refactor(2): Core Platform abstractions (IProcessRunner/IMediaMuxer + Desktop impls) - Hls/Dash/YtDlp through injection seams, threading contract documented (66 tests GREEN)

VideoDownloader.Core/Platform/ProcessModels.cs

@@ -0,0 +1,83 @@
+using System.Text;
+namespace VideoDownloader.Core.Platform;
+
+/// <summary>프로세스 실행 명세. EnvPrefix 값은 기존 값 앞에 붙는다(PATH 선두 주입용).</summary>
+public sealed record ProcessSpec(
+    string ExePath,
+    IReadOnlyList<string> Args,
+    IReadOnlyDictionary<string, string>? EnvPrefix = null);
+
+/// <summary>프로세스 실행 결과. Stdout/Stderr 은 전체 누적(라인 탭과 별개).</summary>
+public sealed record ProcessResult(int ExitCode, string Stdout, string Stderr);
+
+/// <summary>
+/// 프로세스 실행 추상화(재구성 ② / M0 전제). 모바일(iOS)에선 구현체를 주입하지 않고
+/// 데스크톱(Win/macOS/Linux)은 DesktopProcessRunner 사용. 단일 프리미티브로
+/// yt-dlp 라인 스트리밍 · -J 캡처 · ffmpeg 리먹스/DASH 진행 파싱을 모두 커버한다.
+/// </summary>
+public interface IProcessRunner
+{
+    /// <summary>실행. onLine?(stream:"out"|"err", line) 실시간 탭. 취소 시 트리 킬.</summary>
+    Task<ProcessResult> RunAsync(ProcessSpec spec, Action<string, string>? onLine, CancellationToken ct);
+}
+
+/// <summary>데스크톱 구현 — 기존 YtDlpRunner/HlsDownloader 의 검증된 안전 규칙:
+/// stdout/stderr 동시 드레인(데드락 방지), 취소/실패 시 entireProcessTree 킬, 인자 배열 전달.</summary>
+public sealed class DesktopProcessRunner : IProcessRunner
+{
+    public static DesktopProcessRunner Default { get; } = new();
+
+    public async Task<ProcessResult> RunAsync(ProcessSpec spec, Action<string, string>? onLine, CancellationToken ct)
+    {
+        System.Diagnostics.Process? proc = null;
+        try
+        {
+            var psi = new System.Diagnostics.ProcessStartInfo(spec.ExePath)
+            {
+                UseShellExecute = false,
+                CreateNoWindow = true,
+                RedirectStandardError = true,
+                RedirectStandardOutput = true,
+            };
+            foreach (var a in spec.Args) psi.ArgumentList.Add(a);
+            if (spec.EnvPrefix != null)
+            {
+                foreach (var (key, prefix) in spec.EnvPrefix)
+                {
+                    var cur = psi.Environment.TryGetValue(key, out var existing) ? (existing ?? "") : "";
+                    psi.Environment[key] = prefix + Path.PathSeparator + cur;
+                }
+            }
+
+            proc = System.Diagnostics.Process.Start(psi)
+                ?? throw new InvalidOperationException($"{spec.ExePath} 시작 실패");
+            await using var _ = ct.Register(() =>
+            {
+                try { if (!proc.HasExited) proc.Kill(entireProcessTree: true); } catch { }
+            });
+
+            var stdout = new System.Text.StringBuilder();
+            var stderr = new System.Text.StringBuilder();
+            var outTask = TapAsync(proc.StandardOutput, "out", stdout, onLine, ct);
+            var errTask = TapAsync(proc.StandardError, "err", stderr, onLine, ct);
+            await proc.WaitForExitAsync(ct);
+            await Task.WhenAll(outTask, errTask);
+            return new ProcessResult(proc.ExitCode, stdout.ToString(), stderr.ToString());
+        }
+        finally
+        {
+            try { if (proc is { HasExited: false }) proc.Kill(entireProcessTree: true); } catch { }
+        }
+    }
+
+    private static async Task TapAsync(StreamReader reader, string stream, StringBuilder acc,
+        Action<string, string>? onLine, CancellationToken ct)
+    {
+        string? line;
+        while ((line = await reader.ReadLineAsync(ct)) != null)
+        {
+            acc.AppendLine(line);
+            if (onLine != null && !string.IsNullOrWhiteSpace(line)) onLine(stream, line);
+        }
+    }
+}