feat(chromium): add 'waitForExpression' form field, deprecate 'waitWindowStatus' form field

pkg/modules/chromium/chromium.go

@@ -30,6 +30,10 @@ var (
 	// allowed/denied lists.
 	ErrURLNotAuthorized = errors.New("URL not authorized")
 
+	// ErrInvalidEvaluationExpression happens if an evaluation expression
+	// returns an exception or undefined.
+	ErrInvalidEvaluationExpression = errors.New("invalid evaluation expression")
+
 	// ErrInvalidPrinterSettings happens if the Options have one or more
 	// aberrant values.
 	ErrInvalidPrinterSettings = errors.New("invalid printer settings")
@@ -71,6 +75,11 @@ type Options struct {
 	// Optional.
 	WaitWindowStatus string
 
+	// WaitForExpression is the custom JavaScript expression to wait before
+	// converting an HTML document to PDF until it returns true
+	// Optional.
+	WaitForExpression string
+
 	// UserAgent overrides the default User-Agent header.
 	// Optional.
 	UserAgent string
@@ -149,6 +158,7 @@ func DefaultOptions() Options {
 	return Options{
 		WaitDelay:         0,
 		WaitWindowStatus:  "",
+		WaitForExpression: "",
 		UserAgent:         "",
 		ExtraHTTPHeaders:  nil,
 		Landscape:         false,
@@ -454,42 +464,61 @@ func (mod Chromium) PDF(ctx context.Context, logger *zap.Logger, URL, outputPath
 				return nil
 			}),
 			chromedp.ActionFunc(func(ctx context.Context) error {
-				if options.WaitWindowStatus == "" {
+				if options.WaitWindowStatus == "" && options.WaitForExpression == "" {
 					return nil
 				}
 
-				// We wait until the evaluation of
-				// "window.status === options.WaitWindowStatus" is true or
-				// until the context is done.
-				logger.Debug(fmt.Sprintf("wait for window.status === '%s' before print", options.WaitWindowStatus))
+				evaluate := func(expression string) error {
+					// We wait until the evaluation of the expression is true or
+					// until the context is done.
+					logger.Debug(fmt.Sprintf("wait until '%s' is true before print", expression))
 
-				ticker := time.NewTicker(time.Duration(100) * time.Millisecond)
+					ticker := time.NewTicker(time.Duration(100) * time.Millisecond)
 
-				for {
-					select {
-					case <-ctx.Done():
-						ticker.Stop()
-
-						return fmt.Errorf("wait for window.status === '%s': %w", options.WaitWindowStatus, ctx.Err())
-					case <-ticker.C:
-						var ok bool
-
-						evaluate := chromedp.Evaluate(fmt.Sprintf("window.status === '%s'", options.WaitWindowStatus), &ok)
-						err := evaluate.Do(ctx)
-
-						if err != nil {
-							return fmt.Errorf("evaluate: %w", err)
-						}
-
-						if ok {
+					for {
+						select {
+						case <-ctx.Done():
 							ticker.Stop()
 
-							return nil
-						}
+							return fmt.Errorf("context done while evaluating '%s': %w", expression, ctx.Err())
+						case <-ticker.C:
+							var ok bool
 
-						continue
+							evaluate := chromedp.Evaluate(expression, &ok)
+							err := evaluate.Do(ctx)
+
+							if err != nil {
+								return fmt.Errorf("evaluate: %v: %w", err, ErrInvalidEvaluationExpression)
+							}
+
+							if ok {
+								ticker.Stop()
+
+								return nil
+							}
+
+							continue
+						}
 					}
 				}
+
+				if options.WaitWindowStatus != "" {
+					logger.Warn("option 'WaitWindowStatus' is deprecated; prefer 'WaitForExpression' instead")
+
+					err := evaluate(fmt.Sprintf("window.status === '%s'", options.WaitWindowStatus))
+					if err != nil {
+						return fmt.Errorf("wait for window.status === '%s': %w", options.WaitWindowStatus, err)
+					}
+				}
+
+				if options.WaitForExpression != "" {
+					err := evaluate(options.WaitForExpression)
+					if err != nil {
+						return fmt.Errorf("wait for expression '%s': %w", options.WaitForExpression, err)
+					}
+				}
+
+				return nil
 			}),
 			chromedp.ActionFunc(func(ctx context.Context) error {
 				printToPDF := page.PrintToPDF().

pkg/modules/chromium/chromium_test.go

@@ -285,6 +285,21 @@ func TestChromium_PDF(t *testing.T) {
 				WaitWindowStatus: "ready",
 			},
 		},
+		{
+			timeout: time.Duration(3) * time.Second,
+			URL:     "file:///tests/test/testdata/chromium/html/sample2/index.html",
+			options: Options{
+				WaitForExpression: "window.status === 'foo'",
+			},
+			expectErr: true,
+		},
+		{
+			timeout: time.Duration(3) * time.Second,
+			URL:     "file:///tests/test/testdata/chromium/html/sample2/index.html",
+			options: Options{
+				WaitForExpression: "window.status === 'ready'",
+			},
+		},
 		{
 			URL: "file:///tests/test/testdata/chromium/html/sample4/index.html",
 			options: Options{

pkg/modules/chromium/routes.go

@@ -28,6 +28,7 @@ func FormDataChromiumPDFOptions(ctx *api.Context) (*api.FormData, Options) {
 	var (
 		waitDelay                                        time.Duration
 		waitWindowStatus                                 string
+		waitForExpression                                string
 		userAgent                                        string
 		extraHTTPHeaders                                 map[string]string
 		landscape, printBackground                       bool
@@ -41,6 +42,7 @@ func FormDataChromiumPDFOptions(ctx *api.Context) (*api.FormData, Options) {
 	form := ctx.FormData().
 		Duration("waitDelay", &waitDelay, defaultOptions.WaitDelay).
 		String("waitWindowStatus", &waitWindowStatus, defaultOptions.WaitWindowStatus).
+		String("waitForExpression", &waitForExpression, defaultOptions.WaitForExpression).
 		String("userAgent", &userAgent, defaultOptions.UserAgent).
 		Custom("extraHttpHeaders", func(value string) error {
 			if value == "" {
@@ -73,6 +75,7 @@ func FormDataChromiumPDFOptions(ctx *api.Context) (*api.FormData, Options) {
 	options := Options{
 		WaitDelay:         waitDelay,
 		WaitWindowStatus:  waitWindowStatus,
+		WaitForExpression: waitForExpression,
 		UserAgent:         userAgent,
 		ExtraHTTPHeaders:  extraHTTPHeaders,
 		Landscape:         landscape,
@@ -291,6 +294,23 @@ func convertURL(ctx *api.Context, chromium API, engine gotenberg.PDFEngine, URL,
 			)
 		}
 
+		if errors.Is(err, ErrInvalidEvaluationExpression) {
+			if options.WaitForExpression == "" {
+				// We do not expect the 'waitWindowStatus' form field to return
+				// an ErrInvalidEvaluationExpression error. In such a scenario,
+				// we return a 500.
+				return fmt.Errorf("convert to PDF: %w", err)
+			}
+
+			return api.WrapError(
+				fmt.Errorf("convert to PDF: %w", err),
+				api.NewSentinelHTTPError(
+					http.StatusBadRequest,
+					fmt.Sprintf("The expression '%s' (waitForExpression) returned an exception or undefined", options.WaitForExpression),
+				),
+			)
+		}
+
 		if errors.Is(err, ErrInvalidPrinterSettings) {
 			return api.WrapError(
 				fmt.Errorf("convert to PDF: %w", err),

pkg/modules/chromium/routes_test.go

@@ -523,6 +523,7 @@ func TestConvertURL(t *testing.T) {
 		api                    API
 		engine                 gotenberg.PDFEngine
 		PDFformat              string
+		options                Options
 		expectErr              bool
 		expectHTTPErr          bool
 		expectHTTPStatus       int
@@ -538,10 +539,44 @@ func TestConvertURL(t *testing.T) {
 
 				return chromiumAPI
 			}(),
+			options:          DefaultOptions(),
 			expectErr:        true,
 			expectHTTPErr:    true,
 			expectHTTPStatus: http.StatusForbidden,
 		},
+		{
+			ctx: &api.MockContext{Context: &api.Context{}},
+			api: func() API {
+				chromiumAPI := struct{ ProtoAPI }{}
+				chromiumAPI.pdf = func(_ context.Context, _ *zap.Logger, _, _ string, _ Options) error {
+					return ErrInvalidEvaluationExpression
+				}
+
+				return chromiumAPI
+			}(),
+			options:   DefaultOptions(),
+			expectErr: true,
+		},
+		{
+			ctx: &api.MockContext{Context: &api.Context{}},
+			api: func() API {
+				chromiumAPI := struct{ ProtoAPI }{}
+				chromiumAPI.pdf = func(_ context.Context, _ *zap.Logger, _, _ string, _ Options) error {
+					return ErrInvalidEvaluationExpression
+				}
+
+				return chromiumAPI
+			}(),
+			options: func() Options {
+				options := DefaultOptions()
+				options.WaitForExpression = "foo"
+
+				return options
+			}(),
+			expectErr:        true,
+			expectHTTPErr:    true,
+			expectHTTPStatus: http.StatusBadRequest,
+		},
 		{
 			ctx: &api.MockContext{Context: &api.Context{}},
 			api: func() API {
@@ -552,6 +587,7 @@ func TestConvertURL(t *testing.T) {
 
 				return chromiumAPI
 			}(),
+			options:          DefaultOptions(),
 			expectErr:        true,
 			expectHTTPErr:    true,
 			expectHTTPStatus: http.StatusBadRequest,
@@ -566,6 +602,7 @@ func TestConvertURL(t *testing.T) {
 
 				return chromiumAPI
 			}(),
+			options:          DefaultOptions(),
 			expectErr:        true,
 			expectHTTPErr:    true,
 			expectHTTPStatus: http.StatusBadRequest,
@@ -580,6 +617,7 @@ func TestConvertURL(t *testing.T) {
 
 				return chromiumAPI
 			}(),
+			options:   DefaultOptions(),
 			expectErr: true,
 		},
 		{
@@ -600,6 +638,7 @@ func TestConvertURL(t *testing.T) {
 				}
 			}(),
 			PDFformat:        "foo",
+			options:          DefaultOptions(),
 			expectErr:        true,
 			expectHTTPErr:    true,
 			expectHTTPStatus: http.StatusBadRequest,
@@ -622,6 +661,7 @@ func TestConvertURL(t *testing.T) {
 				}
 			}(),
 			PDFformat: "foo",
+			options:   DefaultOptions(),
 			expectErr: true,
 		},
 		{
@@ -642,6 +682,7 @@ func TestConvertURL(t *testing.T) {
 				}
 			}(),
 			PDFformat:              "foo",
+			options:                DefaultOptions(),
 			expectOutputPathsCount: 1,
 		},
 		{
@@ -659,6 +700,7 @@ func TestConvertURL(t *testing.T) {
 
 				return chromiumAPI
 			}(),
+			options:   DefaultOptions(),
 			expectErr: true,
 		},
 		{
@@ -671,10 +713,11 @@ func TestConvertURL(t *testing.T) {
 
 				return chromiumAPI
 			}(),
+			options:                DefaultOptions(),
 			expectOutputPathsCount: 1,
 		},
 	} {
-		err := convertURL(tc.ctx.Context, tc.api, tc.engine, "", tc.PDFformat, DefaultOptions())
+		err := convertURL(tc.ctx.Context, tc.api, tc.engine, "", tc.PDFformat, tc.options)
 
 		if tc.expectErr && err == nil {
 			t.Errorf("test %d: expected error but got: %v", i, err)