import 'dart:convert';

import 'package:postgres/postgres.dart';

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

final class PostgresSyncedResourceRepository
    implements SyncedResourceRepository {
  const PostgresSyncedResourceRepository(this.connection);

  final Connection connection;

  @override
  Future<SyncWriteResult> upsertWithLww(SyncedResource resource) async {
    final result = await connection.execute(
      Sql.named('''
        WITH upserted AS (
          INSERT INTO synced_resources (
            server_id, owner_user_id, resource_type, client_id, payload_json,
            schema_version, client_updated_at, deleted_at, origin_device_id
          )
          VALUES (
            @server_id::uuid, @owner_user_id::uuid, @resource_type, @client_id,
            @payload_json::jsonb, @schema_version, @client_updated_at,
            @deleted_at, @origin_device_id
          )
          ON CONFLICT (owner_user_id, resource_type, client_id)
          DO UPDATE SET
            payload_json = EXCLUDED.payload_json,
            schema_version = EXCLUDED.schema_version,
            client_updated_at = EXCLUDED.client_updated_at,
            deleted_at = EXCLUDED.deleted_at,
            origin_device_id = EXCLUDED.origin_device_id
          WHERE synced_resources.client_updated_at < EXCLUDED.client_updated_at
          RETURNING
            server_id, owner_user_id, resource_type, client_id, payload_json,
            schema_version, client_updated_at, server_updated_at, deleted_at,
            origin_device_id, 'accepted'::text AS write_status
        )
        SELECT * FROM upserted
        UNION ALL
        SELECT
          existing.server_id, existing.owner_user_id, existing.resource_type,
          existing.client_id, existing.payload_json, existing.schema_version,
          existing.client_updated_at, existing.server_updated_at,
          existing.deleted_at, existing.origin_device_id,
          'ignoredOlder'::text AS write_status
        FROM synced_resources existing
        WHERE existing.owner_user_id = @owner_user_id::uuid
          AND existing.resource_type = @resource_type
          AND existing.client_id = @client_id
          AND NOT EXISTS (SELECT 1 FROM upserted)
        LIMIT 1
      '''),
      parameters: {
        'server_id': resource.serverId,
        'owner_user_id': resource.ownerUserId,
        'resource_type': resource.resourceType.wireName,
        'client_id': resource.clientId,
        'payload_json': jsonEncode(resource.payloadJson),
        'schema_version': resource.schemaVersion,
        'client_updated_at': resource.clientUpdatedAt,
        'deleted_at': resource.deletedAt,
        'origin_device_id': resource.originDeviceId,
      },
    );
    final row = result.single;
    final values = row.toColumnMap() as Map<String, Object?>;
    return SyncWriteResult(
      status: values['write_status'] == 'accepted'
          ? SyncWriteStatus.accepted
          : SyncWriteStatus.ignoredOlder,
      resource: _resourceFromValues(values),
    );
  }

  @override
  Future<List<SyncedResource>> findAllForUserSince({
    required String ownerUserId,
    DateTime? since,
  }) async {
    final result = since == null
        ? await connection.execute(
            Sql.named('''
              SELECT server_id, owner_user_id, resource_type, client_id,
                     payload_json, schema_version, client_updated_at,
                     server_updated_at, deleted_at, origin_device_id
              FROM synced_resources
              WHERE owner_user_id = @owner_user_id::uuid
              ORDER BY server_updated_at ASC, server_id ASC
            '''),
            parameters: {'owner_user_id': ownerUserId},
          )
        : await connection.execute(
            Sql.named('''
              SELECT server_id, owner_user_id, resource_type, client_id,
                     payload_json, schema_version, client_updated_at,
                     server_updated_at, deleted_at, origin_device_id
              FROM synced_resources
              WHERE owner_user_id = @owner_user_id::uuid
                AND server_updated_at > @since
              ORDER BY server_updated_at ASC, server_id ASC
            '''),
            parameters: {'owner_user_id': ownerUserId, 'since': since.toUtc()},
          );
    return [
      for (final row in result)
        _resourceFromValues(row.toColumnMap() as Map<String, Object?>),
    ];
  }
}

SyncedResource _resourceFromValues(Map<String, Object?> values) {
  return SyncedResource(
    serverId: _stringValue(values['server_id']),
    ownerUserId: _stringValue(values['owner_user_id']),
    resourceType: SyncedResourceType.parse(
      _stringValue(values['resource_type']),
    ),
    clientId: _stringValue(values['client_id']),
    payloadJson: _payloadValue(values['payload_json']),
    schemaVersion: values['schema_version'] as int,
    clientUpdatedAt: _dateTimeValue(values['client_updated_at']),
    serverUpdatedAt: _dateTimeValue(values['server_updated_at']),
    deletedAt: _nullableDateTimeValue(values['deleted_at']),
    originDeviceId: values['origin_device_id'] as String?,
  );
}

Map<String, Object?> _payloadValue(Object? value) {
  if (value is Map<String, Object?>) {
    return value;
  }
  if (value is Map) {
    return Map<String, Object?>.from(value);
  }
  if (value is String) {
    final decoded = jsonDecode(value);
    if (decoded is Map<String, Object?>) {
      return decoded;
    }
    if (decoded is Map) {
      return Map<String, Object?>.from(decoded);
    }
  }
  throw const FormatException('Expected JSON object payload.');
}

String _stringValue(Object? value) {
  if (value == null) {
    throw const FormatException('Expected non-null string value.');
  }
  return value.toString();
}

DateTime _dateTimeValue(Object? value) {
  final result = _nullableDateTimeValue(value);
  if (result == null) {
    throw const FormatException('Expected non-null DateTime value.');
  }
  return result;
}

DateTime? _nullableDateTimeValue(Object? value) {
  if (value == null) {
    return null;
  }
  if (value is DateTime) {
    return value.toUtc();
  }
  return DateTime.parse(value.toString()).toUtc();
}