import 'dart:convert';
import 'dart:io';

import 'package:comunic/helpers/account_credentials_helper.dart';
import 'package:comunic/models/api_request.dart';
import 'package:comunic/models/api_response.dart';
import 'package:comunic/models/config.dart';

/// API Helper
///
/// @author Pierre HUBERT

class APIHelper {
  final _httpClient = HttpClient();

  /// Execute a [request] on the server and returns a [APIResponse]
  ///
  /// This method should never throw but the response code of the [APIResponse]
  /// should be verified before accessing response content
  Future<APIResponse> exec(APIRequest request) async {
    try {
      //Add API tokens
      request.addString("serviceName", config().serviceName);
      request.addString("serviceToken", config().serviceToken);

      //Add user tokens (if required)
      if (request.needLogin) {
        final tokens = await AccountCredentialsHelper().get();
        assert(tokens != null);
        request.addString("userToken1", tokens.tokenOne);
        request.addString("userToken2", tokens.tokenTwo);
      }

      // Prepare request body
      String requestBody = "";
      request.args.forEach((key, value) => requestBody +=
          Uri.encodeQueryComponent(key) +
              "=" +
              Uri.encodeQueryComponent(value) +
              "&");

      List<int> bodyBytes = utf8.encode(requestBody);

      // Determine server URL
      final path = config().apiServerUri + request.uri;
      Uri url;
      if (!config().apiServerSecure)
        url = Uri.http(config().apiServerName, path);
      else
        url = Uri.https(config().apiServerName, path);

      //Connect to server
      final connection = await _httpClient.postUrl(url);
      connection.headers.set("Content-Length", bodyBytes.length.toString());
      connection.headers
          .set("Content-Type", "application/x-www-form-urlencoded");
      connection.add(bodyBytes);

      final response = await connection.close();

      if (response.statusCode != HttpStatus.ok)
        return APIResponse(response.statusCode, null);

      //Save & return response
      final responseBody = await response.transform(utf8.decoder).join();

      return APIResponse(response.statusCode, responseBody);
    } on Exception catch (e) {
      print(e.toString());
      print("Could not execute a request!");
      return APIResponse(-1, null);
    }
  }
}