/// Thin HTTP client for the personal ingtrak FastAPI backend.
library;

import 'dart:convert';

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

import '../models/bank.dart';
import '../utils/constants.dart';

/// Talks to Enable Banking via the local ingtrak API (no app-user auth).
class IngtrakApi {
  IngtrakApi({http.Client? client, this.baseUrl = kApiBaseUrl})
      : _client = client ?? http.Client();

  final http.Client _client;
  final String baseUrl;

  Uri _uri(String path, [Map<String, String>? query]) {
    final normalized = baseUrl.endsWith('/')
        ? baseUrl.substring(0, baseUrl.length - 1)
        : baseUrl;
    return Uri.parse('$normalized$path').replace(queryParameters: query);
  }

  Future<Map<String, dynamic>> _decodeObject(http.Response response) {
    final decoded = jsonDecode(response.body);
    if (decoded is! Map<String, dynamic>) {
      throw const IngtrakApiException('Unexpected response shape');
    }
    return Future.value(decoded);
  }

  void _ensureOk(http.Response response) {
    if (response.statusCode >= 200 && response.statusCode < 300) return;
    throw IngtrakApiException(
      _messageFromBody(response) ??
          'Request failed (${response.statusCode})',
      statusCode: response.statusCode,
    );
  }

  String? _messageFromBody(http.Response response) {
    try {
      final decoded = jsonDecode(response.body);
      if (decoded is Map<String, dynamic>) {
        final detail = decoded['detail'];
        if (detail is String) return detail;
        if (detail is Map) {
          final nested = detail['enablebanking'];
          if (nested is Map && nested['message'] is String) {
            return nested['message'] as String;
          }
          if (detail['message'] is String) {
            return detail['message'] as String;
          }
        }
      }
    } catch (_) {
      // Fall through to generic message.
    }
    return null;
  }

  Future<bool> health() async {
    final response = await _client.get(
      _uri('/health'),
      headers: const {'Accept': 'application/json'},
    );
    _ensureOk(response);
    final body = await _decodeObject(response);
    return body['status'] == 'ok';
  }

  /// `POST /api/connect` → open [ConnectStart.authUrl] in a browser.
  Future<ConnectStart> startConnect({
    String? aspspName,
    String? aspspCountry,
  }) async {
    final payload = <String, String>{};
    if (aspspName != null && aspspName.isNotEmpty) {
      payload['aspspName'] = aspspName;
    }
    if (aspspCountry != null && aspspCountry.isNotEmpty) {
      payload['aspspCountry'] = aspspCountry;
    }

    final response = await _client.post(
      _uri('/api/connect'),
      headers: const {
        'Accept': 'application/json',
        'Content-Type': 'application/json',
      },
      body: jsonEncode(payload),
    );
    _ensureOk(response);
    return ConnectStart.fromJson(await _decodeObject(response));
  }

  /// `POST /api/connect/complete` after the deep-link redirect.
  Future<ConnectStatus> completeConnect({
    required String code,
    String? state,
  }) async {
    final payload = <String, String>{'code': code};
    if (state != null && state.isNotEmpty) {
      payload['state'] = state;
    }

    final response = await _client.post(
      _uri('/api/connect/complete'),
      headers: const {
        'Accept': 'application/json',
        'Content-Type': 'application/json',
      },
      body: jsonEncode(payload),
    );
    _ensureOk(response);
    return ConnectStatus.fromJson(await _decodeObject(response));
  }

  Future<ConnectStatus> fetchStatus() async {
    final response = await _client.get(
      _uri('/api/connect/status'),
      headers: const {'Accept': 'application/json'},
    );
    _ensureOk(response);
    return ConnectStatus.fromJson(await _decodeObject(response));
  }

  Future<BankBalance> fetchBalance() async {
    final response = await _client.get(
      _uri('/api/balance'),
      headers: const {'Accept': 'application/json'},
    );
    _ensureOk(response);
    return BankBalance.fromJson(await _decodeObject(response));
  }

  Future<List<BankTransaction>> fetchTransactions({int days = 90}) async {
    final response = await _client.get(
      _uri('/api/transactions', {'days': '$days'}),
      headers: const {'Accept': 'application/json'},
    );
    _ensureOk(response);

    final decoded = jsonDecode(response.body);
    if (decoded is! List) {
      throw const IngtrakApiException('Unexpected transactions response');
    }

    return decoded
        .whereType<Map<String, dynamic>>()
        .map(BankTransaction.fromJson)
        .toList(growable: false);
  }

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

class IngtrakApiException implements Exception {
  const IngtrakApiException(this.message, {this.statusCode});

  final String message;
  final int? statusCode;

  bool get isNotLinked => statusCode == 409;

  @override
  String toString() => message;
}