add auth

frontend/src/auth/AuthContext.tsx

@@ -0,0 +1,86 @@
+import { useState, useEffect, useCallback, type ReactNode } from "react";
+import { AuthContext, type AuthUser } from "./AuthTypes";
+
+const BASE = "/api";
+
+async function fetchMe(token: string) {
+  try {
+    const res = await fetch(`${BASE}/auth/me`, {
+      headers: {
+        "Content-Type": "application/json",
+        Authorization: `Bearer ${token}`,
+      },
+    });
+    if (!res.ok) return null;
+    return res.json();
+  } catch {
+    return null;
+  }
+}
+
+export function AuthProvider({ children }: { children: ReactNode }) {
+  const [user, setUser] = useState<AuthUser | null>(null);
+  const [token, setToken] = useState<string | null>(() => localStorage.getItem("token"));
+  const [isLoading, setIsLoading] = useState(true);
+
+  useEffect(() => {
+    let cancelled = false;
+
+    async function validateToken() {
+      if (!token) return;
+      const u = await fetchMe(token);
+      if (cancelled) return;
+      if (u) {
+        setUser(u);
+      } else {
+        localStorage.removeItem("token");
+        setToken(null);
+      }
+    }
+
+    validateToken().finally(() => {
+      if (!cancelled) setIsLoading(false);
+    });
+
+    return () => {
+      cancelled = true;
+    };
+  }, [token]);
+
+  const login = useCallback(async (username: string, password: string) => {
+    const res = await fetch(`${BASE}/auth/login`, {
+      method: "POST",
+      headers: { "Content-Type": "application/json" },
+      body: JSON.stringify({ username, password }),
+    });
+    if (!res.ok) {
+      const text = await res.text().catch(() => "");
+      throw new Error(`${res.status}: ${text}`);
+    }
+    const data = await res.json();
+    const newToken = data.access_token;
+    localStorage.setItem("token", newToken);
+    setToken(newToken);
+  }, []);
+
+  const logout = useCallback(() => {
+    localStorage.removeItem("token");
+    setToken(null);
+    setUser(null);
+  }, []);
+
+  return (
+    <AuthContext.Provider
+      value={{
+        user,
+        token,
+        isAuthenticated: !!user,
+        isLoading,
+        login,
+        logout,
+      }}
+    >
+      {children}
+    </AuthContext.Provider>
+  );
+}