feat(pdfengines): one flag per PDF engine method for a more granular selection of PDF engines

pkg/modules/pdfengines/pdfengines.go

@@ -27,9 +27,12 @@ func init() {
 // the [api.Router] interface to expose relevant PDF processing routes if
 // enabled.
 type PdfEngines struct {
-	names         []string
-	engines       []gotenberg.PdfEngine
-	disableRoutes bool
+	mergeNames        []string
+	convertNames      []string
+	readMetadataNames []string
+	writeMedataNames  []string
+	engines           []gotenberg.PdfEngine
+	disableRoutes     bool
 }
 
 // Descriptor returns a PdfEngines' module descriptor.
@@ -38,9 +41,18 @@ func (mod *PdfEngines) Descriptor() gotenberg.ModuleDescriptor {
 		ID: "pdfengines",
 		FlagSet: func() *flag.FlagSet {
 			fs := flag.NewFlagSet("pdfengines", flag.ExitOnError)
-			fs.StringSlice("pdfengines-engines", make([]string, 0), "Set the PDF engines and their order - all by default")
+			fs.StringSlice("pdfengines-merge-engines", []string{"qpdf", "pdfcpu", "pdftk"}, "Set the PDF engines and their order for the merge feature")
+			fs.StringSlice("pdfengines-convert-engines", []string{"libreoffice-pdfengine"}, "Set the PDF engines and their order for the convert feature")
+			fs.StringSlice("pdfengines-read-metadata-engines", []string{"exiftool"}, "Set the PDF engines and their order for the read metadata feature")
+			fs.StringSlice("pdfengines-write-metadata-engines", []string{"exiftool"}, "Set the PDF engines and their order for the write metadata feature")
 			fs.Bool("pdfengines-disable-routes", false, "Disable the routes")
 
+			fs.StringSlice("pdfengines-engines", make([]string, 0), "Set the default PDF engines and their default order - all by default")
+			err := fs.MarkDeprecated("pdfengines-engines", "use other flags for a more granular selection of PDF engines per method")
+			if err != nil {
+				panic(err)
+			}
+
 			return fs
 		}(),
 		New: func() gotenberg.Module { return new(PdfEngines) },
@@ -51,7 +63,10 @@ func (mod *PdfEngines) Descriptor() gotenberg.ModuleDescriptor {
 // selected by the user thanks to the "engines" flag.
 func (mod *PdfEngines) Provision(ctx *gotenberg.Context) error {
 	flags := ctx.ParsedFlags()
-	names := flags.MustStringSlice("pdfengines-engines")
+	mergeNames := flags.MustStringSlice("pdfengines-merge-engines")
+	convertNames := flags.MustStringSlice("pdfengines-convert-engines")
+	readMetadataNames := flags.MustStringSlice("pdfengines-read-metadata-engines")
+	writeMetadataNames := flags.MustStringSlice("pdfengines-write-metadata-engines")
 	mod.disableRoutes = flags.MustBool("pdfengines-disable-routes")
 
 	engines, err := ctx.Modules(new(gotenberg.PdfEngine))
@@ -65,26 +80,37 @@ func (mod *PdfEngines) Provision(ctx *gotenberg.Context) error {
 		mod.engines[i] = engine.(gotenberg.PdfEngine)
 	}
 
-	if len(names) > 0 {
-		// Selection from user.
-		mod.names = names
-
-		// Example in case of deprecated module name.
-		//for i, name := range names {
-		//	if name == "unoconv-pdfengine" || name == "uno-pdfengine" {
-		//		logger.Warn(fmt.Sprintf("%s is deprecated; prefer libreoffice-pdfengine instead", name))
-		//		mod.names[i] = "libreoffice-pdfengine"
-		//	}
-		//}
-
-		return nil
+	defaultNames := make([]string, len(mod.engines))
+	for i, engine := range mod.engines {
+		defaultNames[i] = engine.(gotenberg.Module).Descriptor().ID
 	}
 
-	// No selection from user, use all PDF engines available.
-	mod.names = make([]string, len(mod.engines))
+	// Example in case of deprecated module name.
+	//for i, name := range defaultNames {
+	//	if name == "unoconv-pdfengine" || name == "uno-pdfengine" {
+	//		logger.Warn(fmt.Sprintf("%s is deprecated; prefer libreoffice-pdfengine instead", name))
+	//		mod.defaultNames[i] = "libreoffice-pdfengine"
+	//	}
+	//}
 
-	for i, engine := range mod.engines {
-		mod.names[i] = engine.(gotenberg.Module).Descriptor().ID
+	mod.mergeNames = defaultNames
+	if len(mergeNames) > 0 {
+		mod.mergeNames = mergeNames
+	}
+
+	mod.convertNames = defaultNames
+	if len(convertNames) > 0 {
+		mod.convertNames = convertNames
+	}
+
+	mod.readMetadataNames = defaultNames
+	if len(readMetadataNames) > 0 {
+		mod.readMetadataNames = readMetadataNames
+	}
+
+	mod.writeMedataNames = defaultNames
+	if len(writeMetadataNames) > 0 {
+		mod.writeMedataNames = writeMetadataNames
 	}
 
 	return nil
@@ -105,22 +131,40 @@ func (mod *PdfEngines) Validate() error {
 	}
 
 	nonExistingEngines := make([]string, 0)
+	findNonExistingEngines := func(names []string) {
+		for _, name := range names {
+			engineExists := false
 
-	for _, name := range mod.names {
-		engineExists := false
+			for _, engine := range mod.engines {
+				if name == engine.(gotenberg.Module).Descriptor().ID {
+					engineExists = true
+					break
+				}
+			}
 
-		for _, engine := range mod.engines {
-			if name == engine.(gotenberg.Module).Descriptor().ID {
-				engineExists = true
-				break
+			if engineExists {
+				continue
+			}
+
+			alreadyInSlice := false
+			for _, engine := range nonExistingEngines {
+				if engine == name {
+					alreadyInSlice = true
+					break
+				}
+			}
+
+			if !alreadyInSlice {
+				nonExistingEngines = append(nonExistingEngines, name)
 			}
 		}
-
-		if !engineExists {
-			nonExistingEngines = append(nonExistingEngines, name)
-		}
 	}
 
+	findNonExistingEngines(mod.mergeNames)
+	findNonExistingEngines(mod.convertNames)
+	findNonExistingEngines(mod.readMetadataNames)
+	findNonExistingEngines(mod.writeMedataNames)
+
 	if len(nonExistingEngines) == 0 {
 		return nil
 	}
@@ -132,24 +176,35 @@ func (mod *PdfEngines) Validate() error {
 // modules.
 func (mod *PdfEngines) SystemMessages() []string {
 	return []string{
-		strings.Join(mod.names[:], " "),
+		fmt.Sprintf("merge engines - %s", strings.Join(mod.mergeNames[:], " ")),
+		fmt.Sprintf("convert engines - %s", strings.Join(mod.convertNames[:], " ")),
+		fmt.Sprintf("read metadata engines - %s", strings.Join(mod.readMetadataNames[:], " ")),
+		fmt.Sprintf("write medata engines - %s", strings.Join(mod.writeMedataNames[:], " ")),
 	}
 }
 
 // PdfEngine returns a [gotenberg.PdfEngine].
 func (mod *PdfEngines) PdfEngine() (gotenberg.PdfEngine, error) {
-	engines := make([]gotenberg.PdfEngine, len(mod.names))
-
-	for i, name := range mod.names {
-		for _, engine := range mod.engines {
-			if name == engine.(gotenberg.Module).Descriptor().ID {
-				engines[i] = engine
-				break
+	engines := func(names []string) []gotenberg.PdfEngine {
+		list := make([]gotenberg.PdfEngine, len(names))
+		for i, name := range names {
+			for _, engine := range mod.engines {
+				if name == engine.(gotenberg.Module).Descriptor().ID {
+					list[i] = engine
+					break
+				}
 			}
 		}
+
+		return list
 	}
 
-	return newMultiPdfEngines(engines...), nil
+	return newMultiPdfEngines(
+		engines(mod.mergeNames),
+		engines(mod.convertNames),
+		engines(mod.readMetadataNames),
+		engines(mod.writeMedataNames),
+	), nil
 }
 
 // Routes returns the HTTP routes.