/* FIXME :
 :extend() is not handled specifically : its highlighting is buggy.
 Mixin usage must be inside a ruleset to be highlighted.
 At-rules (e.g. import) containing interpolations are buggy.
 Detached rulesets are highlighted as at-rules.
 A comment before a mixin usage prevents the latter to be properly highlighted.
 */

Prism.languages.less = Prism.languages.extend('css', {
  comment: [
    /\/\*[\s\S]*?\*\//,
    {
      pattern: /(^|[^\\])\/\/.*/,
      lookbehind: true,
    },
  ],
  atrule: {
    pattern:
      /@[\w-](?:\((?:[^(){}]|\([^(){}]*\))*\)|[^(){};\s]|\s+(?!\s))*?(?=\s*\{)/,
    inside: {
      punctuation: /[:()]/,
    },
  },
  // selectors and mixins are considered the same
  selector: {
    pattern:
      /(?:@\{[\w-]+\}|[^{};\s@])(?:@\{[\w-]+\}|\((?:[^(){}]|\([^(){}]*\))*\)|[^(){};@\s]|\s+(?!\s))*?(?=\s*\{)/,
    inside: {
      // mixin parameters
      variable: /@+[\w-]+/,
    },
  },

  property: /(?:@\{[\w-]+\}|[\w-])+(?:\+_?)?(?=\s*:)/,
  operator: /[+\-*\/]/,
});

Prism.languages.insertBefore('less', 'property', {
  variable: [
    // Variable declaration (the colon must be consumed!)
    {
      pattern: /@[\w-]+\s*:/,
      inside: {
        punctuation: /:/,
      },
    },

    // Variable usage
    /@@?[\w-]+/,
  ],
  'mixin-usage': {
    pattern: /([{;]\s*)[.#](?!\d)[\w-].*?(?=[(;])/,
    lookbehind: true,
    alias: 'function',
  },
});