import 'dart:convert';

import 'package:postgres/postgres.dart';

/// Per-user trading worker cursor ([user_trading_state]).
class UserTradingStateDb {
  UserTradingStateDb(this._connection);

  final Connection _connection;

  static const String ingestContextKey = 'ingest_last_fetch';
  static const String rulesContextKey = 'rules';
  static const String pendingOrdersContextKey = 'pending_orders';
  static const String skippedContextKey = 'skipped';
  static const String guessScoreContextKey = 'guess_score';
  static const String guessSymbolCooldownContextKey = 'guess_symbol_cooldown';

  Future<void> ensureExists(String firebaseUid) async {
    await _connection.execute(
      Sql.named(
        '''
        INSERT INTO user_trading_state (firebase_uid)
        VALUES (@uid)
        ON CONFLICT (firebase_uid) DO NOTHING
        ''',
      ),
      parameters: <String, dynamic>{'uid': firebaseUid},
    );
  }

  Future<Map<String, dynamic>> getContext(String firebaseUid) async {
    await ensureExists(firebaseUid);
    final Result result = await _connection.execute(
      Sql.named(
        'SELECT context FROM user_trading_state WHERE firebase_uid = @uid',
      ),
      parameters: <String, dynamic>{'uid': firebaseUid},
    );
    if (result.isEmpty) {
      return <String, dynamic>{};
    }
    return _readJsonMap(result.first[0]);
  }

  /// ISO-8601 timestamp of last successful fetch for [dataInputId], or null.
  Future<DateTime?> getInputLastFetch(
    String firebaseUid,
    String dataInputId,
  ) async {
    final Map<String, dynamic> context = await getContext(firebaseUid);
    final Map<String, dynamic> ingest = Map<String, dynamic>.from(
      context[ingestContextKey] as Map? ?? <String, dynamic>{},
    );
    final String? raw = ingest[dataInputId] as String?;
    if (raw == null || raw.isEmpty) {
      return null;
    }
    return DateTime.parse(raw).toUtc();
  }

  Future<void> recordInputFetch(
    String firebaseUid,
    String dataInputId,
    DateTime fetchedAt,
  ) async {
    await ensureExists(firebaseUid);
    final Map<String, dynamic> context = await getContext(firebaseUid);
    final Map<String, dynamic> ingest = Map<String, dynamic>.from(
      context[ingestContextKey] as Map? ?? <String, dynamic>{},
    );
    ingest[dataInputId] = fetchedAt.toUtc().toIso8601String();
    context[ingestContextKey] = ingest;

    await _connection.execute(
      Sql.named(
        '''
        UPDATE user_trading_state
        SET context = @context::jsonb,
            last_ingest_at = @last_ingest_at,
            updated_at = now()
        WHERE firebase_uid = @uid
        ''',
      ),
      parameters: <String, dynamic>{
        'uid': firebaseUid,
        'context': jsonEncode(context),
        'last_ingest_at': fetchedAt.toUtc(),
      },
    );
  }

  Future<Map<String, dynamic>?> getRuleState(
    String firebaseUid,
    String ruleId,
  ) async {
    final Map<String, dynamic> context = await getContext(firebaseUid);
    final Map<String, dynamic> rules = Map<String, dynamic>.from(
      context[rulesContextKey] as Map? ?? <String, dynamic>{},
    );
    final Map? raw = rules[ruleId] as Map?;
    if (raw == null) {
      return null;
    }
    return Map<String, dynamic>.from(raw);
  }

  Future<DateTime?> getRuleLastFiredAt(
    String firebaseUid,
    String ruleId,
  ) async {
    final Map<String, dynamic>? state = await getRuleState(firebaseUid, ruleId);
    final String? raw = state?['last_fired_at'] as String?;
    if (raw == null || raw.isEmpty) {
      return null;
    }
    return DateTime.parse(raw).toUtc();
  }

  Future<void> setRuleState({
    required String firebaseUid,
    required String ruleId,
    required Map<String, dynamic> state,
  }) async {
    await ensureExists(firebaseUid);
    final Map<String, dynamic> context = await getContext(firebaseUid);
    final Map<String, dynamic> rules = Map<String, dynamic>.from(
      context[rulesContextKey] as Map? ?? <String, dynamic>{},
    );
    rules[ruleId] = state;
    context[rulesContextKey] = rules;
    await _writeContext(firebaseUid, context, touchEvalAt: true);
  }

  Future<List<Map<String, dynamic>>> listPendingOrders(
    String firebaseUid,
  ) async {
    final Map<String, dynamic> context = await getContext(firebaseUid);
    final List<dynamic> raw =
        context[pendingOrdersContextKey] as List<dynamic>? ?? <dynamic>[];
    return raw
        .whereType<Map>()
        .map((Map<dynamic, dynamic> m) => Map<String, dynamic>.from(m))
        .toList();
  }

  Future<void> addPendingOrder({
    required String firebaseUid,
    required Map<String, dynamic> order,
  }) async {
    await ensureExists(firebaseUid);
    final Map<String, dynamic> context = await getContext(firebaseUid);
    final List<dynamic> existing =
        context[pendingOrdersContextKey] as List<dynamic>? ?? <dynamic>[];
    final List<Map<String, dynamic>> orders = <Map<String, dynamic>>[
      ...existing.whereType<Map>().map(
            (Map<dynamic, dynamic> m) => Map<String, dynamic>.from(m),
          ),
      order,
    ];
    context[pendingOrdersContextKey] = orders;
    await _writeContext(firebaseUid, context, touchEvalAt: true);
  }

  Future<void> removePendingOrder({
    required String firebaseUid,
    required String clientOrderId,
  }) async {
    await ensureExists(firebaseUid);
    final Map<String, dynamic> context = await getContext(firebaseUid);
    final List<dynamic> existing =
        context[pendingOrdersContextKey] as List<dynamic>? ?? <dynamic>[];
    final List<Map<String, dynamic>> kept = existing
        .whereType<Map>()
        .map((Map<dynamic, dynamic> m) => Map<String, dynamic>.from(m))
        .where((Map<String, dynamic> m) =>
            m['client_order_id'] != clientOrderId)
        .toList();
    context[pendingOrdersContextKey] = kept;
    await _writeContext(firebaseUid, context, touchEvalAt: false);
  }

  Future<Map<String, dynamic>?> getGuessScore(String firebaseUid) async {
    final Map<String, dynamic> context = await getContext(firebaseUid);
    final Object? raw = context[guessScoreContextKey];
    if (raw is Map) {
      return Map<String, dynamic>.from(raw);
    }
    return null;
  }

  Future<void> recordGuessScore({
    required String firebaseUid,
    required int scoreDelta,
    required String symbol,
    required DateTime at,
  }) async {
    await ensureExists(firebaseUid);
    final Map<String, dynamic> context = await getContext(firebaseUid);
    final Map<String, dynamic> prior = Map<String, dynamic>.from(
      context[guessScoreContextKey] as Map? ?? <String, dynamic>{},
    );
    final int total = ((prior['total'] as num?)?.toInt() ?? 0) + scoreDelta;
    context[guessScoreContextKey] = <String, dynamic>{
      'total': total,
      'last': <String, dynamic>{
        'score_delta': scoreDelta,
        'symbol': symbol,
        'at': at.toUtc().toIso8601String(),
      },
    };
    await _writeContext(firebaseUid, context, touchEvalAt: true);
  }

  Future<DateTime?> getGuessSymbolLastPickedAt(
    String firebaseUid,
    String symbol,
  ) async {
    final Map<String, dynamic> context = await getContext(firebaseUid);
    final Map<String, dynamic> cooldown = Map<String, dynamic>.from(
      context[guessSymbolCooldownContextKey] as Map? ?? <String, dynamic>{},
    );
    final String? raw = cooldown[symbol] as String?;
    if (raw == null || raw.isEmpty) {
      return null;
    }
    return DateTime.parse(raw).toUtc();
  }

  Future<bool> isGuessSymbolOnCooldown({
    required String firebaseUid,
    required String symbol,
    required DateTime now,
    int cooldownHours = 24,
  }) async {
    final DateTime? last =
        await getGuessSymbolLastPickedAt(firebaseUid, symbol);
    if (last == null) {
      return false;
    }
    return now.difference(last) < Duration(hours: cooldownHours);
  }

  Future<void> recordGuessSymbolPicked({
    required String firebaseUid,
    required String symbol,
    required DateTime at,
  }) async {
    await ensureExists(firebaseUid);
    final Map<String, dynamic> context = await getContext(firebaseUid);
    final Map<String, dynamic> cooldown = Map<String, dynamic>.from(
      context[guessSymbolCooldownContextKey] as Map? ?? <String, dynamic>{},
    );
    cooldown[symbol] = at.toUtc().toIso8601String();
    context[guessSymbolCooldownContextKey] = cooldown;
    await _writeContext(firebaseUid, context, touchEvalAt: true);
  }

  Future<void> recordSkip({
    required String firebaseUid,
    required String ruleId,
    required String questionId,
    required DateTime at,
  }) async {
    await ensureExists(firebaseUid);
    final Map<String, dynamic> context = await getContext(firebaseUid);
    final List<dynamic> existing =
        context[skippedContextKey] as List<dynamic>? ?? <dynamic>[];
    final List<Map<String, dynamic>> skipped = <Map<String, dynamic>>[
      ...existing.whereType<Map>().map(
            (Map<dynamic, dynamic> m) => Map<String, dynamic>.from(m),
          ),
      <String, dynamic>{
        'rule_id': ruleId,
        'question_id': questionId,
        'at': at.toUtc().toIso8601String(),
      },
    ];
    context[skippedContextKey] = skipped;
    await _writeContext(firebaseUid, context, touchEvalAt: false);
  }

  Future<void> _writeContext(
    String firebaseUid,
    Map<String, dynamic> context, {
    required bool touchEvalAt,
  }) async {
    final String setEval = touchEvalAt ? ', last_eval_at = now()' : '';
    await _connection.execute(
      Sql.named(
        '''
        UPDATE user_trading_state
        SET context = @context::jsonb,
            updated_at = now()
            $setEval
        WHERE firebase_uid = @uid
        ''',
      ),
      parameters: <String, dynamic>{
        'uid': firebaseUid,
        'context': jsonEncode(context),
      },
    );
  }

  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>;
  }
}