import { API_BASE_URL } from "./api";

const AUTH_TOKEN_KEY = "auth_token";
const AUTH_USER_KEY = "auth_user";

export interface AuthUser {
  id?: string;
  name?: string;
  email?: string;
  role?: string;
  permissions?: string[];
  roleId?: string;
  userName?: string;
  phone?: string;
  [key: string]: unknown;
}

export interface LoginResponse {
  token: string;
  user: AuthUser;
}

export function getStoredToken() {
  if (typeof window === "undefined") return null;
  return localStorage.getItem(AUTH_TOKEN_KEY);
}

export function getStoredUser(): AuthUser | null {
  if (typeof window === "undefined") return null;

  const raw = localStorage.getItem(AUTH_USER_KEY);
  if (!raw) return null;

  try {
    return JSON.parse(raw) as AuthUser;
  } catch {
    return null;
  }
}

export function saveAuth(token: string, user: AuthUser) {
  if (typeof window === "undefined") return;
  localStorage.setItem(AUTH_TOKEN_KEY, token);
  localStorage.setItem(AUTH_USER_KEY, JSON.stringify(user));
}

export function clearAuth() {
  if (typeof window === "undefined") return;
  localStorage.removeItem(AUTH_TOKEN_KEY);
  localStorage.removeItem(AUTH_USER_KEY);
}

export async function loginUser(identity: string, password: string) {
  const response = await fetch(`${API_BASE_URL}/v1/auth/login`, {
    method: "POST",
    headers: { "Content-Type": "application/json" },
    body: JSON.stringify({ identity, password }),
  });

  const payload = (await response.json().catch(() => ({}))) as {
    success?: boolean;
    message?: string;
    data?: {
      token?: string;
      user?: AuthUser;
    };
    token?: string;
    user?: AuthUser;
  };

  if (!response.ok) {
    throw new Error(payload.message || "Login failed. Please check your credentials.");
  }

  const token = payload.data?.token ?? payload.token;
  const user = payload.data?.user ?? payload.user;

  if (!token || !user) {
    throw new Error("The server did not return a valid session payload.");
  }

  const rolePermissions = (user as { role?: { permissions?: Array<{ permission?: { slug?: string } }> } }).role?.permissions ?? [];
  const permissions = Array.isArray(rolePermissions)
    ? rolePermissions
        .map((entry) => entry?.permission?.slug)
        .filter((slug): slug is string => Boolean(slug))
    : [];

  saveAuth(token, { ...user, permissions });

  return { token, user: { ...user, permissions } } as LoginResponse;
}