Continue plan implementation and updates

HttpCompatibility.cs

@@ -0,0 +1,175 @@
+using System;
+using System.Collections.Generic;
+using System.IO;
+using System.Linq;
+using System.Net;
+using System.Net.Http;
+using System.Net.Http.Headers;
+using System.Text;
+using System.Threading.Tasks;
+
+namespace Ketarin
+{
+    /// <summary>
+    /// Provides HTTP compatibility methods for .NET 6 migration.
+    /// Handles deprecated WebClient and HttpWebRequest usage.
+    /// </summary>
+    internal static class HttpCompatibility
+    {
+        private static readonly HttpClient _httpClient = new HttpClient();
+
+        static HttpCompatibility()
+        {
+            // Configure default headers
+            _httpClient.DefaultRequestHeaders.UserAgent.ParseAdd("Mozilla/4.0 (compatible; Ketarin; +https://ketarin.org/)");
+            _httpClient.DefaultRequestHeaders.Accept.ParseAdd("*/*");
+            _httpClient.Timeout = TimeSpan.FromSeconds(30); // Default timeout
+
+            // Ignore SSL certificate validation errors (similar to original behavior)
+            var handler = new HttpClientHandler();
+            handler.ServerCertificateCustomValidationCallback = (sender, cert, chain, sslPolicyErrors) => true;
+            _httpClient = new HttpClient(handler);
+        }
+
+        /// <summary>
+        /// Downloads a string from the specified URL asynchronously.
+        /// </summary>
+        public static async Task<string> DownloadStringAsync(string url, string userAgent = null)
+        {
+            using var request = new HttpRequestMessage(HttpMethod.Get, url);
+
+            if (!string.IsNullOrEmpty(userAgent))
+            {
+                request.Headers.UserAgent.ParseAdd(userAgent);
+            }
+
+            using var response = await _httpClient.SendAsync(request);
+            response.EnsureSuccessStatusCode();
+
+            return await response.Content.ReadAsStringAsync();
+        }
+
+        /// <summary>
+        /// Downloads data from the specified URL asynchronously.
+        /// </summary>
+        public static async Task<byte[]> DownloadDataAsync(string url, string userAgent = null)
+        {
+            using var request = new HttpRequestMessage(HttpMethod.Get, url);
+
+            if (!string.IsNullOrEmpty(userAgent))
+            {
+                request.Headers.UserAgent.ParseAdd(userAgent);
+            }
+
+            using var response = await _httpClient.SendAsync(request);
+            response.EnsureSuccessStatusCode();
+
+            return await response.Content.ReadAsByteArrayAsync();
+        }
+
+        /// <summary>
+        /// Downloads a file from the specified URL to the specified path asynchronously.
+        /// </summary>
+        public static async Task DownloadFileAsync(string url, string filePath, string userAgent = null)
+        {
+            using var request = new HttpRequestMessage(HttpMethod.Get, url);
+
+            if (!string.IsNullOrEmpty(userAgent))
+            {
+                request.Headers.UserAgent.ParseAdd(userAgent);
+            }
+
+            using var response = await _httpClient.SendAsync(request);
+            response.EnsureSuccessStatusCode();
+
+            using var fileStream = File.Create(filePath);
+            await response.Content.CopyToAsync(fileStream);
+        }
+
+        /// <summary>
+        /// Sends a POST request with form data asynchronously.
+        /// </summary>
+        public static async Task<string> PostFormDataAsync(string url, Dictionary<string, string> formData, string userAgent = null)
+        {
+            using var content = new FormUrlEncodedContent(formData);
+
+            using var request = new HttpRequestMessage(HttpMethod.Post, url)
+            {
+                Content = content
+            };
+
+            if (!string.IsNullOrEmpty(userAgent))
+            {
+                request.Headers.UserAgent.ParseAdd(userAgent);
+            }
+
+            request.Content.Headers.ContentType = new MediaTypeHeaderValue("application/x-www-form-urlencoded");
+
+            using var response = await _httpClient.SendAsync(request);
+            response.EnsureSuccessStatusCode();
+
+            return await response.Content.ReadAsStringAsync();
+        }
+
+        /// <summary>
+        /// Gets the response URI after following redirects.
+        /// </summary>
+        public static async Task<Uri> GetResponseUriAsync(string url, string userAgent = null)
+        {
+            using var request = new HttpRequestMessage(HttpMethod.Head, url);
+
+            if (!string.IsNullOrEmpty(userAgent))
+            {
+                request.Headers.UserAgent.ParseAdd(userAgent);
+            }
+
+            using var response = await _httpClient.SendAsync(request, HttpCompletionOption.ResponseHeadersRead);
+
+            return response.RequestMessage.RequestUri;
+        }
+
+        /// <summary>
+        /// Sets the default timeout for HTTP operations.
+        /// </summary>
+        public static void SetTimeout(int seconds)
+        {
+            _httpClient.Timeout = TimeSpan.FromSeconds(seconds);
+        }
+
+        /// <summary>
+        /// Gets the current timeout setting.
+        /// </summary>
+        public static int GetTimeout()
+        {
+            return (int)_httpClient.Timeout.TotalSeconds;
+        }
+
+        /// <summary>
+        /// Adds a request to the cancellation list (for compatibility).
+        /// </summary>
+        public static void AddRequestToCancel(HttpRequestMessage request)
+        {
+            // Implementation would depend on the Updater class
+            // This is a placeholder for compatibility
+        }
+
+        /// <summary>
+        /// Checks if the given URI needs protocol fixing.
+        /// </summary>
+        public static Uri FixNoProtocolUri(Uri uri)
+        {
+            if (uri == null) return null;
+
+            string uriString = uri.ToString();
+
+            // If no protocol is specified, assume http
+            if (!uriString.Contains("://"))
+            {
+                uriString = "http://" + uriString;
+                return new Uri(uriString);
+            }
+
+            return uri;
+        }
+    }
+}