ConnectionManager.txt

using System;
using System.Collections.Generic;
using System.Linq;
using System.Net.Http.Headers;
using System.Net.Http;
using System.Net;
using System.Text;
using System.Threading.Tasks;
using System.Net.Http.Json;
using Microsoft.Extensions.Options;

namespace {TargetNamespace} {
    public class ConnectionManager {
        private readonly HttpClient _httpClient;
        private readonly GenesysCloudCredentials _credentials;
        private AuthTokenInfo? _tokenInfo;
        private DateTime _tokenExpiresAt = DateTime.MinValue;
        /// <summary>
        /// Initializes a new instance of the <see cref="ConnectionManager"/> class through dependency injection.
        /// </summary>
        /// <param name="genesysCloudCredentials">An instance of <see cref="IOptions<GenesysCloudCredentials>"/> which holds the credentials for the access.</param>
        public ConnectionManager(IOptions<GenesysCloudCredentials> genesysCloudCredentials) {
            _credentials = genesysCloudCredentials.Value;
            _httpClient = new HttpClient {
                BaseAddress = new Uri($"https://api.{_credentials.Environment}")
            };
        }

        /// <summary>
        /// Initializes a new instance of the <see cref="ConnectionManager"/> class.
        /// </summary>
        /// <param name="genesysCloudCredentials">An instance of <see cref="GenesysCloudCredentials"/> which holds the credentials for the access.</param>
        public ConnectionManager(GenesysCloudCredentials genesysCloudCredentials) {
            _credentials = genesysCloudCredentials;
            _httpClient = new HttpClient {
                BaseAddress = new Uri($"https://api.{_credentials.Environment}")
            };
        }

        internal async Task<HttpClient> GetClient() {
            await CheckToken();
            return _httpClient;
        }

        private async Task CheckToken() {
            if (_tokenInfo == null || _tokenInfo.AccessToken == null || _tokenExpiresAt < DateTime.Now) {
                await GetToken();
            }
            if (_tokenInfo == null || _tokenInfo.AccessToken == null) {
                throw new Exception("Token invalid");
            }
            if ((_tokenExpiresAt - DateTime.Now).TotalMinutes < 5 && _tokenInfo.RefreshToken != null) {
                await GetToken(_tokenInfo.RefreshToken);
            }
        }

        private async Task GetToken(string? refreshToken = null) {
            var basicAuthauth = System.Convert.ToBase64String(System.Text.Encoding.UTF8.GetBytes($"{_credentials.ClientId}:{_credentials.ClientSecret}"));
            _httpClient.DefaultRequestHeaders.Authorization = new AuthenticationHeaderValue("Basic", basicAuthauth);
            var form = new List<KeyValuePair<string, string>>();
            if (string.IsNullOrEmpty(refreshToken)) {
                form.Add(new KeyValuePair<string, string>("grant_type", "client_credentials"));
            }
            else {
                form.Add(new KeyValuePair<string, string>("grant_type", "refresh_token"));
                form.Add(new KeyValuePair<string, string>("refresh_token", refreshToken));
            }

            var response = await _httpClient.PostAsync($"https://login.{_credentials.Environment}/oauth/token", new FormUrlEncodedContent(form));
            response.EnsureSuccessStatusCode();
            _tokenInfo = await response.Content.ReadFromJsonAsync<AuthTokenInfo>();
            if (_tokenInfo != null) {
                _httpClient.DefaultRequestHeaders.Authorization = new AuthenticationHeaderValue("Bearer", _tokenInfo.AccessToken);
                if (_tokenInfo.ExpiresIn.HasValue) {
                    _tokenExpiresAt = DateTime.Now.AddSeconds((int)_tokenInfo.ExpiresIn);
                }
            }
        }

    }
}