import 'dart:async';
import 'dart:convert';

import 'package:flutter/material.dart';

import '../application/application.dart';
import '../domain/domain.dart';
import 'history_screen.dart';

enum WorkoutExecutionMode { active, rest, paused, finished }

final class WorkoutExecutionScreen extends StatefulWidget {
  const WorkoutExecutionScreen({
    required this.initialSession,
    required this.activeUseCases,
    required this.closeUseCase,
    required this.historyUseCases,
    required this.workoutTemplateUseCases,
    super.key,
  });

  final ActiveWorkoutSession initialSession;
  final ActiveWorkoutSessionUseCases activeUseCases;
  final CloseWorkoutSessionUseCase closeUseCase;
  final WorkoutHistoryUseCases historyUseCases;
  final WorkoutTemplateUseCases workoutTemplateUseCases;

  @override
  State<WorkoutExecutionScreen> createState() => _WorkoutExecutionScreenState();
}

final class _WorkoutExecutionScreenState extends State<WorkoutExecutionScreen> {
  late ActiveWorkoutSession _session;
  late final WorkoutExecutionPlan _plan;
  late WorkoutExecutionMode _mode;
  Timer? _ticker;
  Timer? _restTicker;
  WorkoutHistory? _completedHistory;
  String? _activeRestStateId;
  late DateTime _seriesStartedAt;
  var _reps = 0;
  final _scoreController = TextEditingController();
  var _remainingRestSeconds = 0;

  ExecutionPosition get _position => ExecutionPosition(
    programIndex: _session.currentProgramIndex,
    exerciseIndex: _session.currentExerciseIndex,
    setIndex: _session.currentSetIndex,
  );

  ExecutionExercise get _exercise => _plan.exerciseAt(_position);

  @override
  void initState() {
    super.initState();
    _session = widget.initialSession;
    _plan = WorkoutExecutionPlan.fromSession(_session);
    _mode = _session.status == ActiveWorkoutStatus.running
        ? WorkoutExecutionMode.active
        : WorkoutExecutionMode.paused;
    _seriesStartedAt = DateTime.now().toUtc();
    _ticker = Timer.periodic(const Duration(seconds: 1), (_) {
      if (mounted) setState(() {});
    });
    unawaited(_restoreActiveRest());
  }

  @override
  void dispose() {
    _ticker?.cancel();
    _restTicker?.cancel();
    _scoreController.dispose();
    super.dispose();
  }

  @override
  Widget build(BuildContext context) {
    return PopScope(
      canPop: false,
      child: Scaffold(
        appBar: AppBar(
          title: Text(_plan.name),
          actions: [TextButton(onPressed: _pause, child: const Text('Pause'))],
        ),
        body: switch (_mode) {
          WorkoutExecutionMode.active => _buildActive(),
          WorkoutExecutionMode.rest => _buildRest(),
          WorkoutExecutionMode.paused => _buildPaused(),
          WorkoutExecutionMode.finished => _buildFinished(),
        },
      ),
    );
  }

  Widget _buildActive() {
    return ListView(
      padding: const EdgeInsets.all(16),
      children: [
        _Header(
          elapsedLabel: _formatDuration(
            Duration(
              milliseconds: widget.activeUseCases.elapsedActiveMilliseconds(
                _session,
              ),
            ),
          ),
          progressLabel: _plan.progressLabel(_position),
        ),
        const SizedBox(height: 24),
        Text(_exercise.name, style: Theme.of(context).textTheme.headlineMedium),
        const SizedBox(height: 16),
        SetMeasureInput(
          exercise: _exercise,
          reps: _reps,
          scoreController: _scoreController,
          onRepsChanged: (value) => setState(() => _reps = value),
        ),
        const SizedBox(height: 24),
        FilledButton(
          onPressed: () => _finishSet(skipped: false),
          style: FilledButton.styleFrom(minimumSize: const Size.fromHeight(56)),
          child: const Text('Terminer la série'),
        ),
        const SizedBox(height: 12),
        OutlinedButton(
          onPressed: () => _finishSet(skipped: true),
          style: OutlinedButton.styleFrom(
            minimumSize: const Size.fromHeight(52),
          ),
          child: const Text('Passer'),
        ),
      ],
    );
  }

  Widget _buildRest() {
    final next = _plan.nextPosition(_position);
    final nextExercise = next == null ? null : _plan.exerciseAt(next);
    return Padding(
      padding: const EdgeInsets.all(24),
      child: Column(
        crossAxisAlignment: CrossAxisAlignment.stretch,
        children: [
          const Text('Repos avant la prochaine série'),
          const SizedBox(height: 24),
          Center(
            child: Text(
              _formatDuration(Duration(seconds: _remainingRestSeconds)),
              style: Theme.of(context).textTheme.displayLarge,
            ),
          ),
          if (next != null && nextExercise != null) ...[
            const SizedBox(height: 24),
            Text(
              'Ensuite : ${nextExercise.name} · '
              'Série ${next.setIndex + 1}/${nextExercise.setsCount}',
              textAlign: TextAlign.center,
            ),
          ],
          const Spacer(),
          Row(
            children: [
              Expanded(
                child: OutlinedButton(
                  onPressed: () => _adjustRest(-15),
                  child: const Text('-15 s'),
                ),
              ),
              const SizedBox(width: 12),
              Expanded(
                child: OutlinedButton(
                  onPressed: () => _adjustRest(15),
                  child: const Text('+15 s'),
                ),
              ),
            ],
          ),
          const SizedBox(height: 12),
          FilledButton(
            onPressed: _skipRest,
            style: FilledButton.styleFrom(
              minimumSize: const Size.fromHeight(52),
            ),
            child: const Text('Ignorer le repos'),
          ),
          const SizedBox(height: 12),
          TextButton(onPressed: _pause, child: const Text('Pause')),
        ],
      ),
    );
  }

  Widget _buildPaused() {
    return Padding(
      padding: const EdgeInsets.all(24),
      child: Column(
        crossAxisAlignment: CrossAxisAlignment.stretch,
        children: [
          Text('Pause', style: Theme.of(context).textTheme.headlineMedium),
          const SizedBox(height: 24),
          FilledButton(
            onPressed: _resume,
            style: FilledButton.styleFrom(
              minimumSize: const Size.fromHeight(56),
            ),
            child: const Text('Reprendre'),
          ),
          const SizedBox(height: 12),
          OutlinedButton(
            onPressed: _quitAndSave,
            child: const Text('Quitter et sauvegarder'),
          ),
          const Spacer(),
          TextButton(
            onPressed: _confirmAbandon,
            child: const Text('Abandonner la séance'),
          ),
        ],
      ),
    );
  }

  Widget _buildFinished() {
    final elapsed = Duration(
      milliseconds: widget.activeUseCases.elapsedActiveMilliseconds(_session),
    );
    return Padding(
      padding: const EdgeInsets.all(24),
      child: Column(
        crossAxisAlignment: CrossAxisAlignment.stretch,
        children: [
          Text(
            'Séance terminée',
            style: Theme.of(context).textTheme.headlineMedium,
          ),
          const SizedBox(height: 12),
          Text('Temps total : ${_formatDuration(elapsed)}'),
          const SizedBox(height: 24),
          OutlinedButton(
            onPressed: _completedHistory == null ? null : _openHistoryDetail,
            child: const Text('Voir le détail'),
          ),
          OutlinedButton(
            onPressed: _completedHistory == null ? null : _restartCompleted,
            child: const Text('Relancer cette séance'),
          ),
          FilledButton(
            onPressed: () {
              Navigator.of(context).popUntil((route) => route.isFirst);
            },
            child: const Text('Retour à l’accueil'),
          ),
        ],
      ),
    );
  }

  Future<void> _pause() async {
    _restTicker?.cancel();
    _session = await widget.activeUseCases.pause(_session.metadata.id);
    if (!mounted) return;
    setState(() => _mode = WorkoutExecutionMode.paused);
  }

  Future<void> _resume() async {
    _session = await widget.activeUseCases.resume(_session.metadata.id);
    if (!mounted) return;
    final restoredRest = await _restoreActiveRest();
    if (!mounted || restoredRest) return;
    setState(() => _mode = WorkoutExecutionMode.active);
  }

  Future<void> _quitAndSave() async {
    await widget.activeUseCases.quitAndSave(_session.metadata.id);
    if (!mounted) return;
    Navigator.of(context).popUntil((route) => route.isFirst);
  }

  Future<void> _confirmAbandon() async {
    final confirmed = await showDialog<bool>(
      context: context,
      builder: (context) => AlertDialog(
        title: const Text('Abandonner la séance ?'),
        content: const Text('Cette action est définitive.'),
        actions: [
          TextButton(
            onPressed: () => Navigator.of(context).pop(false),
            child: const Text('Annuler'),
          ),
          FilledButton(
            onPressed: () => Navigator.of(context).pop(true),
            child: const Text('Abandonner'),
          ),
        ],
      ),
    );
    if (confirmed != true) return;
    await widget.activeUseCases.abandon(_session.metadata.id);
    if (!mounted) return;
    Navigator.of(context).popUntil((route) => route.isFirst);
  }

  Future<void> _finishSet({required bool skipped}) async {
    final score = double.tryParse(_scoreController.text.trim());
    final actualTimeMs = DateTime.now()
        .toUtc()
        .difference(_seriesStartedAt)
        .inMilliseconds;
    await widget.activeUseCases.recordCurrentSetResult(
      sessionId: _session.metadata.id,
      programSnapshotId: _plan.programAt(_position).id,
      exerciseSnapshotId: _exercise.id,
      programIndex: _position.programIndex,
      exerciseIndex: _position.exerciseIndex,
      setIndex: _position.setIndex,
      actualReps: skipped ? null : (_exercise.repsEnabled ? _reps : null),
      actualScore: skipped ? null : (_exercise.scoreEnabled ? score : null),
      scoreUnitSnapshot: _exercise.scoreUnit,
      actualTimeMs: skipped
          ? null
          : (_exercise.timeEnabled ? actualTimeMs : null),
    );

    final next = _plan.nextPosition(_position);
    if (next == null) {
      await _complete();
      return;
    }
    final shouldRest = _plan.shouldShowRestAfter(_position);
    if (shouldRest) {
      final rest = await widget.activeUseCases.startRestAfterSet(
        sessionId: _session.metadata.id,
        afterProgramIndex: _position.programIndex,
        afterExerciseIndex: _position.exerciseIndex,
        afterSetIndex: _position.setIndex,
        plannedRestSeconds: _exercise.restSeconds,
      );
      if (!mounted) return;
      _activeRestStateId = rest.metadata.id;
      _remainingRestSeconds = _exercise.restSeconds;
      _startRestTicker(next);
      setState(() => _mode = WorkoutExecutionMode.rest);
      return;
    }
    await _moveTo(next);
  }

  void _startRestTicker(ExecutionPosition next) {
    _restTicker?.cancel();
    _restTicker = Timer.periodic(const Duration(seconds: 1), (timer) {
      if (!mounted) return;
      if (_remainingRestSeconds <= 1) {
        timer.cancel();
        unawaited(_finishRestAndMove(next));
      } else {
        setState(() => _remainingRestSeconds -= 1);
      }
    });
  }

  Future<bool> _restoreActiveRest() async {
    final rest = await widget.activeUseCases.findActiveRest(
      sessionId: _session.metadata.id,
    );
    if (!mounted || rest == null) {
      return false;
    }
    final after = ExecutionPosition(
      programIndex: rest.afterProgramIndex,
      exerciseIndex: rest.afterExerciseIndex,
      setIndex: rest.afterSetIndex,
    );
    final next = _plan.nextPosition(after);
    final remaining = _remainingSecondsFor(rest);
    _activeRestStateId = rest.metadata.id;
    if (next == null || remaining <= 0) {
      await _finishRestAndMove(next);
      return true;
    }
    _remainingRestSeconds = remaining;
    _startRestTicker(next);
    if (!mounted) return true;
    setState(() => _mode = WorkoutExecutionMode.rest);
    return true;
  }

  int _remainingSecondsFor(ActiveRestState rest) {
    final elapsedSeconds = DateTime.now()
        .toUtc()
        .difference(rest.startedAt.toUtc())
        .inSeconds;
    return (rest.adjustedRestSeconds - elapsedSeconds).clamp(0, 9999).toInt();
  }

  Future<void> _adjustRest(int deltaSeconds) async {
    final restStateId = _activeRestStateId;
    setState(() {
      _remainingRestSeconds = (_remainingRestSeconds + deltaSeconds)
          .clamp(0, 9999)
          .toInt();
    });
    if (restStateId == null) return;
    await widget.activeUseCases.adjustRestSeconds(
      restStateId: restStateId,
      deltaSeconds: deltaSeconds,
    );
  }

  Future<void> _skipRest() async {
    _restTicker?.cancel();
    final next = _plan.nextPosition(_position);
    await _finishRestAndMove(next);
  }

  Future<void> _finishRestAndMove(ExecutionPosition? next) async {
    final restStateId = _activeRestStateId;
    _activeRestStateId = null;
    if (restStateId != null) {
      await widget.activeUseCases.skipRest(restStateId: restStateId);
    }
    if (next == null) {
      await _complete();
      return;
    }
    await _moveTo(next);
  }

  Future<void> _moveTo(ExecutionPosition position) async {
    _scoreController.clear();
    _reps = 0;
    _activeRestStateId = null;
    _seriesStartedAt = DateTime.now().toUtc();
    _session = await widget.activeUseCases.updateProgress(
      sessionId: _session.metadata.id,
      programIndex: position.programIndex,
      exerciseIndex: position.exerciseIndex,
      setIndex: position.setIndex,
    );
    if (!mounted) return;
    setState(() => _mode = WorkoutExecutionMode.active);
  }

  Future<void> _complete() async {
    _session = await widget.activeUseCases.complete(_session.metadata.id);
    _completedHistory = await widget.closeUseCase.close(
      sessionId: _session.metadata.id,
      nameSnapshot: _plan.name,
      completed: true,
    );
    if (!mounted) return;
    setState(() => _mode = WorkoutExecutionMode.finished);
  }

  Future<void> _openHistoryDetail() async {
    final history = _completedHistory;
    if (history == null) return;
    await Navigator.of(context).push(
      MaterialPageRoute(
        builder: (context) => HistoryDetailScreen(
          history: history,
          historyUseCases: widget.historyUseCases,
          workoutTemplateUseCases: widget.workoutTemplateUseCases,
          activeUseCases: widget.activeUseCases,
          closeUseCase: widget.closeUseCase,
        ),
      ),
    );
  }

  Future<void> _restartCompleted() async {
    final history = _completedHistory;
    if (history == null) return;
    ActiveWorkoutSession session;
    final sourceId = history.sourceWorkoutTemplateId;
    if (sourceId != null &&
        await widget.workoutTemplateUseCases.findById(sourceId) != null) {
      session = await widget.activeUseCases.startFromTemplate(sourceId);
    } else {
      if (mounted) {
        ScaffoldMessenger.of(context).showSnackBar(
          const SnackBar(
            content: Text(
              "La séance originale n'existe plus. Une copie va être utilisée.",
            ),
          ),
        );
      }
      session = await widget.activeUseCases.startFromHistory(history);
    }
    if (!mounted) return;
    await Navigator.of(context).pushReplacement(
      MaterialPageRoute(
        builder: (context) => WorkoutExecutionScreen(
          initialSession: session,
          activeUseCases: widget.activeUseCases,
          closeUseCase: widget.closeUseCase,
          historyUseCases: widget.historyUseCases,
          workoutTemplateUseCases: widget.workoutTemplateUseCases,
        ),
      ),
    );
  }
}

final class SetMeasureInput extends StatelessWidget {
  const SetMeasureInput({
    required this.exercise,
    required this.reps,
    required this.scoreController,
    required this.onRepsChanged,
    super.key,
  });

  final ExecutionExercise exercise;
  final int reps;
  final TextEditingController scoreController;
  final ValueChanged<int> onRepsChanged;

  @override
  Widget build(BuildContext context) {
    return Column(
      crossAxisAlignment: CrossAxisAlignment.stretch,
      children: [
        if (exercise.timeEnabled)
          Card(
            child: Padding(
              padding: const EdgeInsets.all(24),
              child: Column(
                children: [
                  const Text('Temps'),
                  const SizedBox(height: 8),
                  Text(
                    exercise.targetTimeSeconds == null
                        ? 'Chronométrer'
                        : '${exercise.targetTimeSeconds} s',
                    style: Theme.of(context).textTheme.displaySmall,
                  ),
                ],
              ),
            ),
          ),
        if (exercise.repsEnabled) ...[
          const SizedBox(height: 12),
          Row(
            children: [
              const Expanded(child: Text('Répétitions')),
              IconButton(
                onPressed: () =>
                    onRepsChanged((reps - 1).clamp(0, 999).toInt()),
                icon: const Icon(Icons.remove),
              ),
              Text('$reps'),
              IconButton(
                onPressed: () => onRepsChanged(reps + 1),
                icon: const Icon(Icons.add),
              ),
            ],
          ),
        ],
        if (exercise.scoreEnabled) ...[
          const SizedBox(height: 12),
          TextField(
            controller: scoreController,
            decoration: InputDecoration(
              labelText: exercise.scoreUnit == null
                  ? 'Score'
                  : 'Score (${exercise.scoreUnit})',
              border: const OutlineInputBorder(),
            ),
            keyboardType: TextInputType.number,
          ),
        ],
      ],
    );
  }
}

final class WorkoutExecutionPlan {
  const WorkoutExecutionPlan({required this.name, required this.programs});

  factory WorkoutExecutionPlan.fromSession(ActiveWorkoutSession session) {
    final snapshot =
        jsonDecode(session.resolvedTemplateSnapshotJson)
            as Map<String, dynamic>;
    final overrides = snapshot['overrides'] as List<dynamic>? ?? const [];
    final programs = (snapshot['programs'] as List<dynamic>? ?? const []).map((
      rawProgram,
    ) {
      final program = rawProgram as Map<String, dynamic>;
      final programSnapshot =
          jsonDecode(program['programSnapshotJson'] as String)
              as Map<String, dynamic>;
      return ExecutionProgram.fromSnapshot(
        id: program['id'] as String,
        name: program['programNameSnapshot'] as String,
        snapshot: programSnapshot,
        overrides: overrides,
      );
    }).toList();
    return WorkoutExecutionPlan(
      name: snapshot['name'] as String? ?? 'Séance',
      programs: programs,
    );
  }

  final String name;
  final List<ExecutionProgram> programs;

  ExecutionProgram programAt(ExecutionPosition position) {
    return programs[position.programIndex];
  }

  ExecutionExercise exerciseAt(ExecutionPosition position) {
    return programAt(position).exercises[position.exerciseIndex];
  }

  ExecutionPosition? nextPosition(ExecutionPosition position) {
    final exercise = exerciseAt(position);
    if (position.setIndex + 1 < exercise.setsCount) {
      return position.copyWith(setIndex: position.setIndex + 1);
    }
    final program = programAt(position);
    if (position.exerciseIndex + 1 < program.exercises.length) {
      return ExecutionPosition(
        programIndex: position.programIndex,
        exerciseIndex: position.exerciseIndex + 1,
        setIndex: 0,
      );
    }
    if (position.programIndex + 1 < programs.length) {
      return ExecutionPosition(
        programIndex: position.programIndex + 1,
        exerciseIndex: 0,
        setIndex: 0,
      );
    }
    return null;
  }

  bool shouldShowRestAfter(ExecutionPosition position) {
    return nextPosition(position) != null &&
        exerciseAt(position).restSeconds > 0;
  }

  String progressLabel(ExecutionPosition position) {
    final program = programAt(position);
    final exercise = exerciseAt(position);
    return 'Programme ${position.programIndex + 1}/${programs.length} · '
        'Exercice ${position.exerciseIndex + 1}/${program.exercises.length} · '
        'Série ${position.setIndex + 1}/${exercise.setsCount}';
  }
}

final class ExecutionProgram {
  const ExecutionProgram({
    required this.id,
    required this.name,
    required this.exercises,
  });

  factory ExecutionProgram.fromSnapshot({
    required String id,
    required String name,
    required Map<String, dynamic> snapshot,
    required List<dynamic> overrides,
  }) {
    final exercises = (snapshot['exercises'] as List<dynamic>? ?? const []).map(
      (raw) {
        final exercise = raw as Map<String, dynamic>;
        Map<String, dynamic>? override;
        for (final rawOverride in overrides) {
          final item = rawOverride as Map<String, dynamic>;
          if (item['workoutTemplateProgramId'] == id &&
              item['snapshotProgramExerciseId'] == exercise['id']) {
            override = item;
            break;
          }
        }
        return ExecutionExercise.fromSnapshot(exercise, override);
      },
    ).toList();
    return ExecutionProgram(id: id, name: name, exercises: exercises);
  }

  final String id;
  final String name;
  final List<ExecutionExercise> exercises;
}

final class ExecutionExercise {
  const ExecutionExercise({
    required this.id,
    required this.name,
    required this.setsCount,
    required this.timeEnabled,
    required this.repsEnabled,
    required this.scoreEnabled,
    required this.restSeconds,
    this.targetTimeSeconds,
    this.targetReps,
    this.targetScore,
    this.scoreUnit,
  });

  factory ExecutionExercise.fromSnapshot(
    Map<String, dynamic> exercise,
    Map<String, dynamic>? override,
  ) {
    return ExecutionExercise(
      id: exercise['id'] as String,
      name: exercise['exerciseNameSnapshot'] as String,
      setsCount:
          (override?['setsCountOverride'] as int?) ??
          (exercise['setsCount'] as int),
      timeEnabled: exercise['timeEnabled'] as bool,
      repsEnabled: exercise['repsEnabled'] as bool,
      scoreEnabled: exercise['scoreEnabled'] as bool,
      restSeconds: exercise['restSecondsOverride'] as int? ?? 0,
      targetTimeSeconds:
          (override?['targetTimeSecondsOverride'] as int?) ??
          (exercise['targetTimeSeconds'] as int?),
      targetReps:
          (override?['targetRepsOverride'] as int?) ??
          (exercise['targetReps'] as int?),
      targetScore:
          (override?['targetScoreOverride'] as num?)?.toDouble() ??
          (exercise['targetScore'] as num?)?.toDouble(),
      scoreUnit: exercise['scoreUnitSnapshot'] as String?,
    );
  }

  final String id;
  final String name;
  final int setsCount;
  final bool timeEnabled;
  final bool repsEnabled;
  final bool scoreEnabled;
  final int restSeconds;
  final int? targetTimeSeconds;
  final int? targetReps;
  final double? targetScore;
  final String? scoreUnit;
}

final class ExecutionPosition {
  const ExecutionPosition({
    required this.programIndex,
    required this.exerciseIndex,
    required this.setIndex,
  });

  final int programIndex;
  final int exerciseIndex;
  final int setIndex;

  ExecutionPosition copyWith({int? setIndex}) {
    return ExecutionPosition(
      programIndex: programIndex,
      exerciseIndex: exerciseIndex,
      setIndex: setIndex ?? this.setIndex,
    );
  }
}

final class _Header extends StatelessWidget {
  const _Header({required this.elapsedLabel, required this.progressLabel});

  final String elapsedLabel;
  final String progressLabel;

  @override
  Widget build(BuildContext context) {
    return Column(
      crossAxisAlignment: CrossAxisAlignment.start,
      children: [
        Text(elapsedLabel, style: Theme.of(context).textTheme.headlineSmall),
        const SizedBox(height: 4),
        Text(progressLabel),
      ],
    );
  }
}

String _formatDuration(Duration duration) {
  final minutes = duration.inMinutes.remainder(60).toString().padLeft(2, '0');
  final seconds = duration.inSeconds.remainder(60).toString().padLeft(2, '0');
  final hours = duration.inHours;
  if (hours > 0) {
    return '$hours:$minutes:$seconds';
  }
  return '$minutes:$seconds';
}