feat(pdfengines): add rotate feature

pkg/modules/api/middlewares.go

@@ -65,6 +65,10 @@ func ParseError(err error) (int, string) {
 		return http.StatusBadRequest, "At least one PDF engine cannot process the requested stamp source type, while others may have failed due to different issues"
 	}
 
+	if errors.Is(err, gotenberg.ErrPdfRotateAngleNotSupported) {
+		return http.StatusBadRequest, "At least one PDF engine cannot process the requested rotation angle, while others may have failed due to different issues"
+	}
+
 	var invalidArgsError *gotenberg.PdfEngineInvalidArgsError
 	if errors.As(err, &invalidArgsError) {
 		return http.StatusBadRequest, invalidArgsError.Error()

pkg/modules/chromium/routes.go

@@ -419,6 +419,7 @@ func convertUrlRoute(chromium Api, engine gotenberg.PdfEngine) api.Route {
 			watermarkFiles := pdfengines.FormDataPdfWatermarkFiles(form)
 			stamp := pdfengines.FormDataPdfStamp(form, false)
 			stampFiles := pdfengines.FormDataPdfStampFiles(form)
+			rotateAngle, rotatePages := pdfengines.FormDataPdfRotate(form, false)
 
 			var url string
 			err := form.
@@ -435,7 +436,7 @@ func convertUrlRoute(chromium Api, engine gotenberg.PdfEngine) api.Route {
 				stamp.Expression = stampFiles[0]
 			}
 
-			err = convertUrl(ctx, chromium, engine, url, options, mode, pdfFormats, metadata, userPassword, ownerPassword, embedPaths, watermark, stamp)
+			err = convertUrl(ctx, chromium, engine, url, options, mode, pdfFormats, metadata, userPassword, ownerPassword, embedPaths, watermark, stamp, rotateAngle, rotatePages)
 			if err != nil {
 				return fmt.Errorf("convert URL to PDF: %w", err)
 			}
@@ -493,6 +494,7 @@ func convertHtmlRoute(chromium Api, engine gotenberg.PdfEngine) api.Route {
 			watermarkFiles := pdfengines.FormDataPdfWatermarkFiles(form)
 			stamp := pdfengines.FormDataPdfStamp(form, false)
 			stampFiles := pdfengines.FormDataPdfStampFiles(form)
+			rotateAngle, rotatePages := pdfengines.FormDataPdfRotate(form, false)
 
 			var inputPath string
 			err := form.
@@ -510,7 +512,7 @@ func convertHtmlRoute(chromium Api, engine gotenberg.PdfEngine) api.Route {
 			}
 
 			url := fmt.Sprintf("file://%s", inputPath)
-			err = convertUrl(ctx, chromium, engine, url, options, mode, pdfFormats, metadata, userPassword, ownerPassword, embedPaths, watermark, stamp)
+			err = convertUrl(ctx, chromium, engine, url, options, mode, pdfFormats, metadata, userPassword, ownerPassword, embedPaths, watermark, stamp, rotateAngle, rotatePages)
 			if err != nil {
 				return fmt.Errorf("convert HTML to PDF: %w", err)
 			}
@@ -569,6 +571,7 @@ func convertMarkdownRoute(chromium Api, engine gotenberg.PdfEngine) api.Route {
 			watermarkFiles := pdfengines.FormDataPdfWatermarkFiles(form)
 			stamp := pdfengines.FormDataPdfStamp(form, false)
 			stampFiles := pdfengines.FormDataPdfStampFiles(form)
+			rotateAngle, rotatePages := pdfengines.FormDataPdfRotate(form, false)
 
 			var (
 				inputPath     string
@@ -595,7 +598,7 @@ func convertMarkdownRoute(chromium Api, engine gotenberg.PdfEngine) api.Route {
 				return fmt.Errorf("transform markdown file(s) to HTML: %w", err)
 			}
 
-			err = convertUrl(ctx, chromium, engine, url, options, mode, pdfFormats, metadata, userPassword, ownerPassword, embedPaths, watermark, stamp)
+			err = convertUrl(ctx, chromium, engine, url, options, mode, pdfFormats, metadata, userPassword, ownerPassword, embedPaths, watermark, stamp, rotateAngle, rotatePages)
 			if err != nil {
 				return fmt.Errorf("convert markdown to PDF: %w", err)
 			}
@@ -719,7 +722,7 @@ func markdownToHtml(ctx *api.Context, inputPath string, markdownPaths []string)
 	return fmt.Sprintf("file://%s", inputPath), nil
 }
 
-func convertUrl(ctx *api.Context, chromium Api, engine gotenberg.PdfEngine, url string, options PdfOptions, mode gotenberg.SplitMode, pdfFormats gotenberg.PdfFormats, metadata map[string]any, userPassword, ownerPassword string, embedPaths []string, watermark, stamp gotenberg.Stamp) error {
+func convertUrl(ctx *api.Context, chromium Api, engine gotenberg.PdfEngine, url string, options PdfOptions, mode gotenberg.SplitMode, pdfFormats gotenberg.PdfFormats, metadata map[string]any, userPassword, ownerPassword string, embedPaths []string, watermark, stamp gotenberg.Stamp, rotateAngle int, rotatePages string) error {
 	outputPath := ctx.GeneratePath(".pdf")
 	// See https://github.com/gotenberg/gotenberg/issues/1130.
 	filename := ctx.OutputFilename(outputPath)
@@ -801,6 +804,11 @@ func convertUrl(ctx *api.Context, chromium Api, engine gotenberg.PdfEngine, url
 		return fmt.Errorf("stamp PDFs: %w", err)
 	}
 
+	err = pdfengines.RotateStub(ctx, engine, rotateAngle, rotatePages, outputPaths)
+	if err != nil {
+		return fmt.Errorf("rotate PDFs: %w", err)
+	}
+
 	convertOutputPaths, err := pdfengines.ConvertStub(ctx, engine, pdfFormats, outputPaths)
 	if err != nil {
 		return fmt.Errorf("convert PDF(s): %w", err)

pkg/modules/exiftool/exiftool.go

@@ -264,6 +264,11 @@ func (engine *ExifTool) Stamp(ctx context.Context, logger *zap.Logger, inputPath
 	return fmt.Errorf("stamp PDF with ExifTool: %w", gotenberg.ErrPdfEngineMethodNotSupported)
 }
 
+// Rotate is not available in this implementation.
+func (engine *ExifTool) Rotate(ctx context.Context, logger *zap.Logger, inputPath string, angle int, pages string) error {
+	return fmt.Errorf("rotate PDF with ExifTool: %w", gotenberg.ErrPdfEngineMethodNotSupported)
+}
+
 // Interface guards.
 var (
 	_ gotenberg.Module      = (*ExifTool)(nil)

pkg/modules/libreoffice/pdfengine/pdfengine.go

@@ -126,6 +126,11 @@ func (engine *LibreOfficePdfEngine) Stamp(ctx context.Context, logger *zap.Logge
 	return fmt.Errorf("stamp PDF with LibreOffice: %w", gotenberg.ErrPdfEngineMethodNotSupported)
 }
 
+// Rotate is not available in this implementation.
+func (engine *LibreOfficePdfEngine) Rotate(ctx context.Context, logger *zap.Logger, inputPath string, angle int, pages string) error {
+	return fmt.Errorf("rotate PDF with LibreOffice: %w", gotenberg.ErrPdfEngineMethodNotSupported)
+}
+
 // Interface guards.
 var (
 	_ gotenberg.Module      = (*LibreOfficePdfEngine)(nil)

pkg/modules/libreoffice/routes.go

@@ -36,6 +36,7 @@ func convertRoute(libreOffice libreofficeapi.Uno, engine gotenberg.PdfEngine) ap
 			watermarkFiles := pdfengines.FormDataPdfWatermarkFiles(form)
 			stamp := pdfengines.FormDataPdfStamp(form, false)
 			stampFiles := pdfengines.FormDataPdfStampFiles(form)
+			angle, rotatePages := pdfengines.FormDataPdfRotate(form, false)
 
 			zeroValuedSplitMode := gotenberg.SplitMode{}
 
@@ -200,7 +201,7 @@ func convertRoute(libreOffice libreofficeapi.Uno, engine gotenberg.PdfEngine) ap
 				return err
 			}
 
-			hasPostProcessing := watermark.Source != "" || stamp.Source != "" ||
+			hasPostProcessing := watermark.Source != "" || stamp.Source != "" || angle != 0 ||
 				len(embedPaths) > 0 || len(metadata) > 0 || flatten
 
 			outputPaths := make([]string, len(inputPaths))
@@ -317,6 +318,11 @@ func convertRoute(libreOffice libreofficeapi.Uno, engine gotenberg.PdfEngine) ap
 				return fmt.Errorf("stamp PDFs: %w", err)
 			}
 
+			err = pdfengines.RotateStub(ctx, engine, angle, rotatePages, outputPaths)
+			if err != nil {
+				return fmt.Errorf("rotate PDFs: %w", err)
+			}
+
 			if flatten {
 				err = pdfengines.FlattenStub(ctx, engine, outputPaths)
 				if err != nil {

pkg/modules/pdfcpu/pdfcpu.go

@@ -10,6 +10,7 @@ import (
 	"os/exec"
 	"path/filepath"
 	"sort"
+	"strconv"
 	"strings"
 	"syscall"
 
@@ -389,6 +390,27 @@ func (engine *PdfCpu) Stamp(ctx context.Context, logger *zap.Logger, inputPath s
 	return engine.applyStampOrWatermark(ctx, logger, "stamp", inputPath, stamp)
 }
 
+// Rotate rotates pages of a PDF file by the given angle using pdfcpu.
+func (engine *PdfCpu) Rotate(ctx context.Context, logger *zap.Logger, inputPath string, angle int, pages string) error {
+	args := []string{"rotate"}
+	if pages != "" {
+		args = append(args, "-pages", pages)
+	}
+	args = append(args, "--", inputPath, strconv.Itoa(angle), inputPath)
+
+	cmd, err := gotenberg.CommandContext(ctx, logger, engine.binPath, args...)
+	if err != nil {
+		return fmt.Errorf("create command: %w", err)
+	}
+
+	_, err = cmd.Exec()
+	if err != nil {
+		return fmt.Errorf("rotate PDF with pdfcpu: %w", err)
+	}
+
+	return nil
+}
+
 func (engine *PdfCpu) applyStampOrWatermark(ctx context.Context, logger *zap.Logger, command string, inputPath string, stamp gotenberg.Stamp) error {
 	var mode string
 	switch stamp.Source {

pkg/modules/pdfengines/multi.go

@@ -24,6 +24,7 @@ type multiPdfEngines struct {
 	writeBookmarksEngines []gotenberg.PdfEngine
 	watermarkEngines      []gotenberg.PdfEngine
 	stampEngines          []gotenberg.PdfEngine
+	rotateEngines         []gotenberg.PdfEngine
 }
 
 func newMultiPdfEngines(
@@ -38,7 +39,8 @@ func newMultiPdfEngines(
 	readBookmarksEngines,
 	writeBookmarksEngines,
 	watermarkEngines,
-	stampEngines []gotenberg.PdfEngine,
+	stampEngines,
+	rotateEngines []gotenberg.PdfEngine,
 ) *multiPdfEngines {
 	return &multiPdfEngines{
 		mergeEngines:          mergeEngines,
@@ -53,6 +55,7 @@ func newMultiPdfEngines(
 		writeBookmarksEngines: writeBookmarksEngines,
 		watermarkEngines:      watermarkEngines,
 		stampEngines:          stampEngines,
+		rotateEngines:         rotateEngines,
 	}
 }
 
@@ -425,6 +428,31 @@ func (multi *multiPdfEngines) Stamp(ctx context.Context, logger *zap.Logger, inp
 	return fmt.Errorf("stamp PDF with multi PDF engines: %w", err)
 }
 
+// Rotate rotates pages of a PDF file using the first available engine that
+// supports rotation.
+func (multi *multiPdfEngines) Rotate(ctx context.Context, logger *zap.Logger, inputPath string, angle int, pages string) error {
+	var err error
+	errChan := make(chan error, 1)
+
+	for _, engine := range multi.rotateEngines {
+		go func(engine gotenberg.PdfEngine) {
+			errChan <- engine.Rotate(ctx, logger, inputPath, angle, pages)
+		}(engine)
+
+		select {
+		case rotateErr := <-errChan:
+			errored := multierr.AppendInto(&err, rotateErr)
+			if !errored {
+				return nil
+			}
+		case <-ctx.Done():
+			return ctx.Err()
+		}
+	}
+
+	return fmt.Errorf("rotate PDF with multi PDF engines: %w", err)
+}
+
 // Interface guards.
 var (
 	_ gotenberg.PdfEngine = (*multiPdfEngines)(nil)

pkg/modules/pdfengines/pdfengines.go

@@ -40,6 +40,7 @@ type PdfEngines struct {
 	writeBookmarksNames []string
 	watermarkNames      []string
 	stampNames          []string
+	rotateNames         []string
 	engines             []gotenberg.PdfEngine
 	disableRoutes       bool
 }
@@ -62,6 +63,7 @@ func (mod *PdfEngines) Descriptor() gotenberg.ModuleDescriptor {
 			fs.StringSlice("pdfengines-write-bookmarks-engines", []string{"pdfcpu"}, "Set the PDF engines and their order for the write bookmarks feature - empty means all")
 			fs.StringSlice("pdfengines-watermark-engines", []string{"pdfcpu", "pdftk"}, "Set the PDF engines and their order for the watermark feature - empty means all")
 			fs.StringSlice("pdfengines-stamp-engines", []string{"pdfcpu", "pdftk"}, "Set the PDF engines and their order for the stamp feature - empty means all")
+			fs.StringSlice("pdfengines-rotate-engines", []string{"pdfcpu", "pdftk"}, "Set the PDF engines and their order for the rotate feature - empty means all")
 			fs.Bool("pdfengines-disable-routes", false, "Disable the routes")
 
 			// Deprecated flags.
@@ -93,6 +95,7 @@ func (mod *PdfEngines) Provision(ctx *gotenberg.Context) error {
 	writeBookmarksNames := flags.MustStringSlice("pdfengines-write-bookmarks-engines")
 	watermarkNames := flags.MustStringSlice("pdfengines-watermark-engines")
 	stampNames := flags.MustStringSlice("pdfengines-stamp-engines")
+	rotateNames := flags.MustStringSlice("pdfengines-rotate-engines")
 	mod.disableRoutes = flags.MustBool("pdfengines-disable-routes")
 
 	engines, err := ctx.Modules(new(gotenberg.PdfEngine))
@@ -179,6 +182,11 @@ func (mod *PdfEngines) Provision(ctx *gotenberg.Context) error {
 		mod.stampNames = stampNames
 	}
 
+	mod.rotateNames = defaultNames
+	if len(rotateNames) > 0 {
+		mod.rotateNames = rotateNames
+	}
+
 	return nil
 }
 
@@ -232,6 +240,7 @@ func (mod *PdfEngines) Validate() error {
 	findNonExistingEngines(mod.writeBookmarksNames)
 	findNonExistingEngines(mod.watermarkNames)
 	findNonExistingEngines(mod.stampNames)
+	findNonExistingEngines(mod.rotateNames)
 
 	if len(nonExistingEngines) == 0 {
 		return nil
@@ -256,6 +265,7 @@ func (mod *PdfEngines) SystemMessages() []string {
 		fmt.Sprintf("write bookmarks engines - %s", strings.Join(mod.writeBookmarksNames[:], " ")),
 		fmt.Sprintf("watermark engines - %s", strings.Join(mod.watermarkNames[:], " ")),
 		fmt.Sprintf("stamp engines - %s", strings.Join(mod.stampNames[:], " ")),
+		fmt.Sprintf("rotate engines - %s", strings.Join(mod.rotateNames[:], " ")),
 	}
 }
 
@@ -288,6 +298,7 @@ func (mod *PdfEngines) PdfEngine() (gotenberg.PdfEngine, error) {
 		engines(mod.writeBookmarksNames),
 		engines(mod.watermarkNames),
 		engines(mod.stampNames),
+		engines(mod.rotateNames),
 	), nil
 }
 
@@ -317,6 +328,7 @@ func (mod *PdfEngines) Routes() ([]api.Route, error) {
 		embedRoute(engine),
 		watermarkRoute(engine),
 		stampRoute(engine),
+		rotateRoute(engine),
 	}, nil
 }
 

pkg/modules/pdfengines/routes.go

@@ -166,6 +166,56 @@ func FormDataPdfBookmarks(form *api.FormData, mandatory bool) any {
 	return bookmarks
 }
 
+// FormDataPdfRotate creates rotation parameters from the form data.
+func FormDataPdfRotate(form *api.FormData, mandatory bool) (int, string) {
+	var angle int
+	var pages string
+
+	angleFunc := func(value string) error {
+		if value == "" {
+			return nil
+		}
+		v, err := strconv.Atoi(value)
+		if err != nil {
+			return err
+		}
+		if v != 90 && v != 180 && v != 270 {
+			return errors.New("wrong value, expected 90, 180, or 270")
+		}
+		angle = v
+		return nil
+	}
+
+	if mandatory {
+		form.MandatoryCustom("rotateAngle", func(value string) error {
+			return angleFunc(value)
+		})
+	} else {
+		form.Custom("rotateAngle", func(value string) error {
+			return angleFunc(value)
+		})
+	}
+	form.String("rotatePages", &pages, "")
+
+	return angle, pages
+}
+
+// RotateStub rotates pages of PDF files. If angle is 0, it does nothing.
+func RotateStub(ctx *api.Context, engine gotenberg.PdfEngine, angle int, pages string, inputPaths []string) error {
+	if angle == 0 {
+		return nil
+	}
+
+	for _, inputPath := range inputPaths {
+		err := engine.Rotate(ctx, ctx.Log(), inputPath, angle, pages)
+		if err != nil {
+			return fmt.Errorf("rotate '%s': %w", inputPath, err)
+		}
+	}
+
+	return nil
+}
+
 // ValidatePdfFormatsCompat checks for incompatible combinations of PDF formats
 // with other features and returns an appropriate error if found.
 func ValidatePdfFormatsCompat(pdfFormats gotenberg.PdfFormats, userPassword string, embedPaths []string) error {
@@ -561,6 +611,7 @@ func mergeRoute(engine gotenberg.PdfEngine) api.Route {
 			watermarkFiles := FormDataPdfWatermarkFiles(form)
 			stamp := FormDataPdfStamp(form, false)
 			stampFiles := FormDataPdfStampFiles(form)
+			angle, rotatePages := FormDataPdfRotate(form, false)
 
 			var inputPaths []string
 			var flatten bool
@@ -604,6 +655,11 @@ func mergeRoute(engine gotenberg.PdfEngine) api.Route {
 				return fmt.Errorf("stamp PDFs: %w", err)
 			}
 
+			err = RotateStub(ctx, engine, angle, rotatePages, outputPaths)
+			if err != nil {
+				return fmt.Errorf("rotate PDFs: %w", err)
+			}
+
 			if flatten {
 				err = FlattenStub(ctx, engine, outputPaths)
 				if err != nil {
@@ -706,6 +762,7 @@ func splitRoute(engine gotenberg.PdfEngine) api.Route {
 			watermarkFiles := FormDataPdfWatermarkFiles(form)
 			stamp := FormDataPdfStamp(form, false)
 			stampFiles := FormDataPdfStampFiles(form)
+			angle, rotatePages := FormDataPdfRotate(form, false)
 
 			var inputPaths []string
 			var flatten bool
@@ -744,6 +801,11 @@ func splitRoute(engine gotenberg.PdfEngine) api.Route {
 				return fmt.Errorf("stamp PDFs: %w", err)
 			}
 
+			err = RotateStub(ctx, engine, angle, rotatePages, outputPaths)
+			if err != nil {
+				return fmt.Errorf("rotate PDFs: %w", err)
+			}
+
 			if flatten {
 				err = FlattenStub(ctx, engine, outputPaths)
 				if err != nil {
@@ -1216,3 +1278,38 @@ func stampRoute(engine gotenberg.PdfEngine) api.Route {
 		},
 	}
 }
+
+// rotateRoute returns an [api.Route] which can rotate pages of PDFs.
+func rotateRoute(engine gotenberg.PdfEngine) api.Route {
+	return api.Route{
+		Method:      http.MethodPost,
+		Path:        "/forms/pdfengines/rotate",
+		IsMultipart: true,
+		Handler: func(c echo.Context) error {
+			ctx := c.Get("context").(*api.Context)
+
+			form := ctx.FormData()
+			angle, pages := FormDataPdfRotate(form, true)
+
+			var inputPaths []string
+			err := form.
+				MandatoryPaths([]string{".pdf"}, &inputPaths).
+				Validate()
+			if err != nil {
+				return fmt.Errorf("validate form data: %w", err)
+			}
+
+			err = RotateStub(ctx, engine, angle, pages, inputPaths)
+			if err != nil {
+				return fmt.Errorf("rotate PDFs: %w", err)
+			}
+
+			err = ctx.AddOutputPaths(inputPaths...)
+			if err != nil {
+				return fmt.Errorf("add output paths: %w", err)
+			}
+
+			return nil
+		},
+	}
+}

pkg/modules/pdftk/pdftk.go

@@ -261,6 +261,47 @@ func (engine *PdfTk) Stamp(ctx context.Context, logger *zap.Logger, inputPath st
 	return nil
 }
 
+// Rotate rotates all pages of a PDF file by the given angle using PDFtk.
+// Page-specific rotation is not supported; if pages is non-empty,
+// ErrPdfEngineMethodNotSupported is returned.
+func (engine *PdfTk) Rotate(ctx context.Context, logger *zap.Logger, inputPath string, angle int, pages string) error {
+	if pages != "" {
+		return fmt.Errorf("rotate PDF with PDFtk (page-specific rotation): %w", gotenberg.ErrPdfEngineMethodNotSupported)
+	}
+
+	var direction string
+	switch angle {
+	case 90:
+		direction = "east"
+	case 180:
+		direction = "south"
+	case 270:
+		direction = "west"
+	default:
+		return fmt.Errorf("rotate PDF with PDFtk: %w", gotenberg.ErrPdfRotateAngleNotSupported)
+	}
+
+	tmpPath := inputPath + ".tmp"
+	args := []string{inputPath, "cat", "1-end" + direction, "output", tmpPath}
+
+	cmd, err := gotenberg.CommandContext(ctx, logger, engine.binPath, args...)
+	if err != nil {
+		return fmt.Errorf("create command: %w", err)
+	}
+
+	_, err = cmd.Exec()
+	if err != nil {
+		return fmt.Errorf("rotate PDF with PDFtk: %w", err)
+	}
+
+	err = os.Rename(tmpPath, inputPath)
+	if err != nil {
+		return fmt.Errorf("rename temporary output file with input file: %w", err)
+	}
+
+	return nil
+}
+
 // Interface guards.
 var (
 	_ gotenberg.Module      = (*PdfTk)(nil)

pkg/modules/qpdf/qpdf.go

@@ -231,6 +231,11 @@ func (engine *QPdf) Stamp(ctx context.Context, logger *zap.Logger, inputPath str
 	return fmt.Errorf("stamp PDF with QPDF: %w", gotenberg.ErrPdfEngineMethodNotSupported)
 }
 
+// Rotate is not available in this implementation.
+func (engine *QPdf) Rotate(ctx context.Context, logger *zap.Logger, inputPath string, angle int, pages string) error {
+	return fmt.Errorf("rotate PDF with QPDF: %w", gotenberg.ErrPdfEngineMethodNotSupported)
+}
+
 var (
 	_ gotenberg.Module      = (*QPdf)(nil)
 	_ gotenberg.Provisioner = (*QPdf)(nil)