/**
 * Shared password-strength UI: live rule checklist, strength meter,
 * confirm-password match indicator, and show/hide toggle.
 *
 * The RULES below mirror validate_password() in
 * app/services/validation_service.py exactly. This is the single
 * client-side copy of that policy — every password form (register,
 * profile, admin create/edit user, password reset) includes this file
 * instead of re-implementing the checks, so the two can never drift
 * out of sync with each other. The server remains the source of truth;
 * this file only gives the user live feedback before they submit.
 */
(function (global) {
  'use strict';

  const RULES = {
    len    : pw => pw.length >= 8 && pw.length <= 128,
    upper  : pw => /[A-Z]/.test(pw),
    digit  : pw => /\d/.test(pw),
    special: pw => /[!@#$%^&*()\-_=+\[\]{};:'",.<>?/\\|`~]/.test(pw),
  };

  const LEVELS = [
    { label: 'Very Weak', color: '#ef4444', pct: 12  },
    { label: 'Weak',      color: '#f97316', pct: 30  },
    { label: 'Fair',      color: '#eab308', pct: 52  },
    { label: 'Good',      color: '#22c55e', pct: 76  },
    { label: 'Strong',    color: '#059669', pct: 100 },
  ];

  function score(pw) {
    let s = 0;
    if (RULES.len(pw))     s++;
    if (RULES.upper(pw))   s++;
    if (RULES.digit(pw))   s++;
    if (RULES.special(pw)) s++;
    if (pw.length >= 16)   s++;   // bonus for extra length
    return s;
  }

  function allRulesMet(pw) {
    return RULES.len(pw) && RULES.upper(pw) && RULES.digit(pw) && RULES.special(pw);
  }

  function byId(idOrEl) {
    return typeof idOrEl === 'string' ? document.getElementById(idOrEl) : idOrEl;
  }

  function setRuleEl(el, met) {
    if (!el) return;
    el.classList.toggle('met', met);
    el.classList.toggle('unmet', !met);
    const icon = el.querySelector('.ri');
    if (icon) {
      icon.innerHTML = met
        ? '<i class="bi bi-check-circle-fill"></i>'
        : '<i class="bi bi-circle"></i>';
    }
  }

  function toggleVisibility(inputEl, btnEl) {
    if (!inputEl || !btnEl) return;
    const showing = inputEl.type === 'password';
    inputEl.type = showing ? 'text' : 'password';
    const icon = btnEl.querySelector('i');
    if (icon) icon.className = showing ? 'bi bi-eye-slash' : 'bi bi-eye';
    btnEl.title = showing ? 'Hide password' : 'Show password';
  }

  /**
   * Wire up a password field with a live strength bar + rule checklist,
   * and optionally a confirm-password field with a match indicator.
   *
   * opts:
   *   password       - id/element of the password <input>          (required)
   *   confirm        - id/element of the confirm-password <input>  (optional)
   *   strengthBar    - id/element of the strength bar fill
   *   strengthLabel  - id/element of the strength label text
   *   strengthWrap   - id/element to show/hide with the strength bar
   *   rulesWrap      - id/element of the checklist container to show/hide
   *   rules          - { len, upper, digit, special } -> ids/elements of checklist rows
   *   matchMsg       - id/element for the confirm-match message
   *   toggles        - [{ input, button }, ...] show/hide password buttons
   *   onChange()     - called after every recompute (e.g. to gate a submit button)
   */
  function init(opts) {
    const pwEl = byId(opts.password);
    if (!pwEl) return null;

    const confirmEl     = byId(opts.confirm);
    const barEl          = byId(opts.strengthBar);
    const labelEl         = byId(opts.strengthLabel);
    const strengthWrapEl  = byId(opts.strengthWrap);
    const rulesWrapEl     = byId(opts.rulesWrap);
    const matchMsgEl      = byId(opts.matchMsg);
    const ruleEls = {};
    if (opts.rules) {
      Object.keys(opts.rules).forEach(k => { ruleEls[k] = byId(opts.rules[k]); });
    }

    function renderStrength() {
      const pw = pwEl.value;

      if (pw.length === 0) {
        if (barEl) barEl.style.width = '0%';
        if (labelEl) { labelEl.textContent = ''; labelEl.style.color = ''; }
        if (strengthWrapEl) strengthWrapEl.style.display = 'none';
        if (rulesWrapEl) rulesWrapEl.style.display = 'none';
        pwEl.classList.remove('valid', 'invalid');
      } else {
        if (strengthWrapEl) strengthWrapEl.style.display = 'block';
        if (rulesWrapEl) rulesWrapEl.style.display = 'grid';
        Object.keys(ruleEls).forEach(k => setRuleEl(ruleEls[k], RULES[k](pw)));

        const s   = score(pw);
        const lvl = LEVELS[Math.max(0, s - 1)] || LEVELS[0];
        if (barEl) { barEl.style.width = lvl.pct + '%'; barEl.style.background = lvl.color; }
        if (labelEl) {
          const shieldIcon = s >= 4 ? 'shield-fill' : s >= 2 ? 'shield-half' : 'shield';
          labelEl.innerHTML   = `<i class="bi bi-${shieldIcon}"></i> ${lvl.label}`;
          labelEl.style.color = lvl.color;
        }

        const met = allRulesMet(pw);
        pwEl.classList.toggle('valid', met);
        pwEl.classList.toggle('invalid', !met);
      }

      renderMatch();
      if (opts.onChange) opts.onChange();
    }

    function renderMatch() {
      if (!confirmEl) return;
      const pw  = pwEl.value;
      const pw2 = confirmEl.value;

      if (pw2.length === 0) {
        if (matchMsgEl) { matchMsgEl.innerHTML = ''; matchMsgEl.classList.remove('ok', 'fail'); }
        confirmEl.classList.remove('valid', 'invalid');
        return;
      }

      const ok = pw === pw2;
      if (matchMsgEl) {
        matchMsgEl.innerHTML = ok
          ? '<i class="bi bi-check-circle-fill"></i> Passwords match'
          : '<i class="bi bi-x-circle-fill"></i> Passwords do not match';
        matchMsgEl.classList.toggle('ok', ok);
        matchMsgEl.classList.toggle('fail', !ok);
      }
      confirmEl.classList.toggle('valid', ok);
      confirmEl.classList.toggle('invalid', !ok);
    }

    pwEl.addEventListener('input', renderStrength);
    if (confirmEl) {
      confirmEl.addEventListener('input', function () {
        renderMatch();
        if (opts.onChange) opts.onChange();
      });
    }

    if (opts.toggles) {
      opts.toggles.forEach(({ input, button }) => {
        const inputEl  = byId(input);
        const buttonEl = byId(button);
        if (buttonEl) buttonEl.addEventListener('click', () => toggleVisibility(inputEl, buttonEl));
      });
    }

    return { allRulesMet, score, renderStrength, renderMatch };
  }

  global.PasswordStrength = { init, RULES, allRulesMet, score };
})(window);