(() => {
  'use strict';

  const RESOURCE = 'fiverp-auth';

  const stage    = document.getElementById('stage');
  const slab     = document.getElementById('slab');
  const railFill = document.getElementById('railFill');
  const permit   = document.getElementById('permit');
  const sheen    = document.getElementById('sheen');
  const seal     = document.getElementById('seal');

  const cardNo     = document.getElementById('cardNo');
  const cardFirst  = document.getElementById('cardFirst');
  const cardLast   = document.getElementById('cardLast');
  const cardDob    = document.getElementById('cardDob');
  const cardIssue  = document.getElementById('cardIssue');
  const cardExpiry = document.getElementById('cardExpiry');
  const cardSign   = document.getElementById('cardSign');
  const mrz1       = document.getElementById('mrz1');
  const mrz2       = document.getElementById('mrz2');
  const stampDate  = document.getElementById('stampDate');

  const views = {
    login:    document.getElementById('formLogin'),
    account:  document.getElementById('formAccount'),
    identity: document.getElementById('formIdentity')
  };

  let current = 'login';
  let busy = false;
  // Set when sign-in finds an account whose registration never reached step 2.
  let resuming = false;

  // ------------------------------------------------------------------ post
  function post(endpoint, data) {
    return fetch(`https://${RESOURCE}/${endpoint}`, {
      method: 'POST',
      headers: { 'Content-Type': 'application/json; charset=UTF-8' },
      body: JSON.stringify(data || {})
    }).catch(() => {});
  }

  // ------------------------------------------------------------------ views
  function show(view) {
    current = view;
    slab.dataset.view = view;

    Object.entries(views).forEach(([name, form]) => {
      form.classList.toggle('is-current', name === view);
    });

    document.querySelectorAll('.rail-step').forEach((step) => {
      const which = step.dataset.step;
      step.classList.toggle('is-active', which === view);
      step.classList.toggle('is-done', which === 'account' && view === 'identity');
    });
    railFill.classList.toggle('is-full', view === 'identity');

    const first = views[view].querySelector('input');
    if (first) setTimeout(() => first.focus(), 240);
  }

  function notice(view, message, good) {
    const el = views[view].querySelector('[data-notice]');
    if (!message) {
      el.classList.remove('is-shown', 'is-good');
      el.textContent = '';
      return;
    }
    el.textContent = message;
    el.classList.add('is-shown');
    el.classList.toggle('is-good', !!good);
  }

  function setBusy(view, state) {
    busy = state;
    const btn = views[view].querySelector('.btn');
    btn.classList.toggle('is-busy', state);
    btn.disabled = state;
  }

  function values(view) {
    const out = {};
    views[view].querySelectorAll('input').forEach((input) => {
      out[input.name] = input.value.trim();
    });
    return out;
  }

  function markBad(view, names) {
    views[view].querySelectorAll('input').forEach((input) => {
      input.classList.toggle('is-bad', names.includes(input.name));
    });
  }

  // =========================================================== the passport
  // Everything on the data page is derived from the name, so the same resident
  // always gets the same document — it reads as a record, not a random mock-up.

  function seedOf(text) {
    let hash = 0;
    for (let i = 0; i < text.length; i++) hash = (hash * 31 + text.charCodeAt(i)) >>> 0;
    return hash;
  }

  function passportNumber(seed) {
    return String(seed % 1000000000).padStart(9, '0');
  }

  const MONTHS = ['JAN','FEB','MAR','APR','MAY','JUN','JUL','AUG','SEP','OCT','NOV','DEC'];

  function human(date) {
    return String(date.getDate()).padStart(2, '0') + ' ' +
           MONTHS[date.getMonth()] + ' ' + date.getFullYear();
  }

  // MRZ dates are YYMMDD.
  function mrzDate(date) {
    return String(date.getFullYear() % 100).padStart(2, '0') +
           String(date.getMonth() + 1).padStart(2, '0') +
           String(date.getDate()).padStart(2, '0');
  }

  // ICAO 9303 check digit: weights cycle 7-3-1 over the field.
  function checkDigit(field) {
    const WEIGHTS = [7, 3, 1];
    let sum = 0;
    for (let i = 0; i < field.length; i++) {
      const c = field[i];
      let v;
      if (c >= '0' && c <= '9') v = c.charCodeAt(0) - 48;
      else if (c >= 'A' && c <= 'Z') v = c.charCodeAt(0) - 55;
      else v = 0;                       // '<' filler
      sum += v * WEIGHTS[i % 3];
    }
    return String(sum % 10);
  }

  function pad(text, length) {
    return (text + '<'.repeat(length)).slice(0, length);
  }

  function buildDocument(firstName, lastName) {
    const seed = seedOf((firstName + lastName).toLowerCase());
    const number = passportNumber(seed);

    const now = new Date();
    const issue = new Date(now.getFullYear(), now.getMonth(), now.getDate());
    const expiry = new Date(issue.getFullYear() + 10, issue.getMonth(), issue.getDate());
    // A plausible adult birth date, stable for this name.
    const dob = new Date(
      now.getFullYear() - (21 + (seed % 34)),
      (seed >>> 7) % 12,
      1 + ((seed >>> 13) % 28)
    );

    const surname = lastName.toUpperCase();
    const given = firstName.toUpperCase();

    const line1 = pad('P<USA' + surname + '<<' + given, 44);

    const numCd    = checkDigit(number);
    const dobCd    = checkDigit(mrzDate(dob));
    const expCd    = checkDigit(mrzDate(expiry));
    const personal = '<'.repeat(14);
    const personalCd = checkDigit(personal);
    const composite = number + numCd + mrzDate(dob) + dobCd +
                      mrzDate(expiry) + expCd + personal + personalCd;

    const line2 = number + numCd + 'USA' + mrzDate(dob) + dobCd + 'X' +
                  mrzDate(expiry) + expCd + personal + personalCd +
                  checkDigit(composite);

    return { number, issue, expiry, dob, line1, line2 };
  }

  function printName(el, text) {
    if (!text) { el.textContent = ''; return; }
    if (el.textContent === text) return;
    el.textContent = '';
    const span = document.createElement('span');
    span.className = 'printed';
    span.textContent = text;
    el.appendChild(span);
  }

  const BLANK1 = 'P<USA' + '<'.repeat(39);
  const BLANK2 = '<'.repeat(10) + 'USA' + '<'.repeat(31);

  function fillPassport(firstName, lastName) {
    printName(cardFirst, firstName.toUpperCase());
    printName(cardLast, lastName.toUpperCase());

    // Below two letters there is not enough to derive a document from.
    if (firstName.length < 2 || lastName.length < 2) {
      cardNo.textContent = '—';
      cardDob.textContent = '—';
      cardIssue.textContent = '—';
      cardExpiry.textContent = '—';
      cardSign.textContent = '';
      mrz1.textContent = BLANK1;
      mrz2.textContent = BLANK2;
      return;
    }

    const doc = buildDocument(firstName, lastName);
    cardNo.textContent     = doc.number;
    cardDob.textContent    = human(doc.dob);
    cardIssue.textContent  = human(doc.issue);
    cardExpiry.textContent = human(doc.expiry);
    cardSign.textContent   = firstName + ' ' + lastName;
    mrz1.textContent       = doc.line1;
    mrz2.textContent       = doc.line2;
    stampDate.textContent  = human(doc.issue);
  }

  function syncPassport() {
    const { firstName, lastName } = values('identity');
    fillPassport(firstName, lastName);
  }

  function issuePassport() {
    permit.classList.add('is-issued');
    seal.classList.add('is-stamped');
    sheen.style.opacity = '0.85';
  }

  // Laminate glare tracks the cursor across the page.
  permit.addEventListener('pointermove', (e) => {
    const box = permit.getBoundingClientRect();
    sheen.style.setProperty('--mx', `${((e.clientX - box.left) / box.width) * 100}%`);
    sheen.style.setProperty('--my', `${((e.clientY - box.top) / box.height) * 100}%`);
  });

  // --------------------------------------------------------- password meter
  const pwInput = views.account.querySelector('input[name="password"]');
  const meter = views.account.querySelector('[data-meter]');

  pwInput.addEventListener('input', () => {
    const v = pwInput.value;
    meter.classList.toggle('is-live', v.length > 0);
    let level = 1;
    if (v.length >= 8 && /[A-Za-z]/.test(v) && /\d/.test(v)) level = 2;
    if (v.length >= 12 && /[A-Za-z]/.test(v) && /\d/.test(v) && /[^A-Za-z0-9]/.test(v)) level = 3;
    meter.dataset.level = String(level);
    meter.querySelector('i').style.width = `${level * 33.4}%`;
  });

  views.identity.querySelectorAll('input').forEach((input) => {
    input.addEventListener('input', () => {
      // Keep the document honest: only English letters ever reach it.
      input.value = input.value.replace(/[^A-Za-z]/g, '');
      syncPassport();
    });
  });

  // ------------------------------------------------------------ validation
  const RE_EMAIL = /^[^\s@]+@[^\s@]+\.[a-z]{2,}$/i;
  const RE_USERNAME = /^[A-Za-z0-9_]{3,32}$/;
  const RE_NAME = /^[A-Za-z]{2,24}$/;

  function checkAccount(v) {
    if (!RE_EMAIL.test(v.email)) return ['Enter a valid email address.', ['email']];
    if (!RE_USERNAME.test(v.username)) return ['Username must be 3–32 characters, letters, numbers or underscore.', ['username']];
    if (v.password.length < 8) return ['Password must be at least 8 characters.', ['password']];
    return null;
  }

  function checkIdentity(v) {
    if (!RE_NAME.test(v.firstName)) return ['First name must be 2–24 English letters.', ['firstName']];
    if (!RE_NAME.test(v.lastName)) return ['Last name must be 2–24 English letters.', ['lastName']];
    return null;
  }

  // ---------------------------------------------------------------- submits
  views.login.addEventListener('submit', (e) => {
    e.preventDefault();
    if (busy) return;
    const v = values('login');
    if (!v.username || !v.password) {
      markBad('login', [!v.username ? 'username' : 'password']);
      return notice('login', 'Enter your username and password.');
    }
    markBad('login', []);
    notice('login', '');
    setBusy('login', true);
    post('login', v);
  });

  views.account.addEventListener('submit', (e) => {
    e.preventDefault();
    if (busy) return;
    const v = values('account');
    const bad = checkAccount(v);
    if (bad) { markBad('account', bad[1]); return notice('account', bad[0]); }
    markBad('account', []);
    notice('account', '');
    setBusy('account', true);
    post('registerAccount', v);
  });

  views.identity.addEventListener('submit', (e) => {
    e.preventDefault();
    if (busy) return;
    const v = values('identity');
    const bad = checkIdentity(v);
    if (bad) { markBad('identity', bad[1]); return notice('identity', bad[0]); }
    markBad('identity', []);
    notice('identity', '');
    setBusy('identity', true);
    post(resuming ? 'resumeIdentity' : 'registerIdentity', v);
  });

  document.querySelectorAll('[data-goto]').forEach((btn) => {
    btn.addEventListener('click', () => {
      if (busy) return;
      notice(current, '');
      show(btn.dataset.goto);
    });
  });

  // ------------------------------------------------------ messages from Lua
  window.addEventListener('message', (event) => {
    const msg = event.data || {};
    const p = msg.payload || {};

    switch (msg.action) {
      case 'open':
        stage.classList.add('is-open');
        stage.setAttribute('aria-hidden', 'false');
        show('login');
        break;

      case 'close':
        stage.classList.remove('is-open');
        stage.setAttribute('aria-hidden', 'true');
        break;

      case 'accountResult':
        setBusy('account', false);
        if (p.ok) {
          notice('account', '');
          show('identity');
          syncPassport();
        } else {
          notice('account', p.error || 'Something went wrong.');
        }
        break;

      case 'identityResult':
        setBusy('identity', false);
        if (p.ok) {
          fillPassport(String(p.firstName), String(p.lastName));
          issuePassport();
          notice('identity', `Passport issued. Welcome to Los Santos, ${p.firstName}.`, true);
          views.identity.querySelector('.btn span').textContent = 'Entering the city…';
          views.identity.querySelector('.btn').disabled = true;
          // Nothing left to go back to once the document exists.
          views.identity.querySelector('.switch').style.display = 'none';
        } else {
          if (p.reset) { resuming = false; show('account'); }
          notice(p.reset ? 'account' : 'identity', p.error || 'Something went wrong.');
        }
        break;

      case 'loginResult':
        setBusy('login', false);
        if (p.ok && p.needsIdentity) {
          // Account is real but has no resident yet — finish step 2.
          resuming = true;
          show('identity');
          syncPassport();
          notice('identity', 'Your file is open. Name your resident to finish.', true);
        } else if (p.ok) {
          notice('login', `Signed in. Returning to the city, ${p.firstName}.`, true);
          views.login.querySelector('.btn span').textContent = 'Entering the city…';
          views.login.querySelector('.btn').disabled = true;
        } else {
          markBad('login', ['username', 'password']);
          notice('login', p.error || 'Something went wrong.');
        }
        break;
    }
  });

  // Clear the error ring as soon as the player starts fixing the field.
  document.querySelectorAll('input').forEach((input) => {
    input.addEventListener('input', () => input.classList.remove('is-bad'));
  });
})();