import 'package:drift/drift.dart';
import 'package:drift_flutter/drift_flutter.dart';
import 'package:path_provider/path_provider.dart';
import 'package:uuid/uuid.dart';

import '../models/payment_method.dart';
import '../models/remote_command.dart';

part 'app_database.g.dart';

class PaymentMethodConverter extends TypeConverter<PaymentMethod, String> {
  const PaymentMethodConverter();

  @override
  PaymentMethod fromSql(String fromDb) => PaymentMethod.fromValue(fromDb);

  @override
  String toSql(PaymentMethod value) => value.value;
}

@DataClassName('ProductRow')
class Products extends Table {
  TextColumn get id => text()();

  TextColumn get name => text()();

  TextColumn get category => text()();

  IntColumn get stockQuantity => integer()();

  IntColumn get lowStockThreshold => integer()();

  /// Products like tap water that are never counted; their stock is ignored.
  BoolColumn get infiniteStock =>
      boolean().withDefault(const Constant(false))();

  IntColumn get priceInCents => integer()();

  TextColumn get imagePath => text().nullable()();

  BoolColumn get active => boolean().withDefault(const Constant(true))();

  @override
  Set<Column> get primaryKey => {id};
}

@DataClassName('BarTabRow')
class BarTabs extends Table {
  TextColumn get id => text()();

  TextColumn get customerName => text()();

  DateTimeColumn get openedAt => dateTime()();

  IntColumn get version => integer().withDefault(const Constant(0))();

  @override
  Set<Column> get primaryKey => {id};
}

@DataClassName('TabItemRow')
class TabItems extends Table {
  TextColumn get id => text()();

  TextColumn get tabId =>
      text().references(BarTabs, #id, onDelete: KeyAction.cascade)();

  TextColumn get productId => text().references(Products, #id)();

  TextColumn get productName => text()();

  IntColumn get quantity => integer()();

  IntColumn get unitPriceInCents => integer()();

  DateTimeColumn get createdAt => dateTime()();

  @override
  Set<Column> get primaryKey => {id};
}

@DataClassName('TabItemPurchaseRow')
class TabItemPurchases extends Table {
  TextColumn get id => text()();

  TextColumn get tabItemId =>
      text().references(TabItems, #id, onDelete: KeyAction.cascade)();

  DateTimeColumn get purchasedAt => dateTime()();

  DateTimeColumn get removedAt => dateTime().nullable()();

  @override
  Set<Column> get primaryKey => {id};
}

@DataClassName('ClosedTabsRow')
class ClosedTabs extends Table {
  TextColumn get id => text()();

  TextColumn get originalTabId => text()();

  TextColumn get customerName => text()();

  DateTimeColumn get closedAt => dateTime()();

  TextColumn get paymentMethod => text()
      .map(const PaymentMethodConverter())
      .withDefault(const Constant('cash'))();

  @override
  Set<Column> get primaryKey => {id};
}

@DataClassName('ClosedTabItemRow')
class ClosedTabItems extends Table {
  TextColumn get id => text()();

  TextColumn get closedTabId => text()();

  TextColumn get productId => text()();

  TextColumn get productName => text()();

  IntColumn get quantity => integer()();

  IntColumn get unitPriceInCents => integer()();

  DateTimeColumn get purchasedAt => dateTime().nullable()();

  DateTimeColumn get removedAt => dateTime().nullable()();

  @override
  Set<Column> get primaryKey => {id};
}

@DataClassName('AppSettingsRow')
class AppSettingsTable extends Table {
  @override
  String get tableName => 'app_settings';

  TextColumn get id => text()();

  BoolColumn get pinRequired => boolean().withDefault(const Constant(false))();

  BoolColumn get autoLockEnabled =>
      boolean().withDefault(const Constant(true))();

  TextColumn get themeMode => text().withDefault(const Constant('system'))();

  TextColumn get language => text().withDefault(const Constant('system'))();

  IntColumn get barGridRows => integer().withDefault(const Constant(3))();

  @override
  Set<Column> get primaryKey => {id};
}

@DataClassName('RemoteSyncStateRow')
class RemoteSyncState extends Table {
  TextColumn get deviceId => text()();

  TextColumn get serverCursor => text().nullable()();

  DateTimeColumn get lastSuccessfulSyncAt => dateTime().nullable()();

  DateTimeColumn get lastAttemptedSyncAt => dateTime().nullable()();

  IntColumn get consecutiveFailureCount =>
      integer().withDefault(const Constant(0))();

  @override
  Set<Column> get primaryKey => {deviceId};
}

@DataClassName('ProcessedRemoteCommandRow')
class ProcessedRemoteCommands extends Table {
  TextColumn get commandId => text()();

  TextColumn get commandType => text()();

  DateTimeColumn get processedAt => dateTime()();

  TextColumn get result => textEnum<CommandResult>()();

  @override
  Set<Column> get primaryKey => {commandId};
}

@DriftDatabase(
  tables: [
    Products,
    BarTabs,
    TabItems,
    TabItemPurchases,
    ClosedTabs,
    ClosedTabItems,
    AppSettingsTable,
    RemoteSyncState,
    ProcessedRemoteCommands,
  ],
)
class AppDatabase extends _$AppDatabase {
  AppDatabase([QueryExecutor? executor]) : super(executor ?? _openConnection());

  @override
  int get schemaVersion => 14;

  @override
  MigrationStrategy get migration {
    return MigrationStrategy(
      onCreate: (migrator) async {
        await migrator.createAll();
      },
      onUpgrade: (migrator, from, to) async {
        Future<bool> hasTableColumn(String tableName, String columnName) async {
          final columns = await migrator.database
              .customSelect('PRAGMA table_info($tableName)')
              .get();

          return columns.any((column) => column.data['name'] == columnName);
        }

        Future<bool> hasSettingsColumn(String columnName) {
          return hasTableColumn('app_settings', columnName);
        }

        if (from < 2) {
          await migrator.createTable(barTabs);
          await migrator.createTable(tabItems);
        }

        if (from < 3) {
          await migrator.addColumn(products, products.imagePath);
        }

        if (from < 4) {
          await migrator.createTable(closedTabs);
          await migrator.createTable(closedTabItems);
        }

        if (from < 5) {
          await migrator.createTable(appSettingsTable);
        }

        if (from < 6 &&
            !await hasTableColumn('closed_tabs', 'payment_method')) {
          await migrator.addColumn(closedTabs, closedTabs.paymentMethod);
        }

        if (from < 7 && !await hasSettingsColumn('language')) {
          await migrator.addColumn(appSettingsTable, appSettingsTable.language);
        }

        if (from < 8 && !await hasSettingsColumn('bar_grid_rows')) {
          await migrator.addColumn(
            appSettingsTable,
            appSettingsTable.barGridRows,
          );
        }

        if (from < 9 && !await hasSettingsColumn('auto_lock_enabled')) {
          await migrator.addColumn(
            appSettingsTable,
            appSettingsTable.autoLockEnabled,
          );
        }

        if (from < 10) {
          if (!await hasTableColumn('closed_tab_items', 'purchased_at')) {
            await migrator.addColumn(
              closedTabItems,
              closedTabItems.purchasedAt,
            );
          }
          if (!await hasTableColumn('closed_tab_items', 'removed_at')) {
            await migrator.addColumn(closedTabItems, closedTabItems.removedAt);
          }
        }

        if (from < 11) {
          await migrator.createTable(tabItemPurchases);
        }

        if (from < 12) {
          if (!await hasTableColumn('bar_tabs', 'version')) {
            await migrator.addColumn(barTabs, barTabs.version);
          }
          await migrator.createTable(remoteSyncState);
          await migrator.createTable(processedRemoteCommands);
        }

        if (from < 13) {
          // Tabs never close (only their items are archived), so the status
          // and closed_at columns were never anything but 'open' and null.
          if (await hasTableColumn('bar_tabs', 'status')) {
            await migrator.alterTable(TableMigration(barTabs));
          }
          await _backfillPurchaseRows();
          await _deleteOrphanedPurchaseRows();
        }

        if (from < 14 && !await hasTableColumn('products', 'infinite_stock')) {
          await migrator.addColumn(products, products.infiniteStock);
        }
      },
    );
  }

  /// Items added before purchases were tracked have fewer active purchase
  /// rows than their quantity. Insert the missing ones once, here, so the
  /// services can rely on `quantity == active purchases`.
  Future<void> _backfillPurchaseRows() async {
    const uuid = Uuid();

    final rows = await customSelect(
      'SELECT i.id, i.quantity, i.created_at, '
      '(SELECT COUNT(*) FROM tab_item_purchases p '
      'WHERE p.tab_item_id = i.id AND p.removed_at IS NULL) AS active_count '
      'FROM tab_items i',
      readsFrom: {tabItems, tabItemPurchases},
    ).get();

    for (final row in rows) {
      final missing = row.read<int>('quantity') - row.read<int>('active_count');
      if (missing <= 0) continue;

      final itemId = row.read<String>('id');
      final createdAt = row.read<DateTime>('created_at');

      for (var index = 0; index < missing; index++) {
        await into(tabItemPurchases).insert(
          TabItemPurchasesCompanion.insert(
            id: uuid.v4(),
            tabItemId: itemId,
            purchasedAt: createdAt,
          ),
        );
      }
    }
  }

  /// Foreign keys aren't enforced, so deleting tab items used to leave their
  /// purchase rows behind.
  Future<void> _deleteOrphanedPurchaseRows() async {
    await customStatement(
      'DELETE FROM tab_item_purchases '
      'WHERE tab_item_id NOT IN (SELECT id FROM tab_items)',
    );
  }

  static QueryExecutor _openConnection() {
    return driftDatabase(
      name: 'kooltap',
      native: const DriftNativeOptions(
        databaseDirectory: getApplicationSupportDirectory,
      ),
    );
  }
}