"use client";

import React, {
  createContext,
  useContext,
  useState,
  useEffect,
  useCallback,
} from "react";
import { useRouter } from "next/navigation";
import {
  User,
  getAuthToken,
  setAuthToken,
  getStoredUser,
  setStoredUser,
  clearAuth,
  isTokenExpired,
} from "@/lib/auth";

interface AuthContextType {
  user: User | null;
  isLoading: boolean;
  isAuthenticated: boolean;
  login: (token: string) => Promise<void>;
  logout: () => void;
  checkAuth: () => void;
}

const AuthContext = createContext<AuthContextType | undefined>(undefined);

export function AuthProvider({ children }: { children: React.ReactNode }) {
  const [user, setUser] = useState<User | null>(null);
  const [isLoading, setIsLoading] = useState(true);
  const router = useRouter();

  const checkAuth = useCallback(() => {
    const token = getAuthToken();
    const storedUser = getStoredUser();

    if (token && storedUser && !isTokenExpired(token)) {
      setUser(storedUser);
    } else {
      clearAuth();
      setUser(null);
    }
    setIsLoading(false);
  }, []);

  useEffect(() => {
    checkAuth();
  }, [checkAuth]);

  const login = useCallback(
    async (token: string) => {
      try {
        // Decode JWT to get user info
        const base64Url = token.split(".")[1];
        const base64 = base64Url.replace(/-/g, "+").replace(/_/g, "/");
        const jsonPayload = decodeURIComponent(
          atob(base64)
            .split("")
            .map((c) => "%" + ("00" + c.charCodeAt(0).toString(16)).slice(-2))
            .join(""),
        );

        const claims = JSON.parse(jsonPayload);

        // Extract user info from JWT claims
        const userInfo: User = {
          username: claims.github_username || claims.sub,
          email: claims.email,
          name: claims.name,
          avatar_url: claims.avatar_url,
          organizations: claims.github_orgs,
        };

        setAuthToken(token);
        setStoredUser(userInfo);
        setUser(userInfo);
        router.push("/"); // Redirect to home after login
      } catch (error) {
        // Clear token if we can't decode it
        clearAuth();
        throw new Error("Failed to decode authentication token");
      }
    },
    [router],
  );

  const logout = useCallback(() => {
    clearAuth();
    setUser(null);
    router.push("/login");
  }, [router]);

  const value = {
    user,
    isLoading,
    isAuthenticated: !!user,
    login,
    logout,
    checkAuth,
  };

  return <AuthContext.Provider value={value}>{children}</AuthContext.Provider>;
}

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