wip: try out header signals

src/Form/FormAnalyzer.js

@@ -229,6 +229,55 @@ class FormAnalyzer {
         });
     }
 
+
+    updateFormHeaderSignals() {
+
+        const isVisuallyBeforeForm = (el) => el.getBoundingClientRect().top < this.form.getBoundingClientRect().top;
+
+        const isHeaderSized = (el) => {
+            if (el instanceof HTMLHeadingElement) {
+                return true;
+            }
+
+            const computedStyle = window.getComputedStyle(el);
+            const fontWeight = computedStyle.fontWeight;
+            const isRelativelyTall = parseFloat(computedStyle.height) / this.form.clientHeight > 0.1;
+            if (fontWeight === 'bold' || parseFloat(fontWeight) >= 700 || isRelativelyTall) {
+                return true
+            }
+        }
+
+        const allSiblings = Array.from(this.form.parentElement?.children ?? [])
+            .filter((element) => element !== this.form)
+        if (allSiblings.length === 0) return false;
+
+
+        allSiblings.forEach((sibling) => {
+            if (sibling instanceof HTMLElement && sibling.childElementCount === 1 && isVisuallyBeforeForm(sibling) && isHeaderSized(sibling)) {
+                const string = sibling.textContent?.trim();
+                if (string) {
+                    if (safeRegexTest(/^(sign[- ]?in|log[- ]?in)$/, string)) {
+                        return this.decreaseSignalBy(3, 'Strong login header before form');
+                    } else if (safeRegexTest(/^(sign[- ]?up)$/, string)) {
+                        return this.increaseSignalBy(3, 'Strong signup header before form');
+                    }
+                }
+            }
+        });
+    }
+
+    hasPasswordHints() {
+        return Array.from(this.form.querySelectorAll('div, span'))
+            .filter(
+                (div) =>
+                    div.textContent != null &&
+                    div.textContent.trim() !== '' &&
+                    window.getComputedStyle(div).display !== 'none' &&
+                    window.getComputedStyle(div).visibility !== 'hidden',
+            )
+            .some((div) => div.textContent && safeRegexTest(this.matching.getDDGMatcherRegex('passwordHintsRegex'), div.textContent));
+    }
+
     /**
      * Function that checks if the element is an external link or a custom web element that
      * encapsulates a link.
@@ -336,19 +385,10 @@ class FormAnalyzer {
             this.increaseSignalBy(relevantFields.length * 1.5, 'many fields: it is probably not a login');
         }
 
-        // If the form contains password hints, it's highly likely a signup form.
-        const hasPasswordHints = Array.from(this.form.querySelectorAll('div, span'))
-            .filter(
-                (div) =>
-                    div.textContent != null &&
-                    div.textContent.trim() !== '' &&
-                    window.getComputedStyle(div).display !== 'none' &&
-                    window.getComputedStyle(div).visibility !== 'hidden',
-            )
-            .some((div) => div.textContent && safeRegexTest(this.matching.getDDGMatcherRegex('passwordHintsRegex'), div.textContent));
+        this.updateFormHeaderSignals();
 
-        if (hasPasswordHints) {
-            this.increaseSignalBy(6, 'Password hints');
+        if (this.hasPasswordHints()) {
+            this.increaseSignalBy(3, 'Password hints');
         }
 
         // If we can't decide at this point, try reading page headings