Data-Coupler/DataConnection/REST/Implementations/BaseRestServiceClient.cs

using DataConnection.REST.Configuration;
using DataConnection.REST.Interfaces;
using System;
using System.Net.Http;
using System.Net.Http.Headers;
using System.Net.Http.Json;
using System.Text;
using System.Threading;
using System.Threading.Tasks;

namespace DataConnection.REST.Implementations
{
    /// <summary>
    /// Base implementation for a REST service client using HttpClient.
    /// </summary>
    public class BaseRestServiceClient : IRestServiceClient, IDisposable
    {
        protected readonly HttpClient _httpClient;
        protected readonly RestServiceOptions _options;

        public BaseRestServiceClient(HttpClient httpClient, RestServiceOptions options)
        {
            _httpClient = httpClient ?? throw new ArgumentNullException(nameof(httpClient));
            _options = options ?? throw new ArgumentNullException(nameof(options));

            ConfigureHttpClient();
        }

        protected virtual void ConfigureHttpClient()
        {
            if (!string.IsNullOrWhiteSpace(_options.BaseUrl))
            {
                _httpClient.BaseAddress = new Uri(_options.BaseUrl);
            }

            _httpClient.Timeout = TimeSpan.FromSeconds(_options.TimeoutSeconds);
            _httpClient.DefaultRequestHeaders.Accept.Clear();
            _httpClient.DefaultRequestHeaders.Accept.Add(new MediaTypeWithQualityHeaderValue("application/json"));

            // Add authentication headers based on options
            if (!string.IsNullOrWhiteSpace(_options.ApiKey))
            {
                // Example: Add API key header (adjust header name as needed)
                _httpClient.DefaultRequestHeaders.TryAddWithoutValidation("X-API-KEY", _options.ApiKey);
            }
            else if (!string.IsNullOrWhiteSpace(_options.AuthToken))
            {
                _httpClient.DefaultRequestHeaders.Authorization = new AuthenticationHeaderValue("Bearer", _options.AuthToken);
            }
            else if (!string.IsNullOrWhiteSpace(_options.Username) && !string.IsNullOrWhiteSpace(_options.Password))
            {
                var basicAuthValue = Convert.ToBase64String(Encoding.UTF8.GetBytes($"{_options.Username}:{_options.Password}"));
                _httpClient.DefaultRequestHeaders.Authorization = new AuthenticationHeaderValue("Basic", basicAuthValue);
            }
            // Add other authentication methods (e.g., OAuth) if necessary
        }

        public virtual async Task<T?> GetAsync<T>(string requestUri, CancellationToken cancellationToken = default)
        {
            try
            {
                var response = await _httpClient.GetAsync(requestUri, cancellationToken);
                response.EnsureSuccessStatusCode(); // Throws exception for non-success status codes
                return await response.Content.ReadFromJsonAsync<T>(cancellationToken: cancellationToken);
            }
            catch (HttpRequestException ex)
            {
                // Log or handle specific HTTP request errors
                Console.WriteLine($"HTTP Request Error: {ex.Message}");
                // Consider custom exception handling
                throw;
            }
            catch (Exception ex)
            {
                 // Log or handle other errors (e.g., deserialization)
                Console.WriteLine($"Error during GET request: {ex.Message}");
                throw;
            }
        }

        public virtual async Task<TResponse?> PostAsync<TRequest, TResponse>(string requestUri, TRequest payload, CancellationToken cancellationToken = default)
        {
             try
            {
                var response = await _httpClient.PostAsJsonAsync(requestUri, payload, cancellationToken);
                response.EnsureSuccessStatusCode();
                return await response.Content.ReadFromJsonAsync<TResponse>(cancellationToken: cancellationToken);
            }
            catch (HttpRequestException ex)
            {
                Console.WriteLine($"HTTP Request Error: {ex.Message}");
                 throw;
            }
            catch (Exception ex)
            {
                 Console.WriteLine($"Error during POST request: {ex.Message}");
                throw;
            }
        }

        // Implement other methods (PUT, DELETE, etc.) similarly

        public void Dispose()
        {
            Dispose(true);
            GC.SuppressFinalize(this);
        }

        protected virtual void Dispose(bool disposing)
        {
            if (disposing)
            {
                // HttpClient is typically managed by HttpClientFactory,
                // but if created directly, dispose it here.
                // _httpClient?.Dispose();
            }
        }
    }
}