Add feature to manipulator service to force encode to target extension (#79)

* Add feature to manipulator service to force encode to target extension

* Add target image for encoding to different file extension

* Update naming from TargetExtension to TargetFormat

---------

Co-authored-by: Kenneth Halim <kanisius.halim@gojek.com>

Author: kanisiuskenneth

pkg/processor/native/_testdata/test_png_to_jpg.jpg

@@ -66,6 +66,9 @@ func (m *manipulator) Process(spec processSpec) ([]byte, error) {
 	if err != nil {
 		return nil, err
 	}
+	if spec.TargetFormat != "" {
+		f = spec.TargetFormat
+	}
 	m.metricService.TrackDuration(decodeDurationKey, t, spec.ImageData)
 	if params[fit] == crop {
 		t = time.Now()

pkg/service/manipulator.go

@@ -56,6 +56,24 @@ func TestManipulator_Process_ReturnsImageAsWebPIfCallerSupportsWebP(t *testing.T
 	assert.Equal(t, expectedImg, img)
 }
 
+// Integration test to verify the flow of encoding with target format
+func TestManipulator_Process_ReturnsImageWithTargetFormat(t *testing.T) {
+	// Use real processor to ensure that right encoder is being used
+	p := native.NewBildProcessor()
+	m := NewManipulator(p, nil, metrics.NewPrometheus(prometheus.NewRegistry()))
+
+	img, _ := ioutil.ReadFile("../processor/native/_testdata/test.png")
+	expectedImg, _ := ioutil.ReadFile("../processor/native/_testdata/test_png_to_jpg.jpg")
+	ext := "jpg"
+	s := NewSpecBuilder().
+		WithImageData(img).
+		WithTargetFormat(ext).
+		Build()
+	img, err := m.Process(s)
+	assert.Nil(t, err)
+	assert.Equal(t, expectedImg, img)
+}
+
 func TestManipulator_Process(t *testing.T) {
 	mp := &mockProcessor{}
 	ms := &metrics.MockMetricService{}

pkg/service/manipulator_test.go

@@ -12,10 +12,19 @@ type processSpec struct {
 	ImageData []byte
 	// Params hold the key-value pairs for the processing job and tells the manipulator what to do with the image
 	Params map[string]string
+	// Reformat image to target format
+	TargetFormat string
 	// Formats have the information of accepted formats, whether darkroom can return the image using webp or not
 	formats []string
 }
 
+const (
+	extJPG  = "jpg"
+	extPNG  = "png"
+	extWebP = "webp"
+	extJPEG = "jpeg"
+)
+
 func (ps *processSpec) IsWebPSupported() bool {
 	for _, f := range ps.formats {
 		if f == "image/webp" {
@@ -30,6 +39,7 @@ type SpecBuilder interface {
 	WithImageData(img []byte) SpecBuilder
 	WithParams(params map[string]string) SpecBuilder
 	WithFormats(formats []string) SpecBuilder
+	WithTargetFormat(ext string) SpecBuilder
 	Build() processSpec
 }
 
@@ -38,6 +48,7 @@ type specBuilder struct {
 	imageData []byte
 	params    map[string]string
 	formats   []string
+	extension string
 }
 
 func (sb *specBuilder) WithScope(scope string) SpecBuilder {
@@ -60,12 +71,21 @@ func (sb *specBuilder) WithFormats(formats []string) SpecBuilder {
 	return sb
 }
 
+func (sb *specBuilder) WithTargetFormat(ext string) SpecBuilder {
+	switch ext {
+	case extJPG, extJPEG, extPNG, extWebP:
+		sb.extension = ext
+	}
+	return sb
+}
+
 func (sb *specBuilder) Build() processSpec {
 	return processSpec{
-		Scope:     sb.scope,
-		ImageData: sb.imageData,
-		Params:    sb.params,
-		formats:   sb.formats,
+		Scope:        sb.scope,
+		ImageData:    sb.imageData,
+		Params:       sb.params,
+		formats:      sb.formats,
+		TargetFormat: sb.extension,
 	}
 }
 

pkg/service/spec.go

@@ -11,18 +11,20 @@ func TestSpecBuilder_Build(t *testing.T) {
 	img := []byte("imageData")
 	params := map[string]string{"foo": "bar"}
 	formats := []string{"image/webp", "image/apng"}
-
+	ext := "png"
 	spec := NewSpecBuilder().
 		WithScope(scope).
 		WithImageData(img).
 		WithParams(params).
 		WithFormats(formats).
+		WithTargetFormat(ext).
 		Build()
 
 	assert.Equal(t, spec.Scope, scope)
 	assert.Equal(t, spec.ImageData, img)
 	assert.Equal(t, spec.Params, params)
 	assert.Equal(t, spec.formats, formats)
+	assert.Equal(t, spec.TargetFormat, ext)
 }
 
 func TestSpec_IsWebPSupported(t *testing.T) {
@@ -34,3 +36,9 @@ func TestSpec_IsWebPSupported(t *testing.T) {
 	spec = NewSpecBuilder().WithFormats(f).Build()
 	assert.False(t, spec.IsWebPSupported())
 }
+
+func TestSpec_Build_TargetExtensionNotValid(t *testing.T) {
+	ext := "gif"
+	spec := NewSpecBuilder().WithTargetFormat(ext).Build()
+	assert.Empty(t, spec.TargetFormat)
+}