/* Structured-file reading aids for the blob view: fold blocks, search keys
   and values, filter the file down to what matched.

   Everything here is progressive enhancement. The server renders a plain
   numbered table with structure hung off data attributes (see
   internal/modules/structured.go); this file builds the toolbar and the fold
   controls at runtime, so a page loaded without JS is exactly the table it
   has always been rather than a dead search box. */
(function () {
  var src = document.querySelector('.source.structured');
  if (!src) return;
  var rows = Array.prototype.slice.call(src.querySelectorAll('tbody > tr'));
  if (!rows.length) return;

  // One record per line. Text is read once from textContent -- never
  // innerHTML, which would match highlight markup as if it were content.
  // The alias links and anchor-use badges are chrome the server added, not
  // file content -- searching "uses" must not match every anchor.
  function cellText(cell) {
    if (!cell) return '';
    var s = '';
    for (var i = 0; i < cell.childNodes.length; i++) {
      var c = cell.childNodes[i];
      if (c.nodeType === 1 && (c.className === 'aref' || c.className === 'anchor-uses')) continue;
      s += c.textContent;
    }
    return s;
  }

  var R = rows.map(function (tr) {
    var cell = tr.querySelector('.lc');
    var text = cellText(cell);
    var key = tr.dataset.key || '';
    var val = text;
    if (key) {
      var at = text.indexOf(key);
      var colon = text.indexOf(':', at < 0 ? 0 : at + key.length);
      if (colon >= 0) val = text.slice(colon + 1);
    }
    return {
      tr: tr, cell: cell,
      n: +tr.dataset.n,
      depth: +tr.dataset.depth || 0,
      foldTo: +tr.dataset.foldTo || 0,
      key: key.toLowerCase(),
      text: text.toLowerCase(),
      blank: text.trim() === '',
      val: val.trim().toLowerCase(),
      match: false
    };
  });
  var byLine = {};
  R.forEach(function (r) { byLine[r.n] = r; });

  var collapsed = {};      // opener line number -> true
  var scope = 'all';       // all | keys | values
  var filtering = false;
  var matches = [];
  var cursor = -1;

  /* ---- fold controls ------------------------------------------------ */

  // Minified or tab-indented files have no indentation to fold on. They get
  // search, but no gutter reserved for chevrons that will never appear and
  // no collapse-all that would do nothing.
  var foldable = R.some(function (r) { return r.foldTo > 0; });
  if (foldable) src.classList.add('foldable');

  R.forEach(function (r) {
    if (!r.foldTo || !r.cell) return;
    var b = document.createElement('button');
    b.className = 'fold';
    b.type = 'button';
    b.setAttribute('aria-expanded', 'true');
    b.title = 'Collapse lines ' + (r.n + 1) + '–' + r.foldTo;
    b.addEventListener('click', function () {
      if (collapsed[r.n]) delete collapsed[r.n]; else collapsed[r.n] = true;
      render();
    });
    r.tr.querySelector('.ln').appendChild(b);
    // On the cell, not the row: attr() in ::after only reads the attributes
    // of the element the pseudo-element belongs to.
    r.cell.dataset.foldNote = '⋯ ' + (r.foldTo - r.n) + ' lines';
  });

  function foldAll(on) {
    collapsed = {};
    if (on) R.forEach(function (r) { if (r.foldTo) collapsed[r.n] = true; });
    render();
  }

  // A match hidden inside a collapsed block reads as "no results", so open
  // every block enclosing it before rendering.
  function expose(n) {
    for (var o in collapsed) {
      var r = byLine[o];
      if (r && r.n < n && n <= r.foldTo) delete collapsed[o];
    }
  }

  /* ---- search ------------------------------------------------------- */

  function hay(r) {
    return scope === 'keys' ? r.key : scope === 'values' ? r.val : r.text;
  }

  var lastQ = '';
  function search(q) {
    q = lastQ = q.trim().toLowerCase();
    matches = [];
    R.forEach(function (r) {
      r.match = q !== '' && hay(r).indexOf(q) >= 0;
      if (r.match) matches.push(r);
    });
    matches.forEach(function (r) { expose(r.n); });
    cursor = matches.length ? 0 : -1;
    render();
  }

  // In filter mode a matching line keeps the ancestors that give it its path
  // and the block it owns -- a bare list of hits out of context is worse
  // than the file.
  function keepSet() {
    var keep = {}, stack = [];
    R.forEach(function (r) {
      // A blank line carries no indentation, so it is not a level -- letting
      // one truncate the stack would strip the parents off every match
      // below a blank line inside a nested block.
      if (r.blank) return;
      stack.length = Math.min(stack.length, r.depth);
      stack[r.depth] = r;
      if (!r.match) return;
      stack.forEach(function (a) { if (a) keep[a.n] = true; });
      for (var i = r.n; i <= r.foldTo; i++) keep[i] = true;
    });
    return keep;
  }

  /* ---- render ------------------------------------------------------- */

  function render() {
    if (filtering && !matches.length) {
      filtering = false;
      filterBtn.setAttribute('aria-pressed', 'false');
    }
    var keep = filtering ? keepSet() : null;
    var hideUntil = 0;
    R.forEach(function (r) {
      var hidden = r.n <= hideUntil || (keep !== null && !keep[r.n]);
      if (collapsed[r.n]) hideUntil = Math.max(hideUntil, r.foldTo);
      r.tr.classList.toggle('is-hidden', hidden);
      r.tr.classList.toggle('is-collapsed', !!collapsed[r.n]);
      r.tr.classList.toggle('is-match', r.match);
      r.tr.classList.remove('is-current');
      var b = r.tr.querySelector('.fold');
      if (b) b.setAttribute('aria-expanded', collapsed[r.n] ? 'false' : 'true');
    });
    if (cursor >= 0 && matches[cursor]) matches[cursor].tr.classList.add('is-current');
    count.textContent = matches.length
      ? (cursor + 1) + ' / ' + matches.length
      : (input.value.trim() ? 'no matches' : '');
    filterBtn.disabled = !matches.length;
  }

  function step(d) {
    if (!matches.length) return;
    cursor = (cursor + d + matches.length) % matches.length;
    render();
    matches[cursor].tr.scrollIntoView({ block: 'center' });
  }

  /* ---- toolbar ------------------------------------------------------ */

  var bar = document.createElement('div');
  bar.className = 'sbar';

  var input = document.createElement('input');
  input.type = 'search';
  input.className = 'sbar-q';
  input.placeholder = 'Search keys and values…  (/)';
  input.setAttribute('aria-label', 'Search this file');

  var scopes = document.createElement('div');
  scopes.className = 'sbar-scope';
  ['all', 'keys', 'values'].forEach(function (s) {
    var b = document.createElement('button');
    b.type = 'button';
    b.textContent = s;
    b.setAttribute('aria-pressed', String(s === scope));
    b.addEventListener('click', function () {
      scope = s;
      Array.prototype.forEach.call(scopes.children, function (c) {
        c.setAttribute('aria-pressed', String(c === b));
      });
      search(input.value);
    });
    scopes.appendChild(b);
  });

  var count = document.createElement('span');
  count.className = 'sbar-count';

  function chip(label, title, fn) {
    var b = document.createElement('button');
    b.type = 'button';
    b.className = 'sbar-btn';
    b.textContent = label;
    b.title = title;
    b.addEventListener('click', fn);
    return b;
  }

  var prev = chip('↑', 'Previous match (Shift+Enter)', function () { step(-1); });
  var next = chip('↓', 'Next match (Enter)', function () { step(1); });

  var filterBtn = chip('filter', 'Show only matching lines and their parents', function () {
    filtering = !filtering;
    filterBtn.setAttribute('aria-pressed', String(filtering));
    render();
  });
  filterBtn.setAttribute('aria-pressed', 'false');
  filterBtn.disabled = true;

  var allCollapsed = false;
  var foldBtn = chip('collapse all', 'Fold every block', function () {
    allCollapsed = !allCollapsed;
    foldBtn.textContent = allCollapsed ? 'expand all' : 'collapse all';
    foldAll(allCollapsed);
  });

  bar.appendChild(input);
  bar.appendChild(scopes);
  bar.appendChild(count);
  bar.appendChild(prev);
  bar.appendChild(next);
  bar.appendChild(filterBtn);
  if (foldable) bar.appendChild(foldBtn);
  src.parentNode.insertBefore(bar, src);

  var timer;
  input.addEventListener('input', function () {
    clearTimeout(timer);
    timer = setTimeout(function () { search(input.value); }, 90);
  });
  input.addEventListener('keydown', function (e) {
    if (e.key === 'Enter') {
      e.preventDefault();
      clearTimeout(timer);
      // Enter on a query the debounce hasn't run yet searches; Enter on the
      // same query walks the results.
      if (input.value.trim().toLowerCase() !== lastQ) search(input.value);
      else step(e.shiftKey ? -1 : 1);
    }
    else if (e.key === 'Escape') { input.value = ''; search(''); input.blur(); }
  });
  document.addEventListener('keydown', function (e) {
    if (e.key !== '/' || e.target === input || /^(INPUT|TEXTAREA|SELECT)$/.test(e.target.tagName)) return;
    e.preventDefault();
    input.focus();
    input.select();
  });

  // Deep links (#L42, and the alias jump links) must survive folding.
  window.addEventListener('hashchange', function () {
    var m = /^#L(\d+)$/.exec(location.hash);
    if (!m) return;
    expose(+m[1]);
    if (filtering) { filtering = false; filterBtn.setAttribute('aria-pressed', 'false'); }
    render();
  });

  render();
})();