/**
 * useAuth — authentication context provider.
 *
 * Validates a stored token against /api/auth/me on load and exposes
 * login/logout backed by the backend auth routes; persists the token in
 * localStorage.
 *
 * Architecture: wraps the whole app in App.jsx; consumed by InfoBar,
 * LoginButton, LoginModal, and RosterManager.
 *
 * Design: one shared context so every auth-gated component reads the same
 * session state.
 */

import { createContext, useContext, useState, useEffect, useCallback } from "react";
import { apiUrl } from "../utils/api";

const AuthContext = createContext(null);

export function AuthProvider({ children }) {
  const [token, setToken] = useState(() => localStorage.getItem("valhalla_token"));
  const [user, setUser] = useState(null);
  const [loading, setLoading] = useState(true);

  useEffect(() => {
    if (!token) {
      setLoading(false);
      return;
    }
    fetch(apiUrl("/api/auth/me"), {
      headers: { Authorization: `Bearer ${token}` },
    })
      .then((r) => (r.ok ? r.json() : Promise.reject()))
      .then((u) => setUser(u))
      .catch(() => {
        localStorage.removeItem("valhalla_token");
        setToken(null);
      })
      .finally(() => setLoading(false));
  }, [token]);

  const login = useCallback(async (email, password) => {
    const res = await fetch(apiUrl("/api/auth/login"), {
      method: "POST",
      headers: { "Content-Type": "application/json" },
      body: JSON.stringify({ email, password }),
    });
    if (!res.ok) {
      const err = await res.json().catch(() => ({ detail: "Login failed" }));
      throw new Error(err.detail || "Login failed");
    }
    const data = await res.json();
    localStorage.setItem("valhalla_token", data.token);
    setToken(data.token);
    setUser(data.user);
    return data;
  }, []);

  const logout = useCallback(async () => {
    if (token) {
      await fetch(apiUrl("/api/auth/logout"), {
        method: "POST",
        headers: { "Content-Type": "application/json" },
        body: JSON.stringify({ token }),
      }).catch(() => {});
    }
    localStorage.removeItem("valhalla_token");
    setToken(null);
    setUser(null);
  }, [token]);

  return (
    <AuthContext.Provider
      value={{ token, user, isAuthenticated: !!user, loading, login, logout }}
    >
      {children}
    </AuthContext.Provider>
  );
}

export function useAuth() {
  const ctx = useContext(AuthContext);
  if (!ctx) throw new Error("useAuth must be used within AuthProvider");
  return ctx;
}