feat(pdfengines): add support for flattening annotations (#1105)

* initial changes

* Add tests

* Fix edge case when we need to regenerate appearances

* Fix comments

* Add missing comment

* Add missing comment

* Add missing comment

* Add flatten option to the merge route

* Add flatten option to the libreoffice convert route

* Add flatten option to the chromium convert route

* Revert "Add flatten option to the chromium convert route"

This reverts commit cdab8b4e6b.

* Ignore lint false positives

* Add missing tests

* Add flatten route tests

* Replace input instead of creating a new file

* create copy before flatten in tests

---------

Co-authored-by: Peter Chakalov <peter.chakalov@abraxa.com>

pkg/modules/libreoffice/routes_test.go

@@ -402,6 +402,38 @@ func TestConvertRoute(t *testing.T) {
 			expectHttpError:        false,
 			expectOutputPathsCount: 0,
 		},
+		{
+			scenario: "PDF engine flatten error",
+			ctx: func() *api.ContextMock {
+				ctx := &api.ContextMock{Context: new(api.Context)}
+				ctx.SetFiles(map[string]string{
+					"document.docx": "/document.docx",
+				})
+				ctx.SetValues(map[string][]string{
+					"flatten": {
+						"true",
+					},
+				})
+				ctx.SetCancelled(true)
+				return ctx
+			}(),
+			libreOffice: &libreofficeapi.ApiMock{
+				PdfMock: func(ctx context.Context, logger *zap.Logger, inputPath, outputPath string, options libreofficeapi.Options) error {
+					return nil
+				},
+				ExtensionsMock: func() []string {
+					return []string{".docx"}
+				},
+			},
+			engine: &gotenberg.PdfEngineMock{
+				FlattenMock: func(ctx context.Context, logger *zap.Logger, inputPath string) error {
+					return errors.New("foo")
+				},
+			},
+			expectError:            true,
+			expectHttpError:        false,
+			expectOutputPathsCount: 0,
+		},
 		{
 			scenario: "cannot add output paths",
 			ctx: func() *api.ContextMock {
@@ -454,6 +486,9 @@ func TestConvertRoute(t *testing.T) {
 					"metadata": {
 						"{\"Creator\": \"foo\", \"Producer\": \"bar\" }",
 					},
+					"flatten": {
+						"true",
+					},
 				})
 				return ctx
 			}(),
@@ -475,6 +510,9 @@ func TestConvertRoute(t *testing.T) {
 				WriteMetadataMock: func(ctx context.Context, logger *zap.Logger, metadata map[string]interface{}, inputPath string) error {
 					return nil
 				},
+				FlattenMock: func(ctx context.Context, logger *zap.Logger, inputPath string) error {
+					return nil
+				},
 			},
 			expectError:            false,
 			expectHttpError:        false,
@@ -502,6 +540,9 @@ func TestConvertRoute(t *testing.T) {
 					"metadata": {
 						"{\"Creator\": \"foo\", \"Producer\": \"bar\" }",
 					},
+					"flatten": {
+						"true",
+					},
 				})
 				ctx.SetPathRename(&gotenberg.PathRenameMock{RenameMock: func(oldpath, newpath string) error {
 					return nil
@@ -526,6 +567,9 @@ func TestConvertRoute(t *testing.T) {
 				WriteMetadataMock: func(ctx context.Context, logger *zap.Logger, metadata map[string]interface{}, inputPath string) error {
 					return nil
 				},
+				FlattenMock: func(ctx context.Context, logger *zap.Logger, inputPath string) error {
+					return nil
+				},
 			},
 			expectError:            false,
 			expectHttpError:        false,