feat(pdfengines): add write metadata option on merge route

pkg/modules/pdfengines/routes.go

@@ -27,12 +27,22 @@ func mergeRoute(engine gotenberg.PdfEngine) api.Route {
 				inputPaths []string
 				pdfa       string
 				pdfua      bool
+				metadata   map[string]interface{}
 			)
 
 			err := ctx.FormData().
 				MandatoryPaths([]string{".pdf"}, &inputPaths).
 				String("pdfa", &pdfa, "").
 				Bool("pdfua", &pdfua, false).
+				Custom("metadata", func(value string) error {
+					if len(value) > 0 {
+						err := json.Unmarshal([]byte(value), &metadata)
+						if err != nil {
+							return fmt.Errorf("unmarshal metadata: %w", err)
+						}
+					}
+					return nil
+				}).
 				Validate()
 			if err != nil {
 				return fmt.Errorf("validate form data: %w", err)
@@ -68,6 +78,14 @@ func mergeRoute(engine gotenberg.PdfEngine) api.Route {
 				outputPath = convertOutputPath
 			}
 
+			// Writes and potentially overrides metadata entries, if any.
+			if len(metadata) > 0 {
+				err = engine.WriteMetadata(ctx, ctx.Log(), metadata, outputPath)
+				if err != nil {
+					return fmt.Errorf("write metadata: %w", err)
+				}
+			}
+
 			// Last but not least, add the output path to the context so that
 			// the API is able to send it as a response to the client.
 			err = ctx.AddOutputPaths(outputPath)

pkg/modules/pdfengines/routes_test.go

@@ -35,7 +35,27 @@ func TestMergeHandler(t *testing.T) {
 			expectOutputPathsCount: 0,
 		},
 		{
-			scenario: "error from PDF engine",
+			scenario: "invalid metadata form field",
+			ctx: func() *api.ContextMock {
+				ctx := &api.ContextMock{Context: new(api.Context)}
+				ctx.SetFiles(map[string]string{
+					"file.pdf":  "/file.pdf",
+					"file2.pdf": "/file2.pdf",
+				})
+				ctx.SetValues(map[string][]string{
+					"metadata": {
+						"foo",
+					},
+				})
+				return ctx
+			}(),
+			expectError:            true,
+			expectHttpError:        true,
+			expectHttpStatus:       http.StatusBadRequest,
+			expectOutputPathsCount: 0,
+		},
+		{
+			scenario: "PDF engine merge error",
 			ctx: func() *api.ContextMock {
 				ctx := &api.ContextMock{Context: new(api.Context)}
 				ctx.SetFiles(map[string]string{
@@ -53,6 +73,60 @@ func TestMergeHandler(t *testing.T) {
 			expectHttpError:        false,
 			expectOutputPathsCount: 0,
 		},
+		{
+			scenario: "PDF engine convert error",
+			ctx: func() *api.ContextMock {
+				ctx := &api.ContextMock{Context: new(api.Context)}
+				ctx.SetFiles(map[string]string{
+					"file.pdf":  "/file.pdf",
+					"file2.pdf": "/file2.pdf",
+				})
+				ctx.SetValues(map[string][]string{
+					"pdfa": {
+						gotenberg.PdfA1b,
+					},
+				})
+				return ctx
+			}(),
+			engine: &gotenberg.PdfEngineMock{
+				MergeMock: func(ctx context.Context, logger *zap.Logger, inputPaths []string, outputPath string) error {
+					return nil
+				},
+				ConvertMock: func(ctx context.Context, logger *zap.Logger, formats gotenberg.PdfFormats, inputPath, outputPath string) error {
+					return errors.New("foo")
+				},
+			},
+			expectError:            true,
+			expectHttpError:        false,
+			expectOutputPathsCount: 0,
+		},
+		{
+			scenario: "PDF engine write metadata error",
+			ctx: func() *api.ContextMock {
+				ctx := &api.ContextMock{Context: new(api.Context)}
+				ctx.SetFiles(map[string]string{
+					"file.pdf":  "/file.pdf",
+					"file2.pdf": "/file2.pdf",
+				})
+				ctx.SetValues(map[string][]string{
+					"metadata": {
+						"{\"Creator\": \"foo\", \"Producer\": \"bar\" }",
+					},
+				})
+				return ctx
+			}(),
+			engine: &gotenberg.PdfEngineMock{
+				MergeMock: func(ctx context.Context, logger *zap.Logger, inputPaths []string, outputPath string) error {
+					return nil
+				},
+				WriteMetadataMock: func(ctx context.Context, logger *zap.Logger, metadata map[string]interface{}, inputPath string) error {
+					return errors.New("foo")
+				},
+			},
+			expectError:            true,
+			expectHttpError:        false,
+			expectOutputPathsCount: 0,
+		},
 		{
 			scenario: "cannot add output paths",
 			ctx: func() *api.ContextMock {
@@ -75,25 +149,6 @@ func TestMergeHandler(t *testing.T) {
 		},
 		{
 			scenario: "success",
-			ctx: func() *api.ContextMock {
-				ctx := &api.ContextMock{Context: new(api.Context)}
-				ctx.SetFiles(map[string]string{
-					"file.pdf":  "/file.pdf",
-					"file2.pdf": "/file2.pdf",
-				})
-				return ctx
-			}(),
-			engine: &gotenberg.PdfEngineMock{
-				MergeMock: func(ctx context.Context, logger *zap.Logger, inputPaths []string, outputPath string) error {
-					return nil
-				},
-			},
-			expectError:            false,
-			expectHttpError:        false,
-			expectOutputPathsCount: 1,
-		},
-		{
-			scenario: "error from PDF engine (convert)",
 			ctx: func() *api.ContextMock {
 				ctx := &api.ContextMock{Context: new(api.Context)}
 				ctx.SetFiles(map[string]string{
@@ -104,6 +159,9 @@ func TestMergeHandler(t *testing.T) {
 					"pdfa": {
 						gotenberg.PdfA1b,
 					},
+					"metadata": {
+						"{\"Creator\": \"foo\", \"Producer\": \"bar\" }",
+					},
 				})
 				return ctx
 			}(),
@@ -112,36 +170,9 @@ func TestMergeHandler(t *testing.T) {
 					return nil
 				},
 				ConvertMock: func(ctx context.Context, logger *zap.Logger, formats gotenberg.PdfFormats, inputPath, outputPath string) error {
-					return errors.New("foo")
-				},
-			},
-			expectError:            true,
-			expectHttpError:        false,
-			expectOutputPathsCount: 0,
-		},
-		{
-			scenario: "success with PDF/A & PDF/UA form fields",
-			ctx: func() *api.ContextMock {
-				ctx := &api.ContextMock{Context: new(api.Context)}
-				ctx.SetFiles(map[string]string{
-					"file.pdf":  "/file.pdf",
-					"file2.pdf": "/file2.pdf",
-				})
-				ctx.SetValues(map[string][]string{
-					"pdfa": {
-						gotenberg.PdfA1b,
-					},
-					"pdfua": {
-						"true",
-					},
-				})
-				return ctx
-			}(),
-			engine: &gotenberg.PdfEngineMock{
-				MergeMock: func(ctx context.Context, logger *zap.Logger, inputPaths []string, outputPath string) error {
 					return nil
 				},
-				ConvertMock: func(ctx context.Context, logger *zap.Logger, formats gotenberg.PdfFormats, inputPath, outputPath string) error {
+				WriteMetadataMock: func(ctx context.Context, logger *zap.Logger, metadata map[string]interface{}, inputPath string) error {
 					return nil
 				},
 			},