Phase B (T1-5/T1-6/T2-2/T2-8/T2-12): download manager flyout w/ speed+pause/resume/cancel, bookmark bar, tab sleeping, tab search (open+closed), context menu w/ 'download video from this link' (79 tests GREEN)

VideoDownloader.App/Browser/Features/PageDownloadTracker.cs

@@ -0,0 +1,108 @@
+using System.Collections.ObjectModel;
+using System.ComponentModel;
+using System.Runtime.CompilerServices;
+
+namespace VideoDownloader.App.Browser.Features;
+
+/// <summary>CoreWebView2DownloadOperation 의 최소 추상화(단위 테스트 fake 교체 가능).</summary>
+public interface IDownloadOperation
+{
+    string Uri { get; }
+    string FileName { get; }
+    long BytesReceived { get; }
+    long TotalBytesToReceive { get; }
+    /// <summary>InProgress / Interrupted / Completed / Cancelled</summary>
+    string State { get; }
+    void Pause();
+    void Resume();
+    void Cancel();
+    /// <summary>BytesReceived/State 변경 통지(구현은 호스트 스레드에서 발화).</summary>
+    event Action? Changed;
+}
+
+/// <summary>다운로드 매니저 UI 항목(T1-5) — 진행률/속도/상태를 INPC 로 노출.</summary>
+public sealed class PageDownloadItem : INotifyPropertyChanged
+{
+    public IDownloadOperation Op { get; }
+    public string FileName { get; }
+    public string Uri { get; }
+    public long TotalBytes { get; }
+    private long _received;
+    private long _bps;
+    private string _state;
+
+    public PageDownloadItem(IDownloadOperation op, string fileName)
+    {
+        Op = op;
+        FileName = fileName;
+        Uri = op.Uri;
+        TotalBytes = op.TotalBytesToReceive;
+        _received = op.BytesReceived;
+        _state = op.State;
+        op.Changed += () =>
+        {
+            _received = op.BytesReceived;
+            _state = op.State;
+            OnPropertyChangedAll();
+        };
+    }
+
+    public double Percent => TotalBytes > 0 ? Math.Clamp(_received * 100.0 / TotalBytes, 0, 100) : 0;
+    public long BytesPerSecond => _bps;
+    public string State => _state;
+    public bool IsFinished => _state is "Completed" or "Interrupted" or "Cancelled";
+    public bool CanControl => _state == "InProgress";
+
+    public string SpeedText => _bps switch
+    {
+        <= 0 => "—",
+        < 1024 => $"{(double)_bps:F1} B/s",
+        < 1024 * 1024 => $"{_bps / 1024.0:F1} KB/s",
+        _ => $"{_bps / 1024.0 / 1024.0:F1} MB/s",
+    };
+
+    private long? _lastSpeedReceived;
+
+    /// <summary>속도 갱신: (현재까지 수신 바이트, 직전 호출로부터 경과).</summary>
+    public void UpdateSpeed(long receivedNow, TimeSpan elapsed)
+    {
+        _received = receivedNow;
+        if (elapsed.TotalSeconds > 0)
+        {
+            var delta = Math.Max(0, receivedNow - (_lastSpeedReceived ?? 0));
+            _bps = (long)(delta / elapsed.TotalSeconds);
+        }
+        _lastSpeedReceived = receivedNow;
+        OnPropertyChangedAll();
+    }
+
+    public event PropertyChangedEventHandler? PropertyChanged;
+    private void OnPropertyChangedAll()
+    {
+        foreach (var n in new[] { nameof(Percent), nameof(BytesPerSecond), nameof(SpeedText), nameof(State), nameof(IsFinished), nameof(CanControl) })
+            PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(n));
+    }
+}
+
+/// <summary>페이지 다운로드 목록(T1-5) — 최신순, 일시정지/재개/취소, 완료 정리.</summary>
+public sealed class PageDownloadTracker
+{
+    public ObservableCollection<PageDownloadItem> Items { get; } = new();
+
+    public PageDownloadItem Add(IDownloadOperation op, string fileName)
+    {
+        var item = new PageDownloadItem(op, fileName);
+        Items.Insert(0, item);
+        return item;
+    }
+
+    public void Pause(PageDownloadItem item) => item.Op.Pause();
+    public void Resume(PageDownloadItem item) => item.Op.Resume();
+    public void Cancel(PageDownloadItem item) => item.Op.Cancel();
+
+    public void ClearCompleted()
+    {
+        foreach (var done in Items.Where(i => i.IsFinished).ToList())
+            Items.Remove(done);
+    }
+}