import 'dart:io';

import 'package:path/path.dart' as p;
import 'package:path_provider/path_provider.dart';
import 'package:sqflite/sqflite.dart';

import '../models/fuel_entry.dart';
import '../models/vehicle.dart';
import 'db_schema.dart';

const dbFileName = 'fuel_tax_tracker.db';
const receiptsFolderName = 'receipts';

/// Owns the local SQLite database (vehicles + fuel_entries) and the
/// `receipts/` folder of not-yet-uploaded receipt photos, both under
/// `ApplicationDocumentsDirectory/FuelTaxTracker`.
///
/// Every row carries `updated_at` (for newest-wins merging), `deleted_at`
/// (a soft-delete tombstone — see [Vehicle.deletedAt]/[FuelEntry.deletedAt]
/// for why deletes aren't real `DELETE`s), and `dirty` (local-only: "not
/// yet pushed to Drive"). `dirty` is intentionally not exposed on the
/// domain model classes — it's sync bookkeeping the UI layer never needs to
/// know about; only [DriveSyncService] reads/clears it.
class DatabaseService {
  late Directory _rootDirectory;
  late Database _db;

  Directory get rootDirectory => _rootDirectory;

  Directory get receiptsDirectory =>
      Directory(p.join(_rootDirectory.path, receiptsFolderName));

  /// Raw handle for [DriveSyncService], which needs to run ATTACH-based
  /// merge SQL and VACUUM INTO snapshots that go beyond simple CRUD.
  Database get rawDb => _db;

  String get databasePath => _db.path;

  Future<void> init() async {
    final docsDir = await getApplicationDocumentsDirectory();
    _rootDirectory = Directory(p.join(docsDir.path, 'FuelTaxTracker'));
    await _rootDirectory.create(recursive: true);
    await receiptsDirectory.create(recursive: true);

    final dbPath = p.join(_rootDirectory.path, dbFileName);
    _db = await openDatabase(dbPath, version: 1, onCreate: _onCreate);
  }

  Future<void> _onCreate(Database db, int version) async {
    await db.execute(createVehiclesTableSql);
    await db.execute(createFuelEntriesTableSql);
    await db.execute(createFuelEntriesIndexSql);
  }

  Future<List<Vehicle>> getVehicles() async {
    final rows = await _db.query('vehicles', where: 'deleted_at IS NULL');
    return rows.map(Vehicle.fromMap).toList();
  }

  Future<List<FuelEntry>> getFuelEntries() async {
    final rows = await _db.query('fuel_entries', where: 'deleted_at IS NULL');
    return rows.map(FuelEntry.fromMap).toList();
  }

  /// Inserts or fully overwrites a vehicle row and marks it dirty (pending
  /// push to Drive).
  Future<void> saveVehicle(Vehicle vehicle) async {
    final map = Map<String, Object?>.from(vehicle.toMap())..['dirty'] = 1;
    await _db.insert('vehicles', map, conflictAlgorithm: ConflictAlgorithm.replace);
  }

  Future<void> saveFuelEntry(FuelEntry entry) async {
    final map = Map<String, Object?>.from(entry.toMap())..['dirty'] = 1;
    await _db.insert('fuel_entries', map, conflictAlgorithm: ConflictAlgorithm.replace);
  }

  Future<void> softDeleteVehicle(String id, DateTime deletedAt) async {
    await _db.update(
      'vehicles',
      {
        'deleted_at': deletedAt.millisecondsSinceEpoch,
        'updated_at': deletedAt.millisecondsSinceEpoch,
        'dirty': 1,
      },
      where: 'id = ?',
      whereArgs: [id],
    );
  }

  Future<void> softDeleteFuelEntry(String id, DateTime deletedAt) async {
    await _db.update(
      'fuel_entries',
      {
        'deleted_at': deletedAt.millisecondsSinceEpoch,
        'updated_at': deletedAt.millisecondsSinceEpoch,
        'dirty': 1,
      },
      where: 'id = ?',
      whereArgs: [id],
    );
  }

  /// Soft-deletes every active fuel entry for [vehicleId] (cascade for a
  /// vehicle deletion) and returns their local receipt image paths, if
  /// any, so the caller can clean those files up too.
  Future<List<String>> softDeleteFuelEntriesForVehicle(
    String vehicleId,
    DateTime deletedAt,
  ) async {
    final rows = await _db.query(
      'fuel_entries',
      where: 'vehicle_id = ? AND deleted_at IS NULL',
      whereArgs: [vehicleId],
    );
    final localPaths =
        rows.map((r) => r['receipt_image_path'] as String?).whereType<String>().toList();

    await _db.update(
      'fuel_entries',
      {
        'deleted_at': deletedAt.millisecondsSinceEpoch,
        'updated_at': deletedAt.millisecondsSinceEpoch,
        'dirty': 1,
      },
      where: 'vehicle_id = ? AND deleted_at IS NULL',
      whereArgs: [vehicleId],
    );

    return localPaths;
  }

  Future<String> storeReceiptImage(File sourceImage, String fuelEntryId) async {
    final ext = p.extension(sourceImage.path);
    final destPath = p.join(receiptsDirectory.path, '$fuelEntryId$ext');
    final copied = await sourceImage.copy(destPath);
    return copied.path;
  }

  Future<void> deleteReceiptImageFile(String? path) async {
    if (path == null) return;
    final file = File(path);
    if (await file.exists()) {
      await file.delete();
    }
  }
}