Feature/#103 navigate back (#107)

* #103 Added NAVIGATE_BACK function

* Commented out debugging test

* Updated implementation

examples/navigate_back.fql

@@ -0,0 +1,7 @@
+LET origin = "https://github.com/"
+LET doc = DOCUMENT(origin, true)
+
+NAVIGATE(doc, "https://github.com/features")
+NAVIGATE_BACK(doc)
+
+RETURN doc.url == origin

examples/navigate_back_2.fql

@@ -0,0 +1,9 @@
+LET origin = "https://github.com/"
+LET doc = DOCUMENT(origin, true)
+
+NAVIGATE(doc, "https://github.com/features")
+NAVIGATE(doc, "https://github.com/business")
+NAVIGATE(doc, "https://github.com/marketplace")
+NAVIGATE_BACK(doc, 3)
+
+RETURN doc.url == origin

pkg/compiler/compiler_test.go

@@ -2104,22 +2104,19 @@ func TestParam(t *testing.T) {
 //		c := compiler.New()
 //
 //		out, err := c.MustCompile(`
-//LET google = DOCUMENT("https://www.google.com/", true)
+//LET origin = "https://github.com/"
+//LET doc = DOCUMENT(origin, true)
 //
-//INPUT(google, 'input[name="q"]', "ferret", 25)
-//CLICK(google, 'input[name="btnK"]')
+//NAVIGATE(doc, "https://github.com/features")
 //
-//WAIT_NAVIGATION(google)
-//WAIT_ELEMENT(google, '.g', 5000)
+//LOG("NAVIGATE", doc.url)
+//
+//NAVIGATE_BACK(doc)
+//
+//LOG("NAVIGATE_BACK", doc.url)
+//
+//RETURN doc.url == origin
 //
-//FOR result IN ELEMENTS(google, '.g')
-//    // filter out extra elements like videos and 'People also ask'
-//    FILTER TRIM(result.attributes.class) == 'g'
-//    RETURN {
-//        title: INNER_TEXT(result, 'h3'),
-//        description: INNER_TEXT(result, '.st'),
-//        url: INNER_TEXT(result, 'cite')
-//    }
 //			`).Run(context.Background())
 //
 //		So(err, ShouldBeNil)

pkg/html/dynamic/document.go

@@ -603,6 +603,46 @@ func (doc *HTMLDocument) Navigate(url values.String, timeout values.Int) error {
 	return doc.WaitForNavigation(timeout)
 }
 
+func (doc *HTMLDocument) NavigateBack(skip values.Int, timeout values.Int) (values.Boolean, error) {
+	ctx := context.Background()
+	history, err := doc.client.Page.GetNavigationHistory(ctx)
+
+	if err != nil {
+		return values.False, err
+	}
+
+	// we are in the beginning
+	if history.CurrentIndex == 0 {
+		return values.False, nil
+	}
+
+	if skip < 1 {
+		skip = 1
+	}
+
+	to := history.CurrentIndex - int(skip)
+
+	if to < 0 {
+		// TODO: Return error?
+		return values.False, nil
+	}
+
+	prev := history.Entries[to]
+	err = doc.client.Page.NavigateToHistoryEntry(ctx, page.NewNavigateToHistoryEntryArgs(prev.ID))
+
+	if err != nil {
+		return values.False, err
+	}
+
+	err = doc.WaitForNavigation(timeout)
+
+	if err != nil {
+		return values.False, err
+	}
+
+	return values.True, nil
+}
+
 func (doc *HTMLDocument) CaptureScreenshot(params *ScreenshotArgs) (core.Value, error) {
 	ctx := context.Background()
 	metrics, err := doc.client.Page.GetLayoutMetrics(ctx)

pkg/stdlib/html/lib.go

@@ -24,6 +24,7 @@ func NewLib() map[string]core.Function {
 		"CLICK":           Click,
 		"CLICK_ALL":       ClickAll,
 		"NAVIGATE":        Navigate,
+		"NAVIGATE_BACK":   NavigateBack,
 		"INPUT":           Input,
 		"INNER_HTML":      InnerHTML,
 		"INNER_HTML_ALL":  InnerHTMLAll,

pkg/stdlib/html/navigate_back.go

@@ -0,0 +1,62 @@
+package html
+
+import (
+	"context"
+	"github.com/MontFerret/ferret/pkg/html/dynamic"
+	"github.com/MontFerret/ferret/pkg/runtime/core"
+	"github.com/MontFerret/ferret/pkg/runtime/values"
+)
+
+/*
+ * Navigates a document back within its navigation history.
+ * The operation blocks the execution until the page gets loaded.
+ * If the history is empty, the function returns FALSE.
+ * @param doc (Document) - Target document.
+ * @param entry (Int, optional) - Optional value indicating how many pages to skip. Default 1.
+ * @param timeout (Int, optional) - Optional timeout. Default is 5000.
+ * @returns (Boolean) - Returns TRUE if history exists and the operation succeeded, otherwise FALSE.
+ */
+func NavigateBack(_ context.Context, args ...core.Value) (core.Value, error) {
+	err := core.ValidateArgs(args, 1, 3)
+
+	if err != nil {
+		return values.False, err
+	}
+
+	err = core.ValidateType(args[0], core.HTMLDocumentType)
+
+	if err != nil {
+		return values.None, err
+	}
+
+	doc, ok := args[0].(*dynamic.HTMLDocument)
+
+	if !ok {
+		return values.False, core.Errors(core.ErrInvalidType, ErrNotDynamic)
+	}
+
+	skip := values.NewInt(1)
+	timeout := values.NewInt(defaultTimeout)
+
+	if len(args) > 1 {
+		err = core.ValidateType(args[1], core.IntType)
+
+		if err != nil {
+			return values.None, err
+		}
+
+		skip = args[1].(values.Int)
+	}
+
+	if len(args) > 2 {
+		err = core.ValidateType(args[2], core.IntType)
+
+		if err != nil {
+			return values.None, err
+		}
+
+		timeout = args[2].(values.Int)
+	}
+
+	return doc.NavigateBack(skip, timeout)
+}