import 'dart:convert';

import 'package:postgres/postgres.dart';

/// Normalized market data row persisted for rule evaluation.
class MarketDataSnapshot {
  MarketDataSnapshot({
    required this.symbol,
    required this.metric,
    required this.asOf,
    this.id,
    this.assetClass = 'us_equity',
    this.feed = 'iex',
    this.price,
    this.volume,
    this.raw,
    this.createdAt,
  });

  final int? id;
  final String symbol;
  final String assetClass;
  final String feed;
  final String metric;
  final num? price;
  final num? volume;
  final DateTime asOf;
  final Map<String, dynamic>? raw;
  final DateTime? createdAt;
}

/// Postgres access for [market_data_snapshots].
class MarketDataDb {
  MarketDataDb(this._connection);

  final Connection _connection;

  Future<MarketDataSnapshot> insertSnapshot({
    required String symbol,
    required String metric,
    required DateTime asOf,
    String assetClass = 'us_equity',
    String feed = 'iex',
    num? price,
    num? volume,
    Map<String, dynamic>? raw,
  }) async {
    final Result result = await _connection.execute(
      Sql.named(
        '''
        INSERT INTO market_data_snapshots (
          symbol, asset_class, feed, metric, price, volume, as_of, raw
        ) VALUES (
          @symbol, @asset_class, @feed, @metric, @price, @volume, @as_of, @raw::jsonb
        )
        RETURNING id, symbol, asset_class, feed, metric, price, volume, as_of, raw, created_at
        ''',
      ),
      parameters: <String, dynamic>{
        'symbol': symbol,
        'asset_class': assetClass,
        'feed': feed,
        'metric': metric,
        'price': price,
        'volume': volume,
        'as_of': asOf.toUtc(),
        'raw': raw == null ? null : jsonEncode(raw),
      },
    );
    return _rowToSnapshot(result.first);
  }

  /// Newest snapshot for [symbol] and [metric] by [as_of].
  Future<MarketDataSnapshot?> latestForSymbol(
    String symbol,
    String metric,
  ) async {
    final Result result = await _connection.execute(
      Sql.named(
        '''
        SELECT id, symbol, asset_class, feed, metric, price, volume, as_of, raw, created_at
        FROM market_data_snapshots
        WHERE symbol = @symbol AND metric = @metric
        ORDER BY as_of DESC
        LIMIT 1
        ''',
      ),
      parameters: <String, dynamic>{
        'symbol': symbol,
        'metric': metric,
      },
    );
    if (result.isEmpty) {
      return null;
    }
    return _rowToSnapshot(result.first);
  }

  MarketDataSnapshot _rowToSnapshot(ResultRow row) {
    final Object? rawValue = row[8];
    Map<String, dynamic>? raw;
    if (rawValue is Map<String, dynamic>) {
      raw = rawValue;
    } else if (rawValue != null) {
      raw = jsonDecode(rawValue.toString()) as Map<String, dynamic>;
    }

    return MarketDataSnapshot(
      id: (row[0]! as num).toInt(),
      symbol: row[1]! as String,
      assetClass: row[2]! as String,
      feed: row[3]! as String,
      metric: row[4]! as String,
      price: _readOptionalNumeric(row[5]),
      volume: _readOptionalNumeric(row[6]),
      asOf: (row[7]! as DateTime).toUtc(),
      raw: raw,
      createdAt: (row[9]! as DateTime).toUtc(),
    );
  }

  static num? _readOptionalNumeric(Object? value) {
    if (value == null) {
      return null;
    }
    if (value is num) {
      return value;
    }
    if (value is String) {
      return num.parse(value);
    }
    return num.parse(value.toString());
  }
}