refactor<*>: rewrite all with AvaloniaUI

src/Models/AvatarManager.cs

@@ -0,0 +1,120 @@
+using Avalonia.Media.Imaging;
+using Avalonia.Threading;
+using System;
+using System.Collections.Generic;
+using System.IO;
+using System.Net.Http;
+using System.Threading;
+using System.Threading.Tasks;
+
+namespace SourceGit.Models {
+    public interface IAvatarHost {
+        void OnAvatarResourceReady(string md5, Bitmap bitmap);
+    }
+
+    public static class AvatarManager {
+        static AvatarManager() {
+            _storePath = Path.Combine(Environment.GetFolderPath(Environment.SpecialFolder.ApplicationData), "SourceGit", "avatars");
+            if (!Directory.Exists(_storePath)) Directory.CreateDirectory(_storePath);
+
+            Task.Run(() => {
+                while (true) {
+                    var md5 = null as string;
+
+                    lock (_synclock) {
+                        foreach (var one in _requesting) {
+                            md5 = one;
+                            break;
+                        }
+                    }
+
+                    if (md5 == null) {
+                        Thread.Sleep(100);
+                        continue;
+                    }
+
+                    var localFile = Path.Combine(_storePath, md5);
+                    var img = null as Bitmap;
+                    try {
+                        var client = new HttpClient() { Timeout = TimeSpan.FromSeconds(2) };
+                        var task = client.GetAsync($"https://cravatar.cn/avatar/{md5}?d=404");
+                        task.Wait();
+
+                        var rsp = task.Result;
+                        if (rsp.IsSuccessStatusCode) {
+                            using (var stream = rsp.Content.ReadAsStream()) {
+                                using (var writer = File.OpenWrite(localFile)) {
+                                    stream.CopyTo(writer);
+                                }
+                            }
+
+                            using (var reader = File.OpenRead(localFile)) {
+                                img = Bitmap.DecodeToWidth(reader, 128);
+                            }
+                        }
+                    } catch { }
+
+                    lock (_synclock) {
+                        _requesting.Remove(md5);
+                    }
+
+                    Dispatcher.UIThread.InvokeAsync(() => {
+                        if (_resources.ContainsKey(md5)) _resources[md5] = img;
+                        else _resources.Add(md5, img);
+                        if (img != null) NotifyResourceReady(md5, img);
+                    });
+                }
+            });
+        }
+
+        public static void Subscribe(IAvatarHost host) {
+            _avatars.Add(new WeakReference<IAvatarHost>(host));
+        }
+
+        public static Bitmap Request(string md5, bool forceRefetch = false) {
+            if (forceRefetch) {
+                if (_resources.ContainsKey(md5)) _resources.Remove(md5);                
+            } else {
+                if (_resources.ContainsKey(md5)) return _resources[md5];
+
+                var localFile = Path.Combine(_storePath, md5);
+                if (File.Exists(localFile)) {
+                    try {
+                        using (var stream = File.OpenRead(localFile)) {
+                            var img = Bitmap.DecodeToWidth(stream, 128);
+                            _resources.Add(md5, img);
+                            return img;
+                        }
+                    } catch { }
+                }
+            }
+
+            lock (_synclock) {
+                if (!_requesting.Contains(md5)) _requesting.Add(md5);
+            }
+
+            return null;
+        }
+
+        private static void NotifyResourceReady(string md5, Bitmap bitmap) {
+            List<WeakReference<IAvatarHost>> invalids = new List<WeakReference<IAvatarHost>>();
+            foreach (var avatar in _avatars) {
+                IAvatarHost retrived = null;
+                if (avatar.TryGetTarget(out retrived)) {
+                    retrived.OnAvatarResourceReady(md5, bitmap);
+                    break;
+                } else {
+                    invalids.Add(avatar);
+                }
+            }
+
+            foreach (var invalid in invalids) _avatars.Remove(invalid);
+        }
+
+        private static object _synclock = new object();
+        private static string _storePath = string.Empty;
+        private static List<WeakReference<IAvatarHost>> _avatars = new List<WeakReference<IAvatarHost>>();
+        private static Dictionary<string, Bitmap> _resources = new Dictionary<string, Bitmap>();
+        private static HashSet<string> _requesting = new HashSet<string>();
+    }
+}