import 'dart:convert';

import 'package:http/http.dart' as http;

import 'alpaca_env.dart';
import 'alpaca_models.dart';

/// REST client for Alpaca's Trading-API `/v2/assets` endpoint.
///
/// The asset universe lives behind the trading host, NOT the data host —
/// see [AlpacaEnv.tradingBaseUrl]. We treat it as read-only here; the
/// tradable_assets sync (§2.2) is the only writer to the DB.
class AlpacaAssetsClient {
  AlpacaAssetsClient({
    required AlpacaEnv env,
    http.Client? httpClient,
  })  : _env = env,
        _client = httpClient ?? http.Client();

  final AlpacaEnv _env;
  final http.Client _client;

  /// `GET ${tradingBaseUrl}/v2/assets?status=active&asset_class=us_equity`.
  ///
  /// Filters to `tradable=true` are applied **server-side** by the caller
  /// (the asset-universe sync) so the client stays a thin wrapper and the
  /// audit trail in [tradable_assets] still records inactive symbols when
  /// they later disappear.
  Future<List<AlpacaAsset>> listActiveTradable() async {
    _env.requireCredentials();

    final Uri uri = Uri.parse('${_env.tradingBaseUrl}/v2/assets').replace(
      queryParameters: <String, String>{
        'status': 'active',
        'asset_class': 'us_equity',
      },
    );

    final http.Response response;
    try {
      response = await _client.get(uri, headers: _env.authHeaders);
    } on http.ClientException catch (e) {
      throw AlpacaAssetsException(
        'GET /v2/assets transport error: ${e.message}',
      );
    }

    if (response.statusCode != 200) {
      throw AlpacaAssetsException(
        'GET /v2/assets failed: '
        '${response.statusCode} ${response.body}',
      );
    }

    final dynamic decoded = jsonDecode(response.body);
    if (decoded is! List) {
      throw AlpacaAssetsException(
        'GET /v2/assets returned non-list body: ${response.body}',
      );
    }
    return decoded
        .whereType<Map>()
        .map((Map<dynamic, dynamic> m) =>
            AlpacaAsset.fromJson(Map<String, dynamic>.from(m)))
        .toList(growable: false);
  }

  void close() => _client.close();
}

/// Thrown by [AlpacaAssetsClient] when an upstream HTTP call fails.
///
/// The message always includes the HTTP status code (when applicable) and
/// the response body so the caller's audit row can capture it verbatim.
class AlpacaAssetsException implements Exception {
  AlpacaAssetsException(this.message);

  final String message;

  @override
  String toString() => message;
}