// #112/#127/#139: theme switcher. Swatch colors are derived from computed CSS vars per preset.
(function () {
  // #112: derive each preset's swatches from the real CSS variables in
  // app.css by temporarily applying data-preset, so they can never drift.
  // #127: 5 theme pairs, light swatches top row, dark bottom row.
  var pairs = [
    { id: 'midnight',        name: 'Midnight' },
    { id: 'smooth',          name: 'Smooth' },
    { id: 'pastel-lavender', name: 'Pastel Lavender' },
    { id: 'pastel-peach',    name: 'Pastel Peach' },
    { id: 'pastel-cloud',    name: 'Pastel Cloud' }
  ];
  var SWATCH_VARS = ['--bg', '--surface', '--surface-2', '--muted', '--accent'];

  function presetColors(id) {
    var root = document.documentElement;
    var prev = root.getAttribute('data-preset');
    root.setAttribute('data-preset', id);
    var cs = getComputedStyle(root);
    var colors = SWATCH_VARS.map(function (v) { return cs.getPropertyValue(v).trim(); });
    if (prev === null) root.removeAttribute('data-preset'); else root.setAttribute('data-preset', prev);
    return colors;
  }

  // current base pair + dark flag from the resolved data-preset.
  // "midnight" is itself the dark variant, so check dark ids first.
  function state() {
    var p = document.documentElement.dataset.preset || 'midnight';
    if (p === 'midnight' || /-dark$/.test(p)) {
      return { base: p === 'midnight' ? 'midnight' : p.replace(/-dark$/, ''), dark: true };
    }
    return { base: p === 'midnight-light' ? 'midnight' : p, dark: false };
  }

  var grid = document.getElementById('theme-grid');
  var cards = {};
  // #132: midnight is dark-first (root preset = midnight = dark; its light
  // variant is midnight-light), the others are light-first. Resolve the
  // LIGHT and DARK preset ids generically so the light swatches always
  // render in the top row of every card.
  function lightPreset(id) {
    if (id === 'midnight') return 'midnight-light';
    return id; // light-first bases use themselves as the light variant
  }
  function darkPreset(id) {
    if (id === 'midnight') return 'midnight'; // root preset is midnight's dark
    return id + '-dark';
  }
  pairs.forEach(function (t) {
    var light = presetColors(lightPreset(t.id));
    var dark = presetColors(darkPreset(t.id));
    var btn = document.createElement('button');
    btn.type = 'button';
    btn.className = 'theme-card';
    btn.setAttribute('aria-pressed', 'false');
    btn.setAttribute('data-pair', t.id);
    // #139: build the swatches via DOM APIs (CSSOM styles) instead of
    // innerHTML strings: re-parsing serialized inline styles would trip
    // style-src 'self'.
    var label = document.createElement('strong');
    label.textContent = t.name;
    btn.appendChild(label);
    [light, dark].forEach(function (colors) {
      var row = document.createElement('span');
      row.className = 'swatches';
      colors.forEach(function (c) {
        var sw = document.createElement('span');
        sw.className = 'swatch';
        sw.style.backgroundColor = c;
        row.appendChild(sw);
      });
      btn.appendChild(row);
    });
    btn.addEventListener('click', function () {
      var dark = state().dark;
      // #294: use the generic variant resolvers - midnight is dark-first
      // (dark preset = 'midnight', light = 'midnight-light'), so a raw
      // t.id + '-dark' build landed on nonexistent/forced-dark presets.
      document.documentElement.dataset.preset = dark ? darkPreset(t.id) : lightPreset(t.id);
      try { localStorage.setItem('palette-theme', t.id); } catch (e) {}
      Object.keys(cards).forEach(function (k) { cards[k].setAttribute('aria-pressed', 'false'); });
      btn.setAttribute('aria-pressed', 'true');
    });
    cards[t.id] = btn;
    grid.appendChild(btn);
  });

  function sync() {
    var s = state();
    Object.keys(cards).forEach(function (k) {
      cards[k].setAttribute('aria-pressed', k === s.base ? 'true' : 'false');
    });
    var dt = document.getElementById('settings-dark-toggle');
    if (dt) dt.setAttribute('aria-pressed', s.dark ? 'true' : 'false');
  }
  sync();
  // topbar.js already binds every .dark-toggle (deferred, so the settings
  // button exists by then). Only wire here if it somehow did not run,
  // otherwise the button would toggle twice per click and never change (#197).
  var dt = document.getElementById('settings-dark-toggle');
  if (dt && !dt.dataset.darkWired) {
    dt.addEventListener('click', function () {
      var btns = document.querySelectorAll('.topbar .dark-toggle');
      if (btns.length) btns[0].click(); else document.dispatchEvent(new CustomEvent('palette-darkchange'));
    });
  }
  document.addEventListener('palette-darkchange', sync);
})();