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