// ===============================
// AUTH.JS
// Login, JWT, redirect e auto logout
// ===============================

// Deve rimanere globale se viene usata da altri file
function parseJwt(token) {
  try {
    const payload = token.split(".")[1];

    if (!payload) return null;

    const base64 = payload
      .replace(/-/g, "+")
      .replace(/_/g, "/")
      .padEnd(Math.ceil(payload.length / 4) * 4, "=");

    const json = decodeURIComponent(
      atob(base64)
        .split("")
        .map((char) =>
          `%${char.charCodeAt(0).toString(16).padStart(2, "0")}`
        )
        .join("")
    );

    return JSON.parse(json);
  } catch (error) {
    console.error("[AUTH] JWT non valido:", error);
    return null;
  }
}

(() => {
  "use strict";

  const LOGIN_ENDPOINT = "/auth/login";
  const LOGIN_PAGE = "/login";
  const TOKEN_KEY = "token";

  let autoLogoutTimer = null;

  // -------------------------------
  // TOKEN
  // -------------------------------

  function saveToken(token) {
    try {
      localStorage.setItem(TOKEN_KEY, token);
    } catch (error) {
      console.error("[AUTH] Errore salvataggio token:", error);
    }
  }

  function getToken() {
    try {
      return localStorage.getItem(TOKEN_KEY) || "";
    } catch {
      return "";
    }
  }

  function clearToken() {
    clearTimeout(autoLogoutTimer);
    autoLogoutTimer = null;

    try {
      localStorage.removeItem(TOKEN_KEY);
    } catch (error) {
      console.error("[AUTH] Errore rimozione token:", error);
    }
  }

  // -------------------------------
  // LOGIN
  // -------------------------------

  async function login(email, password) {
    const response = await fetch(LOGIN_ENDPOINT, {
      method: "POST",
      headers: {
        "Content-Type": "application/json",
      },
      body: JSON.stringify({ email, password }),
    });

    if (!response.ok) {
      const message = await response.text();
      throw new Error(message || "Credenziali non valide");
    }

    const data = await response.json();

    if (!data?.token) {
      throw new Error("Token mancante nella risposta");
    }

    saveToken(data.token);
    scheduleAutoLogout();

    window.dispatchEvent(
      new CustomEvent("login:success", {
        detail: data,
      })
    );

    return data;
  }

  // -------------------------------
  // VERIFICA AUTENTICAZIONE
  // -------------------------------

  function isLoggedIn() {
    const token = getToken();
    const payload = token ? parseJwt(token) : null;

    if (!payload?.exp) {
      return false;
    }

    const valid = payload.exp * 1000 > Date.now();

    console.log("[AUTH CHECK]", {
      valid,
      user: payload.name,
      exp: new Date(payload.exp * 1000).toISOString(),
    });

    return valid;
  }

  function getUser() {
    const token = getToken();
    return token ? parseJwt(token) : null;
  }

  function requireAuth(redirectUrl = LOGIN_PAGE) {
    if (isLoggedIn()) {
      return true;
    }

    clearToken();

    const currentPath =
      window.location.pathname +
      window.location.search +
      window.location.hash;

    const separator = redirectUrl.includes("?") ? "&" : "?";

    window.location.replace(
      `${redirectUrl}${separator}redirect=${encodeURIComponent(currentPath)}`
    );

    return false;
  }

  // -------------------------------
  // AUTO LOGOUT
  // -------------------------------

  function scheduleAutoLogout() {
    clearTimeout(autoLogoutTimer);
    autoLogoutTimer = null;

    const payload = getUser();
    const expiresAt = payload?.exp ? payload.exp * 1000 : 0;
    const timeout = expiresAt - Date.now();

    if (!expiresAt) {
      return;
    }

    if (timeout <= 0) {
      logout({ redirect: true });
      return;
    }

    autoLogoutTimer = setTimeout(() => {
      logout({ redirect: true });
    }, timeout);
  }

  function logout(options = {}) {
    clearToken();

    if (window.AppAuthLogout?.logout) {
      return window.AppAuthLogout.logout(options);
    }

    if (options.redirect !== false) {
      window.location.replace(LOGIN_PAGE);
    }
  }

  // -------------------------------
  // INIT
  // -------------------------------

  function init() {
    if (isLoggedIn()) {
      scheduleAutoLogout();
    }
  }

  // -------------------------------
  // API GLOBALE
  // -------------------------------

  window.AppAuth = Object.freeze({
    login,
    logout,
    isLoggedIn,
    getUser,
    requireAuth,
    scheduleAutoLogout,
  });

  if (document.readyState === "loading") {
    document.addEventListener("DOMContentLoaded", init, { once: true });
  } else {
    init();
  }
})();