Fix preview or viewing of shared animated GIFs (#6386)

* Fix preview or viewing of shared animated GIFs

---------

Co-authored-by: Roman Perekhod <rperekhod@owncloud.com>

services/thumbnails/pkg/thumbnail/encoding.go

@@ -80,6 +80,7 @@ func (e JpegEncoder) MimeType() string {
 
 type GifEncoder struct{}
 
+// Encode encodes the image to a gif format
 func (e GifEncoder) Encode(w io.Writer, img interface{}) error {
 	g, ok := img.(*gif.GIF)
 	if !ok {
@@ -92,6 +93,7 @@ func (e GifEncoder) Types() []string {
 	return []string{typeGif}
 }
 
+// MimeType returns the mimetype used by the encoder.
 func (e GifEncoder) MimeType() string {
 	return "image/gif"
 }
@@ -110,3 +112,14 @@ func EncoderForType(fileType string) (Encoder, error) {
 		return nil, ErrNoEncoderForType
 	}
 }
+
+// GetExtForMime return the supported extension by mime
+func GetExtForMime(mime string) string {
+	ext := strings.TrimPrefix(strings.TrimSpace(strings.ToLower(mime)), "image/")
+	switch ext {
+	case typeJpg, typeJpeg, typePng, typeGif:
+		return ext
+	default:
+		return ""
+	}
+}

services/thumbnails/pkg/thumbnail/thumbnail.go

@@ -104,6 +104,7 @@ func mapToStorageRequest(r Request) storage.Request {
 	}
 }
 
+// IsMimeTypeSupported validate if the mime type is supported
 func IsMimeTypeSupported(m string) bool {
 	mimeType, _, err := mime.ParseMediaType(m)
 	if err != nil {
@@ -112,3 +113,22 @@ func IsMimeTypeSupported(m string) bool {
 	_, supported := SupportedMimeTypes[mimeType]
 	return supported
 }
+
+// PrepareRequest prepare the request based on image parameters
+func PrepareRequest(width, height int, tType, checksum string) (Request, error) {
+	generator, err := GeneratorForType(tType)
+	if err != nil {
+		return Request{}, err
+	}
+	encoder, err := EncoderForType(tType)
+	if err != nil {
+		return Request{}, err
+	}
+
+	return Request{
+		Resolution: image.Rect(0, 0, width, height),
+		Generator:  generator,
+		Encoder:    encoder,
+		Checksum:   checksum,
+	}, nil
+}

services/thumbnails/pkg/thumbnail/thumbnail_test.go

@@ -4,6 +4,7 @@ import (
 	"image"
 	"os"
 	"path/filepath"
+	"reflect"
 	"testing"
 
 	"github.com/owncloud/ocis/v2/ocis-pkg/log"
@@ -45,3 +46,86 @@ func BenchmarkGet(b *testing.B) {
 		_, _ = sut.Generate(req, img)
 	}
 }
+
+func TestPrepareRequest(t *testing.T) {
+	type args struct {
+		width    int
+		height   int
+		tType    string
+		checksum string
+	}
+	tests := []struct {
+		name    string
+		args    args
+		want    Request
+		wantErr bool
+	}{
+		{
+			name: "Test successful prepare the request for jpg",
+			args: args{
+				width:    32,
+				height:   32,
+				tType:    "jpg",
+				checksum: "1872ade88f3013edeb33decd74a4f947",
+			},
+			want: Request{
+				Resolution: image.Rect(0, 0, 32, 32),
+				Encoder:    JpegEncoder{},
+				Generator:  SimpleGenerator{},
+				Checksum:   "1872ade88f3013edeb33decd74a4f947",
+			},
+		},
+		{
+			name: "Test successful prepare the request for png",
+			args: args{
+				width:    32,
+				height:   32,
+				tType:    "png",
+				checksum: "1872ade88f3013edeb33decd74a4f947",
+			},
+			want: Request{
+				Resolution: image.Rect(0, 0, 32, 32),
+				Encoder:    PngEncoder{},
+				Generator:  SimpleGenerator{},
+				Checksum:   "1872ade88f3013edeb33decd74a4f947",
+			},
+		},
+		{
+			name: "Test successful prepare the request for gif",
+			args: args{
+				width:    32,
+				height:   32,
+				tType:    "gif",
+				checksum: "1872ade88f3013edeb33decd74a4f947",
+			},
+			want: Request{
+				Resolution: image.Rect(0, 0, 32, 32),
+				Encoder:    GifEncoder{},
+				Generator:  GifGenerator{},
+				Checksum:   "1872ade88f3013edeb33decd74a4f947",
+			},
+		},
+		{
+			name: "Test error when prepare the request for bmp",
+			args: args{
+				width:    32,
+				height:   32,
+				tType:    "bmp",
+				checksum: "1872ade88f3013edeb33decd74a4f947",
+			},
+			wantErr: true,
+		},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			got, err := PrepareRequest(tt.args.width, tt.args.height, tt.args.tType, tt.args.checksum)
+			if (err != nil) != tt.wantErr {
+				t.Errorf("PrepareRequest() error = %v, wantErr %v", err, tt.wantErr)
+				return
+			}
+			if !reflect.DeepEqual(got, tt.want) {
+				t.Errorf("PrepareRequest() got = %v, want %v", got, tt.want)
+			}
+		})
+	}
+}