text: /**
   * Copyright 2015 Google Inc. All Rights Reserved.
   *
   * Licensed under the Apache License, Version 2.0 (the "License");
   * you may not use this file except in compliance with the License.
   * You may obtain a copy of the License at
   *
   *      http://www.apache.org/licenses/LICENSE-2.0
   *
   * Unless required by applicable law or agreed to in writing, software
   * distributed under the License is distributed on an "AS-IS" BASIS,
   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
   * See the License for the specific language governing permissions and
   * limitations under the License.
   */
  
  "use strict";
  
  const striptags = require('striptags');
  const PARAGRAPH = /\<p(\s[^\>]+)?\>([\s\S]*?)\<\/p\>/;
  
  /**
   * Contains the content of an example.
   */
  module.exports = class Document {
  
    constructor() {
      this.sections = [];
      this.head = '';
      this.styles = '';
      this.title = '';
      this.metadata = {};
      this.body = '';
      this.elementsAfterBody = '';
      this.isAmpStory = false;
      this.isAmpWeb = false;
      this.isAmpAds = false;
      this.isAmpEmail = false;
    }
  
    addSection(section) {
      const prevSection = this.lastSection();
      if (prevSection) {
        prevSection.isLastSection = false;
      } else {
        section.isFirstSection = true;
      }
      this.sections.push(section);
    }
  
    appendHead(line) {
      this.head += line + '\n';
    }
  
    appendStyles(line) {
      this.styles += line + '\n';
    }
  
    /**
     * Returns a short description consisting of the first
     * sentence in the doc strings. The description may contain
     * some html tags (code).
     */
    description() {
      if (this._description) {
        return this._description;
      }
      for (let i = 0; i < this.sections.length; i++) {
        const section = this.sections[i];
        if (!section.doc) {
          continue;
        }
        const desc = this.extractDescription(section.markedDoc());
        if (desc) {
          this._description = desc;
          return desc;
        }
      }
      return '';
    }
  
    formats() {
      if (this.metadata.formats) {
        return this.metadata.formats;
      }
  
      if (this.isAmpStory) {
        return ['stories'];
      }
      if (this.isAmpAds) {
        return ['ads'];
      }
      if (this.isAmpEmail) {
        return ['email'];
      }
  
      // Use websites as fallback as isAmpWebsites could be true for all formats
      return ['websites'];
    }
  
    /**
     * Returns true if the document contains a canonical link
     */
    hasCanonical() {
      return this.head.indexOf('rel="canonical"') > -1;
    }
  
    /**
     * Returns true if the document imports the given component
     */
    importsComponent(componentName) {
      return this.head.indexOf('custom-element="' + componentName + '"') > -1;
    }
  
    includesLink(relType) {
      return this.head.indexOf('rel="' + relType + '"') > -1;
    }
  
    headings() {
      let result = [];
      this.sections.forEach(s => {
        result = result.concat(s.headings);
      });
      return result;
    }
  
    isAmpAdSample() {
      return this.isAmpAds;
    }
  
    isAmpExperimentalAdSample() {
      return this.metadata.preview && this.metadata.preview.toLowerCase() == "a4a-experimental";
    }
  
    isAmpHtmlEmail() {
      return this.isAmpEmail;
    }
  
    /* private */
    extractDescription(htmlString) {
      let desc = this.extractFirstParagraph(htmlString);
      desc = striptags(desc);
      desc = this.extractFirstSentence(desc);
      desc = desc.trim();
      desc = this.decodeHTMLEntities(desc);
      return desc;
    }
  
    decodeHTMLEntities(string) {
      return (string+"").replace(/&#\d+;/gm,function(s) {
        return String.fromCharCode(s.match(/\d+/gm)[0]);
      })
    }
  
    extractFirstParagraph(string) {
      const paragraphs = PARAGRAPH.exec(string);
      if (!paragraphs) {
        return '';
      }
      return paragraphs[2];
    }
  
    extractFirstSentence(str) {
      let current;
      let prev;
      const result = [];
      for (var i = 0, len = str.length; i < len; i++) {
        current = str[i];
        if (prev == '.' && (current === ' ' || current === '\r' || current === '\n' )) {
          break;
        }
        if (current !== '\r' && current !== '\n') {
          result.push(current);
        }
        if (prev !== '\n' && current === '\n') {
          result.push(' ');
        }
        prev = current;
      }
      return result.join('');
    }
  
    lastSection() {
      return this.sections[this.sections.length - 1];
    }
  
  };
  