import 'dart:io';

import 'package:postgres/postgres.dart';

class ProfileDb {
  ProfileDb(this._connection);

  final Connection _connection;

  static Future<ProfileDb> connect(String databaseUrl) async {
    final Uri uri = Uri.parse(databaseUrl);
    final Connection connection = await Connection.open(
      Endpoint(
        host: uri.host.isEmpty ? 'localhost' : uri.host,
        port: uri.hasPort ? uri.port : 5432,
        database: uri.pathSegments.isNotEmpty ? uri.pathSegments.last : 'postgres',
        username: uri.userInfo.isNotEmpty ? uri.userInfo.split(':').first : null,
        password: uri.userInfo.contains(':')
            ? uri.userInfo.split(':').skip(1).join(':')
            : null,
      ),
      settings: const ConnectionSettings(sslMode: SslMode.disable),
    );
    return ProfileDb(connection);
  }

  Connection get connection => _connection;

  Future<void> migrate() async {
    final List<File> files = Directory('migrations')
        .listSync()
        .whereType<File>()
        .where((File f) => f.path.endsWith('.sql'))
        .toList()
      ..sort((File a, File b) => a.path.compareTo(b.path));

    for (final File file in files) {
      final String sql = await file.readAsString();
      final List<String> statements = sql
          .split(';')
          .map((String s) => s.trim())
          .where((String s) => s.isNotEmpty)
          .toList();

      for (final String statement in statements) {
        await _connection.execute(statement);
      }
    }
  }

  Future<Map<String, dynamic>?> getProfile(String firebaseUid) async {
    final Result result = await _connection.execute(
      Sql.named(
        'SELECT firebase_uid, email, display_name, photo_url, locale, timezone, '
        'onboarding_done, revision, updated_at '
        'FROM users WHERE firebase_uid = @uid',
      ),
      parameters: <String, dynamic>{'uid': firebaseUid},
    );
    if (result.isEmpty) {
      return null;
    }
    final ResultRow row = result.first;
    return _rowToJson(row);
  }

  Future<Map<String, dynamic>> upsertProfile({
    required String firebaseUid,
    required Map<String, dynamic> body,
    required int clientRevision,
  }) async {
    final Result existing = await _connection.execute(
      Sql.named('SELECT revision FROM users WHERE firebase_uid = @uid'),
      parameters: <String, dynamic>{'uid': firebaseUid},
    );

    if (existing.isNotEmpty) {
      final int serverRevision = (existing.first[0]! as num).toInt();
      if (clientRevision < serverRevision) {
        final Map<String, dynamic>? current = await getProfile(firebaseUid);
        throw StaleRevisionException(current!);
      }
    }

    await _connection.execute(
      Sql.named(
        '''
        INSERT INTO users (
          firebase_uid, email, display_name, photo_url, locale, timezone,
          onboarding_done, revision, updated_at
        ) VALUES (
          @uid, @email, @display_name, @photo_url, @locale, @timezone,
          @onboarding_done, @revision, @updated_at
        )
        ON CONFLICT (firebase_uid) DO UPDATE SET
          email = EXCLUDED.email,
          display_name = EXCLUDED.display_name,
          photo_url = EXCLUDED.photo_url,
          locale = EXCLUDED.locale,
          timezone = EXCLUDED.timezone,
          onboarding_done = EXCLUDED.onboarding_done,
          revision = EXCLUDED.revision,
          updated_at = EXCLUDED.updated_at
        ''',
      ),
      parameters: <String, dynamic>{
        'uid': firebaseUid,
        'email': body['email'],
        'display_name': body['displayName'],
        'photo_url': body['photoUrl'],
        'locale': body['locale'] ?? 'en',
        'timezone': body['timezone'],
        'onboarding_done': body['onboardingCompleted'] ?? false,
        'revision': clientRevision,
        'updated_at': DateTime.parse(body['updatedAt'] as String).toUtc(),
      },
    );

    return (await getProfile(firebaseUid))!;
  }

  Future<void> close() => _connection.close();

  Map<String, dynamic> _rowToJson(ResultRow row) {
    final DateTime updatedAt = row[8]! as DateTime;
    return <String, dynamic>{
      'firebaseUid': row[0]! as String,
      'email': row[1] as String?,
      'displayName': row[2] as String?,
      'photoUrl': row[3] as String?,
      'locale': row[4]! as String,
      'timezone': row[5] as String?,
      'onboardingCompleted': row[6]! as bool,
      'revision': (row[7]! as num).toInt(),
      'updatedAt': updatedAt.toUtc().toIso8601String(),
    };
  }
}

class StaleRevisionException implements Exception {
  StaleRevisionException(this.serverProfile);

  final Map<String, dynamic> serverProfile;
}