initial changes

Makefile

@@ -74,6 +74,7 @@ LOG_FIELDS_PREFIX=
 PDFENGINES_ENGINES=
 PDFENGINES_MERGE_ENGINES=qpdf,pdfcpu,pdftk
 PDFENGINES_SPLIT_ENGINES=pdfcpu,qpdf,pdftk
+PDFENGINES_FLATTEN_ENGINES=qpdf
 PDFENGINES_CONVERT_ENGINES=libreoffice-pdfengine
 PDFENGINES_READ_METADATA_ENGINES=exiftool
 PDFENGINES_WRITE_METADATA_ENGINES=exiftool
@@ -143,6 +144,7 @@ run: ## Start a Gotenberg container
 	--pdfengines-engines=$(PDFENGINES_ENGINES) \
 	--pdfengines-merge-engines=$(PDFENGINES_MERGE_ENGINES) \
 	--pdfengines-split-engines=$(PDFENGINES_SPLIT_ENGINES) \
+	--pdfengines-convert-engines=$(PDFENGINES_FLATTEN_ENGINES) \
 	--pdfengines-convert-engines=$(PDFENGINES_CONVERT_ENGINES) \
 	--pdfengines-read-metadata-engines=$(PDFENGINES_READ_METADATA_ENGINES) \
 	--pdfengines-write-metadata-engines=$(PDFENGINES_WRITE_METADATA_ENGINES) \

pkg/gotenberg/mocks.go

@@ -38,6 +38,7 @@ func (mod *ValidatorMock) Validate() error {
 type PdfEngineMock struct {
 	MergeMock         func(ctx context.Context, logger *zap.Logger, inputPaths []string, outputPath string) error
 	SplitMock         func(ctx context.Context, logger *zap.Logger, mode SplitMode, inputPath, outputDirPath string) ([]string, error)
+	FlattenMock       func(ctx context.Context, logger *zap.Logger, inputPath, outputPath string) error
 	ConvertMock       func(ctx context.Context, logger *zap.Logger, formats PdfFormats, inputPath, outputPath string) error
 	ReadMetadataMock  func(ctx context.Context, logger *zap.Logger, inputPath string) (map[string]interface{}, error)
 	WriteMetadataMock func(ctx context.Context, logger *zap.Logger, metadata map[string]interface{}, inputPath string) error
@@ -51,6 +52,10 @@ func (engine *PdfEngineMock) Split(ctx context.Context, logger *zap.Logger, mode
 	return engine.SplitMock(ctx, logger, mode, inputPath, outputDirPath)
 }
 
+func (engine *PdfEngineMock) Flatten(ctx context.Context, logger *zap.Logger, inputPath, outputPath string) error {
+	return engine.FlattenMock(ctx, logger, inputPath, outputPath)
+}
+
 func (engine *PdfEngineMock) Convert(ctx context.Context, logger *zap.Logger, formats PdfFormats, inputPath, outputPath string) error {
 	return engine.ConvertMock(ctx, logger, formats, inputPath, outputPath)
 }

pkg/gotenberg/pdfengine.go

@@ -96,6 +96,10 @@ type PdfEngine interface {
 	// Split splits a given PDF file.
 	Split(ctx context.Context, logger *zap.Logger, mode SplitMode, inputPath, outputDirPath string) ([]string, error)
 
+	// Flatten PDF refers to merging the annotations (such as markup, widgets, 3D models, etc.) into a static area that is part of the PDF document
+	// By flattening and merging existing annotation appearances with page content, the original annotations are deleted from the PDF pages.
+	Flatten(ctx context.Context, logger *zap.Logger, inputPath, outputPath string) error
+
 	// Convert transforms a given PDF to the specified formats defined in
 	// PdfFormats. If no format, it does nothing.
 	Convert(ctx context.Context, logger *zap.Logger, formats PdfFormats, inputPath, outputPath string) error

pkg/modules/exiftool/exiftool.go

@@ -63,6 +63,11 @@ func (engine *ExifTool) Split(ctx context.Context, logger *zap.Logger, mode gote
 	return nil, fmt.Errorf("split PDF with ExifTool: %w", gotenberg.ErrPdfEngineMethodNotSupported)
 }
 
+// Flatten is not available in this implementation.
+func (engine *ExifTool) Flatten(ctx context.Context, logger *zap.Logger, inputPath, outputPath string) error {
+	return fmt.Errorf("flatten PDF with ExifTool: %w", gotenberg.ErrPdfEngineMethodNotSupported)
+}
+
 // Convert is not available in this implementation.
 func (engine *ExifTool) Convert(ctx context.Context, logger *zap.Logger, formats gotenberg.PdfFormats, inputPath, outputPath string) error {
 	return fmt.Errorf("convert PDF to '%+v' with ExifTool: %w", formats, gotenberg.ErrPdfEngineMethodNotSupported)

pkg/modules/libreoffice/pdfengine/pdfengine.go

@@ -56,6 +56,11 @@ func (engine *LibreOfficePdfEngine) Split(ctx context.Context, logger *zap.Logge
 	return nil, fmt.Errorf("split PDF with LibreOffice: %w", gotenberg.ErrPdfEngineMethodNotSupported)
 }
 
+// Flatten is not available in this implementation.
+func (engine *LibreOfficePdfEngine) Flatten(ctx context.Context, logger *zap.Logger, inputPath, outputPath string) error {
+	return fmt.Errorf("Flatten PDF with LibreOffice: %w", gotenberg.ErrPdfEngineMethodNotSupported)
+}
+
 // Convert converts the given PDF to a specific PDF format. Currently, only the
 // PDF/A-1b, PDF/A-2b, PDF/A-3b and PDF/UA formats are available. If another
 // PDF format is requested, it returns a [gotenberg.ErrPdfFormatNotSupported]

pkg/modules/pdfcpu/pdfcpu.go

@@ -107,6 +107,11 @@ func (engine *PdfCpu) Split(ctx context.Context, logger *zap.Logger, mode gotenb
 	return outputPaths, nil
 }
 
+// Flatten is not available in this implementation.
+func (engine *PdfCpu) Flatten(ctx context.Context, logger *zap.Logger, inputPath, outputPath string) error {
+	return fmt.Errorf("flatten PDF with pdfcpu: %w", gotenberg.ErrPdfEngineMethodNotSupported)
+}
+
 // Convert is not available in this implementation.
 func (engine *PdfCpu) Convert(ctx context.Context, logger *zap.Logger, formats gotenberg.PdfFormats, inputPath, outputPath string) error {
 	return fmt.Errorf("convert PDF to '%+v' with pdfcpu: %w", formats, gotenberg.ErrPdfEngineMethodNotSupported)

pkg/modules/pdfengines/multi.go

@@ -14,6 +14,7 @@ import (
 type multiPdfEngines struct {
 	mergeEngines         []gotenberg.PdfEngine
 	splitEngines         []gotenberg.PdfEngine
+	flattenEngines       []gotenberg.PdfEngine
 	convertEngines       []gotenberg.PdfEngine
 	readMetadataEngines  []gotenberg.PdfEngine
 	writeMetadataEngines []gotenberg.PdfEngine
@@ -22,6 +23,7 @@ type multiPdfEngines struct {
 func newMultiPdfEngines(
 	mergeEngines,
 	splitEngines,
+	flattenEngines,
 	convertEngines,
 	readMetadataEngines,
 	writeMetadataEngines []gotenberg.PdfEngine,
@@ -29,6 +31,7 @@ func newMultiPdfEngines(
 	return &multiPdfEngines{
 		mergeEngines:         mergeEngines,
 		splitEngines:         splitEngines,
+		flattenEngines:       flattenEngines,
 		convertEngines:       convertEngines,
 		readMetadataEngines:  readMetadataEngines,
 		writeMetadataEngines: writeMetadataEngines,
@@ -98,6 +101,29 @@ func (multi *multiPdfEngines) Split(ctx context.Context, logger *zap.Logger, mod
 	return nil, fmt.Errorf("split PDF with multi PDF engines: %w", err)
 }
 
+func (multi *multiPdfEngines) Flatten(ctx context.Context, logger *zap.Logger, inputPath, outputPath string) error {
+	var err error
+	errChan := make(chan error, 1)
+
+	for _, engine := range multi.flattenEngines {
+		go func(engine gotenberg.PdfEngine) {
+			errChan <- engine.Flatten(ctx, logger, inputPath, outputPath)
+		}(engine)
+
+		select {
+		case mergeErr := <-errChan:
+			errored := multierr.AppendInto(&err, mergeErr)
+			if !errored {
+				return nil
+			}
+		case <-ctx.Done():
+			return ctx.Err()
+		}
+	}
+
+	return fmt.Errorf("flatten PDF with multi PDF engines: %w", err)
+}
+
 // Convert converts the given PDF to a specific PDF format. thanks to its
 // children. If the context is done, it stops and returns an error.
 func (multi *multiPdfEngines) Convert(ctx context.Context, logger *zap.Logger, formats gotenberg.PdfFormats, inputPath, outputPath string) error {

pkg/modules/pdfengines/pdfengines.go

@@ -29,6 +29,7 @@ func init() {
 type PdfEngines struct {
 	mergeNames         []string
 	splitNames         []string
+	flattenNames       []string
 	convertNames       []string
 	readMetadataNames  []string
 	writeMetadataNames []string
@@ -44,6 +45,7 @@ func (mod *PdfEngines) Descriptor() gotenberg.ModuleDescriptor {
 			fs := flag.NewFlagSet("pdfengines", flag.ExitOnError)
 			fs.StringSlice("pdfengines-merge-engines", []string{"qpdf", "pdfcpu", "pdftk"}, "Set the PDF engines and their order for the merge feature - empty means all")
 			fs.StringSlice("pdfengines-split-engines", []string{"pdfcpu", "qpdf", "pdftk"}, "Set the PDF engines and their order for the split feature - empty means all")
+			fs.StringSlice("pdfengines-flatten-engines", []string{"qpdf"}, "Set the PDF engines and their order for the flatten feature - empty means all")
 			fs.StringSlice("pdfengines-convert-engines", []string{"libreoffice-pdfengine"}, "Set the PDF engines and their order for the convert feature - empty means all")
 			fs.StringSlice("pdfengines-read-metadata-engines", []string{"exiftool"}, "Set the PDF engines and their order for the read metadata feature - empty means all")
 			fs.StringSlice("pdfengines-write-metadata-engines", []string{"exiftool"}, "Set the PDF engines and their order for the write metadata feature - empty means all")
@@ -67,6 +69,7 @@ func (mod *PdfEngines) Provision(ctx *gotenberg.Context) error {
 	flags := ctx.ParsedFlags()
 	mergeNames := flags.MustStringSlice("pdfengines-merge-engines")
 	splitNames := flags.MustStringSlice("pdfengines-split-engines")
+	flattenNames := flags.MustStringSlice("pdfengines-flatten-engines")
 	convertNames := flags.MustStringSlice("pdfengines-convert-engines")
 	readMetadataNames := flags.MustStringSlice("pdfengines-read-metadata-engines")
 	writeMetadataNames := flags.MustStringSlice("pdfengines-write-metadata-engines")
@@ -106,6 +109,10 @@ func (mod *PdfEngines) Provision(ctx *gotenberg.Context) error {
 		mod.splitNames = splitNames
 	}
 
+	if len(flattenNames) > 0 {
+		mod.flattenNames = flattenNames
+	}
+
 	mod.convertNames = defaultNames
 	if len(convertNames) > 0 {
 		mod.convertNames = convertNames
@@ -212,6 +219,7 @@ func (mod *PdfEngines) PdfEngine() (gotenberg.PdfEngine, error) {
 	return newMultiPdfEngines(
 		engines(mod.mergeNames),
 		engines(mod.splitNames),
+		engines(mod.flattenNames),
 		engines(mod.convertNames),
 		engines(mod.readMetadataNames),
 		engines(mod.writeMetadataNames),
@@ -234,6 +242,7 @@ func (mod *PdfEngines) Routes() ([]api.Route, error) {
 	return []api.Route{
 		mergeRoute(engine),
 		splitRoute(engine),
+		flattenRoute(engine),
 		convertRoute(engine),
 		readMetadataRoute(engine),
 		writeMetadataRoute(engine),

pkg/modules/pdfengines/pdfengines_test.go

@@ -27,6 +27,7 @@ func TestPdfEngines_Provision(t *testing.T) {
 		ctx                             *gotenberg.Context
 		expectedMergePdfEngines         []string
 		expectedSplitPdfEngines         []string
+		expectedFlattenPdfEngines       []string
 		expectedConvertPdfEngines       []string
 		expectedReadMetadataPdfEngines  []string
 		expectedWriteMetadataPdfEngines []string
@@ -68,6 +69,7 @@ func TestPdfEngines_Provision(t *testing.T) {
 			}(),
 			expectedMergePdfEngines:         []string{"qpdf", "pdfcpu", "pdftk"},
 			expectedSplitPdfEngines:         []string{"pdfcpu", "qpdf", "pdftk"},
+			expectedFlattenPdfEngines:       []string{"qpdf"},
 			expectedConvertPdfEngines:       []string{"libreoffice-pdfengine"},
 			expectedReadMetadataPdfEngines:  []string{"exiftool"},
 			expectedWriteMetadataPdfEngines: []string{"exiftool"},
@@ -109,7 +111,7 @@ func TestPdfEngines_Provision(t *testing.T) {
 				}
 
 				fs := new(PdfEngines).Descriptor().FlagSet
-				err := fs.Parse([]string{"--pdfengines-merge-engines=b", "--pdfengines-split-engines=a", "--pdfengines-convert-engines=b", "--pdfengines-read-metadata-engines=a", "--pdfengines-write-metadata-engines=a"})
+				err := fs.Parse([]string{"--pdfengines-merge-engines=b", "--pdfengines-split-engines=a", "--pdfengines-flatten-engines=c", "--pdfengines-convert-engines=b", "--pdfengines-read-metadata-engines=a", "--pdfengines-write-metadata-engines=a"})
 				if err != nil {
 					t.Fatalf("expected no error but got: %v", err)
 				}
@@ -128,6 +130,7 @@ func TestPdfEngines_Provision(t *testing.T) {
 
 			expectedMergePdfEngines:         []string{"b"},
 			expectedSplitPdfEngines:         []string{"a"},
+			expectedFlattenPdfEngines:       []string{"c"},
 			expectedConvertPdfEngines:       []string{"b"},
 			expectedReadMetadataPdfEngines:  []string{"a"},
 			expectedWriteMetadataPdfEngines: []string{"a"},
@@ -185,6 +188,10 @@ func TestPdfEngines_Provision(t *testing.T) {
 				t.Fatalf("expected %d merge names but got %d", len(tc.expectedMergePdfEngines), len(mod.mergeNames))
 			}
 
+			if len(tc.expectedFlattenPdfEngines) != len(mod.flattenNames) {
+				t.Fatalf("expected %d flatten names but got %d", len(tc.expectedFlattenPdfEngines), len(mod.flattenNames))
+			}
+
 			if len(tc.expectedConvertPdfEngines) != len(mod.convertNames) {
 				t.Fatalf("expected %d convert names but got %d", len(tc.expectedConvertPdfEngines), len(mod.convertNames))
 			}
@@ -382,7 +389,7 @@ func TestPdfEngines_Routes(t *testing.T) {
 	}{
 		{
 			scenario:      "routes not disabled",
-			expectRoutes:  5,
+			expectRoutes:  6,
 			disableRoutes: false,
 		},
 		{

pkg/modules/pdfengines/routes.go

@@ -202,6 +202,20 @@ func SplitPdfStub(ctx *api.Context, engine gotenberg.PdfEngine, mode gotenberg.S
 	return outputPaths, nil
 }
 
+func FlattenStub(ctx *api.Context, engine gotenberg.PdfEngine, inputPaths []string) ([]string, error) {
+	outputPaths := make([]string, len(inputPaths))
+	for i, inputPath := range inputPaths {
+		outputPaths[i] = ctx.GeneratePath(".pdf")
+
+		err := engine.Flatten(ctx, ctx.Log(), inputPath, outputPaths[i])
+		if err != nil {
+			return nil, fmt.Errorf("flatten '%s': %w", inputPath, err)
+		}
+	}
+
+	return outputPaths, nil
+}
+
 // ConvertStub transforms a given PDF to the specified formats defined in
 // [gotenberg.PdfFormats]. If no format, it does nothing and returns the input
 // paths.
@@ -347,6 +361,51 @@ func splitRoute(engine gotenberg.PdfEngine) api.Route {
 	}
 }
 
+func flattenRoute(engine gotenberg.PdfEngine) api.Route {
+	return api.Route{
+		Method:      http.MethodPost,
+		Path:        "/forms/pdfengines/flatten",
+		IsMultipart: true,
+		Handler: func(c echo.Context) error {
+			ctx := c.Get("context").(*api.Context)
+
+			form := ctx.FormData()
+
+			var inputPaths []string
+			err := form.
+				MandatoryPaths([]string{".pdf"}, &inputPaths).
+				Validate()
+			if err != nil {
+				return fmt.Errorf("validate form data: %w", err)
+			}
+
+			outputPaths, err := FlattenStub(ctx, engine, inputPaths)
+			if err != nil {
+				return fmt.Errorf("convert PDFs: %w", err)
+			}
+
+			if len(outputPaths) > 1 {
+				// If .zip archive, keep the original filename.
+				for i, inputPath := range inputPaths {
+					err = ctx.Rename(outputPaths[i], inputPath)
+					if err != nil {
+						return fmt.Errorf("rename output path: %w", err)
+					}
+
+					outputPaths[i] = inputPath
+				}
+			}
+
+			err = ctx.AddOutputPaths(outputPaths...)
+			if err != nil {
+				return fmt.Errorf("add output paths: %w", err)
+			}
+
+			return nil
+		},
+	}
+}
+
 // convertRoute returns an [api.Route] which can convert PDFs to a specific ODF
 // format.
 func convertRoute(engine gotenberg.PdfEngine) api.Route {

pkg/modules/pdftk/pdftk.go

@@ -99,6 +99,11 @@ func (engine *PdfTk) Merge(ctx context.Context, logger *zap.Logger, inputPaths [
 	return fmt.Errorf("merge PDFs with PDFtk: %w", err)
 }
 
+// Flatten is not available in this implementation.
+func (engine *PdfTk) Flatten(ctx context.Context, logger *zap.Logger, inputPath, outputPath string) error {
+	return fmt.Errorf("flatten PDF with PDFtk: %w", gotenberg.ErrPdfEngineMethodNotSupported)
+}
+
 // Convert is not available in this implementation.
 func (engine *PdfTk) Convert(ctx context.Context, logger *zap.Logger, formats gotenberg.PdfFormats, inputPath, outputPath string) error {
 	return fmt.Errorf("convert PDF to '%+v' with PDFtk: %w", formats, gotenberg.ErrPdfEngineMethodNotSupported)

pkg/modules/qpdf/qpdf.go

@@ -101,6 +101,11 @@ func (engine *QPdf) Merge(ctx context.Context, logger *zap.Logger, inputPaths []
 	return fmt.Errorf("merge PDFs with QPDF: %w", err)
 }
 
+// Flatten is not available in this implementation.
+func (engine *QPdf) Flatten(ctx context.Context, logger *zap.Logger, inputPath, outputPath string) error {
+	return fmt.Errorf("flatten PDF with QPDF: %w", gotenberg.ErrPdfEngineMethodNotSupported)
+}
+
 // Convert is not available in this implementation.
 func (engine *QPdf) Convert(ctx context.Context, logger *zap.Logger, formats gotenberg.PdfFormats, inputPath, outputPath string) error {
 	return fmt.Errorf("convert PDF to '%+v' with QPDF: %w", formats, gotenberg.ErrPdfEngineMethodNotSupported)