"use strict";

Object.defineProperty(exports, "__esModule", {
  value: true
});
exports.onAttrs = onAttrs;
exports.redundantScriptTypes = void 0;
// https://developer.mozilla.org/en-US/docs/Web/HTTP/Basics_of_HTTP/MIME_types#JavaScript_types
const redundantScriptTypes = exports.redundantScriptTypes = new Set(['application/javascript', 'application/ecmascript', 'application/x-ecmascript', 'application/x-javascript', 'text/javascript', 'text/ecmascript', 'text/javascript1.0', 'text/javascript1.1', 'text/javascript1.2', 'text/javascript1.3', 'text/javascript1.4', 'text/javascript1.5', 'text/jscript', 'text/livescript', 'text/x-ecmascript', 'text/x-javascript']);

// https://html.spec.whatwg.org/multipage/common-microsyntaxes.html#missing-value-default
const missingValueDefaultAttributes = {
  'form': {
    'method': 'get'
  },
  input: {
    type: 'text'
  },
  button: {
    // https://html.spec.whatwg.org/multipage/form-elements.html#attr-button-type
    type: 'submit'
  },
  'script': {
    'language': 'javascript',
    'type': attrs => {
      for (const [attrName, attrValue] of Object.entries(attrs)) {
        if (attrName.toLowerCase() !== 'type') {
          continue;
        }
        return redundantScriptTypes.has(attrValue);
      }
      return false;
    },
    // Remove attribute if the function returns false
    'charset': attrs => {
      // The charset attribute only really makes sense on “external” SCRIPT elements:
      // http://perfectionkills.com/optimizing-html/#8_script_charset
      return !attrs.src;
    }
  },
  'style': {
    'media': 'all',
    'type': 'text/css'
  },
  'link': {
    media: 'all',
    'type': attrs => {
      // https://html.spec.whatwg.org/multipage/links.html#link-type-stylesheet
      let isRelStyleSheet = false;
      let isTypeTextCSS = false;
      if (attrs) {
        for (const [attrName, attrValue] of Object.entries(attrs)) {
          if (attrName.toLowerCase() === 'rel' && attrValue === 'stylesheet') {
            isRelStyleSheet = true;
          }
          if (attrName.toLowerCase() === 'type' && attrValue === 'text/css') {
            isTypeTextCSS = true;
          }
        }
      }

      // Only "text/css" is redudant for link[rel=stylesheet]. Otherwise "type" shouldn't be removed
      return isRelStyleSheet && isTypeTextCSS;
    }
  },
  // See: https://html.spec.whatwg.org/#lazy-loading-attributes
  img: {
    'loading': 'eager',
    // https://html.spec.whatwg.org/multipage/embedded-content.html#dom-img-decoding
    decoding: 'auto'
  },
  iframe: {
    'loading': 'eager'
  },
  // https://html.spec.whatwg.org/multipage/media.html#htmltrackelement
  track: {
    kind: 'subtitles'
  },
  textarea: {
    // https://html.spec.whatwg.org/multipage/form-elements.html#dom-textarea-wrap
    wrap: 'soft'
  },
  area: {
    // https://html.spec.whatwg.org/multipage/image-maps.html#attr-area-shape
    shape: 'rect'
  }
};
const tagsHaveMissingValueDefaultAttributes = new Set(Object.keys(missingValueDefaultAttributes));

/** Removes redundant attributes */
function onAttrs() {
  return (attrs, node) => {
    if (!node.tag) return attrs;
    const newAttrs = attrs;
    if (tagsHaveMissingValueDefaultAttributes.has(node.tag)) {
      const tagRedundantAttributes = missingValueDefaultAttributes[node.tag];
      for (const redundantAttributeName of Object.keys(tagRedundantAttributes)) {
        let tagRedundantAttributeValue = tagRedundantAttributes[redundantAttributeName];
        let isRemove = false;
        if (typeof tagRedundantAttributeValue === 'function') {
          isRemove = tagRedundantAttributeValue(attrs);
        } else if (attrs[redundantAttributeName] === tagRedundantAttributeValue) {
          isRemove = true;
        }
        if (isRemove) {
          delete newAttrs[redundantAttributeName];
        }
      }
    }
    return newAttrs;
  };
}