[Glitch] Profile editing: Add warning for links

Port 12c6c6dcf9 to glitch-soc

Signed-off-by: Claire <claire.github-309c@sitedethib.com>

app/javascript/flavours/glitch/utils/checks.test.ts

@@ -0,0 +1,21 @@
+import { isUrlWithoutProtocol } from './checks';
+
+describe('isUrlWithoutProtocol', () => {
+  test.concurrent.each([
+    ['example.com', true],
+    ['sub.domain.co.uk', true],
+    ['example', false], // No dot
+    ['example..com', false], // Consecutive dots
+    ['example.com.', false], // Trailing dot
+    ['example.c', false], // TLD too short
+    ['example.123', false], // Numeric TLDs are not valid
+    ['example.com/path', true], // Paths are allowed
+    ['example.com?query=string', true], // Query strings are allowed
+    ['example.com#fragment', true], // Fragments are allowed
+    ['example .com', false], // Spaces are not allowed
+    ['example://com', false], // Protocol inside the string is not allowed
+    ['example.com^', false], // Invalid characters not allowed
+  ])('should return %s for input "%s"', (input, expected) => {
+    expect(isUrlWithoutProtocol(input)).toBe(expected);
+  });
+});

app/javascript/flavours/glitch/utils/checks.ts

@@ -9,3 +9,29 @@ export function isValidUrl(
     return false;
   }
 }
+
+/**
+ * Checks if the input string is probably a URL without a protocol. Note this is not full URL validation,
+ * and is mostly used to detect link-like inputs.
+ * @see https://www.xjavascript.com/blog/check-if-a-javascript-string-is-a-url/
+ * @param input The input string to check
+ */
+export function isUrlWithoutProtocol(input: string): boolean {
+  if (!input.length || input.includes(' ') || input.includes('://')) {
+    return false;
+  }
+
+  try {
+    const url = new URL(`http://${input}`);
+    const { host } = url;
+    return (
+      host !== '' && // Host is not empty
+      host.includes('.') && // Host contains at least one dot
+      !host.endsWith('.') && // No trailing dot
+      !host.includes('..') && // No consecutive dots
+      /\.[\w]{2,}$/.test(host) // TLD is at least 2 characters
+    );
+  } catch {}
+
+  return false;
+}