Merge remote-tracking branch 'upstream/main' into merge-gramsrv-0e2fcdf9

internal/app/files/emoji_animation.go

@@ -0,0 +1,79 @@
+package files
+
+import (
+	"bytes"
+	"compress/gzip"
+	"context"
+	"fmt"
+	"io"
+
+	"telesrv/internal/domain"
+)
+
+const maxEmojiAnimationBytes = 2 << 20
+
+// DocumentAnimationJSON returns the Lottie JSON for an animated custom-emoji
+// document, decompressing TGS (gzip) transparently. Non-emoji documents and
+// documents without a stored blob return found=false. It backs the admin emoji
+// browser preview and reuses the existing file-blob storage (doc:<id> key).
+func (s *Service) DocumentAnimationJSON(ctx context.Context, documentID int64) ([]byte, bool, error) {
+	if s == nil || s.media == nil || s.blobs == nil || documentID <= 0 {
+		return nil, false, nil
+	}
+	doc, found, err := s.GetDocument(ctx, documentID)
+	if err != nil {
+		return nil, false, err
+	}
+	if !found || !documentIsCustomEmoji(doc) {
+		return nil, false, nil
+	}
+	blob, found, err := s.media.GetFileBlob(ctx, fmt.Sprintf("doc:%d", documentID))
+	if err != nil {
+		return nil, false, err
+	}
+	if !found || blob.Size <= 0 || blob.Size > maxEmojiAnimationBytes {
+		return nil, false, nil
+	}
+	data, total, err := s.blobs.GetRange(ctx, blob.ObjectKey, 0, blob.Size)
+	if err != nil {
+		return nil, false, err
+	}
+	if int64(len(data)) != total {
+		return nil, false, nil
+	}
+	out, err := gunzipIfNeeded(data)
+	if err != nil {
+		return nil, false, err
+	}
+	return out, true, nil
+}
+
+func documentIsCustomEmoji(doc domain.Document) bool {
+	for _, a := range doc.Attributes {
+		if a.Kind == domain.DocAttrCustomEmoji {
+			return true
+		}
+	}
+	return false
+}
+
+// gunzipIfNeeded transparently decompresses TGS (gzip-wrapped Lottie); raw JSON
+// (non-gzip) is returned unchanged.
+func gunzipIfNeeded(data []byte) ([]byte, error) {
+	if len(data) < 2 || data[0] != 0x1f || data[1] != 0x8b {
+		return data, nil
+	}
+	gz, err := gzip.NewReader(bytes.NewReader(data))
+	if err != nil {
+		return nil, fmt.Errorf("open tgs gzip: %w", err)
+	}
+	defer gz.Close()
+	out, err := io.ReadAll(io.LimitReader(gz, maxEmojiAnimationBytes+1))
+	if err != nil {
+		return nil, fmt.Errorf("decompress tgs: %w", err)
+	}
+	if len(out) > maxEmojiAnimationBytes {
+		return nil, fmt.Errorf("decompressed tgs too large")
+	}
+	return out, nil
+}