyncApi;
  final SyncMetadataRepository metadataRepository;
  final RemoteResourceMappingRepository mappingRepository;
  final LocalSyncChangeRepository localChanges;
  final Clock clock;
  final String deviceId;

  Future<SyncMetadataSnapshot> currentStatus() {
    return metadataRepository.read();
  }

  Future<SyncRunSummary> synchronize({required bool manual}) async {
    final token = await tokenStore.readToken();
    if (token == null) {
      return const SyncRunSummary(
        pushedChanges: 0,
        pulledChanges: 0,
        skipped: true,
        message: 'Not connected.',
      );
    }

    final previousMetadata = await metadataRepository.read();
    final attemptAt = clock.now();
    await metadataRepository.save(
      previousMetadata.copyWith(
        lastAttemptAt: attemptAt,
        status: OnlineSyncStatus.syncing,
      ),
    );

    try {
      final pendingChanges = await localChanges.listPendingChanges();
      var pushedCount = 0;
      if (pendingChanges.isNotEmpty) {
        final pushResult = await remoteSyncApi.push(
          deviceId: deviceId,
          items: pendingChanges.map((change) => change.item).toList(),
          token: token,
        );
        final changesByKey = {
          for (final change in pendingChanges)
            _syncKey(change.item.resourceType, change.item.clientId): change,
        };
        final syncedChangeLogIds = <String>[];
        for (final result in pushResult.results) {
          final change =
              changesByKey[_syncKey(result.resourceType, result.clientId)];
          if (change == null || result.status == RemoteSyncPushStatus.error) {
            continue;
          }
          pushedCount += result.status == RemoteSyncPushStatus.accepted ? 1 : 0;
          syncedChangeLogIds.addAll(change.changeLogIds);
          if (result.serverId != null && result.serverUpdatedAt != null) {
            await mappingRepository.save(
              RemoteResourceMapping(
                resourceType: result.resourceType,
                clientId: result.clientId,
                serverId: result.serverId!,
                serverUpdatedAt: result.serverUpdatedAt!,
              ),
            );
          }
        }
        if (syncedChangeLogIds.isNotEmpty) {
          await localChanges.markChangesSynced(syncedChangeLogIds, clock.now());
        }
      }

      final metadataBeforePull = await metadataRepository.read();
      final pullResult = await remoteSyncApi.pull(
        since: metadataBeforePull.serverCursor,
        token: token,
      );
      var pulledCount = 0;
      for (final item in pullResult.items) {
        await mappingRepository.save(
          RemoteResourceMapping(
            resourceType: item.resourceType,
            clientId: item.clientId,
            serverId: item.serverId,
            serverUpdatedAt: item.serverUpdatedAt,
          ),
        );
        final applied = await localChanges.applyRemoteItem(item);
        if (applied) {
          pulledCount += 1;
        }
      }

      final completedAt = clock.now();
      await metadataRepository.save(
        (await metadataRepository.read()).copyWith(
          serverCursor: pullResult.serverCursor,
          lastSuccessfulSyncAt: completedAt,
          lastFailureAt: null,
          status: OnlineSyncStatus.success,
          pendingPushCount: 0,
        ),
      );
      return SyncRunSummary(
        pushedChanges: pushedCount,
        pulledChanges: pulledCount,
      );
    } catch (error) {
      await metadataRepository.save(
        (await metadataRepository.read()).copyWith(
          lastFailureAt: clock.now(),
          status: OnlineSyncStatus.failure,
        ),
      );
      return SyncRunSummary(
        pushedChanges: 0,
        pulledChanges: 0,
        failed: true,
        message: error.toString(),
      );
    }
  }
}

final class ShareUseCases {
  const ShareUseCases({
    required this.tokenStore,
    required this.remoteShareApi,
    required this.inboxRepository,
    required this.pendingActionRepository,
    required this.localChanges,
    required this.programRepository,
    required this.templateRepository,
    required this.clock,
    required this.ids,
    required this.originDeviceId,
  });

  final AuthTokenStore tokenStore;
  final RemoteShareApi remoteShareApi;
  final ShareInboxRepository inboxRepository;
  final PendingShareActionRepository pendingActionRepository;
  final LocalSyncChangeRepository localChanges;
  final ProgramRepository programRepository;
  final WorkoutTemplateRepository templateRepository;
  final Clock clock;
  final IdGenerator ids;
  final String originDeviceId;

  Future<ShareSendResult> sendShare({
    required ShareResourceType resourceType,
    required String localResourceId,
    required List<String> recipientEmails,
  }) async {
    final emails = recipientEmails
        .map((email) => email.trim())
        .where((email) => email.isNotEmpty)
        .toList(growable: false);
    if (emails.isEmpty) {
      throw const DomainException('At least one recipient email is required.');
    }
    final payload = await _sharePayload(resourceType, localResourceId);
    final token = await tokenStore.readToken();
    if (token == null) {
      return const ShareSendResult(status: ShareSendStatus.notConnected);
    }
    try {
      final result = await remoteShareApi.sendShare(
        resourceType: resourceType,
        payload: payload,
        recipientEmails: emails,
        token: token,
      );
      return ShareSendResult(
        status: ShareSendStatus.sent,
        shareId: result.shareId,
        recipientUserIds: result.recipientUserIds,
        unresolvedEmails: result.unresolvedEmails,
      );
    } catch (_) {
      final action = _pendingShareAction(
        actionType: PendingShareActionType.send,
        resourceType: resourceType,
        payload: payload,
        recipientEmails: emails,
      );
      await pendingActionRepository.add(action);
      return ShareSendResult(
        status: ShareSendStatus.queued,
        pendingActionId: action.id,
      );
    }
  }

  Future<List<ShareInboxItem>> refreshInbox() async {
    final token = await tokenStore.readToken();
    if (token == null) {
      return inboxRepository.listAll();
    }
    try {
      final items = await remoteShareApi.fetchInbox(token);
      await inboxRepository.upsertAll(items);
      return inboxRepository.listAll();
    } catch (_) {
      return inboxRepository.listAll();
    }
  }

  Future<void> acceptShare(String shareId) async {
    final cachedItem = await inboxRepository.findByShareId(shareId);
    final token = await tokenStore.readToken();
    if (token == null) {
      await _acceptCachedShareAndQueueAck(shareId, cachedItem);
      return;
    }
    try {
      final createdResource = await remoteShareApi.acceptShare(shareId, token);
      await localChanges.applyRemoteItem(createdResource);
      await inboxRepository.markStatus(
        shareId,
        ShareInboxStatus.accepted,
        clock.now(),
      );
    } catch (_) {
      await _acceptCachedShareAndQueueAck(shareId, cachedItem);
    }
  }

  Future<void> declineShare(String shareId) async {
    final token = await tokenStore.readToken();
    if (token == null) {
      return;
    }
    try {
      await remoteShareApi.declineShare(shareId, token);
      await inboxRepository.markStatus(
        shareId,
        ShareInboxStatus.declined,
        clock.now(),
      );
    } catch (_) {
      await pendingActionRepository.add(
        _pendingShareAction(
          actionType: PendingShareActionType.decline,
          shareId: shareId,
        ),
      );
    }
  }

  Future<void> revokeShare(String shareId) async {
    final token = await tokenStore.readToken();
    if (token == null) {
      return;
    }
    try {
      await remoteShareApi.revokeShare(shareId, token);
      await inboxRepository.markStatus(
        shareId,
        ShareInboxStatus.revoked,
        clock.now(),
      );
    } catch (_) {
      await pendingActionRepository.add(
        _pendingShareAction(
          actionType: PendingShareActionType.revoke,
          shareId: shareId,
        ),
      );
    }
  }

  Future<void> processPendingShareActions() async {
    final token = await tokenStore.readToken();
    if (token == null) {
      return;
    }
    final actions = await pendingActionRepository.listPending();
    for (final action in actions) {
      final attemptedAt = clock.now();
      try {
        await _processPendingShareAction(action, token);
        await pendingActionRepository.markSucceeded(action.id, attemptedAt);
      } catch (_) {
        await pendingActionRepository.markFailed(action.id, attemptedAt);
      }
    }
  }

  Future<Map<String, Object?>> _sharePayload(
    ShareResourceType resourceType,
    String localResourceId,
  ) async {
    switch (resourceType) {
      case ShareResourceType.program:
        final program = await programRepository.findById(localResourceId);
        if (program == null) {
          throw const DomainException('Program not found.');
        }
        return _programSharePayload(program);
      case ShareResourceType.workoutTemplate:
        final template = await templateRepository.findById(localResourceId);
        if (template == null) {
          throw const DomainException('Workout template not found.');
        }
        return _workoutTemplateSharePayload(template);
    }
  }

  PendingShareAction _pendingShareAction({
    required PendingShareActionType actionType,
    String? shareId,
    ShareResourceType? resourceType,
    Map<String, Object?>? payload,
    List<String>? recipientEmails,
  }) {
    return PendingShareAction(
      id: ids.newId(),
      actionType: actionType,
      shareId: shareId,
      resourceType: resourceType,
      payloadJson: payload == null ? null : jsonEncode(payload),
      recipientEmailsJson: recipientEmails == null
          ? null
          : jsonEncode(recipientEmails),
      createdAt: clock.now(),
    );
  }

  Future<void> _processPendingShareAction(
    PendingShareAction action,
    String token,
  ) async {
    switch (action.actionType) {
      case PendingShareActionType.send:
        await remoteShareApi.sendShare(
          resourceType: action.resourceType!,
          payload: _jsonObject(action.payloadJson),
          recipientEmails: _jsonStringList(action.recipientEmailsJson),
          token: token,
        );
        return;
      case PendingShareActionType.accept:
        final created = await remoteShareApi.acceptShare(
          action.shareId!,
          token,
        );
        await localChanges.applyRemoteItem(created);
        await inboxRepository.markStatus(
          action.shareId!,
          ShareInboxStatus.accepted,
          clock.now(),
        );
        return;
      case PendingShareActionType.decline:
        await remoteShareApi.declineShare(action.shareId!, token);
        await inboxRepository.markStatus(
          action.shareId!,
          ShareInboxStatus.declined,
          clock.now(),
        );
        return;
      case PendingShareActionType.revoke:
        await remoteShareApi.revokeShare(action.shareId!, token);
        await inboxRepository.markStatus(
          action.shareId!,
          ShareInboxStatus.revoked,
          clock.now(),
        );
        return;
    }
  }

  Future<void> _acceptCachedShareAndQueueAck(
    String shareId,
    ShareInboxItem? item,
  ) async {
    if (item != null && item.status == ShareInboxStatus.pending) {
      await _importSharedPayload(item);
      await inboxRepository.markStatus(
        shareId,
        ShareInboxStatus.accepted,
        clock.now(),
      );
    }
    await pendingActionRepository.add(
      _pendingShareAction(
        actionType: PendingShareActionType.accept,
        shareId: shareId,
      ),
    );
  }

  Future<void> _importSharedPayload(ShareInboxItem item) async {
    final payload = _jsonObject(item.payloadJson);
    final now = clock.now();
    switch (item.resourceType) {
      case ShareResourceType.program:
        await programRepository.save(
          _programCopyFromSharePayload(payload, now),
        );
        return;
      case ShareResourceType.workoutTemplate:
        await templateRepository.save(
          _workoutTemplateCopyFromSharePayload(payload, now),
        );
        return;
    }
  }

  Program _programCopyFromSharePayload(
    Map<String, Object?> payload,
    DateTime now,
  ) {
    final programId = ids.newId();
    final programMetadata = EntityMetadata(
      id: programId,
      createdAt: now,
      updatedAt: now,
      originDeviceId: originDeviceId,
    );
    return Program(
      metadata: programMetadata,
      name: _stringFromSharePayload(payload, 'name', 'Programme partagé'),
      defaultRestSeconds: payload['defaultRestSeconds'] as int? ?? 0,
      exercises: _programExerciseCopiesFromSharePayload(
        payload['exercises'],
        programId,
        now,
      ),
    );
  }

  List<ProgramExercise> _programExerciseCopiesFromSharePayload(
    Object? value,
    String programId,
    DateTime now,
  ) {
    if (value is! List) {
      return const [];
    }
    final exercises = <ProgramExercise>[];
    for (var index = 0; index < value.length; index++) {
      final raw = value[index];
      if (raw is! Map) {
        continue;
      }
      final map = Map<String, Object?>.from(raw);
      exercises.add(
        ProgramExercise(
          metadata: EntityMetadata(
            id: ids.newId(),
            createdAt: now,
            updatedAt: now,
            originDeviceId: originDeviceId,
          ),
          programId: programId,
          sourceExerciseId: null,
          position: map['position'] as int? ?? index,
          exerciseNameSnapshot: _stringFromSharePayload(
            map,
            'exerciseNameSnapshot',
            'Exercice partagé',
          ),
          exerciseDescriptionSnapshot:
              map['exerciseDescriptionSnapshot'] as String?,
          exerciseImageMediaIdSnapshot:
              map['exerciseImageMediaIdSnapshot'] as String?,
          exerciseImageMediaIdsSnapshot: _stringListFromSharePayload(
            map['exerciseImageMediaIdsSnapshot'] ??
                map['imageMediaIdsSnapshot'],
          ),
          exerciseVideoMediaIdSnapshot:
              map['exerciseVideoMediaIdSnapshot'] as String?,
          exerciseStepsSnapshot: _exerciseStepsFromSnapshot(
            map['exerciseStepsSnapshot'],
          ),
          exerciseArchivedSnapshot: map['exerciseArchivedSnapshot'] == true,
          availableTimeSnapshot: map['availableTimeSnapshot'] == true,
          availableRepsSnapshot: map['availableRepsSnapshot'] == true,
          availableScoreSnapshot: map['availableScoreSnapshot'] == true,
          scoreInputModeSnapshot: _scoreInputModeFromSnapshot(
            map['scoreInputModeSnapshot'],
          ),
          scoreLabelSnapshot: map['scoreLabelSnapshot'] as String?,
          scoreUnitSnapshot: map['scoreUnitSnapshot'] as String?,
          setsCount: map['setsCount'] as int? ?? 1,
          timeEnabled: map['timeEnabled'] == true,
          repsEnabled: map['repsEnabled'] == true,
          scoreEnabled: map['scoreEnabled'] == true,
          targetTimeSeconds: map['targetTimeSeconds'] as int?,
          targetReps: map['targetReps'] as int?,
          targetScore: (map['targetScore'] as num?)?.toDouble(),
          targetScoreTimeMs: map['targetScoreTimeMs'] as int?,
          restSecondsOverride: map['restSecondsOverride'] as int?,
        ),
      );
    }
    return exercises;
  }

  WorkoutTemplate _workoutTemplateCopyFromSharePayload(
    Map<String, Object?> payload,
    DateTime now,
  ) {
    final templateId = ids.newId();
    final programIdBySharedId = <String, String>{};
    final programs = _workoutTemplateProgramCopiesFromSharePayload(
      payload['programs'],
      templateId,
      programIdBySharedId,
      now,
    );
    return WorkoutTemplate(
      metadata: EntityMetadata(
        id: templateId,
        createdAt: now,
        updatedAt: now,
        originDeviceId: originDeviceId,
      ),
      name: _stringFromSharePayload(payload, 'name', 'Séance partagée'),
      lastStartedAt: null,
      programs: programs,
      overrides: _workoutTemplateOverrideCopiesFromSharePayload(
        payload['overrides'],
        programIdBySharedId,
        now,
      ),
    );
  }

  List<WorkoutTemplateProgram> _workoutTemplateProgramCopiesFromSharePayload(
    Object? value,
    String templateId,
    Map<String, String> programIdBySharedId,
    DateTime now,
  ) {
    if (value is! List) {
      return const [];
    }
    final programs = <WorkoutTemplateProgram>[];
    for (var index = 0; index < value.length; index++) {
      final raw = value[index];
      if (raw is! Map) {
        continue;
      }
      final map = Map<String, Object?>.from(raw);
      final copiedId = ids.newId();
      final sharedId = map['id'] as String?;
      if (sharedId != null) {
        programIdBySharedId[sharedId] = copiedId;
      }
      programs.add(
        WorkoutTemplateProgram(
          metadata: EntityMetadata(
            id: copiedId,
            createdAt: now,
            updatedAt: now,
            originDeviceId: originDeviceId,
          ),
          workoutTemplateId: templateId,
          sourceProgramId: null,
          position: map['position'] as int? ?? index,
          programNameSnapshot: _stringFromSharePayload(
            map,
            'programNameSnapshot',
            'Programme partagé',
          ),
          defaultRestSecondsSnapshot:
              map['defaultRestSecondsSnapshot'] as int? ?? 0,
          programSnapshotJson:
              map['programSnapshotJson'] as String? ?? '{"exercises":[]}',
        ),
      );
    }
    return programs;
  }

  List<WorkoutTemplateExerciseOverride>
  _workoutTemplateOverrideCopiesFromSharePayload(
    Object? value,
    Map<String, String> programIdBySharedId,
    DateTime now,
  ) {
    if (value is! List) {
      return const [];
    }
    final overrides = <WorkoutTemplateExerciseOverride>[];
    for (final raw in value) {
      if (raw is! Map) {
        continue;
      }
      final map = Map<String, Object?>.from(raw);
      final sharedProgramId = map['workoutTemplateProgramId'] as String?;
      final copiedProgramId = programIdBySharedId[sharedProgramId];
      if (copiedProgramId == null) {
        continue;
      }
      final snapshotProgramExerciseId = map['snapshotProgramExerciseId'];
      if (snapshotProgramExerciseId is! String ||
          snapshotProgramExerciseId.trim().isEmpty) {
        continue;
      }
      overrides.add(
        WorkoutTemplateExerciseOverride(
          metadata: EntityMetadata(
            id: ids.newId(),
            createdAt: now,
            updatedAt: now,
            originDeviceId: originDeviceId,
          ),
          workoutTemplateProgramId: copiedProgramId,
          snapshotProgramExerciseId: snapshotProgramExerciseId,
          setsCountOverride: map['setsCountOverride'] as int?,
          targetTimeSecondsOverride: map['targetTimeSecondsOverride'] as int?,
          targetRepsOverride: map['targetRepsOverride'] as int?,
          targetScoreOverride: (map['targetScoreOverride'] as num?)?.toDouble(),
          targetScoreTimeMsOverride: map['targetScoreTimeMsOverride'] as int?,
        ),
      );
    }
    return overrides;
  }
}

final class ExerciseUseCases {
  const ExerciseUseCases({
    required this.repository,
    required this.programRepository,
    required this.clock,
    required this.ids,
    required this.originDeviceId,
  });

  final ExerciseRepository repository;
  final ProgramRepository programRepository;
  final Clock clock;
  final IdGenerator ids;
  final String originDeviceId;

  Future<Exercise> create({
    required String name,
    String? description,
    String? imageMediaId,
    List<String> imageMediaIds = const [],
    String? iconMediaId,
    String? videoMediaId,
    required bool hasTimeMeasure,
    required bool hasRepsMeasure,
    required bool hasScoreMeasure,
    ScoreInputMode scoreInputMode = ScoreInputMode.manual,
    String? scoreLabel,
    String? scoreUnit,
    int? defaultTargetTimeSeconds,
    int? defaultTargetReps,
    double? defaultTargetScore,
    int? defaultTargetScoreTimeMs,
    List<ExerciseStep> steps = const [],
  }) async {
    _validateExerciseSteps(steps);
    _validateExerciseDefaultTargets(
      hasTimeMeasure: hasTimeMeasure,
      hasRepsMeasure: hasRepsMeasure,
      hasScoreMeasure: hasScoreMeasure,
      scoreInputMode: scoreInputMode,
      defaultTargetTimeSeconds: defaultTargetTimeSeconds,
      defaultTargetReps: defaultTargetReps,
      defaultTargetScore: defaultTargetScore,
      defaultTargetScoreTimeMs: defaultTargetScoreTimeMs,
    );
    final now = clock.now();
    final exercise = Exercise(
      metadata: _newMetadata(ids, originDeviceId, now),
      name: name,
      description: description,
      imageMediaIds: _resolveExerciseImageIds(imageMediaId, imageMediaIds),
      iconMediaId: iconMediaId,
      videoMediaId: videoMediaId,
      hasTimeMeasure: hasTimeMeasure,
      hasRepsMeasure: hasRepsMeasure,
      hasScoreMeasure: hasScoreMeasure,
      scoreInputMode: scoreInputMode,
      scoreLabel: scoreLabel,
      scoreUnit: scoreUnit,
      defaultTargetTimeSeconds: defaultTargetTimeSeconds,
      defaultTargetReps: defaultTargetReps,
      defaultTargetScore: defaultTargetScore,
      defaultTargetScoreTimeMs: defaultTargetScoreTimeMs,
      steps: steps,
    );
    await repository.save(exercise);
    return exercise;
  }

  Future<void> save(Exercise exercise) => repository.save(exercise);

  Future<List<Exercise>> listActive() => repository.listActive();

  Future<bool> isUsedInPrograms(String id) {
    return repository.isReferencedByProgram(id);
  }

  Future<Exercise> update({
    required String id,
    required String name,
    String? description,
    String? imageMediaId,
    Object? imageMediaIds = _useCaseUnchanged,
    Object? iconMediaId = _useCaseUnchanged,
    String? videoMediaId,
    required bool hasTimeMeasure,
    required bool hasRepsMeasure,
    required bool hasScoreMeasure,
    ScoreInputMode scoreInputMode = ScoreInputMode.manual,
    String? scoreLabel,
    String? scoreUnit,
    Object? defaultTargetTimeSeconds = _useCaseUnchanged,
    Object? defaultTargetReps = _useCaseUnchanged,
    Object? defaultTargetScore = _useCaseUnchanged,
    Object? defaultTargetScoreTimeMs = _useCaseUnchanged,
    Object? steps = _useCaseUnchanged,
  }) async {
    final exercise = await repository.findById(id);
    if (exercise == null) {
      throw const DomainException('Exercise not found.');
    }
    final resolvedDefaultTargetTimeSeconds =
        defaultTargetTimeSeconds == _useCaseUnchanged
        ? exercise.defaultTargetTimeSeconds
        : defaultTargetTimeSeconds as int?;
    final resolvedDefaultTargetReps = defaultTargetReps == _useCaseUnchanged
        ? exercise.defaultTargetReps
        : defaultTargetReps as int?;
    final resolvedDefaultTargetScore = defaultTargetScore == _useCaseUnchanged
        ? exercise.defaultTargetScore
        : (defaultTargetScore as num?)?.toDouble();
    final resolvedDefaultTargetScoreTimeMs =
        defaultTargetScoreTimeMs == _useCaseUnchanged
        ? exercise.defaultTargetScoreTimeMs
        : defaultTargetScoreTimeMs as int?;
    _validateExerciseDefaultTargets(
      hasTimeMeasure: hasTimeMeasure,
      hasRepsMeasure: hasRepsMeasure,
      hasScoreMeasure: hasScoreMeasure,
      scoreInputMode: scoreInputMode,
      defaultTargetTimeSeconds: resolvedDefaultTargetTimeSeconds,
      defaultTargetReps: resolvedDefaultTargetReps,
      defaultTargetScore: resolvedDefaultTargetScore,
      defaultTargetScoreTimeMs: resolvedDefaultTargetScoreTimeMs,
    );
    final resolvedSteps = steps == _useCaseUnchanged
        ? exercise.steps
        : steps as List<ExerciseStep>;
    _validateExerciseSteps(resolvedSteps);
    final resolvedImageMediaIds = imageMediaIds == _useCaseUnchanged
        ? _resolveExerciseImageIds(imageMediaId, exercise.imageMediaIds)
        : imageMediaIds as List<String>;
    final resolvedIconMediaId = iconMediaId == _useCaseUnchanged
        ? exercise.iconMediaId != null &&
                  resolvedImageMediaIds.contains(exercise.iconMediaId)
              ? exercise.iconMediaId
              : null
        : iconMediaId as String?;
    final updated = exercise.copyWith(
      metadata: exercise.metadata.touch(clock.now()),
      name: name,
      description: description,
      imageMediaIds: resolvedImageMediaIds,
      iconMediaId: resolvedIconMediaId,
      videoMediaId: videoMediaId,
      hasTimeMeasure: hasTimeMeasure,
      hasRepsMeasure: hasRepsMeasure,
      hasScoreMeasure: hasScoreMeasure,
      scoreInputMode: scoreInputMode,
      scoreLabel: scoreLabel,
      scoreUnit: scoreUnit,
      defaultTargetTimeSeconds: resolvedDefaultTargetTimeSeconds,
      defaultTargetReps: resolvedDefaultTargetReps,
      defaultTargetScore: resolvedDefaultTargetScore,
      defaultTargetScoreTimeMs: resolvedDefaultTargetScoreTimeMs,
      steps: resolvedSteps,
    );
    await repository.save(updated);
    return updated;
  }

  Future<Exercise> attachImage({
    required String exerciseId,
    required String mediaAssetId,
  }) async {
    final exercise = await repository.findById(exerciseId);
    if (exercise == null) {
      throw const DomainException('Exercise not found.');
    }
    final updated = exercise.copyWith(
      imageMediaIds: _appendExerciseImage(exercise.imageMediaIds, mediaAssetId),
      metadata: exercise.metadata.touch(clock.now()),
    );
    await repository.save(updated);
    return updated;
  }

  Future<Exercise> addImage({
    required String exerciseId,
    required String mediaAssetId,
  }) async {
    final exercise = await repository.findById(exerciseId);
    if (exercise == null) {
      throw const DomainException('Exercise not found.');
    }
    final updated = exercise.copyWith(
      imageMediaIds: _appendExerciseImage(exercise.imageMediaIds, mediaAssetId),
      metadata: exercise.metadata.touch(clock.now()),
    );
    await repository.save(updated);
    return updated;
  }

  Future<Exercise> removeImage({
    required String exerciseId,
    required String mediaAssetId,
  }) async {
    final exercise = await repository.findById(exerciseId);
    if (exercise == null) {
      throw const DomainException('Exercise not found.');
    }
    final updated = exercise.copyWith(
      imageMediaIds: exercise.imageMediaIds
          .where((imageId) => imageId != mediaAssetId)
          .toList(),
      iconMediaId: exercise.iconMediaId == mediaAssetId
          ? null
          : exercise.iconMediaId,
      metadata: exercise.metadata.touch(clock.now()),
    );
    await repository.save(updated);
    return updated;
  }

  Future<Exercise> reorderImages({
    required String exerciseId,
    required List<String> orderedMediaIds,
  }) async {
    final exercise = await repository.findById(exerciseId);
    if (exercise == null) {
      throw const DomainException('Exercise not found.');
    }
    if (!_sameImageSet(exercise.imageMediaIds, orderedMediaIds)) {
      throw const DomainException(
        'Reordered exercise images must match existing images.',
      );
    }
    final updated = exercise.copyWith(
      imageMediaIds: orderedMediaIds,
      metadata: exercise.metadata.touch(clock.now()),
    );
    await repository.save(updated);
    return updated;
  }

  Future<Exercise> setIcon({
    required String exerciseId,
    required String? mediaAssetId,
  }) async {
    final exercise = await repository.findById(exerciseId);
    if (exercise == null) {
      throw const DomainException('Exercise not found.');
    }
    final updated = exercise.copyWith(
      iconMediaId: mediaAssetId,
      metadata: exercise.metadata.touch(clock.now()),
    );
    await repository.save(updated);
    return updated;
  }

  Future<Exercise> attachVideo({
    required String exerciseId,
    required String mediaAssetId,
  }) async {
    final exercise = await repository.findById(exerciseId);
    if (exercise == null) {
      throw const DomainException('Exercise not found.');
    }
    final updated = exercise.copyWith(
      videoMediaId: mediaAssetId,
      metadata: exercise.metadata.touch(clock.now()),
    );
    await repository.save(updated);
    return updated;
  }

  Future<Exercise> archive(String id) async {
    final exercise = await repository.findById(id);
    if (exercise == null) {
      throw const DomainException('Exercise not found.');
    }
    final archived = exercise.archive(clock.now());
    await repository.save(archived);
    return archived;
  }

  Future<Exercise> delete(String id) async {
    final exercise = await repository.findById(id);
    if (exercise == null) {
      throw const DomainException('Exercise not found.');
    }
    final now = clock.now();
    final deleted = exercise.copyWith(
      metadata: exercise.metadata.markDeleted(now),
    );
    await repository.save(deleted);
    return deleted;
  }
}

final class MediaUseCases {
  const MediaUseCases({
    required this.mediaRepository,
    required this.exerciseRepository,
    required this.storage,
    required this.clock,
    required this.ids,
    required this.originDeviceId,
  });

  final MediaAssetRepository mediaRepository;
  final ExerciseRepository exerciseRepository;
  final LocalMediaStorage storage;
  final Clock clock;
  final IdGenerator ids;
  final String originDeviceId;

  Future<MediaAsset> importMedia({
    required String sourcePath,
    required MediaKind kind,
  }) async {
    final now = clock.now();
    final id = ids.newId();
    final stored = await storage.importFile(
      sourcePath: sourcePath,
      kind: kind,
      stableFileName: id,
    );
    final asset = MediaAsset(
      metadata: EntityMetadata(
        id: id,
        createdAt: now,
        updatedAt: now,
        originDeviceId: originDeviceId,
      ),
      kind: kind,
      localUri: stored.localUri,
      mimeType: stored.mimeType,
      sizeBytes: stored.sizeBytes,
      width: stored.width,
      height: stored.height,
      durationMs: stored.durationMs,
    );
    await mediaRepository.save(asset);
    return asset;
  }

  Future<MediaAsset?> findById(String id) {
    return mediaRepository.findById(id);
  }

  Future<Exercise> attachToExercise({
    required String exerciseId,
    required String mediaAssetId,
  }) async {
    final exercise = await exerciseRepository.findById(exerciseId);
    if (exercise == null) {
      throw const DomainException('Exercise not found.');
    }
    final media = await mediaRepository.findById(mediaAssetId);
    if (media == null) {
      throw const DomainException('Media asset not found.');
    }
    final updated = switch (media.kind) {
      MediaKind.image => exercise.copyWith(
        imageMediaIds: _appendExerciseImage(
          exercise.imageMediaIds,
          media.metadata.id,
        ),
        metadata: exercise.metadata.touch(clock.now()),
      ),
      MediaKind.video => exercise.copyWith(
        videoMediaId: media.metadata.id,
        metadata: exercise.metadata.touch(clock.now()),
      ),
    };
    await exerciseRepository.save(updated);
    return updated;
  }

  Future<int> deleteOrphanedManagedFiles() async {
    final activeAssets = await mediaRepository.listActive();
    final referencedUris = activeAssets.map((asset) => asset.localUri).toSet();
    final managedUris = await storage.listManagedLocalUris();
    final orphanedUris = managedUris.difference(referencedUris);
    for (final uri in orphanedUris) {
      await storage.deleteByLocalUri(uri);
    }
    return orphanedUris.length;
  }
}

final class ProgramUseCases {
  const ProgramUseCases({
    required this.programRepository,
    required this.exerciseRepository,
    required this.templateRepository,
    required this.clock,
    required this.ids,
    required this.originDeviceId,
  });

  final ProgramRepository programRepository;
  final ExerciseRepository exerciseRepository;
  final WorkoutTemplateRepository templateRepository;
  final Clock clock;
  final IdGenerator ids;
  final String originDeviceId;

  Future<Program?> findById(String id) => programRepository.findById(id);

  Future<List<Program>> listActive() => programRepository.listActive();

  Future<bool> isUsedInWorkoutTemplates(String id) async {
    final templates = await templateRepository.listActive();
    return templates.any(
      (template) =>
          template.programs.any((program) => program.sourceProgramId == id),
    );
  }

  Future<Program> create({
    required String name,
    required int defaultRestSeconds,
  }) async {
    final now = clock.now();
    final program = Program(
      metadata: _newMetadata(ids, originDeviceId, now),
      name: name,
      defaultRestSeconds: defaultRestSeconds,
    );
    await programRepository.save(program);
    return program;
  }

  Future<Program> saveConfigured({
    String? id,
    required String name,
    required int defaultRestSeconds,
    required List<ProgramExerciseConfig> exercises,
  }) async {
    final now = clock.now();
    final existing = id == null ? null : await programRepository.findById(id);
    if (id != null && existing == null) {
      throw const DomainException('Program not found.');
    }
    final programId = id ?? ids.newId();
    final metadata =
        existing?.metadata.touch(now) ??
        EntityMetadata(
          id: programId,
          createdAt: now,
          updatedAt: now,
          originDeviceId: originDeviceId,
        );
    final programExercises = <ProgramExercise>[];
    for (var index = 0; index < exercises.length; index++) {
      final input = exercises[index];
      final exerciseMetadata =
          input.existingMetadata?.touch(now) ??
          _newMetadata(ids, originDeviceId, now);
      programExercises.add(
        ProgramExercise(
          metadata: exerciseMetadata,
          programId: programId,
          sourceExerciseId: input.sourceExerciseId,
          position: index,
          exerciseNameSnapshot: input.exerciseNameSnapshot,
          exerciseDescriptionSnapshot: input.exerciseDescriptionSnapshot,
          exerciseImageMediaIdSnapshot: input.exerciseImageMediaIdSnapshot,
          exerciseImageMediaIdsSnapshot: input.exerciseImageMediaIdsSnapshot,
          exerciseVideoMediaIdSnapshot: input.exerciseVideoMediaIdSnapshot,
          exerciseStepsSnapshot: input.exerciseStepsSnapshot,
          exerciseArchivedSnapshot: input.exerciseArchivedSnapshot,
          availableTimeSnapshot: input.availableTimeSnapshot,
          availableRepsSnapshot: input.availableRepsSnapshot,
          availableScoreSnapshot: input.availableScoreSnapshot,
          scoreInputModeSnapshot: input.scoreInputModeSnapshot,
          scoreLabelSnapshot: input.scoreLabelSnapshot,
          scoreUnitSnapshot: input.scoreUnitSnapshot,
          setsCount: input.setsCount,
          timeEnabled: input.enabledMeasures.contains(WorkoutMeasure.time),
          repsEnabled: input.enabledMeasures.contains(WorkoutMeasure.reps),
          scoreEnabled: input.enabledMeasures.contains(WorkoutMeasure.score),
          targetTimeSeconds: input.targetTimeSeconds,
          targetReps: input.targetReps,
          targetScore: input.targetScore,
          targetScoreTimeMs: input.targetScoreTimeMs,
          restSecondsOverride: input.restSecondsOverride,
        ),
      );
    }
    final program = Program(
      metadata: metadata,
      name: name,
      defaultRestSeconds: defaultRestSeconds,
      exercises: programExercises,
    );
    await programRepository.replaceExercises(program, now);
    return program;
  }

  Future<ProgramExercise> addExercise({
    required String programId,
    required String exerciseId,
    required int position,
    required int setsCount,
    required Set<WorkoutMeasure> enabledMeasures,
    int? targetTimeSeconds,
    int? targetReps,
    double? targetScore,
    int? targetScoreTimeMs,
    int? restSecondsOverride,
  }) async {
    final source = await exerciseRepository.findById(exerciseId);
    if (source == null) {
      throw const DomainException('Exercise not found.');
    }
    final now = clock.now();
    final programExercise = ProgramExercise.snapshotFromExercise(
      metadata: _newMetadata(ids, originDeviceId, now),
      programId: programId,
      exercise: source,
      position: position,
      setsCount: setsCount,
      enabledMeasures: enabledMeasures,
      targetTimeSeconds: targetTimeSeconds,
      targetReps: targetReps,
      targetScore: targetScore,
      targetScoreTimeMs: targetScoreTimeMs,
      restSecondsOverride: restSecondsOverride,
    );
    await programRepository.saveExercise(programExercise);
    return programExercise;
  }

  Future<Program> delete(String id) async {
    final program = await programRepository.findById(id);
    if (program == null) {
      throw const DomainException('Program not found.');
    }
    final now = clock.now();
    final deleted = program.copyWith(
      metadata: program.metadata.markDeleted(now),
    );
    final templates = await templateRepository.listActive();
    for (final template in templates) {
      final keptPrograms = template.programs
          .where((templateProgram) => templateProgram.sourceProgramId != id)
          .toList();
      if (keptPrograms.length == template.programs.length) {
        continue;
      }
      final repositionedPrograms = _repositionWorkoutTemplatePrograms(
        keptPrograms,
        now,
      );
      final keptProgramIds = repositionedPrograms
          .map((templateProgram) => templateProgram.metadata.id)
          .toSet();
      await templateRepository.replaceComposition(
        WorkoutTemplate(
          metadata: template.metadata.touch(now),
          name: template.name,
          lastStartedAt: template.lastStartedAt,
          programs: repositionedPrograms,
          overrides: template.overrides
              .where(
                (override) =>
                    keptProgramIds.contains(override.workoutTemplateProgramId),
              )
              .toList(),
        ),
        now,
      );
    }
    await programRepository.save(deleted);
    return deleted;
  }
}

final class ProgramExerciseConfig {
  const ProgramExerciseConfig({
    this.existingMetadata,
    this.sourceExerciseId,
    required this.exerciseNameSnapshot,
    this.exerciseDescriptionSnapshot,
    this.exerciseImageMediaIdSnapshot,
    this.exerciseImageMediaIdsSnapshot = const [],
    this.exerciseVideoMediaIdSnapshot,
    this.exerciseStepsSnapshot = const [],
    this.exerciseArchivedSnapshot = false,
    required this.availableTimeSnapshot,
    required this.availableRepsSnapshot,
    required this.availableScoreSnapshot,
    this.scoreInputModeSnapshot = ScoreInputMode.manual,
    this.scoreLabelSnapshot,
    this.scoreUnitSnapshot,
    required this.setsCount,
    required this.enabledMeasures,
    this.targetTimeSeconds,
    this.targetReps,
    this.targetScore,
    this.targetScoreTimeMs,
    this.restSecondsOverride,
  });

  final EntityMetadata? existingMetadata;
  final String? sourceExerciseId;
  final String exerciseNameSnapshot;
  final String? exerciseDescriptionSnapshot;
  final String? exerciseImageMediaIdSnapshot;
  final List<String> exerciseImageMediaIdsSnapshot;
  final String? exerciseVideoMediaIdSnapshot;
  final List<ExerciseStep> exerciseStepsSnapshot;
  final bool exerciseArchivedSnapshot;
  final bool availableTimeSnapshot;
  final bool availableRepsSnapshot;
  final bool availableScoreSnapshot;
  final ScoreInputMode scoreInputModeSnapshot;
  final String? scoreLabelSnapshot;
  final String? scoreUnitSnapshot;
  final int setsCount;
  final Set<WorkoutMeasure> enabledMeasures;
  final int? targetTimeSeconds;
  final int? targetReps;
  final double? targetScore;
  final int? targetScoreTimeMs;
  final int? restSecondsOverride;
}

final class WorkoutTemplateUseCases {
  const WorkoutTemplateUseCases({
    required this.templateRepository,
    required this.programRepository,
    required this.clock,
    required this.ids,
    required this.originDeviceId,
  });

  final WorkoutTemplateRepository templateRepository;
  final ProgramRepository programRepository;
  final Clock clock;
  final IdGenerator ids;
  final String originDeviceId;

  Future<WorkoutTemplate?> findById(String id) {
    return templateRepository.findById(id);
  }

  Future<List<WorkoutTemplate>> listActive() {
    return templateRepository.listActive();
  }

  Future<WorkoutTemplate> create({required String name}) async {
    final now = clock.now();
    final template = WorkoutTemplate(
      metadata: _newMetadata(ids, originDeviceId, now),
      name: name,
    );
    await templateRepository.save(template);
    return template;
  }

  Future<WorkoutTemplate> saveConfigured({
    String? id,
    required String name,
    required List<WorkoutTemplateProgramConfig> programs,
    required List<WorkoutTemplateExerciseOverrideConfig> overrides,
  }) async {
    final now = clock.now();
    final existing = id == null ? null : await templateRepository.findById(id);
    if (id != null && existing == null) {
      throw const DomainException('Workout template not found.');
    }
    final templateId = id ?? ids.newId();
    final metadata =
        existing?.metadata.touch(now) ??
        EntityMetadata(
          id: templateId,
          createdAt: now,
          updatedAt: now,
          originDeviceId: originDeviceId,
        );
    final templatePrograms = <WorkoutTemplateProgram>[];
    final programIdsByClientKey = <String, String>{};
    for (var index = 0; index < programs.length; index++) {
      final input = programs[index];
      final programMetadata =
          input.existingMetadata?.touch(now) ??
          _newMetadata(ids, originDeviceId, now);
      programIdsByClientKey[input.clientKey] = programMetadata.id;
      templatePrograms.add(
        WorkoutTemplateProgram(
          metadata: programMetadata,
          workoutTemplateId: templateId,
          sourceProgramId: input.sourceProgramId,
          position: index,
          programNameSnapshot: input.programNameSnapshot,
          defaultRestSecondsSnapshot: input.defaultRestSecondsSnapshot,
          programSnapshotJson: input.programSnapshotJson,
        ),
      );
    }
    final templateOverrides = <WorkoutTemplateExerciseOverride>[];
    for (final input in overrides) {
      final programInput = programs.firstWhere(
        (program) => program.clientKey == input.workoutTemplateProgramClientKey,
        orElse: () =>
            throw const DomainException('Workout template program not found.'),
      );
      final workoutTemplateProgramId =
          programIdsByClientKey[input.workoutTemplateProgramClientKey];
      if (workoutTemplateProgramId == null) {
        throw const DomainException('Workout template program not found.');
      }
      _validateOverrideTargets(programInput.programSnapshotJson, input);
      templateOverrides.add(
        WorkoutTemplateExerciseOverride(
          metadata:
              input.existingMetadata?.touch(now) ??
              _newMetadata(ids, originDeviceId, now),
          workoutTemplateProgramId: workoutTemplateProgramId,
          snapshotProgramExerciseId: input.snapshotProgramExerciseId,
          setsCountOverride: input.setsCountOverride,
          targetTimeSecondsOverride: input.targetTimeSecondsOverride,
          targetRepsOverride: input.targetRepsOverride,
          targetScoreOverride: input.targetScoreOverride,
          targetScoreTimeMsOverride: input.targetScoreTimeMsOverride,
        ),
      );
    }
    final template = WorkoutTemplate(
      metadata: metadata,
      name: name,
      lastStartedAt: existing?.lastStartedAt,
      programs: templatePrograms,
      overrides: templateOverrides,
    );
    await templateRepository.replaceComposition(template, now);
    return template;
  }

  Future<WorkoutTemplateProgram> addProgramSnapshot({
    required String workoutTemplateId,
    required String programId,
    required int position,
  }) async {
    final program = await programRepository.findById(programId);
    if (program == null) {
      throw const DomainException('Program not found.');
    }
    final now = clock.now();
    final snapshot = WorkoutTemplateProgram.snapshotFromProgram(
      metadata: _newMetadata(ids, originDeviceId, now),
      workoutTemplateId: workoutTemplateId,
      program: program,
      position: position,
    );
    await templateRepository.saveProgram(snapshot);
    return snapshot;
  }

  Future<WorkoutTemplateExerciseOverride> overrideExerciseTargets({
    required String workoutTemplateProgramId,
    required String snapshotProgramExerciseId,
    int? setsCountOverride,
    int? targetTimeSecondsOverride,
    int? targetRepsOverride,
    double? targetScoreOverride,
    int? targetScoreTimeMsOverride,
    Set<WorkoutMeasure>? attemptedMeasureOverride,
  }) async {
    if (attemptedMeasureOverride != null) {
      throw const DomainException(
        'Workout templates cannot override active measures.',
      );
    }
    final now = clock.now();
    final override = WorkoutTemplateExerciseOverride(
      metadata: _newMetadata(ids, originDeviceId, now),
      workoutTemplateProgramId: workoutTemplateProgramId,
      snapshotProgramExerciseId: snapshotProgramExerciseId,
      setsCountOverride: setsCountOverride,
      targetTimeSecondsOverride: targetTimeSecondsOverride,
      targetRepsOverride: targetRepsOverride,
      targetScoreOverride: targetScoreOverride,
      targetScoreTimeMsOverride: targetScoreTimeMsOverride,
    );
    await templateRepository.saveOverride(override);
    return override;
  }

  Future<WorkoutTemplate> delete(String id) async {
    final template = await templateRepository.findById(id);
    if (template == null) {
      throw const DomainException('Workout template not found.');
    }
    final now = clock.now();
    final deleted = WorkoutTemplate(
      metadata: template.metadata.markDeleted(now),
      name: template.name,
      lastStartedAt: template.lastStartedAt,
    );
    await templateRepository.save(deleted);
    return deleted;
  }
}

final class WorkoutTemplateProgramConfig {
  const WorkoutTemplateProgramConfig({
    required this.clientKey,
    this.existingMetadata,
    this.sourceProgramId,
    required this.programNameSnapshot,
    required this.defaultRestSecondsSnapshot,
    required this.programSnapshotJson,
  });

  final String clientKey;
  final EntityMetadata? existingMetadata;
  final String? sourceProgramId;
  final String programNameSnapshot;
  final int defaultRestSecondsSnapshot;
  final String programSnapshotJson;
}

final class WorkoutTemplateExerciseOverrideConfig {
  const WorkoutTemplateExerciseOverrideConfig({
    this.existingMetadata,
    required this.workoutTemplateProgramClientKey,
    required this.snapshotProgramExerciseId,
    this.setsCountOverride,
    this.targetTimeSecondsOverride,
    this.targetRepsOverride,
    this.targetScoreOverride,
    this.targetScoreTimeMsOverride,
  });

  final EntityMetadata? existingMetadata;
  final String workoutTemplateProgramClientKey;
  final String snapshotProgramExerciseId;
  final int? setsCountOverride;
  final int? targetTimeSecondsOverride;
  final int? targetRepsOverride;
  final double? targetScoreOverride;
  final int? targetScoreTimeMsOverride;
}

final class ActiveWorkoutSessionUseCases {
  const ActiveWorkoutSessionUseCases({
    required this.sessionRepository,
    required this.templateRepository,
    required this.clock,
    required this.ids,
    required this.originDeviceId,
  });

  final ActiveSessionRepository sessionRepository;
  final WorkoutTemplateRepository templateRepository;
  final Clock clock;
  final IdGenerator ids;
  final String originDeviceId;

  Future<ActiveWorkoutSession?> findOpen() => sessionRepository.findOpen();

  Future<ActiveWorkoutSession> startFromTemplate(String templateId) async {
    final template = await templateRepository.findById(templateId);
    if (template == null) {
      throw const DomainException('Workout template not found.');
    }
    final now = clock.now();
    final session = ActiveWorkoutSession(
      metadata: _newMetadata(ids, originDeviceId, now),
      sourceWorkoutTemplateId: templateId,
      status: ActiveWorkoutStatus.running,
      startedAt: now,
      lastPersistedAt: now,
      elapsedActiveMs: 0,
      currentProgramIndex: 0,
      currentExerciseIndex: 0,
      currentSetIndex: 0,
      resolvedTemplateSnapshotJson: jsonEncode({
        'templateId': template.metadata.id,
        'name': template.name,
        'programs': template.programs
            .map(
              (program) => {
                'id': program.metadata.id,
                'programNameSnapshot': program.programNameSnapshot,
                'programSnapshotJson': program.programSnapshotJson,
              },
            )
            .toList(),
        'overrides': template.overrides
            .map(
              (override) => {
                'workoutTemplateProgramId': override.workoutTemplateProgramId,
                'snapshotProgramExerciseId': override.snapshotProgramExerciseId,
                'setsCountOverride': override.setsCountOverride,
                'targetTimeSecondsOverride': override.targetTimeSecondsOverride,
                'targetRepsOverride': override.targetRepsOverride,
                'targetScoreOverride': override.targetScoreOverride,
                'targetScoreTimeMsOverride': override.targetScoreTimeMsOverride,
              },
            )
            .toList(),
      }),
    );
    await sessionRepository.save(session);
    return session;
  }

  Future<ActiveWorkoutSession> startFromHistory(WorkoutHistory history) async {
    final snapshot =
        jsonDecode(history.historySnapshotJson) as Map<String, dynamic>;
    final resolvedTemplateSnapshotJson =
        snapshot['resolvedTemplateSnapshotJson'] as String;
    final now = clock.now();
    final session = ActiveWorkoutSession(
      metadata: _newMetadata(ids, originDeviceId, now),
      sourceWorkoutTemplateId: null,
      status: ActiveWorkoutStatus.running,
      startedAt: now,
      lastPersistedAt: now,
      elapsedActiveMs: 0,
      currentProgramIndex: 0,
      currentExerciseIndex: 0,
      currentSetIndex: 0,
      resolvedTemplateSnapshotJson: resolvedTemplateSnapshotJson,
    );
    await sessionRepository.save(session);
    return session;
  }

  Future<ActiveWorkoutSession> pause(String sessionId) async {
    final session = await _requiredSession(sessionId);
    final now = clock.now();
    final runningStopwatches =
        (await sessionRepository.listScoreStopwatchStates(
          sessionId,
        )).where((state) => state.status == ActiveScoreStopwatchStatus.running);
    for (final state in runningStopwatches) {
      final stopped = state.copyWith(
        metadata: state.metadata.touch(now),
        status: ActiveScoreStopwatchStatus.stopped,
        accumulatedMs: state.elapsedMillisecondsAt(now),
        stoppedAt: now,
      );
      await sessionRepository.saveScoreStopwatchState(stopped);
    }
    final runningStepTimers =
        (await sessionRepository.listExerciseStepProgressStates(
          sessionId,
        )).where(
          (state) =>
              state.status == ActiveExerciseStepProgressStatus.runningTimer,
        );
    for (final state in runningStepTimers) {
      final pausedStep = state.copyWith(
        metadata: state.metadata.touch(now),
        status: ActiveExerciseStepProgressStatus.pausedTimer,
        accumulatedMs: state.elapsedMillisecondsAt(now),
        startedAt: null,
        lastTransitionAt: now,
      );
      await sessionRepository.saveExerciseStepProgressState(pausedStep);
    }
    final paused = session.pause(now);
    await sessionRepository.save(paused);
    return paused;
  }

  Future<ActiveWorkoutSession> resume(String sessionId) async {
    final session = await _requiredSession(sessionId);
    final resumed = session.resume(clock.now());
    await sessionRepository.save(resumed);
    return resumed;
  }

  int elapsedActiveMilliseconds(ActiveWorkoutSession session) {
    return session.elapsedActiveMillisecondsAt(clock.now());
  }

  Future<ActiveSetResult> recordSetResult(ActiveSetResult result) async {
    await sessionRepository.saveSetResult(result);
    return result;
  }

  Future<ActiveSetResult> recordCurrentSetResult({
    required String sessionId,
    required String programSnapshotId,
    required String exerciseSnapshotId,
    required int programIndex,
    required int exerciseIndex,
    required int setIndex,
    int? actualTimeMs,
    int? actualReps,
    double? actualScore,
    int? actualScoreTimeMs,
    ScoreInputMode scoreInputModeSnapshot = ScoreInputMode.manual,
    String? scoreLabelSnapshot,
    String? scoreUnitSnapshot,
  }) async {
    final now = clock.now();
    final resolvedActualScoreTimeMs = await _resolveStopwatchScoreTimeMs(
      sessionId: sessionId,
      programIndex: programIndex,
      exerciseIndex: exerciseIndex,
      setIndex: setIndex,
      scoreInputMode: scoreInputModeSnapshot,
      explicitActualScoreTimeMs: actualScoreTimeMs,
      now: now,
    );
    final result = ActiveSetResult(
      metadata: _newMetadata(ids, originDeviceId, now),
      activeWorkoutSessionId: sessionId,
      programSnapshotId: programSnapshotId,
      exerciseSnapshotId: exerciseSnapshotId,
      programIndex: programIndex,
      exerciseIndex: exerciseIndex,
      setIndex: setIndex,
      completedAt: now,
      actualTimeMs: actualTimeMs,
      actualReps: actualReps,
      actualScore: actualScore,
      actualScoreTimeMs: resolvedActualScoreTimeMs,
      scoreInputModeSnapshot: scoreInputModeSnapshot,
      scoreLabelSnapshot: scoreLabelSnapshot,
      scoreUnitSnapshot: scoreUnitSnapshot,
      status: SetResultStatus.completed,
    );
    await sessionRepository.saveSetResult(result);
    return result;
  }

  Future<ActiveSetResult> upsertSetResultAtPosition({
    required String sessionId,
    required int programIndex,
    required int exerciseIndex,
    required int setIndex,
    required SetResultStatus status,
    int? actualTimeMs,
    int? actualReps,
    double? actualScore,
    int? actualScoreTimeMs,
    ScoreInputMode? scoreInputModeSnapshot,
    String? scoreLabelSnapshot,
    String? scoreUnitSnapshot,
    String? note,
  }) async {
    final session = await _requiredSession(sessionId);
    _ensureEditablePastPosition(
      session: session,
      programIndex: programIndex,
      exerciseIndex: exerciseIndex,
      setIndex: setIndex,
    );
    final snapshot = _findSetSnapshot(
      resolvedTemplateSnapshotJson: session.resolvedTemplateSnapshotJson,
      programIndex: programIndex,
      exerciseIndex: exerciseIndex,
      setIndex: setIndex,
    );
    if (snapshot == null) {
      throw const DomainException(
        'Set position not found in session snapshot.',
      );
    }
    final existingResults = await sessionRepository.listSetResults(sessionId);
    ActiveSetResult? existing;
    for (final result in existingResults) {
      if (result.programIndex == programIndex &&
          result.exerciseIndex == exerciseIndex &&
          result.setIndex == setIndex) {
        existing = result;
        break;
      }
    }
    final now = clock.now();
    final isSkipped = status == SetResultStatus.skipped;
    final resolvedScoreInputMode =
        scoreInputModeSnapshot ?? snapshot.scoreInputModeSnapshot;
    final upserted = ActiveSetResult(
      metadata: existing == null
          ? _newMetadata(ids, originDeviceId, now)
          : existing.metadata.touch(now),
      activeWorkoutSessionId: sessionId,
      programSnapshotId: snapshot.programSnapshotId,
      exerciseSnapshotId: snapshot.exerciseSnapshotId,
      programIndex: programIndex,
      exerciseIndex: exerciseIndex,
      setIndex: setIndex,
      startedAt: existing?.startedAt,
      completedAt: isSkipped ? null : now,
      actualTimeMs: isSkipped ? null : actualTimeMs,
      actualReps: isSkipped ? null : actualReps,
      actualScore: isSkipped ? null : actualScore,
      actualScoreTimeMs: isSkipped ? null : actualScoreTimeMs,
      scoreInputModeSnapshot: resolvedScoreInputMode,
      scoreLabelSnapshot: isSkipped
          ? null
          : scoreLabelSnapshot ?? snapshot.scoreLabelSnapshot,
      scoreUnitSnapshot: isSkipped
          ? null
          : scoreUnitSnapshot ?? snapshot.scoreUnitSnapshot,
      note: note,
      status: status,
    );
    await sessionRepository.saveSetResult(upserted);
    return upserted;
  }

  Future<ActiveScoreStopwatchState> startScoreStopwatch({
    required String sessionId,
    required int programIndex,
    required int exerciseIndex,
    required int setIndex,
  }) async {
    await _requiredSession(sessionId);
    final now = clock.now();
    final existing = await sessionRepository.findScoreStopwatchState(
      sessionId: sessionId,
      programIndex: programIndex,
      exerciseIndex: exerciseIndex,
      setIndex: setIndex,
    );
    if (existing != null) {
      if (existing.status == ActiveScoreStopwatchStatus.running) {
        return existing;
      }
      final resumed = existing.copyWith(
        metadata: existing.metadata.touch(now),
        status: ActiveScoreStopwatchStatus.running,
        startedAt: now,
        stoppedAt: null,
      );
      await sessionRepository.saveScoreStopwatchState(resumed);
      return resumed;
    }
    final state = ActiveScoreStopwatchState(
      metadata: _newMetadata(ids, originDeviceId, now),
      activeWorkoutSessionId: sessionId,
      programIndex: programIndex,
      exerciseIndex: exerciseIndex,
      setIndex: setIndex,
      status: ActiveScoreStopwatchStatus.running,
      startedAt: now,
      accumulatedMs: 0,
    );
    await sessionRepository.saveScoreStopwatchState(state);
    return state;
  }

  Future<ActiveScoreStopwatchState> stopScoreStopwatch({
    required String sessionId,
    required int programIndex,
    required int exerciseIndex,
    required int setIndex,
  }) async {
    final state = await _requiredStopwatchState(
      sessionId: sessionId,
      programIndex: programIndex,
      exerciseIndex: exerciseIndex,
      setIndex: setIndex,
    );
    if (state.status == ActiveScoreStopwatchStatus.stopped) {
      return state;
    }
    final now = clock.now();
    final stopped = state.copyWith(
      metadata: state.metadata.touch(now),
      status: ActiveScoreStopwatchStatus.stopped,
      accumulatedMs: state.elapsedMillisecondsAt(now),
      stoppedAt: now,
    );
    await sessionRepository.saveScoreStopwatchState(stopped);
    return stopped;
  }

  Future<ActiveScoreStopwatchState> resumeScoreStopwatch({
    required String sessionId,
    required int programIndex,
    required int exerciseIndex,
    required int setIndex,
  }) {
    return startScoreStopwatch(
      sessionId: sessionId,
      programIndex: programIndex,
      exerciseIndex: exerciseIndex,
      setIndex: setIndex,
    );
  }

  Future<void> resetScoreStopwatch({
    required String sessionId,
    required int programIndex,
    required int exerciseIndex,
    required int setIndex,
  }) async {
    await sessionRepository.deleteScoreStopwatchState(
      sessionId: sessionId,
      programIndex: programIndex,
      exerciseIndex: exerciseIndex,
      setIndex: setIndex,
      deletedAt: clock.now(),
    );
  }

  Future<ActiveScoreStopwatchState?> findScoreStopwatch({
    required String sessionId,
    required int programIndex,
    required int exerciseIndex,
    required int setIndex,
  }) {
    return sessionRepository.findScoreStopwatchState(
      sessionId: sessionId,
      programIndex: programIndex,
      exerciseIndex: exerciseIndex,
      setIndex: setIndex,
    );
  }

  int scoreStopwatchElapsedMilliseconds(ActiveScoreStopwatchState state) {
    return state.elapsedMillisecondsAt(clock.now());
  }

  Future<List<SetResultPositionState>> listSetResults(String sessionId) async {
    final session = await _requiredSession(sessionId);
    final snapshots = _listSetSnapshots(session.resolvedTemplateSnapshotJson);
    final results = await sessionRepository.listSetResults(sessionId);
    final resultsByPosition = {
      for (final result in results)
        _positionKey(
          result.programIndex,
          result.exerciseIndex,
          result.setIndex,
        ): result,
    };
    return snapshots.map((snapshot) {
      final result =
          resultsByPosition[_positionKey(
            snapshot.programIndex,
            snapshot.exerciseIndex,
            snapshot.setIndex,
          )];
      return SetResultPositionState(
        programIndex: snapshot.programIndex,
        exerciseIndex: snapshot.exerciseIndex,
        setIndex: snapshot.setIndex,
        status: result == null
            ? SetPositionStatus.pending
            : switch (result.status) {
                SetResultStatus.completed => SetPositionStatus.completed,
                SetResultStatus.skipped => SetPositionStatus.skipped,
              },
        result: result,
      );
    }).toList();
  }

  Future<ActiveWorkoutSession> updateProgress({
    required String sessionId,
    required int programIndex,
    required int exerciseIndex,
    required int setIndex,
  }) async {
    final session = await _requiredSession(sessionId);
    final updated = session.copyWith(
      currentProgramIndex: programIndex,
      currentExerciseIndex: exerciseIndex,
      currentSetIndex: setIndex,
      metadata: session.metadata.touch(clock.now()),
    );
    await sessionRepository.save(updated);
    return updated;
  }

  Future<ActiveWorkoutSession> quitAndSave(String sessionId) async {
    final session = await _requiredSession(sessionId);
    final now = clock.now();
    final saved = session.copyWith(
      status: ActiveWorkoutStatus.savedExit,
      lastPersistedAt: now,
      elapsedActiveMs: session.elapsedActiveMillisecondsAt(now),
      metadata: session.metadata.touch(now),
    );
    await sessionRepository.save(saved);
    return saved;
  }

  Future<ActiveWorkoutSession> abandon(String sessionId) async {
    final session = await _requiredSession(sessionId);
    final now = clock.now();
    final abandoned = session.copyWith(
      status: ActiveWorkoutStatus.abandoned,
      endedAt: now,
      lastPersistedAt: now,
      elapsedActiveMs: session.elapsedActiveMillisecondsAt(now),
      metadata: session.metadata.touch(now),
    );
    await sessionRepository.save(abandoned);
    return abandoned;
  }

  Future<ActiveWorkoutSession> complete(String sessionId) async {
    final session = await _requiredSession(sessionId);
    final now = clock.now();
    final completed = session.copyWith(
      status: ActiveWorkoutStatus.completed,
      endedAt: now,
      lastPersistedAt: now,
      elapsedActiveMs: session.elapsedActiveMillisecondsAt(now),
      metadata: session.metadata.touch(now),
    );
    await sessionRepository.save(completed);
    return completed;
  }

  Future<ActiveRestState> startRestAfterSet({
    required String sessionId,
    required int afterProgramIndex,
    required int afterExerciseIndex,
    required int afterSetIndex,
    required int plannedRestSeconds,
    int? adjustedRestSeconds,
  }) async {
    final now = clock.now();
    final rest = ActiveRestState(
      metadata: _newMetadata(ids, originDeviceId, now),
      activeWorkoutSessionId: sessionId,
      afterProgramIndex: afterProgramIndex,
      afterExerciseIndex: afterExerciseIndex,
      afterSetIndex: afterSetIndex,
      plannedRestSeconds: plannedRestSeconds,
      adjustedRestSeconds: adjustedRestSeconds ?? plannedRestSeconds,
      startedAt: now,
    );
    await sessionRepository.saveRestState(rest);
    return rest;
  }

  Future<ActiveRestState> adjustRestSeconds({
    required String restStateId,
    required int deltaSeconds,
  }) async {
    final rest = await sessionRepository.findRestStateById(restStateId);
    if (rest == null) {
      throw const DomainException('Active rest state not found.');
    }
    final now = clock.now();
    final adjusted = rest.copyWith(
      metadata: rest.metadata.touch(now),
      adjustedRestSeconds: (rest.adjustedRestSeconds + deltaSeconds).clamp(
        0,
        1 << 31,
      ),
    );
    await sessionRepository.saveRestState(adjusted);
    return adjusted;
  }

  Future<ActiveRestState> skipRest({required String restStateId}) async {
    final rest = await sessionRepository.findRestStateById(restStateId);
    if (rest == null) {
      throw const DomainException('Active rest state not found.');
    }
    final now = clock.now();
    final skipped = rest.copyWith(
      metadata: rest.metadata.touch(now),
      skippedAt: now,
    );
    await sessionRepository.saveRestState(skipped);
    return skipped;
  }

  Future<ActiveRestState?> findActiveRest({required String sessionId}) async {
    final restStates = await sessionRepository.listRestStates(sessionId);
    final active =
        restStates
            .where((rest) => rest.endedAt == null && rest.skippedAt == null)
            .toList()
          ..sort((left, right) => right.startedAt.compareTo(left.startedAt));
    return active.isEmpty ? null : active.first;
  }

  Future<ActiveWorkoutSession> _requiredSession(String sessionId) async {
    final session = await sessionRepository.findById(sessionId);
    if (session == null) {
      throw const DomainException('Active workout session not found.');
    }
    return session;
  }

  Future<ActiveScoreStopwatchState> _requiredStopwatchState({
    required String sessionId,
    required int programIndex,
    required int exerciseIndex,
    required int setIndex,
  }) async {
    final state = await sessionRepository.findScoreStopwatchState(
      sessionId: sessionId,
      programIndex: programIndex,
      exerciseIndex: exerciseIndex,
      setIndex: setIndex,
    );
    if (state == null) {
      throw const DomainException('Active score stopwatch state not found.');
    }
    return state;
  }

  Future<int?> _resolveStopwatchScoreTimeMs({
    required String sessionId,
    required int programIndex,
    required int exerciseIndex,
    required int setIndex,
    required ScoreInputMode scoreInputMode,
    required int? explicitActualScoreTimeMs,
    required DateTime now,
  }) async {
    if (scoreInputMode != ScoreInputMode.stopwatch) {
      return explicitActualScoreTimeMs;
    }
    final state = await sessionRepository.findScoreStopwatchState(
      sessionId: sessionId,
      programIndex: programIndex,
      exerciseIndex: exerciseIndex,
      setIndex: setIndex,
    );
    if (state == null) {
      return explicitActualScoreTimeMs;
    }
    if (state.status == ActiveScoreStopwatchStatus.stopped) {
      return explicitActualScoreTimeMs ?? state.accumulatedMs;
    }
    final stopped = state.copyWith(
      metadata: state.metadata.touch(now),
      status: ActiveScoreStopwatchStatus.stopped,
      accumulatedMs: state.elapsedMillisecondsAt(now),
      stoppedAt: now,
    );
    await sessionRepository.saveScoreStopwatchState(stopped);
    return explicitActualScoreTimeMs ?? stopped.accumulatedMs;
  }
}

final class ActiveExerciseStepProgressView {
  const ActiveExerciseStepProgressView({
    required this.state,
    required this.steps,
    required this.expectedPassages,
    required this.results,
  });

  final ActiveExerciseStepProgressState state;
  final List<ExerciseStep> steps;
  final int expectedPassages;
  final List<ActiveExerciseStepResult> results;

  ExerciseStep? get currentStep =>
      state.status == ActiveExerciseStepProgressStatus.sequenceComplete
      ? null
      : steps[state.currentStepIndex];
}

final class ActiveExerciseStepUseCases {
  const ActiveExerciseStepUseCases({
    required this.sessionRepository,
    required this.clock,
    required this.ids,
    required this.originDeviceId,
  });

  final ActiveSessionRepository sessionRepository;
  final Clock clock;
  final IdGenerator ids;
  final String originDeviceId;

  Future<ActiveExerciseStepProgressView> startOrResumeProgress({
    required String sessionId,
    required int programIndex,
    required int exerciseIndex,
    required int setIndex,
  }) async {
    final context = await _stepContext(
      sessionId: sessionId,
      programIndex: programIndex,
      exerciseIndex: exerciseIndex,
      setIndex: setIndex,
    );
    final now = clock.now();
    final existing = await sessionRepository.findExerciseStepProgressState(
      sessionId: sessionId,
      programIndex: programIndex,
      exerciseIndex: exerciseIndex,
      setIndex: setIndex,
    );
    final state =
        existing ??
        _initialStepProgressState(
          sessionId: sessionId,
          context: context,
          now: now,
        );
    if (existing == null) {
      await sessionRepository.saveExerciseStepProgressState(state);
    }
    final advanced = await _autoAdvanceElapsedTimers(context, state, now);
    return ActiveExerciseStepProgressView(
      state: advanced,
      steps: context.steps,
      expectedPassages: context.expectedPassages,
      results: await _stepResultsForPosition(context),
    );
  }

  Future<ActiveExerciseStepProgressView> readProgress({
    required String sessionId,
    required int programIndex,
    required int exerciseIndex,
    required int setIndex,
  }) => startOrResumeProgress(
    sessionId: sessionId,
    programIndex: programIndex,
    exerciseIndex: exerciseIndex,
    setIndex: setIndex,
  );

  Future<ActiveExerciseStepProgressState> startTimer({
    required String sessionId,
    required int programIndex,
    required int exerciseIndex,
    required int setIndex,
  }) async {
    final view = await startOrResumeProgress(
      sessionId: sessionId,
      programIndex: programIndex,
      exerciseIndex: exerciseIndex,
      setIndex: setIndex,
    );
    final step = view.currentStep;
    if (step == null || step.type != ExerciseStepType.time) {
      throw const DomainException('Current exercise step is not timed.');
    }
    if (view.state.status == ActiveExerciseStepProgressStatus.runningTimer) {
      return view.state;
    }
    final now = clock.now();
    final running = view.state.copyWith(
      metadata: view.state.metadata.touch(now),
      status: ActiveExerciseStepProgressStatus.runningTimer,
      startedAt: now,
      lastTransitionAt: now,
    );
    await sessionRepository.saveExerciseStepProgressState(running);
    return running;
  }

  Future<ActiveExerciseStepProgressState> pauseTimer({
    required String sessionId,
    required int programIndex,
    required int exerciseIndex,
    required int setIndex,
  }) async {
    final state = await _requiredStepProgressState(
      sessionId: sessionId,
      programIndex: programIndex,
      exerciseIndex: exerciseIndex,
      setIndex: setIndex,
    );
    if (state.status != ActiveExerciseStepProgressStatus.runningTimer) {
      throw const DomainException('Exercise step timer is not running.');
    }
    final now = clock.now();
    final paused = state.copyWith(
      metadata: state.metadata.touch(now),
      status: ActiveExerciseStepProgressStatus.pausedTimer,
      startedAt: null,
      accumulatedMs: state.elapsedMillisecondsAt(now),
      lastTransitionAt: now,
    );
    await sessionRepository.saveExerciseStepProgressState(paused);
    return paused;
  }

  Future<ActiveExerciseStepProgressState> resumeTimer({
    required String sessionId,
    required int programIndex,
    required int exerciseIndex,
    required int setIndex,
  }) {
    return startTimer(
      sessionId: sessionId,
      programIndex: programIndex,
      exerciseIndex: exerciseIndex,
      setIndex: setIndex,
    );
  }

  int elapsedMilliseconds(ActiveExerciseStepProgressState state) {
    return state.elapsedMillisecondsAt(clock.now());
  }

  int remainingMilliseconds({
    required ActiveExerciseStepProgressState state,
    required ExerciseStep step,
  }) {
    final targetMs = step.defaultTargetValue * 1000;
    final remaining = targetMs - elapsedMilliseconds(state);
    return remaining < 0 ? 0 : remaining;
  }

  Future<ActiveExerciseStepResult> completeCurrentStep({
    required String sessionId,
    required int programIndex,
    required int exerciseIndex,
    required int setIndex,
    int? actualReps,
    double? actualScore,
    int? actualScoreTimeMs,
    String? note,
  }) async {
    final context = await _stepContext(
      sessionId: sessionId,
      programIndex: programIndex,
      exerciseIndex: exerciseIndex,
      setIndex: setIndex,
    );
    final now = clock.now();
    final state = await _autoAdvanceElapsedTimers(
      context,
      await _requiredStepProgressState(
        sessionId: sessionId,
        programIndex: programIndex,
        exerciseIndex: exerciseIndex,
        setIndex: setIndex,
      ),
      now,
    );
    final step = _currentStep(context, state);
    if (state.status == ActiveExerciseStepProgressStatus.sequenceComplete) {
      throw const DomainException('Exercise step sequence is complete.');
    }
    final completed = _stepResult(
      context: context,
      state: state,
      step: step,
      status: SetResultStatus.completed,
      now: now,
      actualTimeMs: step.type == ExerciseStepType.time
          ? state.elapsedMillisecondsAt(now)
          : null,
      actualReps: step.type == ExerciseStepType.reps
          ? actualReps ?? step.defaultTargetValue
          : null,
      actualScore: actualScore,
      actualScoreTimeMs: actualScoreTimeMs,
      note: note,
    );
    await sessionRepository.saveExerciseStepResult(completed);
    await sessionRepository.saveExerciseStepProgressState(
      _advanceState(context, state, now),
    );
    return completed;
  }

  Future<ActiveExerciseStepResult> skipCurrentStep({
    required String sessionId,
    required int programIndex,
    required int exerciseIndex,
    required int setIndex,
  }) async {
    final context = await _stepContext(
      sessionId: sessionId,
      programIndex: programIndex,
      exerciseIndex: exerciseIndex,
      setIndex: setIndex,
    );
    final state = await _requiredStepProgressState(
      sessionId: sessionId,
      programIndex: programIndex,
      exerciseIndex: exerciseIndex,
      setIndex: setIndex,
    );
    final now = clock.now();
    final step = _currentStep(context, state);
    final skipped = _stepResult(
      context: context,
      state: state,
      step: step,
      status: SetResultStatus.skipped,
      now: now,
    );
    await sessionRepository.saveExerciseStepResult(skipped);
    await sessionRepository.saveExerciseStepProgressState(
      _advanceState(context, state, now),
    );
    return skipped;
  }

  Future<List<ActiveExerciseStepResult>> skipCurrentPassage({
    required String sessionId,
    required int programIndex,
    required int exerciseIndex,
    required int setIndex,
  }) async {
    final context = await _stepContext(
      sessionId: sessionId,
      programIndex: programIndex,
      exerciseIndex: exerciseIndex,
      setIndex: setIndex,
    );
    var state = await _requiredStepProgressState(
      sessionId: sessionId,
      programIndex: programIndex,
      exerciseIndex: exerciseIndex,
      setIndex: setIndex,
    );
    final now = clock.now();
    final skipped = <ActiveExerciseStepResult>[];
    final passage = state.currentPassageIndex;
    while (state.status != ActiveExerciseStepProgressStatus.sequenceComplete &&
        state.currentPassageIndex == passage) {
      final step = _currentStep(context, state);
      final result = _stepResult(
        context: context,
        state: state,
        step: step,
        status: SetResultStatus.skipped,
        now: now,
      );
      skipped.add(result);
      await sessionRepository.saveExerciseStepResult(result);
      state = _advanceState(context, state, now);
    }
    await sessionRepository.saveExerciseStepProgressState(state);
    return skipped;
  }

  Future<List<ActiveExerciseStepResult>> skipSequence({
    required String sessionId,
    required int programIndex,
    required int exerciseIndex,
    required int setIndex,
  }) async {
    final context = await _stepContext(
      sessionId: sessionId,
      programIndex: programIndex,
      exerciseIndex: exerciseIndex,
      setIndex: setIndex,
    );
    var state = await _requiredStepProgressState(
      sessionId: sessionId,
      programIndex: programIndex,
      exerciseIndex: exerciseIndex,
      setIndex: setIndex,
    );
    final now = clock.now();
    final skipped = <ActiveExerciseStepResult>[];
    while (state.status != ActiveExerciseStepProgressStatus.sequenceComplete) {
      final step = _currentStep(context, state);
      final result = _stepResult(
        context: context,
        state: state,
        step: step,
        status: SetResultStatus.skipped,
        now: now,
      );
      skipped.add(result);
      await sessionRepository.saveExerciseStepResult(result);
      state = _advanceState(context, state, now);
    }
    await sessionRepository.saveExerciseStepProgressState(state);
    return skipped;
  }

  Future<ActiveExerciseStepProgressState> _requiredStepProgressState({
    required String sessionId,
    required int programIndex,
    required int exerciseIndex,
    required int setIndex,
  }) async {
    final state = await sessionRepository.findExerciseStepProgressState(
      sessionId: sessionId,
      programIndex: programIndex,
      exerciseIndex: exerciseIndex,
      setIndex: setIndex,
    );
    if (state == null) {
      throw const DomainException('Exercise step progress state not found.');
    }
    return state;
  }

  Future<_StepSequenceContext> _stepContext({
    required String sessionId,
    required int programIndex,
    required int exerciseIndex,
    required int setIndex,
  }) async {
    final session = await sessionRepository.findById(sessionId);
    if (session == null) {
      throw const DomainException('Active workout session not found.');
    }
    final snapshot = _findExerciseSnapshot(
      resolvedTemplateSnapshotJson: session.resolvedTemplateSnapshotJson,
      programIndex: programIndex,
      exerciseIndex: exerciseIndex,
    );
    if (snapshot == null || snapshot.steps.isEmpty) {
      throw const DomainException('Exercise step sequence not found.');
    }
    return _StepSequenceContext(
      sessionId: sessionId,
      programSnapshotId: snapshot.programSnapshotId,
      exerciseSnapshotId: snapshot.exerciseSnapshotId,
      programIndex: programIndex,
      exerciseIndex: exerciseIndex,
      setIndex: setIndex,
      steps: snapshot.steps,
      expectedPassages: snapshot.repsEnabled
          ? (snapshot.targetReps ?? 1).clamp(1, 1 << 31)
          : 1,
    );
  }

  ActiveExerciseStepProgressState _initialStepProgressState({
    required String sessionId,
    required _StepSequenceContext context,
    required DateTime now,
  }) {
    final firstStep = context.steps.first;
    return ActiveExerciseStepProgressState(
      metadata: _newMetadata(ids, originDeviceId, now),
      activeWorkoutSessionId: sessionId,
      programIndex: context.programIndex,
      exerciseIndex: context.exerciseIndex,
      setIndex: context.setIndex,
      currentPassageIndex: 0,
      currentStepIndex: 0,
      currentStepSnapshotId: firstStep.id,
      status: firstStep.type == ExerciseStepType.time
          ? ActiveExerciseStepProgressStatus.stoppedTimer
          : ActiveExerciseStepProgressStatus.waitingManual,
      accumulatedMs: 0,
      lastTransitionAt: now,
    );
  }

  Future<ActiveExerciseStepProgressState> _autoAdvanceElapsedTimers(
    _StepSequenceContext context,
    ActiveExerciseStepProgressState state,
    DateTime now,
  ) async {
    var current = state;
    while (current.status == ActiveExerciseStepProgressStatus.runningTimer) {
      final step = _currentStep(context, current);
      if (step.type != ExerciseStepType.time) {
        break;
      }
      final targetMs = step.defaultTargetValue * 1000;
      final elapsed = current.elapsedMillisecondsAt(now);
      if (elapsed < targetMs) {
        break;
      }
      final result = _stepResult(
        context: context,
        state: current,
        step: step,
        status: SetResultStatus.completed,
        now: now,
        actualTimeMs: targetMs,
      );
      await sessionRepository.saveExerciseStepResult(result);
      final overflowMs = elapsed - targetMs;
      current = _advanceState(
        context,
        current,
        now,
        runningTimerOverflowMs: overflowMs,
      );
      await sessionRepository.saveExerciseStepProgressState(current);
    }
    return current;
  }

  ActiveExerciseStepProgressState _advanceState(
    _StepSequenceContext context,
    ActiveExerciseStepProgressState state,
    DateTime now, {
    int runningTimerOverflowMs = 0,
  }) {
    var nextPassage = state.currentPassageIndex;
    var nextStep = state.currentStepIndex + 1;
    if (nextStep >= context.steps.length) {
      nextStep = 0;
      nextPassage++;
    }
    if (nextPassage >= context.expectedPassages) {
      return state.copyWith(
        metadata: state.metadata.touch(now),
        status: ActiveExerciseStepProgressStatus.sequenceComplete,
        startedAt: null,
        accumulatedMs: 0,
        lastTransitionAt: now,
      );
    }
    final step = context.steps[nextStep];
    final status = step.type == ExerciseStepType.time
        ? runningTimerOverflowMs > 0
              ? ActiveExerciseStepProgressStatus.runningTimer
              : ActiveExerciseStepProgressStatus.stoppedTimer
        : ActiveExerciseStepProgressStatus.waitingManual;
    return state.copyWith(
      metadata: state.metadata.touch(now),
      currentPassageIndex: nextPassage,
      currentStepIndex: nextStep,
      currentStepSnapshotId: step.id,
      status: status,
      startedAt: status == ActiveExerciseStepProgressStatus.runningTimer
          ? now.subtract(Duration(milliseconds: runningTimerOverflowMs))
          : null,
      accumulatedMs: 0,
      lastTransitionAt: now,
    );
  }

  ExerciseStep _currentStep(
    _StepSequenceContext context,
    ActiveExerciseStepProgressState state,
  ) {
    if (state.status == ActiveExerciseStepProgressStatus.sequenceComplete) {
      throw const DomainException('Exercise step sequence is complete.');
    }
    return context.steps[state.currentStepIndex];
  }

  Future<List<ActiveExerciseStepResult>> _stepResultsForPosition(
    _StepSequenceContext context,
  ) async {
    return (await sessionRepository.listExerciseStepResults(context.sessionId))
        .where(
          (result) =>
              result.programIndex == context.programIndex &&
              result.exerciseIndex == context.exerciseIndex &&
              result.setIndex == context.setIndex,
        )
        .toList();
  }

  ActiveExerciseStepResult _stepResult({
    required _StepSequenceContext context,
    required ActiveExerciseStepProgressState state,
    required ExerciseStep step,
    required SetResultStatus status,
    required DateTime now,
    int? actualTimeMs,
    int? actualReps,
    double? actualScore,
    int? actualScoreTimeMs,
    String? note,
  }) {
    return ActiveExerciseStepResult(
      metadata: _newMetadata(ids, originDeviceId, now),
      activeWorkoutSessionId: context.sessionId,
      programSnapshotId: context.programSnapshotId,
      exerciseSnapshotId: context.exerciseSnapshotId,
      programIndex: context.programIndex,
      exerciseIndex: context.exerciseIndex,
      setIndex: context.setIndex,
      passageIndex: state.currentPassageIndex,
      stepIndex: state.currentStepIndex,
      stepSnapshotId: step.id,
      stepNameSnapshot: step.name,
      stepTypeSnapshot: step.type,
      targetValueSnapshot: step.defaultTargetValue,
      hasScoreSnapshot: step.hasScore,
      scoreInputModeSnapshot: step.hasScore ? step.scoreInputMode : null,
      scoreLabelSnapshot: step.scoreLabel,
      scoreUnitSnapshot: step.scoreUnit,
      targetScoreSnapshot: step.defaultTargetScore,
      targetScoreTimeMsSnapshot: step.defaultTargetScoreTimeMs,
      status: status,
      startedAt: state.startedAt,
      completedAt: status == SetResultStatus.completed ? now : null,
      actualTimeMs: status == SetResultStatus.completed ? actualTimeMs : null,
      actualReps: status == SetResultStatus.completed ? actualReps : null,
      actualScore: status == SetResultStatus.completed ? actualScore : null,
      actualScoreTimeMs: status == SetResultStatus.completed
          ? actualScoreTimeMs
          : null,
      note: note,
    );
  }
}

final class CloseWorkoutSessionUseCase {
  const CloseWorkoutSessionUseCase({
    required this.sessionRepository,
    required this.historyRepository,
    required this.clock,
    required this.ids,
    required this.originDeviceId,
  });

  final ActiveSessionRepository sessionRepository;
  final WorkoutHistoryRepository historyRepository;
  final Clock clock;
  final IdGenerator ids;
  final String originDeviceId;

  Future<WorkoutHistory> close({
    required String sessionId,
    required String nameSnapshot,
    required bool completed,
  }) async {
    final session = await sessionRepository.findById(sessionId);
    if (session == null) {
      throw const DomainException('Active workout session not found.');
    }
    final now = clock.now();
    final results = await sessionRepository.listSetResults(sessionId);
    final stepResults = await sessionRepository.listExerciseStepResults(
      sessionId,
    );
    final historyId = ids.newId();
    final historyResults = _historyResultsFromActiveResults(
      historyId: historyId,
      results: results,
      resolvedTemplateSnapshotJson: session.resolvedTemplateSnapshotJson,
      now: now,
      ids: ids,
      originDeviceId: originDeviceId,
    );
    final historyStepResults = _historyStepResultsFromActiveResults(
      historyId: historyId,
      results: stepResults,
      now: now,
      ids: ids,
      originDeviceId: originDeviceId,
    );
    final history = WorkoutHistory(
      metadata: EntityMetadata(
        id: historyId,
        createdAt: now,
        updatedAt: now,
        originDeviceId: originDeviceId,
      ),
      sourceWorkoutTemplateId: session.sourceWorkoutTemplateId,
      sourceActiveWorkoutSessionId: session.metadata.id,
      nameSnapshot: nameSnapshot,
      startedAt: session.startedAt,
      endedAt: now,
      totalActiveMs: session.elapsedActiveMillisecondsAt(now),
      completed: completed,
      historySnapshotJson: jsonEncode({
        'sessionId': session.metadata.id,
        'resolvedTemplateSnapshotJson': session.resolvedTemplateSnapshotJson,
        'results': results
            .map(
              (result) => {
                'programSnapshotId': result.programSnapshotId,
                'exerciseSnapshotId': result.exerciseSnapshotId,
                'programIndex': result.programIndex,
                'exerciseIndex': result.exerciseIndex,
                'setIndex': result.setIndex,
                'actualTimeMs': result.actualTimeMs,
                'actualReps': result.actualReps,
                'actualScore': result.actualScore,
                'actualScoreTimeMs': result.actualScoreTimeMs,
                'scoreInputModeSnapshot': result.scoreInputModeSnapshot.name,
                'scoreLabelSnapshot': result.scoreLabelSnapshot,
                'scoreUnitSnapshot': result.scoreUnitSnapshot,
                'status': result.status.name,
              },
            )
            .toList(),
        'stepResults': stepResults
            .map(
              (result) => {
                'programSnapshotId': result.programSnapshotId,
                'exerciseSnapshotId': result.exerciseSnapshotId,
                'programIndex': result.programIndex,
                'exerciseIndex': result.exerciseIndex,
                'setIndex': result.setIndex,
                'passageIndex': result.passageIndex,
                'stepIndex': result.stepIndex,
                'stepSnapshotId': result.stepSnapshotId,
                'stepNameSnapshot': result.stepNameSnapshot,
                'stepTypeSnapshot': result.stepTypeSnapshot.name,
                'targetValueSnapshot': result.targetValueSnapshot,
                'hasScoreSnapshot': result.hasScoreSnapshot,
                'scoreInputModeSnapshot': result.scoreInputModeSnapshot?.name,
                'scoreLabelSnapshot': result.scoreLabelSnapshot,
                'scoreUnitSnapshot': result.scoreUnitSnapshot,
                'targetScoreSnapshot': result.targetScoreSnapshot,
                'targetScoreTimeMsSnapshot': result.targetScoreTimeMsSnapshot,
                'status': result.status.name,
                'actualTimeMs': result.actualTimeMs,
                'actualReps': result.actualReps,
                'actualScore': result.actualScore,
                'actualScoreTimeMs': result.actualScoreTimeMs,
                'note': result.note,
              },
            )
            .toList(),
      }),
      results: historyResults,
      stepResults: historyStepResults,
    );
    await historyRepository.save(history);
    return history;
  }
}

final class WorkoutHistoryUseCases {
  const WorkoutHistoryUseCases({required this.repository, required this.clock});

  final WorkoutHistoryRepository repository;
  final Clock clock;

  Future<WorkoutHistory?> findById(String id) => repository.findById(id);

  Future<List<WorkoutHistory>> listActive() => repository.listActive();

  Future<void> delete(String id) => repository.delete(id, clock.now());
}

enum SetPositionStatus { pending, completed, skipped }

final class SetResultPositionState {
  const SetResultPositionState({
    required this.programIndex,
    required this.exerciseIndex,
    required this.setIndex,
    required this.status,
    this.result,
  });

  final int programIndex;
  final int exerciseIndex;
  final int setIndex;
  final SetPositionStatus status;
  final ActiveSetResult? result;
}

List<WorkoutTemplateProgram> _repositionWorkoutTemplatePrograms(
  List<WorkoutTemplateProgram> programs,
  DateTime now,
) {
  return [
    for (var index = 0; index < programs.length; index++)
      WorkoutTemplateProgram(
        metadata: programs[index].metadata.touch(now),
        workoutTemplateId: programs[index].workoutTemplateId,
        sourceProgramId: programs[index].sourceProgramId,
        position: index,
        programNameSnapshot: programs[index].programNameSnapshot,
        defaultRestSecondsSnapshot: programs[index].defaultRestSecondsSnapshot,
        programSnapshotJson: programs[index].programSnapshotJson,
      ),
  ];
}

List<String> _resolveExerciseImageIds(
  String? imageMediaId,
  List<String> imageMediaIds,
) {
  if (imageMediaId != null) {
    return [imageMediaId];
  }
  return imageMediaIds;
}

List<String> _appendExerciseImage(List<String> currentIds, String mediaId) {
  if (currentIds.contains(mediaId)) {
    return currentIds;
  }
  if (currentIds.length >= 5) {
    throw const DomainException('An exercise cannot have more than 5 images.');
  }
  return [...currentIds, mediaId];
}

bool _sameImageSet(List<String> left, List<String> right) {
  if (left.length != right.length) {
    return false;
  }
  return left.toSet().containsAll(right) && right.toSet().containsAll(left);
}

void _validateExerciseSteps(List<ExerciseStep> steps) {
  if (steps.length > 8) {
    throw const DomainException('An exercise cannot have more than 8 steps.');
  }
  for (var index = 0; index < steps.length; index++) {
    final step = steps[index];
    if (step.position != index) {
      throw const DomainException(
        'Exercise step positions must be contiguous and ordered.',
      );
    }
    if (step.name.trim().isEmpty) {
      throw const DomainException('Exercise step name must not be blank.');
    }
    if (step.defaultTargetValue <= 0) {
      throw const DomainException(
        'Exercise step default target value must be positive.',
      );
    }
    if (!step.hasScore) {
      if (step.scoreLabel != null ||
          step.scoreUnit != null ||
          step.defaultTargetScore != null ||
          step.defaultTargetScoreTimeMs != null) {
        throw const DomainException(
          'Disabled exercise step score must not define score values.',
        );
      }
      continue;
    }
    if (step.defaultTargetScore != null &&
        step.defaultTargetScoreTimeMs != null) {
      throw const DomainException(
        'Manual and stopwatch step score targets cannot both be set.',
      );
    }
    switch (step.scoreInputMode) {
      case ScoreInputMode.manual:
        if (step.scoreLabel == null || step.scoreLabel!.trim().isEmpty) {
          throw const DomainException(
            'Exercise step score label must not be blank.',
          );
        }
        if (step.scoreUnit == null || step.scoreUnit!.trim().isEmpty) {
          throw const DomainException(
            'Exercise step score unit must not be blank.',
          );
        }
        if (step.defaultTargetScore != null && step.defaultTargetScore! < 0) {
          throw const DomainException(
            'Exercise step default target score must not be negative.',
          );
        }
        if (step.defaultTargetScoreTimeMs != null) {
          throw const DomainException(
            'Manual exercise step score cannot define stopwatch target.',
          );
        }
      case ScoreInputMode.stopwatch:
        if (step.scoreLabel != null ||
            step.scoreUnit != null ||
            step.defaultTargetScore != null) {
          throw const DomainException(
            'Stopwatch exercise step score cannot define manual score values.',
          );
        }
        if (step.defaultTargetScoreTimeMs != null &&
            step.defaultTargetScoreTimeMs! <= 0) {
          throw const DomainException(
            'Exercise step default target score time ms must be positive.',
          );
        }
    }
  }
}

void _validateAuthInput({required String email, required String password}) {
  final normalizedEmail = email.trim();
  final hasBasicEmailShape = RegExp(
    r'^[^@\s]+@[^@\s]+\.[^@\s]+$',
  ).hasMatch(normalizedEmail);
  if (!hasBasicEmailShape) {
    throw const DomainException('Email format is invalid.');
  }
  if (password.length < 8) {
    throw const DomainException('Password must contain at least 8 characters.');
  }
}

void _validateExerciseDefaultTargets({
  required bool hasTimeMeasure,
  required bool hasRepsMeasure,
  required bool hasScoreMeasure,
  required ScoreInputMode scoreInputMode,
  required int? defaultTargetTimeSeconds,
  required int? defaultTargetReps,
  required double? defaultTargetScore,
  required int? defaultTargetScoreTimeMs,
}) {
  if (hasTimeMeasure &&
      (defaultTargetTimeSeconds == null || defaultTargetTimeSeconds <= 0)) {
    throw const DomainException(
      'Default target time seconds must be positive.',
    );
  }
  if (hasRepsMeasure && (defaultTargetReps == null || defaultTargetReps <= 0)) {
    throw const DomainException('Default target reps must be positive.');
  }
  if (hasScoreMeasure &&
      scoreInputMode == ScoreInputMode.manual &&
      (defaultTargetScore == null || defaultTargetScore < 0)) {
    throw const DomainException('Default target score must not be negative.');
  }
  if (defaultTargetScore != null &&
      (!hasScoreMeasure || scoreInputMode != ScoreInputMode.manual)) {
    throw const DomainException(
      'Default target score requires manual score mode.',
    );
  }
  if (defaultTargetScoreTimeMs != null && defaultTargetScoreTimeMs <= 0) {
    throw const DomainException(
      'Default target score time ms must be positive.',
    );
  }
  if (defaultTargetScoreTimeMs != null &&
      (!hasScoreMeasure || scoreInputMode != ScoreInputMode.stopwatch)) {
    throw const DomainException(
      'Default target score time ms requires stopwatch score mode.',
    );
  }
}

void _validateOverrideTargets(
  String programSnapshotJson,
  WorkoutTemplateExerciseOverrideConfig input,
) {
  final snapshot = jsonDecode(programSnapshotJson) as Map<String, dynamic>;
  final exercises = (snapshot['exercises'] as List<dynamic>? ?? const [])
      .cast<Map<String, dynamic>>();
  final exercise = exercises.cast<Map<String, dynamic>?>().firstWhere(
    (item) =>
        item?['id'] == input.snapshotProgramExerciseId ||
        item?['snapshotProgramExerciseId'] == input.snapshotProgramExerciseId,
    orElse: () => null,
  );
  if (exercise == null) {
    throw const DomainException('Snapshot exercise not found.');
  }
  if (input.targetTimeSecondsOverride != null &&
      exercise['timeEnabled'] != true) {
    throw const DomainException('Cannot override inactive time target.');
  }
  if (input.targetRepsOverride != null && exercise['repsEnabled'] != true) {
    throw const DomainException('Cannot override inactive reps target.');
  }
  if (input.targetScoreOverride != null && exercise['scoreEnabled'] != true) {
    throw const DomainException('Cannot override inactive score target.');
  }
  if (input.targetScoreTimeMsOverride != null &&
      exercise['scoreEnabled'] != true) {
    throw const DomainException('Cannot override inactive score target.');
  }
  final mode = _scoreInputModeFromSnapshot(exercise['scoreInputModeSnapshot']);
  if (input.targetScoreOverride != null && mode != ScoreInputMode.manual) {
    throw const DomainException(
      'Cannot override manual score target on stopwatch score mode.',
    );
  }
  if (input.targetScoreTimeMsOverride != null &&
      mode != ScoreInputMode.stopwatch) {
    throw const DomainException(
      'Cannot override stopwatch score target on manual score mode.',
    );
  }
}

void _ensureEditablePastPosition({
  required ActiveWorkoutSession session,
  required int programIndex,
  required int exerciseIndex,
  required int setIndex,
}) {
  final comparison = _comparePositions(
    programIndex,
    exerciseIndex,
    setIndex,
    session.currentProgramIndex,
    session.currentExerciseIndex,
    session.currentSetIndex,
  );
  if (comparison >= 0) {
    throw const DomainException(
      'Only past set results can be edited outside the normal execution flow.',
    );
  }
}

int _comparePositions(
  int leftProgram,
  int leftExercise,
  int leftSet,
  int rightProgram,
  int rightExercise,
  int rightSet,
) {
  final programComparison = leftProgram.compareTo(rightProgram);
  if (programComparison != 0) {
    return programComparison;
  }
  final exerciseComparison = leftExercise.compareTo(rightExercise);
  if (exerciseComparison != 0) {
    return exerciseComparison;
  }
  return leftSet.compareTo(rightSet);
}

String _positionKey(int programIndex, int exerciseIndex, int setIndex) {
  return '$programIndex:$exerciseIndex:$setIndex';
}

String _syncKey(SyncResourceType resourceType, String clientId) {
  return '${resourceType.name}:$clientId';
}

Map<String, Object?> _programSharePayload(Program program) => {
  'metadata': _metadataSharePayload(program.metadata),
  'id': program.metadata.id,
  'name': program.name,
  'defaultRestSeconds': program.defaultRestSeconds,
  'exercises': program.exercises
      .map((exercise) => exercise.toSnapshotJson())
      .toList(),
};

Map<String, Object?> _workoutTemplateSharePayload(WorkoutTemplate template) => {
  'metadata': _metadataSharePayload(template.metadata),
  'id': template.metadata.id,
  'name': template.name,
  'lastStartedAt': template.lastStartedAt?.toUtc().toIso8601String(),
  'programs': template.programs
      .map(
        (program) => {
          'id': program.metadata.id,
          'sourceProgramId': program.sourceProgramId,
          'position': program.position,
          'programNameSnapshot': program.programNameSnapshot,
          'defaultRestSecondsSnapshot': program.defaultRestSecondsSnapshot,
          'programSnapshotJson': program.programSnapshotJson,
        },
      )
      .toList(),
  'overrides': template.overrides
      .map(
        (override) => {
          'id': override.metadata.id,
          'workoutTemplateProgramId': override.workoutTemplateProgramId,
          'snapshotProgramExerciseId': override.snapshotProgramExerciseId,
          'setsCountOverride': override.setsCountOverride,
          'targetTimeSecondsOverride': override.targetTimeSecondsOverride,
          'targetRepsOverride': override.targetRepsOverride,
          'targetScoreOverride': override.targetScoreOverride,
          'targetScoreTimeMsOverride': override.targetScoreTimeMsOverride,
        },
      )
      .toList(),
};

Map<String, Object?> _metadataSharePayload(EntityMetadata metadata) => {
  'id': metadata.id,
  'createdAt': metadata.createdAt.toUtc().toIso8601String(),
  'updatedAt': metadata.updatedAt.toUtc().toIso8601String(),
  'deletedAt': metadata.deletedAt?.toUtc().toIso8601String(),
  'schemaVersion': metadata.schemaVersion,
  'syncState': metadata.syncState.name,
  'localRevision': metadata.localRevision,
  'originDeviceId': metadata.originDeviceId,
  'futureOwnerProfileId': metadata.futureOwnerProfileId,
  'lastSyncedAt': metadata.lastSyncedAt?.toUtc().toIso8601String(),
  'remoteRevision': metadata.remoteRevision,
};

Map<String, Object?> _jsonObject(String? json) {
  if (json == null) {
    return const {};
  }
  final decoded = jsonDecode(json);
  if (decoded is Map) {
    return Map<String, Object?>.from(decoded);
  }
  return const {};
}

String _stringFromSharePayload(
  Map<String, Object?> payload,
  String key,
  String fallback,
) {
  final value = payload[key];
  return value is String && value.trim().isNotEmpty ? value : fallback;
}

List<String> _stringListFromSharePayload(Object? value) {
  if (value is! List) {
    return const [];
  }
  return value.whereType<String>().toList(growable: false);
}

List<String> _jsonStringList(String? json) {
  if (json == null) {
    return const [];
  }
  final decoded = jsonDecode(json);
  if (decoded is List) {
    return decoded.whereType<String>().toList(growable: false);
  }
  return const [];
}

ScoreInputMode _scoreInputModeFromSnapshot(Object? value) {
  return switch (value) {
    'stopwatch' => ScoreInputMode.stopwatch,
    _ => ScoreInputMode.manual,
  };
}

_SetPositionSnapshot? _findSetSnapshot({
  required String resolvedTemplateSnapshotJson,
  required int programIndex,
  required int exerciseIndex,
  required int setIndex,
}) {
  for (final snapshot in _listSetSnapshots(resolvedTemplateSnapshotJson)) {
    if (snapshot.programIndex == programIndex &&
        snapshot.exerciseIndex == exerciseIndex &&
        snapshot.setIndex == setIndex) {
      return snapshot;
    }
  }
  return null;
}

_ResolvedExerciseSnapshot? _findExerciseSnapshot({
  required String resolvedTemplateSnapshotJson,
  required int programIndex,
  required int exerciseIndex,
}) {
  final decoded =
      jsonDecode(resolvedTemplateSnapshotJson) as Map<String, dynamic>;
  final programs = (decoded['programs'] as List<dynamic>? ?? const []);
  if (programIndex < 0 || programIndex >= programs.length) {
    return null;
  }
  final program = programs[programIndex] as Map<String, dynamic>;
  final programSnapshotId = program['id'] as String? ?? 'program-$programIndex';
  final programName = program['programNameSnapshot'] as String? ?? '';
  final programSnapshotJson = program['programSnapshotJson'] as String?;
  if (programSnapshotJson == null) {
    return null;
  }
  final programSnapshot =
      jsonDecode(programSnapshotJson) as Map<String, dynamic>;
  final exercises =
      (programSnapshot['exercises'] as List<dynamic>? ?? const []);
  if (exerciseIndex < 0 || exerciseIndex >= exercises.length) {
    return null;
  }
  final exercise = exercises[exerciseIndex] as Map<String, dynamic>;
  final id = exercise['id'] as String? ?? 'exercise-$exerciseIndex';
  return _ResolvedExerciseSnapshot(
    programSnapshotId: programSnapshotId,
    exerciseSnapshotId: id,
    programNameSnapshot: programName,
    exerciseNameSnapshot: exercise['exerciseNameSnapshot'] as String? ?? id,
    timeEnabled: exercise['timeEnabled'] == true,
    repsEnabled: exercise['repsEnabled'] == true,
    scoreEnabled: exercise['scoreEnabled'] == true,
    targetTimeSeconds: exercise['targetTimeSeconds'] as int?,
    targetReps: exercise['targetReps'] as int?,
    targetScore: (exercise['targetScore'] as num?)?.toDouble(),
    targetScoreTimeMs: exercise['targetScoreTimeMs'] as int?,
    scoreInputModeSnapshot: _scoreInputModeFromSnapshot(
      exercise['scoreInputModeSnapshot'],
    ),
    scoreLabelSnapshot: exercise['scoreLabelSnapshot'] as String?,
    scoreUnitSnapshot: exercise['scoreUnitSnapshot'] as String?,
    steps: _exerciseStepsFromSnapshot(exercise['exerciseStepsSnapshot']),
  );
}

List<_SetPositionSnapshot> _listSetSnapshots(
  String resolvedTemplateSnapshotJson,
) {
  final decoded =
      jsonDecode(resolvedTemplateSnapshotJson) as Map<String, dynamic>;
  final programs = (decoded['programs'] as List<dynamic>? ?? const []);
  final snapshots = <_SetPositionSnapshot>[];
  for (var programIndex = 0; programIndex < programs.length; programIndex++) {
    final program = programs[programIndex] as Map<String, dynamic>;
    final programSnapshotId =
        program['id'] as String? ?? 'program-$programIndex';
    final programSnapshotJson = program['programSnapshotJson'] as String?;
    if (programSnapshotJson == null) {
      continue;
    }
    final programSnapshot =
        jsonDecode(programSnapshotJson) as Map<String, dynamic>;
    final exercises =
        (programSnapshot['exercises'] as List<dynamic>? ?? const []);
    for (
      var exerciseIndex = 0;
      exerciseIndex < exercises.length;
      exerciseIndex++
    ) {
      final exercise = exercises[exerciseIndex] as Map<String, dynamic>;
      final exerciseSnapshotId =
          exercise['id'] as String? ?? 'exercise-$exerciseIndex';
      final setsCount = exercise['setsCount'] as int? ?? 0;
      for (var setIndex = 0; setIndex < setsCount; setIndex++) {
        snapshots.add(
          _SetPositionSnapshot(
            programSnapshotId: programSnapshotId,
            exerciseSnapshotId: exerciseSnapshotId,
            programIndex: programIndex,
            exerciseIndex: exerciseIndex,
            setIndex: setIndex,
            scoreLabelSnapshot: exercise['scoreLabelSnapshot'] as String?,
            scoreUnitSnapshot: exercise['scoreUnitSnapshot'] as String?,
            scoreInputModeSnapshot: _scoreInputModeFromSnapshot(
              exercise['scoreInputModeSnapshot'],
            ),
          ),
        );
      }
    }
  }
  return snapshots;
}

final class _SetPositionSnapshot {
  const _SetPositionSnapshot({
    required this.programSnapshotId,
    required this.exerciseSnapshotId,
    required this.programIndex,
    required this.exerciseIndex,
    required this.setIndex,
    this.scoreLabelSnapshot,
    this.scoreUnitSnapshot,
    required this.scoreInputModeSnapshot,
  });

  final String programSnapshotId;
  final String exerciseSnapshotId;
  final int programIndex;
  final int exerciseIndex;
  final int setIndex;
  final String? scoreLabelSnapshot;
  final String? scoreUnitSnapshot;
  final ScoreInputMode scoreInputModeSnapshot;
}

final class _StepSequenceContext {
  const _StepSequenceContext({
    required this.sessionId,
    required this.programSnapshotId,
    required this.exerciseSnapshotId,
    required this.programIndex,
    required this.exerciseIndex,
    required this.setIndex,
    required this.steps,
    required this.expectedPassages,
  });

  final String sessionId;
  final String programSnapshotId;
  final String exerciseSnapshotId;
  final int programIndex;
  final int exerciseIndex;
  final int setIndex;
  final List<ExerciseStep> steps;
  final int expectedPassages;
}

List<WorkoutHistorySetResult> _historyResultsFromActiveResults({
  required String historyId,
  required List<ActiveSetResult> results,
  required String resolvedTemplateSnapshotJson,
  required DateTime now,
  required IdGenerator ids,
  required String originDeviceId,
}) {
  final snapshots = _exerciseSnapshotsById(resolvedTemplateSnapshotJson);
  return results.map((result) {
    final snapshot = snapshots[result.exerciseSnapshotId];
    return WorkoutHistorySetResult(
      metadata: _newMetadata(ids, originDeviceId, now),
      workoutHistoryId: historyId,
      programSnapshotId: result.programSnapshotId,
      exerciseSnapshotId: result.exerciseSnapshotId,
      programIndex: result.programIndex,
      exerciseIndex: result.exerciseIndex,
      setIndex: result.setIndex,
      programNameSnapshot:
          snapshot?.programNameSnapshot ?? result.programSnapshotId,
      exerciseNameSnapshot:
          snapshot?.exerciseNameSnapshot ?? result.exerciseSnapshotId,
      timeEnabledSnapshot: snapshot?.timeEnabled ?? result.actualTimeMs != null,
      repsEnabledSnapshot: snapshot?.repsEnabled ?? result.actualReps != null,
      scoreEnabledSnapshot:
          snapshot?.scoreEnabled ??
          (result.actualScore != null || result.actualScoreTimeMs != null),
      targetTimeSecondsSnapshot: snapshot?.targetTimeSeconds,
      targetRepsSnapshot: snapshot?.targetReps,
      targetScoreSnapshot: snapshot?.targetScore,
      targetScoreTimeMsSnapshot: snapshot?.targetScoreTimeMs,
      actualTimeMs: result.actualTimeMs,
      actualReps: result.actualReps,
      actualScore: result.actualScore,
      actualScoreTimeMs: result.actualScoreTimeMs,
      scoreInputModeSnapshot:
          snapshot?.scoreInputModeSnapshot ?? result.scoreInputModeSnapshot,
      scoreLabelSnapshot:
          result.scoreLabelSnapshot ?? snapshot?.scoreLabelSnapshot,
      scoreUnitSnapshot:
          result.scoreUnitSnapshot ?? snapshot?.scoreUnitSnapshot,
      startedAt: result.startedAt,
      completedAt: result.completedAt,
      status: result.status,
    );
  }).toList();
}

Map<String, _ResolvedExerciseSnapshot> _exerciseSnapshotsById(
  String resolvedTemplateSnapshotJson,
) {
  final decoded =
      jsonDecode(resolvedTemplateSnapshotJson) as Map<String, dynamic>;
  final programs = (decoded['programs'] as List<dynamic>? ?? const []);
  final snapshots = <String, _ResolvedExerciseSnapshot>{};
  for (final program in programs.cast<Map<String, dynamic>>()) {
    final programName = program['programNameSnapshot'] as String? ?? '';
    final programSnapshotJson = program['programSnapshotJson'] as String?;
    if (programSnapshotJson == null) {
      continue;
    }
    final programSnapshot =
        jsonDecode(programSnapshotJson) as Map<String, dynamic>;
    final exercises =
        (programSnapshot['exercises'] as List<dynamic>? ?? const []);
    for (final exercise in exercises.cast<Map<String, dynamic>>()) {
      final id = exercise['id'] as String?;
      if (id == null) {
        continue;
      }
      snapshots[id] = _ResolvedExerciseSnapshot(
        programSnapshotId: program['id'] as String? ?? id,
        exerciseSnapshotId: id,
        programNameSnapshot: programName,
        exerciseNameSnapshot: exercise['exerciseNameSnapshot'] as String? ?? id,
        timeEnabled: exercise['timeEnabled'] == true,
        repsEnabled: exercise['repsEnabled'] == true,
        scoreEnabled: exercise['scoreEnabled'] == true,
        targetTimeSeconds: exercise['targetTimeSeconds'] as int?,
        targetReps: exercise['targetReps'] as int?,
        targetScore: (exercise['targetScore'] as num?)?.toDouble(),
        targetScoreTimeMs: exercise['targetScoreTimeMs'] as int?,
        scoreInputModeSnapshot: _scoreInputModeFromSnapshot(
          exercise['scoreInputModeSnapshot'],
        ),
        scoreLabelSnapshot: exercise['scoreLabelSnapshot'] as String?,
        scoreUnitSnapshot: exercise['scoreUnitSnapshot'] as String?,
        steps: _exerciseStepsFromSnapshot(exercise['exerciseStepsSnapshot']),
      );
    }
  }
  return snapshots;
}

final class _ResolvedExerciseSnapshot {
  const _ResolvedExerciseSnapshot({
    required this.programSnapshotId,
    required this.exerciseSnapshotId,
    required this.programNameSnapshot,
    required this.exerciseNameSnapshot,
    required this.timeEnabled,
    required this.repsEnabled,
    required this.scoreEnabled,
    this.targetTimeSeconds,
    this.targetReps,
    this.targetScore,
    this.targetScoreTimeMs,
    required this.scoreInputModeSnapshot,
    this.scoreLabelSnapshot,
    this.scoreUnitSnapshot,
    this.steps = const [],
  });

  final String programSnapshotId;
  final String exerciseSnapshotId;
  final String programNameSnapshot;
  final String exerciseNameSnapshot;
  final bool timeEnabled;
  final bool repsEnabled;
  final bool scoreEnabled;
  final int? targetTimeSeconds;
  final int? targetReps;
  final double? targetScore;
  final int? targetScoreTimeMs;
  final ScoreInputMode scoreInputModeSnapshot;
  final String? scoreLabelSnapshot;
  final String? scoreUnitSnapshot;
  final List<ExerciseStep> steps;
}

List<ExerciseStep> _exerciseStepsFromSnapshot(Object? value) {
  if (value is! List) {
    return const [];
  }
  return value
      .map((item) {
        final json = Map<String, dynamic>.from(item as Map);
        return ExerciseStep(
          id: json['id'] as String,
          position: json['position'] as int,
          name: json['name'] as String,
          type: switch (json['type']) {
            'time' => ExerciseStepType.time,
            'reps' => ExerciseStepType.reps,
            _ => throw const DomainException('Unknown exercise step type.'),
          },
          defaultTargetValue: json['defaultTargetValue'] as int,
          hasScore: json['hasScore'] == true,
          scoreInputMode: _scoreInputModeFromSnapshot(json['scoreInputMode']),
          scoreLabel: json['scoreLabel'] as String?,
          scoreUnit: json['scoreUnit'] as String?,
          defaultTargetScore: (json['defaultTargetScore'] as num?)?.toDouble(),
          defaultTargetScoreTimeMs: json['defaultTargetScoreTimeMs'] as int?,
        );
      })
      .toList(growable: false);
}

List<WorkoutHistoryStepResult> _historyStepResultsFromActiveResults({
  required String historyId,
  required List<ActiveExerciseStepResult> results,
  required DateTime now,
  required IdGenerator ids,
  required String originDeviceId,
}) {
  return results.map((result) {
    return WorkoutHistoryStepResult(
      metadata: _newMetadata(ids, originDeviceId, now),
      workoutHistoryId: historyId,
      programSnapshotId: result.programSnapshotId,
      exerciseSnapshotId: result.exerciseSnapshotId,
      programIndex: result.programIndex,
      exerciseIndex: result.exerciseIndex,
      setIndex: result.setIndex,
      passageIndex: result.passageIndex,
      stepIndex: result.stepIndex,
      stepSnapshotId: result.stepSnapshotId,
      stepNameSnapshot: result.stepNameSnapshot,
      stepTypeSnapshot: result.stepTypeSnapshot,
      targetValueSnapshot: result.targetValueSnapshot,
      hasScoreSnapshot: result.hasScoreSnapshot,
      scoreInputModeSnapshot: result.scoreInputModeSnapshot,
      scoreLabelSnapshot: result.scoreLabelSnapshot,
      scoreUnitSnapshot: result.scoreUnitSnapshot,
      targetScoreSnapshot: result.targetScoreSnapshot,
      targetScoreTimeMsSnapshot: result.targetScoreTimeMsSnapshot,
      status: result.status,
      startedAt: result.startedAt,
      completedAt: result.completedAt,
      actualTimeMs: result.actualTimeMs,
      actualReps: result.actualReps,
      actualScore: result.actualScore,
      actualScoreTimeMs: result.actualScoreTimeMs,
      note: result.note,
    );
  }).toList();
}

EntityMetadata _newMetadata(
  IdGenerator ids,
  String originDeviceId,
  DateTime now,
) {
  return EntityMetadata(
    id: ids.newId(),
    createdAt: now,
    updatedAt: now,
    originDeviceId: originDeviceId,
  );
}