Fix bugs, convert thumbnail to png, add context menu

backend/app/auth/rate_limit.py

@@ -0,0 +1,59 @@
+"""In-memory rate limiting for login attempts."""
+
+import time
+from collections import defaultdict
+from fastapi import HTTPException
+
+from app.config import settings
+
+# In-memory store: IP address -> {"attempts": int, "lockout_until": float}
+_rate_limits: dict[str, dict[str, float]] = defaultdict(
+    lambda: {"attempts": 0, "lockout_until": 0.0}
+)
+
+
+def check_rate_limit(ip: str) -> None:
+    """
+    Check if the IP is currently locked out.
+    Raises a 429 HTTPException if locked out.
+    """
+    now = time.time()
+    record = _rate_limits[ip]
+
+    if record["lockout_until"] > now:
+        remaining = int(record["lockout_until"] - now)
+        raise HTTPException(
+            status_code=429,
+            detail=f"Too many failed attempts. Try again in {remaining} seconds.",
+            headers={"Retry-After": str(remaining)},
+        )
+    
+    # If lockout has expired, reset
+    if record["lockout_until"] > 0 and record["lockout_until"] <= now:
+        record["attempts"] = 0
+        record["lockout_until"] = 0.0
+
+
+def record_failed_attempt(ip: str) -> None:
+    """
+    Record a failed login attempt for the IP.
+    Applies lockout if MAX_ATTEMPTS is reached.
+    """
+    now = time.time()
+    record = _rate_limits[ip]
+    record["attempts"] += 1
+
+    if record["attempts"] >= settings.LOGIN_MAX_ATTEMPTS:
+        record["lockout_until"] = now + settings.LOGIN_LOCKOUT_SECONDS
+        remaining = settings.LOGIN_LOCKOUT_SECONDS
+        raise HTTPException(
+            status_code=429,
+            detail=f"Too many failed attempts. Try again in {remaining} seconds.",
+            headers={"Retry-After": str(remaining)},
+        )
+
+
+def clear_attempts(ip: str) -> None:
+    """Clear all failed attempts for the IP (e.g., after successful login)."""
+    if ip in _rate_limits:
+        _rate_limits[ip] = {"attempts": 0, "lockout_until": 0.0}