/* global hexo */

'use strict';

hexo.extend.helper.register('next_font', function() {
  const config = this.theme.font;

  if (!config || !config.enable) return '';

  const fontStyles = ':300,300italic,400,400italic,700,700italic';
  const fontHost = config.host || '//fonts.googleapis.com';

  // Get a font list from config
  let fontFamilies = ['global', 'title', 'headings', 'posts', 'codes'].map(item => {
    if (config[item] && config[item].family && config[item].external) {
      return config[item].family + fontStyles;
    }
    return '';
  }).filter(item => item !== '');

  fontFamilies = [...new Set(fontFamilies)].join('|');

  // Merge extra parameters to the final processed font string
  return fontFamilies ? `<link rel="stylesheet" href="${fontHost}/css?family=${fontFamilies}&display=swap&subset=latin,latin-ext">` : '';
});