/* global installed onDOMready $create debounce $ scrollElementIntoView
  animateElement */
'use strict';

onDOMready().then(() => {
  let prevText, focusedLink, focusedEntry;
  let prevTime = performance.now();
  let focusedName = '';
  const input = $create('textarea', {
    spellcheck: false,
    attributes: {tabindex: -1},
    oninput: incrementalSearch,
  });
  replaceInlineStyle({
    position: 'absolute',
    color: 'transparent',
    border: '1px solid hsla(180, 100%, 100%, .5)',
    top: '-1000px',
    overflow: 'hidden',
    resize: 'none',
    'background-color': 'hsla(180, 100%, 100%, .2)',
    'pointer-events': 'none',
  });
  document.body.appendChild(input);
  window.addEventListener('keydown', maybeRefocus, true);

  function incrementalSearch({which}, immediately) {
    if (!immediately) {
      debounce(incrementalSearch, 100, {}, true);
      return;
    }
    const direction = which === 38 ? -1 : which === 40 ? 1 : 0;
    const text = input.value.toLocaleLowerCase();
    if (!text.trim() || !direction && (text === prevText || focusedName.startsWith(text))) {
      prevText = text;
      return;
    }
    let textAtPos = 1e6;
    let rotated;
    const entries = [...installed.children];
    const focusedIndex = entries.indexOf(focusedEntry);
    if (focusedIndex > 0) {
      if (direction > 0) {
        rotated = entries.slice(focusedIndex + 1).concat(entries.slice(0, focusedIndex + 1));
      } else if (direction < 0) {
        rotated = entries.slice(0, focusedIndex).reverse().concat(entries.slice(focusedIndex).reverse());
      }
    }
    let found;
    for (const entry of rotated || entries) {
      const name = entry.styleNameLowerCase;
      const pos = name.indexOf(text);
      if (pos === 0) {
        found = entry;
        break;
      } else if (pos > 0 && (pos < textAtPos || direction)) {
        found = entry;
        textAtPos = pos;
        if (direction) {
          break;
        }
      }
    }
    if (found && found !== focusedEntry) {
      focusedEntry = found;
      focusedLink = $('.style-name-link', found);
      focusedName = found.styleNameLowerCase;
      scrollElementIntoView(found, {invalidMarginRatio: .25});
      animateElement(found, {className: 'highlight-quick'});
      resizeTo(focusedLink);
      return true;
    }
  }

  function maybeRefocus(event) {
    if (event.altKey || event.metaKey || $('#message-box')) {
      return;
    }
    const inTextInput = event.target.matches('[type=text], [type=search], [type=number]');
    const {which: k, key} = event;
    // focus search field on "/" or Ctrl-F key
    if (event.ctrlKey
        ? (event.code === 'KeyF' || !event.code && k === 70) && !event.shiftKey
        : (key === '/' || !key && k === 191 && !event.shiftKey) && !inTextInput) {
      event.preventDefault();
      $('#search').focus();
      return;
    }
    if (event.ctrlKey || inTextInput) {
      return;
    }
    const time = performance.now();
    if (
      // 0-9
      k >= 48 && k <= 57 ||
      // a-z
      k >= 65 && k <= 90 ||
      // numpad keys
      k >= 96 && k <= 111 ||
      // marks
      k >= 186
    ) {
      input.focus();
      if (time - prevTime > 1000) {
        input.value = '';
      }
      prevTime = time;
    } else
    if (k === 13 && focusedLink) {
      focusedLink.dispatchEvent(new MouseEvent('click', {bubbles: true}));
    } else
    if ((k === 38 || k === 40) && !event.shiftKey &&
        time - prevTime < 5000 && incrementalSearch(event, true)) {
      prevTime = time;
    } else
    if (event.target === input) {
      (focusedLink || document.body).focus();
      input.value = '';
    }
  }

  function resizeTo(el) {
    const bounds = el.getBoundingClientRect();
    const base = document.scrollingElement;
    replaceInlineStyle({
      left: bounds.left - 2 + base.scrollLeft + 'px',
      top: bounds.top - 1 + base.scrollTop + 'px',
      width: bounds.width + 4 + 'px',
      height: bounds.height + 2 + 'px',
    });
  }

  function replaceInlineStyle(css) {
    for (const prop in css) {
      input.style.setProperty(prop, css[prop], 'important');
    }
  }
});