// ==UserScript==
// @name        GitHub file list beautifier
// @description Adds colors to files by type, displays small images in place of file-type icons in a repository source tree
// @license     MIT License

// @version     3.0.7

// @match       https://github.com/*

// @grant       none
// @run-at      document-end

// @author      wOxxOm
// @namespace   wOxxOm.scripts
// @icon        https://octodex.github.com/images/murakamicat.png
// @downloadURL none
// ==/UserScript==

'use strict';

let savedConfig = {};
try { savedConfig = JSON.parse(localStorage.FileListBeautifier) || {}; }
catch (e) {}

const config = Object.assign({},
  ...Object.entries({
    iconSize: 24,
    colorSeed1: 2,
    colorSeed2: 1299721,
    colorSeed3: 179426453,
  }).map(([k, v]) => ({[k]: +savedConfig[k] || v})));

const styleQueue = [];
const {sheet} = document.head.appendChild(Object.assign(document.createElement('style'), {
  textContent: `
  .wOxxOm-image-icon:not(#foo) {
    max-width: ${config.iconSize}px;
    max-height: ${config.iconSize}px;
    width: auto;
    height: auto;
    margin: auto;
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
  }
  .wOxxOm-image-td:not(#foo) {
    position: relative;
    padding: 0;
    min-width: ${config.iconSize + 4}px;
    line-height: inherit;
  }
  a[file-type=":folder"]:not(#foo) {
    font-weight: bold;
  }
  `
}));

const filetypes = {};
const tables = document.getElementsByTagName('table');
const ME = Symbol(GM_info.script.name);
const ob = new MutationObserver(() => {
  ob.disconnect();
  requestAnimationFrame(start);
});

const {pushState} = unsafeWindow.History.prototype;
unsafeWindow.History.prototype.pushState = function() {
  const res = pushState.apply(this, arguments);
  start();
  return res;
};

let lumaBias, lumaFix, lumaAmp;

addEventListener('popstate', start);

if (document.body) start();
else document.addEventListener('DOMContentLoaded', start, {once: true});

function start() {
  beautify();
  ob.observe(document, {subtree: true, childList: true});
}

// postpone observing until the parser can breathe after the initial burst of activity during page load
function beautify() {
  const table = tables[0];
  if (!table || !table.classList.contains('files'))
    return;
  let didSomeWork = false;
  for (const a of table.getElementsByClassName('js-navigation-open')) {
    if (!a.hasAttribute('href') || ME in a)
      continue;
    a[ME] = true;
    const tr = a.closest('tr');
    if (tr && tr.querySelector('.octicon-file-directory')) {
      a.setAttribute('file-type', ':folder');
      continue;
    }

    didSomeWork = true;

    const ext = a.href.match(/\.(\w+)$|$/)[1] || ':empty';
    a.setAttribute('file-type', ext);
    if (!filetypes[ext])
      addFileTypeStyle(ext);

    if (/^(png|jpe?g|bmp|gif|cur|ico)$/.test(ext)) {
      const m = a.href.match(/github\.com\/(.+?\/)blob\/(.*)$/);
      if (!m) continue;
      const iconCell = a.closest('.js-navigation-item').querySelector('.icon');
      const icon = iconCell.querySelector('.octicon-file, .octicon-file-text');
      if (!icon || icon.style.display === 'none') continue;
      icon.style.display = 'none';
      icon.insertAdjacentElement('afterend', Object.assign(
        document.createElement('img'), {
          className: 'wOxxOm-image-icon',
          src: `https://raw.githubusercontent.com/${m[1]}${m[2]}`,
        }));
      iconCell.classList.add('wOxxOm-image-td');
    }
  }
}

function addFileTypeStyle(type) {
  filetypes[type] = true;
  if (!styleQueue.length)
    requestAnimationFrame(commitStyleQueue);
  styleQueue.push(type);
}

function commitStyleQueue() {
  if (!lumaAmp) initLumaScale();
  for (const type of styleQueue) {
    const hash = calcSimpleHash(type);
    const H = hash % 360;
    const Hq = H / 60;
    const S = hash * config.colorSeed2 % 50 + 50 | 0;
    const redFix = (Hq < 1 ? 1 - Hq : Hq > 4 ? (Hq - 4) / 2 : 0);
    const blueFix = (Hq < 3 || Hq > 5 ? 0 : Hq < 4 ? Hq - 3 : 5 - Hq) * 3;
    const L = hash * config.colorSeed3 % lumaAmp + lumaBias + (redFix + blueFix) * lumaFix * S / 100 | 0;
    sheet.insertRule(`a[file-type="${type}"]:not(#foo) { color: hsl(${H},${S}%,${L}%) !important }`);
  }
  styleQueue.length = 0;
}

function calcSimpleHash(text) {
  let hash = 0;
  for (let i = 0, len = text.length; i < len; i++)
    hash = ((hash << 5) - hash) + text.charCodeAt(i);
  return Math.abs(hash * config.colorSeed1 | 0);
}

function initLumaScale() {
  const [, r, g, b] = getComputedStyle(document.body).backgroundColor.split(/[^\d.]+/).map(parseFloat);
  const isDark = (r * .2126 + g * .7152 + b * .0722) < 128;
  [lumaBias, lumaAmp, lumaFix] = isDark ? [30, 50, 12] : [25, 15, 0];
}