const gulp = require('gulp');
const path = require('path');
const fs = require('fs');
const config = require('../config');

const ICON_PACKAGE_PATH = path.resolve(__dirname, '../../node_modules/@mdi/svg/');
const META_PATH = path.resolve(ICON_PACKAGE_PATH, 'meta.json');
const ICON_PATH = path.resolve(ICON_PACKAGE_PATH, 'svg');
const OUTPUT_DIR = path.resolve(__dirname, '../../build');
const MDI_OUTPUT_PATH = path.resolve(OUTPUT_DIR, 'mdi.html');
const HASS_OUTPUT_PATH = path.resolve(OUTPUT_DIR, 'hass-icons.html');

const BUILT_IN_PANEL_ICONS = [
  'calendar', // Calendar
  'settings', // Config
  'home-assistant', // Hass.io
  'poll-box', // History panel
  'format-list-bulleted-type', // Logbook
  'mailbox', // Mailbox
  'account-location', // Map
  'cart', // Shopping List
];

// Given an icon name, load the SVG file
function loadIcon(name) {
  const iconPath = path.resolve(ICON_PATH, `${name}.svg`);
  try {
    return fs.readFileSync(iconPath, 'utf-8');
  } catch (err) {
    return null;
  }
}

// Given an SVG file, convert it to an iron-iconset-svg definition
function transformXMLtoPolymer(name, xml) {
  const start = xml.indexOf('><path') + 1;
  const end = xml.length - start - 6;
  const path = xml.substr(start, end);
  return `<g id="${name}">${path}</g>`;
}

// Given an iconset name and icon names, generate a polymer iconset
function generateIconset(name, iconNames) {
  const iconDefs = iconNames.map(name => {
    const iconDef = loadIcon(name);
    if (!iconDef) {
      throw new Error(`Unknown icon referenced: ${name}`);
    }
    return transformXMLtoPolymer(name, iconDef)
  }).join('');
  return `<ha-iconset-svg name="${name}" size="24"><svg><defs>${iconDefs}</defs></svg></ha-iconset-svg>`;
}

// Generate the full MDI iconset
function genMDIIcons() {
  const meta = JSON.parse(fs.readFileSync(path.resolve(ICON_PACKAGE_PATH, META_PATH), 'UTF-8'));
  const iconNames = meta.map(iconInfo => iconInfo.name);
  fs.existsSync(OUTPUT_DIR) || fs.mkdirSync(OUTPUT_DIR);
  fs.writeFileSync(MDI_OUTPUT_PATH, generateIconset('mdi', iconNames));
}

// Helper function to map recursively over files in a folder and it's subfolders
function mapFiles(startPath, filter, mapFunc) {
  const files = fs.readdirSync(startPath);
  for (let i = 0; i < files.length; i++) {
    const filename = path.join(startPath, files[i]);
    const stat = fs.lstatSync(filename);
    if (stat.isDirectory()) {
      mapFiles(filename, filter, mapFunc);
    } else if (filename.indexOf(filter) >= 0) {
      mapFunc(filename);
    }
  }
}

// Find all icons used by the project.
function findIcons(path, iconsetName) {
  const iconRegex = new RegExp(`${iconsetName}:[\\w-]+`, 'g');
  const icons = new Set();
  function processFile(filename) {
    const content = fs.readFileSync(filename);
    let match;
    // eslint-disable-next-line
    while (match = iconRegex.exec(content)) {
      // strip off "hass:" and add to set
      icons.add(match[0].substr(iconsetName.length + 1));
    }
  }
  mapFiles(path, '.js', processFile);
  return Array.from(icons);
}

function genHassIcons() {
  const iconNames = findIcons('./src', 'hass').concat(BUILT_IN_PANEL_ICONS);
  fs.existsSync(OUTPUT_DIR) || fs.mkdirSync(OUTPUT_DIR);
  fs.writeFileSync(HASS_OUTPUT_PATH, generateIconset('hass', iconNames));
}

gulp.task('gen-icons-mdi', () => genMDIIcons());
gulp.task('gen-icons-hass', () => genHassIcons());
gulp.task('gen-icons-hassio', () => genHassIcons());
gulp.task('gen-icons', ['gen-icons-hass', 'gen-icons-mdi'], () => {});

module.exports = {
  findIcons,
  generateIconset,
};