import 'dart:convert';

import 'package:postgres/postgres.dart';

import 'trading_config.dart';

/// Loads and merges [trading_config_templates] with [user_trading_config].
class TradingConfigDb {
  TradingConfigDb(this._connection);

  final Connection _connection;

  Future<EffectiveTradingConfig?> resolveEffectiveConfig(String firebaseUid) async {
    final Result result = await _connection.execute(
      Sql.named(
        '''
        SELECT utc.template_name, utc.config, utc.enabled
        FROM user_trading_config utc
        WHERE utc.firebase_uid = @uid
        ''',
      ),
      parameters: <String, dynamic>{'uid': firebaseUid},
    );
    if (result.isEmpty) {
      return null;
    }

    final ResultRow row = result.first;
    final String? templateName = row[0] as String?;
    final Map<String, dynamic> userConfig = _readJsonMap(row[1]);
    final bool userEnabled = row[2]! as bool;

    Map<String, dynamic> merged = userConfig;
    if (templateName != null && templateName.isNotEmpty) {
      final Map<String, dynamic>? templateConfig =
          await _loadTemplateConfig(templateName);
      if (templateConfig != null) {
        merged = EffectiveTradingConfig.mergeJson(templateConfig, userConfig);
      }
    }

    return EffectiveTradingConfig.fromJson(
      merged,
      templateName: templateName,
      userEnabled: userEnabled,
    );
  }

  Future<void> upsertUserConfig({
    required String firebaseUid,
    String? templateName,
    Map<String, dynamic> config = const <String, dynamic>{},
    bool enabled = false,
  }) async {
    await _connection.execute(
      Sql.named(
        '''
        INSERT INTO user_trading_config (firebase_uid, template_name, config, enabled)
        VALUES (@uid, @template_name, @config::jsonb, @enabled)
        ON CONFLICT (firebase_uid) DO UPDATE SET
          template_name = EXCLUDED.template_name,
          config = EXCLUDED.config,
          enabled = EXCLUDED.enabled,
          updated_at = now()
        ''',
      ),
      parameters: <String, dynamic>{
        'uid': firebaseUid,
        'template_name': templateName,
        'config': jsonEncode(config),
        'enabled': enabled,
      },
    );
  }

  Future<Map<String, dynamic>?> _loadTemplateConfig(String name) async {
    final Result result = await _connection.execute(
      Sql.named(
        'SELECT config FROM trading_config_templates WHERE name = @name',
      ),
      parameters: <String, dynamic>{'name': name},
    );
    if (result.isEmpty) {
      return null;
    }
    return _readJsonMap(result.first[0]);
  }

  Map<String, dynamic> _readJsonMap(Object? value) {
    if (value is Map<String, dynamic>) {
      return value;
    }
    if (value is Map) {
      return Map<String, dynamic>.from(value);
    }
    if (value == null) {
      return <String, dynamic>{};
    }
    return jsonDecode(value.toString()) as Map<String, dynamic>;
  }
}