const {promises: fsp} = require('fs');
const {join} = require('path');
const sass = require('sass');
const usercss = require('usercss-meta');

/**
 * Creates the userstyle for a given style.
 * @param {string} style The style's source directory.
 * @param {string} dir The style's output directory.
 */
async function createUserstyle(style, dir) {
  // Read the style's metadata.
  const metadata = await readStyleMetadata(style);

  // Build the style's CSS.
  const scss = sass.renderSync({
    file: join(__dirname, style, `${style}.scss`),
    outputStyle: 'expanded'
  });

  // Insert the `@-moz-document domain()` into the CSS.
  const domain = metadata.domain;
  const css = `\n@-moz-document domain("${domain}") {\n${scss.css.toString()}\n}\n`;

  // Remove the domain from the metadata, as it's not needed in the usercss data.
  delete metadata.domain;

  // Create the userstyle.
  const userstyle = usercss.stringify(metadata, {alignKeys: true}) + css;

  // Create the destination path for the userstyle.
  const destination = join(__dirname, '..', dir, `${style}.user.css`);

  // Write the userstyle to file.
  return fsp.writeFile(destination, userstyle);
}

/**
 * Reads and parses the `metadata.json` file from a given style.
 * @param {string} style The style's source directory.
 */
async function readStyleMetadata(style) {
  return JSON.parse(
    await fsp.readFile(join(__dirname, style, 'metadata.json'), 'utf8')
  );
}

/**
 * Returns whether the given style has an `images/` directory.
 * @param {string} style The style's source directory.
 */
async function styleHasImages(style) {
  try {
    const styleStat = await fsp.stat(join(__dirname, style, 'images'));
    return styleStat.isDirectory();
  } catch {
    return false;
  }
}

module.exports = {
  createUserstyle,
  readStyleMetadata,
  styleHasImages
};