import 'package:sqflite/sqflite.dart';
import 'package:path/path.dart';
import '../models/session.dart';
import '../models/shot.dart';
import '../../core/constants/app_constants.dart';

class DatabaseHelper {
  static DatabaseHelper? _instance;
  static Database? _database;

  DatabaseHelper._internal();

  factory DatabaseHelper() {
    _instance ??= DatabaseHelper._internal();
    return _instance!;
  }

  Future<Database> get database async {
    _database ??= await _initDatabase();
    return _database!;
  }

  Future<Database> _initDatabase() async {
    final databasesPath = await getDatabasesPath();
    final path = join(databasesPath, AppConstants.databaseName);

    return await openDatabase(
      path,
      version: AppConstants.databaseVersion,
      onCreate: _onCreate,
      onUpgrade: _onUpgrade,
    );
  }

  Future<void> _onCreate(Database db, int version) async {
    await db.execute('''
      CREATE TABLE ${AppConstants.sessionsTable} (
        id TEXT PRIMARY KEY,
        target_type TEXT NOT NULL,
        image_path TEXT NOT NULL,
        total_score INTEGER NOT NULL,
        grouping_diameter REAL,
        grouping_center_x REAL,
        grouping_center_y REAL,
        created_at TEXT NOT NULL,
        notes TEXT,
        target_center_x REAL,
        target_center_y REAL,
        target_radius REAL
      )
    ''');

    await db.execute('''
      CREATE TABLE ${AppConstants.shotsTable} (
        id TEXT PRIMARY KEY,
        x REAL NOT NULL,
        y REAL NOT NULL,
        score INTEGER NOT NULL,
        session_id TEXT NOT NULL,
        FOREIGN KEY (session_id) REFERENCES ${AppConstants.sessionsTable}(id) ON DELETE CASCADE
      )
    ''');

    await db.execute('''
      CREATE INDEX idx_shots_session_id ON ${AppConstants.shotsTable}(session_id)
    ''');

    await db.execute('''
      CREATE INDEX idx_sessions_created_at ON ${AppConstants.sessionsTable}(created_at DESC)
    ''');
  }

  Future<void> _onUpgrade(Database db, int oldVersion, int newVersion) async {
    // Handle future database migrations here
  }

  // Session operations
  Future<int> insertSession(Session session) async {
    final db = await database;
    return await db.transaction((txn) async {
      await txn.insert(
        AppConstants.sessionsTable,
        session.toMap(),
        conflictAlgorithm: ConflictAlgorithm.replace,
      );

      for (final shot in session.shots) {
        // Ensure shot has correct session_id
        final shotWithSessionId = shot.copyWith(sessionId: session.id);
        await txn.insert(
          AppConstants.shotsTable,
          shotWithSessionId.toMap(),
          conflictAlgorithm: ConflictAlgorithm.replace,
        );
      }

      return 1;
    });
  }

  Future<Session?> getSession(String id) async {
    final db = await database;
    final sessionMaps = await db.query(
      AppConstants.sessionsTable,
      where: 'id = ?',
      whereArgs: [id],
    );

    if (sessionMaps.isEmpty) return null;

    final shotMaps = await db.query(
      AppConstants.shotsTable,
      where: 'session_id = ?',
      whereArgs: [id],
    );

    final shots = shotMaps.map((map) => Shot.fromMap(map)).toList();
    return Session.fromMap(sessionMaps.first, shots);
  }

  Future<List<Session>> getAllSessions({
    String? targetType,
    int? limit,
    int? offset,
  }) async {
    final db = await database;

    String? whereClause;
    List<dynamic>? whereArgs;

    if (targetType != null) {
      whereClause = 'target_type = ?';
      whereArgs = [targetType];
    }

    final sessionMaps = await db.query(
      AppConstants.sessionsTable,
      where: whereClause,
      whereArgs: whereArgs,
      orderBy: 'created_at DESC',
      limit: limit,
      offset: offset,
    );

    // First, check if there are orphaned shots (with empty session_id)
    // and only one session - if so, assign them to that session
    if (sessionMaps.length == 1) {
      final orphanedShots = await db.query(
        AppConstants.shotsTable,
        where: 'session_id = ?',
        whereArgs: [''],
      );
      if (orphanedShots.isNotEmpty) {
        await db.update(
          AppConstants.shotsTable,
          {'session_id': sessionMaps.first['id']},
          where: 'session_id = ?',
          whereArgs: [''],
        );
      }
    }

    final sessions = <Session>[];
    for (final sessionMap in sessionMaps) {
      final sessionId = sessionMap['id'] as String;

      final shotMaps = await db.query(
        AppConstants.shotsTable,
        where: 'session_id = ?',
        whereArgs: [sessionId],
      );

      final shots = shotMaps.map((map) => Shot.fromMap(map)).toList();
      sessions.add(Session.fromMap(sessionMap, shots));
    }

    return sessions;
  }

  Future<int> updateSession(Session session) async {
    final db = await database;
    return await db.transaction((txn) async {
      await txn.update(
        AppConstants.sessionsTable,
        session.toMap(),
        where: 'id = ?',
        whereArgs: [session.id],
      );

      // Delete existing shots and insert new ones
      await txn.delete(
        AppConstants.shotsTable,
        where: 'session_id = ?',
        whereArgs: [session.id],
      );

      for (final shot in session.shots) {
        // Ensure shot has correct session_id
        final shotWithSessionId = shot.copyWith(sessionId: session.id);
        await txn.insert(
          AppConstants.shotsTable,
          shotWithSessionId.toMap(),
          conflictAlgorithm: ConflictAlgorithm.replace,
        );
      }

      return 1;
    });
  }

  Future<int> deleteSession(String id) async {
    final db = await database;
    return await db.delete(
      AppConstants.sessionsTable,
      where: 'id = ?',
      whereArgs: [id],
    );
  }

  Future<Map<String, dynamic>> getStatistics() async {
    final db = await database;

    final totalSessions = Sqflite.firstIntValue(
      await db.rawQuery('SELECT COUNT(*) FROM ${AppConstants.sessionsTable}'),
    ) ?? 0;

    final totalShots = Sqflite.firstIntValue(
      await db.rawQuery('SELECT COUNT(*) FROM ${AppConstants.shotsTable}'),
    ) ?? 0;

    final avgScore = (await db.rawQuery(
      'SELECT AVG(total_score) as avg FROM ${AppConstants.sessionsTable}',
    )).first['avg'] as double? ?? 0.0;

    final bestScore = Sqflite.firstIntValue(
      await db.rawQuery(
        'SELECT MAX(total_score) FROM ${AppConstants.sessionsTable}',
      ),
    ) ?? 0;

    return {
      'totalSessions': totalSessions,
      'totalShots': totalShots,
      'averageScore': avgScore,
      'bestScore': bestScore,
    };
  }

  Future<void> close() async {
    final db = await database;
    await db.close();
    _database = null;
  }
}