Stream post videos to Spaces (#23)

Pass the spooled video file through instead of buffering it in RAM, and sign Spaces uploads as UNSIGNED-PAYLOAD so the client does not hash the body first.

Reviewed-on: #23
Co-authored-by: codegirl-007 <s.raide@gmail.com>

internal/web/post_images_test.go

@@ -60,20 +60,34 @@ func TestPreparePostImage(t *testing.T) {
 func TestPreparePostVideo(t *testing.T) {
 	t.Parallel()
 
-	prepared, err := preparePostVideoHeader(t, "clip.mp4", tinyMP4())
+	mp4 := tinyMP4()
+	prepared, err := preparePostVideoHeader(t, "clip.mp4", mp4)
 	if err != nil {
 		t.Fatal(err)
 	}
-	if prepared.extension != ".mp4" || prepared.contentType != "video/mp4" || len(prepared.body) == 0 {
-		t.Fatalf("prepared MP4 = %+v", prepared)
-	}
-	prepared, err = preparePostVideoHeader(t, "clip.webm", tinyWebM())
+	defer prepared.body.Close()
+	got, err := io.ReadAll(prepared.body)
 	if err != nil {
 		t.Fatal(err)
 	}
-	if prepared.extension != ".webm" || prepared.contentType != "video/webm" {
+	if prepared.extension != ".mp4" || prepared.contentType != "video/mp4" ||
+		prepared.size != int64(len(mp4)) || !bytes.Equal(got, mp4) {
+		t.Fatalf("prepared MP4 = %+v len(body)=%d", prepared, len(got))
+	}
+
+	webm := tinyWebM()
+	prepared, err = preparePostVideoHeader(t, "clip.webm", webm)
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer prepared.body.Close()
+	if prepared.extension != ".webm" || prepared.contentType != "video/webm" ||
+		prepared.size != int64(len(webm)) {
 		t.Fatalf("prepared WebM = %+v", prepared)
 	}
+	if _, err := preparePostVideoHeader(t, "empty.mp4", nil); err == nil {
+		t.Fatal("empty video unexpectedly succeeded")
+	}
 	if _, err := preparePostVideoHeader(t, "notes.txt", []byte("not a video")); err == nil {
 		t.Fatal("text video upload unexpectedly succeeded")
 	}
@@ -269,6 +283,17 @@ func TestPostVideoMultipartLifecycle(t *testing.T) {
 		!strings.HasPrefix(root.Images[1].ObjectKey, "post-videos/") {
 		t.Fatalf("root media = %+v", root.Images)
 	}
+	clip := tinyMP4()
+	var streamed recordedImageUpload
+	for _, upload := range blobs.recordedUploads() {
+		if strings.HasPrefix(upload.key, "post-videos/") {
+			streamed = upload
+			break
+		}
+	}
+	if streamed.size != int64(len(clip)) || !bytes.Equal(streamed.body, clip) {
+		t.Fatalf("streamed video upload = %+v", streamed)
+	}
 
 	rec = multipartPost(t, handler, "/posts/"+root.ID+"/edit", map[string][]string{
 		"_csrf":                      {csrf},
@@ -513,6 +538,7 @@ func solidJPEG(t *testing.T, width, height int) []byte {
 type recordedImageUpload struct {
 	key         string
 	contentType string
+	size        int64
 	body        []byte
 }
 
@@ -540,6 +566,7 @@ func (b *recordingImageBlob) Upload(_ context.Context, object blob.FileUpload) (
 	b.uploads = append(b.uploads, recordedImageUpload{
 		key:         object.Key,
 		contentType: object.ContentType,
+		size:        object.Size,
 		body:        body,
 	})
 	return "https://cdn.example/" + object.Key, nil
@@ -553,9 +580,13 @@ func (b *recordingImageBlob) Delete(_ context.Context, key string) error {
 }
 
 func (b *recordingImageBlob) uploadCount() int {
+	return len(b.recordedUploads())
+}
+
+func (b *recordingImageBlob) recordedUploads() []recordedImageUpload {
 	b.mu.Lock()
 	defer b.mu.Unlock()
-	return len(b.uploads)
+	return append([]recordedImageUpload(nil), b.uploads...)
 }
 
 func (b *recordingImageBlob) deletedKeys() []string {