// NOTE: staging credentials. Calling an OAuth2 client_credentials flow from
// the browser exposes CLIENT_SECRET to anyone who views the page source.
const AUTH_CONFIG = {
  CLIENT_ID: "4INGOCMoulE0fNY1SQlTbPtsWqqxGj2DdqjADq6u",
  CLIENT_SECRET:
    "KPc4dMSztNwAIB3vii3geXrzC1mKUIsAztz3t2ylC3HlrgJudJWhdrtoY6XeRJIuadTAREYYsXk9XtFHUDfPVcJvyfHMpNkz2VvghwrijhVprok0VYV7XrOirJ5nFUxD",
  TOKEN_URL: "https://accounts-staging.gooyal.ir/oauth2/token/",
  SCOPE: "accounts.invite:submit",
};

const INVITE_URL = "https://accounts-staging.gooyal.ir/users/api/invite_requests/";

const phoneInput = document.getElementById("phoneInput");
const submitBtn = document.getElementById("submitBtn");
const formMessage = document.getElementById("formMessage");

let accessToken = null;
let tokenRequest = null;

function setMessage(text, type) {
  formMessage.textContent = text || "";
  formMessage.classList.remove("error", "success");
  if (type) formMessage.classList.add(type);
}

function setButtonLoading(isLoading, label) {
  submitBtn.disabled = isLoading;
  submitBtn.textContent = label || "ثبت شماره و دانلود برنامه";
}

async function fetchAccessToken() {
  const basicAuth = btoa(`${AUTH_CONFIG.CLIENT_ID}:${AUTH_CONFIG.CLIENT_SECRET}`);

  const response = await fetch(AUTH_CONFIG.TOKEN_URL, {
    method: "POST",
    headers: {
      "Content-Type": "application/x-www-form-urlencoded",
      Authorization: `Basic ${basicAuth}`,
    },
    body: new URLSearchParams({
      grant_type: "client_credentials",
      scope: AUTH_CONFIG.SCOPE,
    }),
  });

  if (!response.ok) {
    throw new Error(`Token request failed (${response.status})`);
  }

  const data = await response.json();
  accessToken = data.access_token;
  return accessToken;
}

// Reuses an in-flight request so concurrent callers don't fire duplicate token requests.
function ensureAccessToken() {
  if (accessToken) return Promise.resolve(accessToken);
  if (!tokenRequest) {
    tokenRequest = fetchAccessToken().finally(() => {
      tokenRequest = null;
    });
  }
  return tokenRequest;
}

function getInviteCode() {
  return new URLSearchParams(window.location.search).get("inviteCode");
}

// Picks where to send the user after a successful submission, based on platform.
function getDownloadRedirectUrl() {
  const ua = navigator.userAgent || "";

  if (/android/i.test(ua)) {
    return "https://myket.ir/app/com.adv.winsoo";
  }
  if (/iphone|ipad|ipod/i.test(ua)) {
    return "https://web.winsoo.ir";
  }
  return "https://winsoo.ir/#Download";
}

const PERSIAN_DIGITS = "۰۱۲۳۴۵۶۷۸۹";
const ARABIC_INDIC_DIGITS = "٠١٢٣٤٥٦٧٨٩";

// Converts Persian (۰-۹) and Arabic-Indic (٠-٩) numerals to Latin digits.
function toLatinDigits(str) {
  return str.replace(/[۰-۹٠-٩]/g, (char) => {
    const persianIndex = PERSIAN_DIGITS.indexOf(char);
    if (persianIndex !== -1) return String(persianIndex);
    return String(ARABIC_INDIC_DIGITS.indexOf(char));
  });
}

// Normalizes Iranian mobile numbers (09xxxxxxxxx, 9xxxxxxxxx, 0098/98/+98 prefixed) to E.164.
function toE164(raw) {
  let cleaned = toLatinDigits(raw.trim()).replace(/[\s-]/g, "");

  if (cleaned.startsWith("+98")) cleaned = cleaned.slice(3);
  else if (cleaned.startsWith("0098")) cleaned = cleaned.slice(4);
  else if (cleaned.startsWith("98")) cleaned = cleaned.slice(2);
  else if (cleaned.startsWith("0")) cleaned = cleaned.slice(1);

  if (!/^9\d{9}$/.test(cleaned)) return null;
  return `+98${cleaned}`;
}

async function submitInviteRequest(inviteCode, mobileNumber, token) {
  const response = await fetch(INVITE_URL, {
    method: "POST",
    headers: {
      "Content-Type": "application/json",
      Authorization: `Bearer ${token}`,
    },
    body: JSON.stringify({
      invite_code: inviteCode,
      mobile_number: mobileNumber,
    }),
  });

  if (!response.ok) {
    let body = null;
    try {
      body = await response.json();
    } catch (_) {
      // no JSON body
    }
    const error = new Error(body?.status_message || `Invite request failed (${response.status})`);
    error.status = response.status;
    error.body = body;
    throw error;
  }

  return response.json();
}

async function handleSubmit() {
  phoneInput.classList.remove("invalid");
  setMessage("", null);

  const inviteCode = getInviteCode();
  if (!inviteCode) {
    setMessage("لینک دعوت نامعتبر است.", "error");
    return;
  }

  const mobileNumber = toE164(phoneInput.value);
  if (!mobileNumber) {
    phoneInput.classList.add("invalid");
    setMessage("شماره موبایل را به‌درستی وارد کنید.", "error");
    return;
  }

  setButtonLoading(true, "در حال ارسال...");

  try {
    const token = await ensureAccessToken();

    try {
      await submitInviteRequest(inviteCode, mobileNumber, token);
    } catch (err) {
      // Token may have expired between page load and submit — retry once with a fresh one.
      if (err.status === 401) {
        accessToken = null;
        const freshToken = await ensureAccessToken();
        await submitInviteRequest(inviteCode, mobileNumber, freshToken);
      } else {
        throw err;
      }
    }

    setMessage("ثبت شماره با موفقیت انجام شد.", "success");
    setButtonLoading(true, "در حال انتقال...");
    setTimeout(() => {
      window.location.href = getDownloadRedirectUrl();
    }, 1200);
    return;
  } catch (err) {
    console.error(err);
    setMessage(err.message || "خطا در ارسال اطلاعات. لطفاً دوباره تلاش کنید.", "error");
  }

  setButtonLoading(false);
}

submitBtn.addEventListener("click", handleSubmit);

ensureAccessToken().catch((err) => {
  console.error("Failed to fetch access token on load:", err);
});