Add Facebook username validation functionality

user_scanner/social/facebook.py

@@ -0,0 +1,55 @@
+import httpx
+from httpx import ConnectError, TimeoutException
+
+def validate_facebook(username):
+    url = f"https://www.facebook.com/{username}"
+
+    headers = {
+        "User-Agent": (
+            "Mozilla/5.0 (Windows NT 10.0; Win64; x64) "
+            "AppleWebKit/537.36 (KHTML, like Gecko) Chrome/120.0 Safari/537.36"
+        )
+    }
+
+    try:
+        r = httpx.get(url, headers=headers, follow_redirects=True, timeout=5)
+
+        final_url = str(r.url).lower()
+
+        unavailable_patterns = [
+            "unsupportedbrowser",
+            "help",                   # fb help redirect
+            "login",                  # login without profile id
+            "/people/",               # but no profile id number
+            "recover",                # account recovery redirect
+        ]
+
+        # Username does NOT exist if URL ends in something not related to profile
+        if any(p in final_url for p in unavailable_patterns) and "profile.php?id=" not in final_url:
+            return 1  # Available
+
+        if "profile.php?id=" in final_url:
+            return 0  # Exists
+
+        # If URL contains the username itself without redirecting to unsupported pages
+        if username.lower() in final_url:
+            return 0  # Exists (custom username)
+
+        return 2
+
+    except (ConnectError, TimeoutException):
+        return 2
+    except Exception:
+        return 2
+
+
+if __name__ == "__main__":
+    user = input("Username?: ").strip()
+    result = validate_facebook(user)
+
+    if result == 1:
+        print("Available!")
+    elif result == 0:
+        print("Unavailable!")
+    else:
+        print("Error occurred!")