text: /* Copyright 2012 Mozilla Foundation
   *
   * 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.
   */
  
  import {
    bytesToString, createPromiseCapability, createValidAbsoluteUrl, FormatError,
    info, InvalidPDFException, isBool, isNum, isString, MissingDataException,
    PermissionFlag, shadow, stringToPDFString, stringToUTF8String,
    toRomanNumerals, unreachable, warn, XRefEntryException, XRefParseException
  } from '../shared/util';
  import {
    Dict, isCmd, isDict, isName, isRef, isRefsEqual, isStream, Ref, RefSet,
    RefSetCache
  } from './primitives';
  import { Lexer, Parser } from './parser';
  import { ChunkedStream } from './chunked_stream';
  import { CipherTransformFactory } from './crypto';
  import { ColorSpace } from './colorspace';
  
  function fetchDestination(dest) {
    return isDict(dest) ? dest.get('D') : dest;
  }
  
  class Catalog {
    constructor(pdfManager, xref) {
      this.pdfManager = pdfManager;
      this.xref = xref;
  
      this.catDict = xref.getCatalogObj();
      if (!isDict(this.catDict)) {
        throw new FormatError('Catalog object is not a dictionary.');
      }
  
      this.fontCache = new RefSetCache();
      this.builtInCMapCache = new Map();
      this.pageKidsCountCache = new RefSetCache();
    }
  
    get metadata() {
      const streamRef = this.catDict.getRaw('Metadata');
      if (!isRef(streamRef)) {
        return shadow(this, 'metadata', null);
      }
  
      const suppressEncryption = !(this.xref.encrypt &&
                                   this.xref.encrypt.encryptMetadata);
      const stream = this.xref.fetch(streamRef, suppressEncryption);
      let metadata;
  
      if (stream && isDict(stream.dict)) {
        const type = stream.dict.get('Type');
        const subtype = stream.dict.get('Subtype');
  
        if (isName(type, 'Metadata') && isName(subtype, 'XML')) {
          // XXX: This should examine the charset the XML document defines,
          // however since there are currently no real means to decode
          // arbitrary charsets, let's just hope that the author of the PDF
          // was reasonable enough to stick with the XML default charset,
          // which is UTF-8.
          try {
            metadata = stringToUTF8String(bytesToString(stream.getBytes()));
          } catch (e) {
            if (e instanceof MissingDataException) {
              throw e;
            }
            info('Skipping invalid metadata.');
          }
        }
      }
      return shadow(this, 'metadata', metadata);
    }
  
    get toplevelPagesDict() {
      const pagesObj = this.catDict.get('Pages');
      if (!isDict(pagesObj)) {
        throw new FormatError('Invalid top-level pages dictionary.');
      }
      return shadow(this, 'toplevelPagesDict', pagesObj);
    }
  
    get documentOutline() {
      let obj = null;
      try {
        obj = this._readDocumentOutline();
      } catch (ex) {
        if (ex instanceof MissingDataException) {
          throw ex;
        }
        warn('Unable to read document outline.');
      }
      return shadow(this, 'documentOutline', obj);
    }
  
    /**
     * @private
     */
    _readDocumentOutline() {
      let obj = this.catDict.get('Outlines');
      if (!isDict(obj)) {
        return null;
      }
      obj = obj.getRaw('First');
      if (!isRef(obj)) {
        return null;
      }
  
      const root = { items: [], };
      const queue = [{ obj, parent: root, }];
      // To avoid recursion, keep track of the already processed items.
      const processed = new RefSet();
      processed.put(obj);
      const xref = this.xref, blackColor = new Uint8ClampedArray(3);
  
      while (queue.length > 0) {
        const i = queue.shift();
        const outlineDict = xref.fetchIfRef(i.obj);
        if (outlineDict === null) {
          continue;
        }
        if (!outlineDict.has('Title')) {
          throw new FormatError('Invalid outline item encountered.');
        }
  
        const data = { url: null, dest: null, };
        Catalog.parseDestDictionary({
          destDict: outlineDict,
          resultObj: data,
          docBaseUrl: this.pdfManager.docBaseUrl,
        });
        const title = outlineDict.get('Title');
        const flags = outlineDict.get('F') || 0;
        const color = outlineDict.getArray('C');
        let rgbColor = blackColor;
  
        // We only need to parse the color when it's valid, and non-default.
        if (Array.isArray(color) && color.length === 3 &&
            (color[0] !== 0 || color[1] !== 0 || color[2] !== 0)) {
          rgbColor = ColorSpace.singletons.rgb.getRgb(color, 0);
        }
  
        const outlineItem = {
          dest: data.dest,
          url: data.url,
          unsafeUrl: data.unsafeUrl,
          newWindow: data.newWindow,
          title: stringToPDFString(title),
          color: rgbColor,
          count: outlineDict.get('Count'),
          bold: !!(flags & 2),
          italic: !!(flags & 1),
          items: [],
        };
  
        i.parent.items.push(outlineItem);
        obj = outlineDict.getRaw('First');
        if (isRef(obj) && !processed.has(obj)) {
          queue.push({ obj, parent: outlineItem, });
          processed.put(obj);
        }
        obj = outlineDict.getRaw('Next');
        if (isRef(obj) && !processed.has(obj)) {
          queue.push({ obj, parent: i.parent, });
          processed.put(obj);
        }
      }
      return (root.items.length > 0 ? root.items : null);
    }
  
    get permissions() {
      let permissions = null;
      try {
        permissions = this._readPermissions();
      } catch (ex) {
        if (ex instanceof MissingDataException) {
          throw ex;
        }
        warn('Unable to read permissions.');
      }
      return shadow(this, 'permissions', permissions);
    }
  
    /**
     * @private
     */
    _readPermissions() {
      const encrypt = this.xref.trailer.get('Encrypt');
      if (!isDict(encrypt)) {
        return null;
      }
  
      let flags = encrypt.get('P');
      if (!isNum(flags)) {
        return null;
      }
  
      // PDF integer objects are represented internally in signed 2's complement
      // form. Therefore, convert the signed decimal integer to a signed 2's
      // complement binary integer so we can use regular bitwise operations on it.
      flags += 2 ** 32;
  
      const permissions = [];
      for (const key in PermissionFlag) {
        const value = PermissionFlag[key];
        if (flags & value) {
          permissions.push(value);
        }
      }
      return permissions;
    }
  
    get numPages() {
      const obj = this.toplevelPagesDict.get('Count');
      if (!Number.isInteger(obj)) {
        throw new FormatError(
          'Page count in top-level pages dictionary is not an integer.');
      }
      return shadow(this, 'numPages', obj);
    }
  
    get destinations() {
      const obj = this._readDests(), dests = Object.create(null);
      if (obj instanceof NameTree) {
        const names = obj.getAll();
        for (let name in names) {
          dests[name] = fetchDestination(names[name]);
        }
      } else if (obj instanceof Dict) {
        obj.forEach(function(key, value) {
          if (value) {
            dests[key] = fetchDestination(value);
          }
        });
      }
      return shadow(this, 'destinations', dests);
    }
  
    getDestination(destinationId) {
      const obj = this._readDests();
      if (obj instanceof NameTree || obj instanceof Dict) {
        return fetchDestination(obj.get(destinationId) || null);
      }
      return null;
    }
  
    /**
     * @private
     */
    _readDests() {
      const obj = this.catDict.get('Names');
      if (obj && obj.has('Dests')) {
        return new NameTree(obj.getRaw('Dests'), this.xref);
      } else if (this.catDict.has('Dests')) { // Simple destination dictionary.
        return this.catDict.get('Dests');
      }
    }
  
    get pageLabels() {
      let obj = null;
      try {
        obj = this._readPageLabels();
      } catch (ex) {
        if (ex instanceof MissingDataException) {
          throw ex;
        }
        warn('Unable to read page labels.');
      }
      return shadow(this, 'pageLabels', obj);
    }
  
    /**
     * @private
     */
    _readPageLabels() {
      const obj = this.catDict.getRaw('PageLabels');
      if (!obj) {
        return null;
      }
  
      const pageLabels = new Array(this.numPages);
      let style = null, prefix = '';
  
      const numberTree = new NumberTree(obj, this.xref);
      const nums = numberTree.getAll();
      let currentLabel = '', currentIndex = 1;
  
      for (let i = 0, ii = this.numPages; i < ii; i++) {
        if (i in nums) {
          const labelDict = nums[i];
          if (!isDict(labelDict)) {
            throw new FormatError('PageLabel is not a dictionary.');
          }
  
          if (labelDict.has('Type') &&
              !isName(labelDict.get('Type'), 'PageLabel')) {
            throw new FormatError('Invalid type in PageLabel dictionary.');
          }
  
          if (labelDict.has('S')) {
            const s = labelDict.get('S');
            if (!isName(s)) {
              throw new FormatError('Invalid style in PageLabel dictionary.');
            }
            style = s.name;
          } else {
            style = null;
          }
  
          if (labelDict.has('P')) {
            const p = labelDict.get('P');
            if (!isString(p)) {
              throw new FormatError('Invalid prefix in PageLabel dictionary.');
            }
            prefix = stringToPDFString(p);
          } else {
            prefix = '';
          }
  
          if (labelDict.has('St')) {
            const st = labelDict.get('St');
            if (!(Number.isInteger(st) && st >= 1)) {
              throw new FormatError('Invalid start in PageLabel dictionary.');
            }
            currentIndex = st;
          } else {
            currentIndex = 1;
          }
        }
  
        switch (style) {
          case 'D':
            currentLabel = currentIndex;
            break;
          case 'R':
          case 'r':
            currentLabel = toRomanNumerals(currentIndex, style === 'r');
            break;
          case 'A':
          case 'a':
            const LIMIT = 26; // Use only the characters A-Z, or a-z.
            const A_UPPER_CASE = 0x41, A_LOWER_CASE = 0x61;
  
            const baseCharCode = (style === 'a' ? A_LOWER_CASE : A_UPPER_CASE);
            const letterIndex = currentIndex - 1;
            const character = String.fromCharCode(baseCharCode +
                                                  (letterIndex % LIMIT));
            const charBuf = [];
            for (let j = 0, jj = (letterIndex / LIMIT) | 0; j <= jj; j++) {
              charBuf.push(character);
            }
            currentLabel = charBuf.join('');
            break;
          default:
            if (style) {
              throw new FormatError(
                `Invalid style "${style}" in PageLabel dictionary.`);
            }
            currentLabel = '';
        }
  
        pageLabels[i] = prefix + currentLabel;
        currentIndex++;
      }
      return pageLabels;
    }
  
    get pageMode() {
      const obj = this.catDict.get('PageMode');
      let pageMode = 'UseNone'; // Default value.
  
      if (isName(obj)) {
        switch (obj.name) {
          case 'UseNone':
          case 'UseOutlines':
          case 'UseThumbs':
          case 'FullScreen':
          case 'UseOC':
          case 'UseAttachments':
            pageMode = obj.name;
        }
      }
      return shadow(this, 'pageMode', pageMode);
    }
  
    get openActionDestination() {
      const obj = this.catDict.get('OpenAction');
      let openActionDest = null;
  
      if (isDict(obj)) {
        // Convert the OpenAction dictionary into a format that works with
        // `parseDestDictionary`, to avoid having to re-implement those checks.
        const destDict = new Dict(this.xref);
        destDict.set('A', obj);
  
        const resultObj = { url: null, dest: null, };
        Catalog.parseDestDictionary({ destDict, resultObj, });
  
        if (Array.isArray(resultObj.dest)) {
          openActionDest = resultObj.dest;
        }
      } else if (Array.isArray(obj)) {
        openActionDest = obj;
      }
      return shadow(this, 'openActionDestination', openActionDest);
    }
  
    get attachments() {
      const obj = this.catDict.get('Names');
      let attachments = null;
  
      if (obj && obj.has('EmbeddedFiles')) {
        const nameTree = new NameTree(obj.getRaw('EmbeddedFiles'), this.xref);
        const names = nameTree.getAll();
        for (const name in names) {
          const fs = new FileSpec(names[name], this.xref);
          if (!attachments) {
            attachments = Object.create(null);
          }
          attachments[stringToPDFString(name)] = fs.serializable;
        }
      }
      return shadow(this, 'attachments', attachments);
    }
  
    get javaScript() {
      const obj = this.catDict.get('Names');
  
      let javaScript = null;
      function appendIfJavaScriptDict(jsDict) {
        const type = jsDict.get('S');
        if (!isName(type, 'JavaScript')) {
          return;
        }
  
        let js = jsDict.get('JS');
        if (isStream(js)) {
          js = bytesToString(js.getBytes());
        } else if (!isString(js)) {
          return;
        }
  
        if (!javaScript) {
          javaScript = [];
        }
        javaScript.push(stringToPDFString(js));
      }
  
      if (obj && obj.has('JavaScript')) {
        const nameTree = new NameTree(obj.getRaw('JavaScript'), this.xref);
        const names = nameTree.getAll();
        for (const name in names) {
          // We don't use most JavaScript in PDF documents. This code is
          // defensive so we don't cause errors on document load.
          const jsDict = names[name];
          if (isDict(jsDict)) {
            appendIfJavaScriptDict(jsDict);
          }
        }
      }
  
      // Append OpenAction actions to the JavaScript array.
      const openActionDict = this.catDict.get('OpenAction');
      if (isDict(openActionDict, 'Action')) {
        const actionType = openActionDict.get('S');
        if (isName(actionType, 'Named')) {
          // The named Print action is not a part of the PDF 1.7 specification,
          // but is supported by many PDF readers/writers (including Adobe's).
          const action = openActionDict.get('N');
          if (isName(action, 'Print')) {
            if (!javaScript) {
              javaScript = [];
            }
            javaScript.push('print({});');
          }
        } else {
          appendIfJavaScriptDict(openActionDict);
        }
      }
  
      return shadow(this, 'javaScript', javaScript);
    }
  
    cleanup() {
      this.pageKidsCountCache.clear();
  
      const promises = [];
      this.fontCache.forEach(function(promise) {
        promises.push(promise);
      });
  
      return Promise.all(promises).then((translatedFonts) => {
        for (let i = 0, ii = translatedFonts.length; i < ii; i++) {
          const font = translatedFonts[i].dict;
          delete font.translated;
        }
        this.fontCache.clear();
        this.builtInCMapCache.clear();
      });
    }
  
    getPageDict(pageIndex) {
      const capability = createPromiseCapability();
      const nodesToVisit = [this.catDict.getRaw('Pages')];
      const xref = this.xref, pageKidsCountCache = this.pageKidsCountCache;
      let count, currentPageIndex = 0;
  
      function next() {
        while (nodesToVisit.length) {
          const currentNode = nodesToVisit.pop();
  
          if (isRef(currentNode)) {
            count = pageKidsCountCache.get(currentNode);
            // Skip nodes where the page can't be.
            if (count > 0 && currentPageIndex + count < pageIndex) {
              currentPageIndex += count;
              continue;
            }
  
            xref.fetchAsync(currentNode).then(function(obj) {
              if (isDict(obj, 'Page') || (isDict(obj) && !obj.has('Kids'))) {
                if (pageIndex === currentPageIndex) {
                  // Cache the Page reference, since it can *greatly* improve
                  // performance by reducing redundant lookups in long documents
                  // where all nodes are found at *one* level of the tree.
                  if (currentNode && !pageKidsCountCache.has(currentNode)) {
                    pageKidsCountCache.put(currentNode, 1);
                  }
                  capability.resolve([obj, currentNode]);
                } else {
                  currentPageIndex++;
                  next();
                }
                return;
              }
              nodesToVisit.push(obj);
              next();
            }, capability.reject);
            return;
          }
  
          // Must be a child page dictionary.
          if (!isDict(currentNode)) {
            capability.reject(new FormatError(
              'Page dictionary kid reference points to wrong type of object.'));
            return;
          }
  
          count = currentNode.get('Count');
          if (Number.isInteger(count) && count >= 0) {
            // Cache the Kids count, since it can reduce redundant lookups in
            // documents where all nodes are found at *one* level of the tree.
            const objId = currentNode.objId;
            if (objId && !pageKidsCountCache.has(objId)) {
              pageKidsCountCache.put(objId, count);
            }
            // Skip nodes where the page can't be.
            if (currentPageIndex + count <= pageIndex) {
              currentPageIndex += count;
              continue;
            }
          }
  
          const kids = currentNode.get('Kids');
          if (!Array.isArray(kids)) {
            // Prevent errors in corrupt PDF documents that violate the
            // specification by *inlining* Page dicts directly in the Kids
            // array, rather than using indirect objects (fixes issue9540.pdf).
            if (isName(currentNode.get('Type'), 'Page') ||
                (!currentNode.has('Type') && currentNode.has('Contents'))) {
              if (currentPageIndex === pageIndex) {
                capability.resolve([currentNode, null]);
                return;
              }
              currentPageIndex++;
              continue;
            }
  
            capability.reject(new FormatError(
              'Page dictionary kids object is not an array.'));
            return;
          }
  
          // Always check all `Kids` nodes, to avoid getting stuck in an empty
          // node further down in the tree (see issue5644.pdf, issue8088.pdf),
          // and to ensure that we actually find the correct `Page` dict.
          for (let last = kids.length - 1; last >= 0; last--) {
            nodesToVisit.push(kids[last]);
          }
        }
        capability.reject(new Error(`Page index ${pageIndex} not found.`));
      }
      next();
      return capability.promise;
    }
  
    getPageIndex(pageRef) {
      // The page tree nodes have the count of all the leaves below them. To get
      // how many pages are before we just have to walk up the tree and keep
      // adding the count of siblings to the left of the node.
      const xref = this.xref;
  
      function pagesBeforeRef(kidRef) {
        let total = 0, parentRef;
  
        return xref.fetchAsync(kidRef).then(function(node) {
          if (isRefsEqual(kidRef, pageRef) && !isDict(node, 'Page') &&
              !(isDict(node) && !node.has('Type') && node.has('Contents'))) {
            throw new FormatError(
              'The reference does not point to a /Page dictionary.');
          }
          if (!node) {
            return null;
          }
          if (!isDict(node)) {
            throw new FormatError('Node must be a dictionary.');
          }
          parentRef = node.getRaw('Parent');
          return node.getAsync('Parent');
        }).then(function(parent) {
          if (!parent) {
            return null;
          }
          if (!isDict(parent)) {
            throw new FormatError('Parent must be a dictionary.');
          }
          return parent.getAsync('Kids');
        }).then(function(kids) {
          if (!kids) {
            return null;
          }
  
          const kidPromises = [];
          let found = false;
          for (let i = 0, ii = kids.length; i < ii; i++) {
            const kid = kids[i];
            if (!isRef(kid)) {
              throw new FormatError('Kid must be a reference.');
            }
            if (isRefsEqual(kid, kidRef)) {
              found = true;
              break;
            }
            kidPromises.push(xref.fetchAsync(kid).then(function(kid) {
              if (!isDict(kid)) {
                throw new FormatError('Kid node must be a dictionary.');
              }
              if (kid.has('Count')) {
                total += kid.get('Count');
              } else { // Page leaf node.
                total++;
              }
            }));
          }
          if (!found) {
            throw new FormatError('Kid reference not found in parent\'s kids.');
          }
          return Promise.all(kidPromises).then(function() {
            return [total, parentRef];
          });
        });
      }
  
      let total = 0;
      function next(ref) {
        return pagesBeforeRef(ref).then(function(args) {
          if (!args) {
            return total;
          }
          const [count, parentRef] = args;
          total += count;
          return next(parentRef);
        });
      }
  
      return next(pageRef);
    }
  
    /**
     * @typedef ParseDestDictionaryParameters
     * @property {Dict} destDict - The dictionary containing the destination.
     * @property {Object} resultObj - The object where the parsed destination
     *   properties will be placed.
     * @property {string} docBaseUrl - (optional) The document base URL that is
     *   used when attempting to recover valid absolute URLs from relative ones.
     */
  
    /**
     * Helper function used to parse the contents of destination dictionaries.
     * @param {ParseDestDictionaryParameters} params
     */
    static parseDestDictionary(params) {
      // Lets URLs beginning with 'www.' default to using the 'http://' protocol.
      function addDefaultProtocolToUrl(url) {
        if (url.indexOf('www.') === 0) {
          return `http://${url}`;
        }
        return url;
      }
  
      // According to ISO 32000-1:2008, section 12.6.4.7, URIs should be encoded
      // in 7-bit ASCII. Some bad PDFs use UTF-8 encoding; see Bugzilla 1122280.
      function tryConvertUrlEncoding(url) {
        try {
          return stringToUTF8String(url);
        } catch (e) {
          return url;
        }
      }
  
      const destDict = params.destDict;
      if (!isDict(destDict)) {
        warn('parseDestDictionary: `destDict` must be a dictionary.');
        return;
      }
      const resultObj = params.resultObj;
      if (typeof resultObj !== 'object') {
        warn('parseDestDictionary: `resultObj` must be an object.');
        return;
      }
      const docBaseUrl = params.docBaseUrl || null;
  
      let action = destDict.get('A'), url, dest;
      if (!isDict(action) && destDict.has('Dest')) {
        // A /Dest entry should *only* contain a Name or an Array, but some bad
        // PDF generators ignore that and treat it as an /A entry.
        action = destDict.get('Dest');
      }
  
      if (isDict(action)) {
        const actionType = action.get('S');
        if (!isName(actionType)) {
          warn('parseDestDictionary: Invalid type in Action dictionary.');
          return;
        }
        const actionName = actionType.name;
  
        switch (actionName) {
          case 'URI':
            url = action.get('URI');
            if (isName(url)) {
              // Some bad PDFs do not put parentheses around relative URLs.
              url = '/' + url.name;
            } else if (isString(url)) {
              url = addDefaultProtocolToUrl(url);
            }
            // TODO: pdf spec mentions urls can be relative to a Base
            // entry in the dictionary.
            break;
  
          case 'GoTo':
            dest = action.get('D');
            break;
  
          case 'Launch':
            // We neither want, nor can, support arbitrary 'Launch' actions.
            // However, in practice they are mostly used for linking to other PDF
            // files, which we thus attempt to support (utilizing `docBaseUrl`).
            /* falls through */
  
          case 'GoToR':
            const urlDict = action.get('F');
            if (isDict(urlDict)) {
              // We assume that we found a FileSpec dictionary
              // and fetch the URL without checking any further.
              url = urlDict.get('F') || null;
            } else if (isString(urlDict)) {
              url = urlDict;
            }
  
            // NOTE: the destination is relative to the *remote* document.
            let remoteDest = action.get('D');
            if (remoteDest) {
              if (isName(remoteDest)) {
                remoteDest = remoteDest.name;
              }
              if (isString(url)) {
                const baseUrl = url.split('#')[0];
                if (isString(remoteDest)) {
                  url = baseUrl + '#' + remoteDest;
                } else if (Array.isArray(remoteDest)) {
                  url = baseUrl + '#' + JSON.stringify(remoteDest);
                }
              }
            }
            // The 'NewWindow' property, equal to `LinkTarget.BLANK`.
            const newWindow = action.get('NewWindow');
            if (isBool(newWindow)) {
              resultObj.newWindow = newWindow;
            }
            break;
  
          case 'Named':
            const namedAction = action.get('N');
            if (isName(namedAction)) {
              resultObj.action = namedAction.name;
            }
            break;
  
          case 'JavaScript':
            const jsAction = action.get('JS');
            let js;
  
            if (isStream(jsAction)) {
              js = bytesToString(jsAction.getBytes());
            } else if (isString(jsAction)) {
              js = jsAction;
            }
  
            if (js) {
              // Attempt to recover valid URLs from `JS` entries with certain
              // white-listed formats:
              //  - window.open('http://example.com')
              //  - app.launchURL('http://example.com', true)
              const URL_OPEN_METHODS = [
                'app.launchURL',
                'window.open'
              ];
              const regex = new RegExp(
                '^\\s*(' + URL_OPEN_METHODS.join('|').split('.').join('\\.') +
                ')\\((?:\'|\")([^\'\"]*)(?:\'|\")(?:,\\s*(\\w+)\\)|\\))', 'i');
  
              const jsUrl = regex.exec(stringToPDFString(js));
              if (jsUrl && jsUrl[2]) {
                url = jsUrl[2];
  
                if (jsUrl[3] === 'true' && jsUrl[1] === 'app.launchURL') {
                  resultObj.newWindow = true;
                }
                break;
              }
            }
            /* falls through */
          default:
            warn(`parseDestDictionary: unsupported action type "${actionName}".`);
            break;
        }
      } else if (destDict.has('Dest')) { // Simple destination.
        dest = destDict.get('Dest');
      }
  
      if (isString(url)) {
        url = tryConvertUrlEncoding(url);
        const absoluteUrl = createValidAbsoluteUrl(url, docBaseUrl);
        if (absoluteUrl) {
          resultObj.url = absoluteUrl.href;
        }
        resultObj.unsafeUrl = url;
      }
      if (dest) {
        if (isName(dest)) {
          dest = dest.name;
        }
        if (isString(dest) || Array.isArray(dest)) {
          resultObj.dest = dest;
        }
      }
    }
  }
  
  var XRef = (function XRefClosure() {
    function XRef(stream, pdfManager) {
      this.stream = stream;
      this.pdfManager = pdfManager;
      this.entries = [];
      this.xrefstms = Object.create(null);
      // prepare the XRef cache
      this.cache = [];
      this.stats = {
        streamTypes: [],
        fontTypes: [],
      };
    }
  
    XRef.prototype = {
      setStartXRef: function XRef_setStartXRef(startXRef) {
        // Store the starting positions of xref tables as we process them
        // so we can recover from missing data errors
        this.startXRefQueue = [startXRef];
      },
  
      parse: function XRef_parse(recoveryMode) {
        var trailerDict;
        if (!recoveryMode) {
          trailerDict = this.readXRef();
        } else {
          warn('Indexing all PDF objects');
          trailerDict = this.indexObjects();
        }
        trailerDict.assignXref(this);
        this.trailer = trailerDict;
  
        let encrypt;
        try {
          encrypt = trailerDict.get('Encrypt');
        } catch (ex) {
          if (ex instanceof MissingDataException) {
            throw ex;
          }
          warn(`XRef.parse - Invalid "Encrypt" reference: "${ex}".`);
        }
        if (isDict(encrypt)) {
          var ids = trailerDict.get('ID');
          var fileId = (ids && ids.length) ? ids[0] : '';
          // The 'Encrypt' dictionary itself should not be encrypted, and by
          // setting `suppressEncryption` we can prevent an infinite loop inside
          // of `XRef_fetchUncompressed` if the dictionary contains indirect
          // objects (fixes issue7665.pdf).
          encrypt.suppressEncryption = true;
          this.encrypt = new CipherTransformFactory(encrypt, fileId,
                                                    this.pdfManager.password);
        }
  
        // Get the root dictionary (catalog) object, and do some basic validation.
        let root;
        try {
          root = trailerDict.get('Root');
        } catch (ex) {
          if (ex instanceof MissingDataException) {
            throw ex;
          }
          warn(`XRef.parse - Invalid "Root" reference: "${ex}".`);
        }
        if (isDict(root) && root.has('Pages')) {
          this.root = root;
        } else {
          if (!recoveryMode) {
            throw new XRefParseException();
          }
          throw new FormatError('Invalid root reference');
        }
      },
  
      processXRefTable: function XRef_processXRefTable(parser) {
        if (!('tableState' in this)) {
          // Stores state of the table as we process it so we can resume
          // from middle of table in case of missing data error
          this.tableState = {
            entryNum: 0,
            streamPos: parser.lexer.stream.pos,
            parserBuf1: parser.buf1,
            parserBuf2: parser.buf2,
          };
        }
  
        var obj = this.readXRefTable(parser);
  
        // Sanity check
        if (!isCmd(obj, 'trailer')) {
          throw new FormatError(
            'Invalid XRef table: could not find trailer dictionary');
        }
        // Read trailer dictionary, e.g.
        // trailer
        //    << /Size 22
        //      /Root 20R
        //      /Info 10R
        //      /ID [ <81b14aafa313db63dbd6f981e49f94f4> ]
        //    >>
        // The parser goes through the entire stream << ... >> and provides
        // a getter interface for the key-value table
        var dict = parser.getObj();
  
        // The pdflib PDF generator can generate a nested trailer dictionary
        if (!isDict(dict) && dict.dict) {
          dict = dict.dict;
        }
        if (!isDict(dict)) {
          throw new FormatError(
            'Invalid XRef table: could not parse trailer dictionary');
        }
        delete this.tableState;
  
        return dict;
      },
  
      readXRefTable: function XRef_readXRefTable(parser) {
        // Example of cross-reference table:
        // xref
        // 0 1                    <-- subsection header (first obj #, obj count)
        // 0000000000 65535 f     <-- actual object (offset, generation #, f/n)
        // 23 2                   <-- subsection header ... and so on ...
        // 0000025518 00002 n
        // 0000025635 00000 n
        // trailer
        // ...
  
        var stream = parser.lexer.stream;
        var tableState = this.tableState;
        stream.pos = tableState.streamPos;
        parser.buf1 = tableState.parserBuf1;
        parser.buf2 = tableState.parserBuf2;
  
        // Outer loop is over subsection headers
        var obj;
  
        while (true) {
          if (!('firstEntryNum' in tableState) || !('entryCount' in tableState)) {
            if (isCmd(obj = parser.getObj(), 'trailer')) {
              break;
            }
            tableState.firstEntryNum = obj;
            tableState.entryCount = parser.getObj();
          }
  
          var first = tableState.firstEntryNum;
          var count = tableState.entryCount;
          if (!Number.isInteger(first) || !Number.isInteger(count)) {
            throw new FormatError(
              'Invalid XRef table: wrong types in subsection header');
          }
          // Inner loop is over objects themselves
          for (var i = tableState.entryNum; i < count; i++) {
            tableState.streamPos = stream.pos;
            tableState.entryNum = i;
            tableState.parserBuf1 = parser.buf1;
            tableState.parserBuf2 = parser.buf2;
  
            var entry = {};
            entry.offset = parser.getObj();
            entry.gen = parser.getObj();
            var type = parser.getObj();
  
            if (isCmd(type, 'f')) {
              entry.free = true;
            } else if (isCmd(type, 'n')) {
              entry.uncompressed = true;
            }
  
            // Validate entry obj
            if (!Number.isInteger(entry.offset) || !Number.isInteger(entry.gen) ||
                !(entry.free || entry.uncompressed)) {
              throw new FormatError(
                `Invalid entry in XRef subsection: ${first}, ${count}`);
            }
  
            // The first xref table entry, i.e. obj 0, should be free. Attempting
            // to adjust an incorrect first obj # (fixes issue 3248 and 7229).
            if (i === 0 && entry.free && first === 1) {
              first = 0;
            }
  
            if (!this.entries[i + first]) {
              this.entries[i + first] = entry;
            }
          }
  
          tableState.entryNum = 0;
          tableState.streamPos = stream.pos;
          tableState.parserBuf1 = parser.buf1;
          tableState.parserBuf2 = parser.buf2;
          delete tableState.firstEntryNum;
          delete tableState.entryCount;
        }
  
        // Sanity check: as per spec, first object must be free
        if (this.entries[0] && !this.entries[0].free) {
          throw new FormatError(
            'Invalid XRef table: unexpected first object');
        }
        return obj;
      },
  
      processXRefStream: function XRef_processXRefStream(stream) {
        if (!('streamState' in this)) {
          // Stores state of the stream as we process it so we can resume
          // from middle of stream in case of missing data error
          var streamParameters = stream.dict;
          var byteWidths = streamParameters.get('W');
          var range = streamParameters.get('Index');
          if (!range) {
            range = [0, streamParameters.get('Size')];
          }
  
          this.streamState = {
            entryRanges: range,
            byteWidths,
            entryNum: 0,
            streamPos: stream.pos,
          };
        }
        this.readXRefStream(stream);
        delete this.streamState;
  
        return stream.dict;
      },
  
      readXRefStream: function XRef_readXRefStream(stream) {
        var i, j;
        var streamState = this.streamState;
        stream.pos = streamState.streamPos;
  
        var byteWidths = streamState.byteWidths;
        var typeFieldWidth = byteWidths[0];
        var offsetFieldWidth = byteWidths[1];
        var generationFieldWidth = byteWidths[2];
  
        var entryRanges = streamState.entryRanges;
        while (entryRanges.length > 0) {
          var first = entryRanges[0];
          var n = entryRanges[1];
  
          if (!Number.isInteger(first) || !Number.isInteger(n)) {
            throw new FormatError(
              `Invalid XRef range fields: ${first}, ${n}`);
          }
          if (!Number.isInteger(typeFieldWidth) ||
              !Number.isInteger(offsetFieldWidth) ||
              !Number.isInteger(generationFieldWidth)) {
            throw new FormatError(
              `Invalid XRef entry fields length: ${first}, ${n}`);
          }
          for (i = streamState.entryNum; i < n; ++i) {
            streamState.entryNum = i;
            streamState.streamPos = stream.pos;
  
            var type = 0, offset = 0, generation = 0;
            for (j = 0; j < typeFieldWidth; ++j) {
              type = (type << 8) | stream.getByte();
            }
            // if type field is absent, its default value is 1
            if (typeFieldWidth === 0) {
              type = 1;
            }
            for (j = 0; j < offsetFieldWidth; ++j) {
              offset = (offset << 8) | stream.getByte();
            }
            for (j = 0; j < generationFieldWidth; ++j) {
              generation = (generation << 8) | stream.getByte();
            }
            var entry = {};
            entry.offset = offset;
            entry.gen = generation;
            switch (type) {
              case 0:
                entry.free = true;
                break;
              case 1:
                entry.uncompressed = true;
                break;
              case 2:
                break;
              default:
                throw new FormatError(`Invalid XRef entry type: ${type}`);
            }
            if (!this.entries[first + i]) {
              this.entries[first + i] = entry;
            }
          }
  
          streamState.entryNum = 0;
          streamState.streamPos = stream.pos;
          entryRanges.splice(0, 2);
        }
      },
  
      indexObjects: function XRef_indexObjects() {
        // Simple scan through the PDF content to find objects,
        // trailers and XRef streams.
        var TAB = 0x9, LF = 0xA, CR = 0xD, SPACE = 0x20;
        var PERCENT = 0x25, LT = 0x3C;
  
        function readToken(data, offset) {
          var token = '', ch = data[offset];
          while (ch !== LF && ch !== CR && ch !== LT) {
            if (++offset >= data.length) {
              break;
            }
            token += String.fromCharCode(ch);
            ch = data[offset];
          }
          return token;
        }
        function skipUntil(data, offset, what) {
          var length = what.length, dataLength = data.length;
          var skipped = 0;
          // finding byte sequence
          while (offset < dataLength) {
            var i = 0;
            while (i < length && data[offset + i] === what[i]) {
              ++i;
            }
            if (i >= length) {
              break; // sequence found
            }
            offset++;
            skipped++;
          }
          return skipped;
        }
        var objRegExp = /^(\d+)\s+(\d+)\s+obj\b/;
        const endobjRegExp = /\bendobj[\b\s]$/;
        const nestedObjRegExp = /\s+(\d+\s+\d+\s+obj[\b\s])$/;
        const CHECK_CONTENT_LENGTH = 25;
  
        var trailerBytes = new Uint8Array([116, 114, 97, 105, 108, 101, 114]);
        var startxrefBytes = new Uint8Array([115, 116, 97, 114, 116, 120, 114,
                                            101, 102]);
        const objBytes = new Uint8Array([111, 98, 106]);
        var xrefBytes = new Uint8Array([47, 88, 82, 101, 102]);
  
        // Clear out any existing entries, since they may be bogus.
        this.entries.length = 0;
  
        var stream = this.stream;
        stream.pos = 0;
        var buffer = stream.getBytes();
        var position = stream.start, length = buffer.length;
        var trailers = [], xrefStms = [];
        while (position < length) {
          var ch = buffer[position];
          if (ch === TAB || ch === LF || ch === CR || ch === SPACE) {
            ++position;
            continue;
          }
          if (ch === PERCENT) { // %-comment
            do {
              ++position;
              if (position >= length) {
                break;
              }
              ch = buffer[position];
            } while (ch !== LF && ch !== CR);
            continue;
          }
          var token = readToken(buffer, position);
          var m;
          if (token.indexOf('xref') === 0 &&
              (token.length === 4 || /\s/.test(token[4]))) {
            position += skipUntil(buffer, position, trailerBytes);
            trailers.push(position);
            position += skipUntil(buffer, position, startxrefBytes);
          } else if ((m = objRegExp.exec(token))) {
            if (typeof this.entries[m[1]] === 'undefined') {
              this.entries[m[1]] = {
                offset: position - stream.start,
                gen: m[2] | 0,
                uncompressed: true,
              };
            }
            let contentLength, startPos = position + token.length;
  
            // Find the next "obj" string, rather than "endobj", to ensure that
            // we won't skip over a new 'obj' operator in corrupt files where
            // 'endobj' operators are missing (fixes issue9105_reduced.pdf).
            while (startPos < buffer.length) {
              let endPos = startPos + skipUntil(buffer, startPos, objBytes) + 4;
              contentLength = endPos - position;
  
              let checkPos = Math.max(endPos - CHECK_CONTENT_LENGTH, startPos);
              let tokenStr = bytesToString(buffer.subarray(checkPos, endPos));
  
              // Check if the current object ends with an 'endobj' operator.
              if (endobjRegExp.test(tokenStr)) {
                break;
              } else {
                // Check if an "obj" occurrence is actually a new object,
                // i.e. the current object is missing the 'endobj' operator.
                let objToken = nestedObjRegExp.exec(tokenStr);
  
                if (objToken && objToken[1]) {
                  warn('indexObjects: Found new "obj" inside of another "obj", ' +
                       'caused by missing "endobj" -- trying to recover.');
                  contentLength -= objToken[1].length;
                  break;
                }
              }
              startPos = endPos;
            }
            let content = buffer.subarray(position, position + contentLength);
  
            // checking XRef stream suspect
            // (it shall have '/XRef' and next char is not a letter)
            var xrefTagOffset = skipUntil(content, 0, xrefBytes);
            if (xrefTagOffset < contentLength &&
                content[xrefTagOffset + 5] < 64) {
              xrefStms.push(position - stream.start);
              this.xrefstms[position - stream.start] = 1; // Avoid recursion
            }
  
            position += contentLength;
          } else if (token.indexOf('trailer') === 0 &&
                     (token.length === 7 || /\s/.test(token[7]))) {
            trailers.push(position);
            position += skipUntil(buffer, position, startxrefBytes);
          } else {
            position += token.length + 1;
          }
        }
        // reading XRef streams
        var i, ii;
        for (i = 0, ii = xrefStms.length; i < ii; ++i) {
          this.startXRefQueue.push(xrefStms[i]);
          this.readXRef(/* recoveryMode */ true);
        }
        // finding main trailer
        let trailerDict;
        for (i = 0, ii = trailers.length; i < ii; ++i) {
          stream.pos = trailers[i];
          var parser = new Parser(new Lexer(stream), /* allowStreams = */ true,
                                  /* xref = */ this, /* recoveryMode = */ true);
          var obj = parser.getObj();
          if (!isCmd(obj, 'trailer')) {
            continue;
          }
          // read the trailer dictionary
          let dict = parser.getObj();
          if (!isDict(dict)) {
            continue;
          }
          // Do some basic validation of the trailer/root dictionary candidate.
          let rootDict;
          try {
            rootDict = dict.get('Root');
          } catch (ex) {
            if (ex instanceof MissingDataException) {
              throw ex;
            }
            continue;
          }
          if (!isDict(rootDict) || !rootDict.has('Pages')) {
            continue;
          }
          // taking the first one with 'ID'
          if (dict.has('ID')) {
            return dict;
          }
          // The current dictionary is a candidate, but continue searching.
          trailerDict = dict;
        }
        // No trailer with 'ID', taking last one (if exists).
        if (trailerDict) {
          return trailerDict;
        }
        // nothing helps
        throw new InvalidPDFException('Invalid PDF structure');
      },
  
      readXRef: function XRef_readXRef(recoveryMode) {
        var stream = this.stream;
        // Keep track of already parsed XRef tables, to prevent an infinite loop
        // when parsing corrupt PDF files where e.g. the /Prev entries create a
        // circular dependency between tables (fixes bug1393476.pdf).
        let startXRefParsedCache = Object.create(null);
  
        try {
          while (this.startXRefQueue.length) {
            var startXRef = this.startXRefQueue[0];
  
            if (startXRefParsedCache[startXRef]) {
              warn('readXRef - skipping XRef table since it was already parsed.');
              this.startXRefQueue.shift();
              continue;
            }
            startXRefParsedCache[startXRef] = true;
  
            stream.pos = startXRef + stream.start;
  
            var parser = new Parser(new Lexer(stream), true, this);
            var obj = parser.getObj();
            var dict;
  
            // Get dictionary
            if (isCmd(obj, 'xref')) {
              // Parse end-of-file XRef
              dict = this.processXRefTable(parser);
              if (!this.topDict) {
                this.topDict = dict;
              }
  
              // Recursively get other XRefs 'XRefStm', if any
              obj = dict.get('XRefStm');
              if (Number.isInteger(obj)) {
                var pos = obj;
                // ignore previously loaded xref streams
                // (possible infinite recursion)
                if (!(pos in this.xrefstms)) {
                  this.xrefstms[pos] = 1;
                  this.startXRefQueue.push(pos);
                }
              }
            } else if (Number.isInteger(obj)) {
              // Parse in-stream XRef
              if (!Number.isInteger(parser.getObj()) ||
                  !isCmd(parser.getObj(), 'obj') ||
                  !isStream(obj = parser.getObj())) {
                throw new FormatError('Invalid XRef stream');
              }
              dict = this.processXRefStream(obj);
              if (!this.topDict) {
                this.topDict = dict;
              }
              if (!dict) {
                throw new FormatError('Failed to read XRef stream');
              }
            } else {
              throw new FormatError('Invalid XRef stream header');
            }
  
            // Recursively get previous dictionary, if any
            obj = dict.get('Prev');
            if (Number.isInteger(obj)) {
              this.startXRefQueue.push(obj);
            } else if (isRef(obj)) {
              // The spec says Prev must not be a reference, i.e. "/Prev NNN"
              // This is a fallback for non-compliant PDFs, i.e. "/Prev NNN 0 R"
              this.startXRefQueue.push(obj.num);
            }
  
            this.startXRefQueue.shift();
          }
  
          return this.topDict;
        } catch (e) {
          if (e instanceof MissingDataException) {
            throw e;
          }
          info('(while reading XRef): ' + e);
        }
  
        if (recoveryMode) {
          return;
        }
        throw new XRefParseException();
      },
  
      getEntry: function XRef_getEntry(i) {
        var xrefEntry = this.entries[i];
        if (xrefEntry && !xrefEntry.free && xrefEntry.offset) {
          return xrefEntry;
        }
        return null;
      },
  
      fetchIfRef: function XRef_fetchIfRef(obj, suppressEncryption) {
        if (!isRef(obj)) {
          return obj;
        }
        return this.fetch(obj, suppressEncryption);
      },
  
      fetch: function XRef_fetch(ref, suppressEncryption) {
        if (!isRef(ref)) {
          throw new Error('ref object is not a reference');
        }
        var num = ref.num;
        if (num in this.cache) {
          var cacheEntry = this.cache[num];
          // In documents with Object Streams, it's possible that cached `Dict`s
          // have not been assigned an `objId` yet (see e.g. issue3115r.pdf).
          if (cacheEntry instanceof Dict && !cacheEntry.objId) {
            cacheEntry.objId = ref.toString();
          }
          return cacheEntry;
        }
  
        var xrefEntry = this.getEntry(num);
  
        // the referenced entry can be free
        if (xrefEntry === null) {
          return (this.cache[num] = null);
        }
  
        if (xrefEntry.uncompressed) {
          xrefEntry = this.fetchUncompressed(ref, xrefEntry, suppressEncryption);
        } else {
          xrefEntry = this.fetchCompressed(ref, xrefEntry, suppressEncryption);
        }
        if (isDict(xrefEntry)) {
          xrefEntry.objId = ref.toString();
        } else if (isStream(xrefEntry)) {
          xrefEntry.dict.objId = ref.toString();
        }
        return xrefEntry;
      },
  
      fetchUncompressed(ref, xrefEntry, suppressEncryption = false) {
        var gen = ref.gen;
        var num = ref.num;
        if (xrefEntry.gen !== gen) {
          throw new XRefEntryException(`Inconsistent generation in XRef: ${ref}`);
        }
        var stream = this.stream.makeSubStream(xrefEntry.offset +
                                               this.stream.start);
        var parser = new Parser(new Lexer(stream), true, this);
        var obj1 = parser.getObj();
        var obj2 = parser.getObj();
        var obj3 = parser.getObj();
  
        if (!Number.isInteger(obj1)) {
          obj1 = parseInt(obj1, 10);
        }
        if (!Number.isInteger(obj2)) {
          obj2 = parseInt(obj2, 10);
        }
        if (obj1 !== num || obj2 !== gen || !isCmd(obj3)) {
          throw new XRefEntryException(`Bad (uncompressed) XRef entry: ${ref}`);
        }
        if (obj3.cmd !== 'obj') {
          // some bad PDFs use "obj1234" and really mean 1234
          if (obj3.cmd.indexOf('obj') === 0) {
            num = parseInt(obj3.cmd.substring(3), 10);
            if (!Number.isNaN(num)) {
              return num;
            }
          }
          throw new XRefEntryException(`Bad (uncompressed) XRef entry: ${ref}`);
        }
        if (this.encrypt && !suppressEncryption) {
          xrefEntry = parser.getObj(this.encrypt.createCipherTransform(num, gen));
        } else {
          xrefEntry = parser.getObj();
        }
        if (!isStream(xrefEntry)) {
          this.cache[num] = xrefEntry;
        }
        return xrefEntry;
      },
  
      fetchCompressed(ref, xrefEntry, suppressEncryption = false) {
        var tableOffset = xrefEntry.offset;
        var stream = this.fetch(new Ref(tableOffset, 0));
        if (!isStream(stream)) {
          throw new FormatError('bad ObjStm stream');
        }
        var first = stream.dict.get('First');
        var n = stream.dict.get('N');
        if (!Number.isInteger(first) || !Number.isInteger(n)) {
          throw new FormatError(
            'invalid first and n parameters for ObjStm stream');
        }
        var parser = new Parser(new Lexer(stream), false, this);
        parser.allowStreams = true;
        var i, entries = [], num, nums = [];
        // read the object numbers to populate cache
        for (i = 0; i < n; ++i) {
          num = parser.getObj();
          if (!Number.isInteger(num)) {
            throw new FormatError(
              `invalid object number in the ObjStm stream: ${num}`);
          }
          nums.push(num);
          var offset = parser.getObj();
          if (!Number.isInteger(offset)) {
            throw new FormatError(
              `invalid object offset in the ObjStm stream: ${offset}`);
          }
        }
        // read stream objects for cache
        for (i = 0; i < n; ++i) {
          entries.push(parser.getObj());
          // The ObjStm should not contain 'endobj'. If it's present, skip over it
          // to support corrupt PDFs (fixes issue 5241, bug 898610, bug 1037816).
          if (isCmd(parser.buf1, 'endobj')) {
            parser.shift();
          }
          num = nums[i];
          var entry = this.entries[num];
          if (entry && entry.offset === tableOffset && entry.gen === i) {
            this.cache[num] = entries[i];
          }
        }
        xrefEntry = entries[xrefEntry.gen];
        if (xrefEntry === undefined) {
          throw new XRefEntryException(`Bad (compressed) XRef entry: ${ref}`);
        }
        return xrefEntry;
      },
  
      async fetchIfRefAsync(obj, suppressEncryption) {
        if (!isRef(obj)) {
          return obj;
        }
        return this.fetchAsync(obj, suppressEncryption);
      },
  
      async fetchAsync(ref, suppressEncryption) {
        try {
          return this.fetch(ref, suppressEncryption);
        } catch (ex) {
          if (!(ex instanceof MissingDataException)) {
            throw ex;
          }
          await this.pdfManager.requestRange(ex.begin, ex.end);
          return this.fetchAsync(ref, suppressEncryption);
        }
      },
  
      getCatalogObj: function XRef_getCatalogObj() {
        return this.root;
      },
    };
  
    return XRef;
  })();
  
  /**
   * A NameTree/NumberTree is like a Dict but has some advantageous properties,
   * see the specification (7.9.6 and 7.9.7) for additional details.
   * TODO: implement all the Dict functions and make this more efficient.
   */
  class NameOrNumberTree {
    constructor(root, xref, type) {
      if (this.constructor === NameOrNumberTree) {
        unreachable('Cannot initialize NameOrNumberTree.');
      }
      this.root = root;
      this.xref = xref;
      this._type = type;
    }
  
    getAll() {
      const dict = Object.create(null);
      if (!this.root) {
        return dict;
      }
      const xref = this.xref;
      // Reading Name/Number tree.
      const processed = new RefSet();
      processed.put(this.root);
      const queue = [this.root];
      while (queue.length > 0) {
        const obj = xref.fetchIfRef(queue.shift());
        if (!isDict(obj)) {
          continue;
        }
        if (obj.has('Kids')) {
          const kids = obj.get('Kids');
          for (let i = 0, ii = kids.length; i < ii; i++) {
            const kid = kids[i];
            if (processed.has(kid)) {
              throw new FormatError(`Duplicate entry in "${this._type}" tree.`);
            }
            queue.push(kid);
            processed.put(kid);
          }
          continue;
        }
        const entries = obj.get(this._type);
        if (Array.isArray(entries)) {
          for (let i = 0, ii = entries.length; i < ii; i += 2) {
            dict[xref.fetchIfRef(entries[i])] = xref.fetchIfRef(entries[i + 1]);
          }
        }
      }
      return dict;
    }
  
    get(key) {
      if (!this.root) {
        return null;
      }
      const xref = this.xref;
      let kidsOrEntries = xref.fetchIfRef(this.root);
      let loopCount = 0;
      const MAX_LEVELS = 10;
  
      // Perform a binary search to quickly find the entry that
      // contains the key we are looking for.
      while (kidsOrEntries.has('Kids')) {
        if (++loopCount > MAX_LEVELS) {
          warn(`Search depth limit reached for "${this._type}" tree.`);
          return null;
        }
  
        const kids = kidsOrEntries.get('Kids');
        if (!Array.isArray(kids)) {
          return null;
        }
  
        let l = 0, r = kids.length - 1;
        while (l <= r) {
          const m = (l + r) >> 1;
          const kid = xref.fetchIfRef(kids[m]);
          const limits = kid.get('Limits');
  
          if (key < xref.fetchIfRef(limits[0])) {
            r = m - 1;
          } else if (key > xref.fetchIfRef(limits[1])) {
            l = m + 1;
          } else {
            kidsOrEntries = xref.fetchIfRef(kids[m]);
            break;
          }
        }
        if (l > r) {
          return null;
        }
      }
  
      // If we get here, then we have found the right entry. Now go through the
      // entries in the dictionary until we find the key we're looking for.
      const entries = kidsOrEntries.get(this._type);
      if (Array.isArray(entries)) {
        // Perform a binary search to reduce the lookup time.
        let l = 0, r = entries.length - 2;
        while (l <= r) {
          // Check only even indices (0, 2, 4, ...) because the
          // odd indices contain the actual data.
          const tmp = (l + r) >> 1, m = tmp + (tmp & 1);
          const currentKey = xref.fetchIfRef(entries[m]);
          if (key < currentKey) {
            r = m - 2;
          } else if (key > currentKey) {
            l = m + 2;
          } else {
            return xref.fetchIfRef(entries[m + 1]);
          }
        }
  
        // Fallback to an exhaustive search, in an attempt to handle corrupt
        // PDF files where keys are not correctly ordered (fixes issue 10272).
        info(`Falling back to an exhaustive search, for key "${key}", ` +
             `in "${this._type}" tree.`);
        for (let m = 0, mm = entries.length; m < mm; m += 2) {
          const currentKey = xref.fetchIfRef(entries[m]);
          if (currentKey === key) {
            warn(`The "${key}" key was found at an incorrect, ` +
                 `i.e. out-of-order, position in "${this._type}" tree.`);
            return xref.fetchIfRef(entries[m + 1]);
          }
        }
      }
      return null;
    }
  }
  
  class NameTree extends NameOrNumberTree {
    constructor(root, xref) {
      super(root, xref, 'Names');
    }
  }
  
  class NumberTree extends NameOrNumberTree {
    constructor(root, xref) {
      super(root, xref, 'Nums');
    }
  }
  
  /**
   * "A PDF file can refer to the contents of another file by using a File
   * Specification (PDF 1.1)", see the spec (7.11) for more details.
   * NOTE: Only embedded files are supported (as part of the attachments support)
   * TODO: support the 'URL' file system (with caching if !/V), portable
   * collections attributes and related files (/RF)
   */
  var FileSpec = (function FileSpecClosure() {
    function FileSpec(root, xref) {
      if (!root || !isDict(root)) {
        return;
      }
      this.xref = xref;
      this.root = root;
      if (root.has('FS')) {
        this.fs = root.get('FS');
      }
      this.description = root.has('Desc') ?
                           stringToPDFString(root.get('Desc')) :
                           '';
      if (root.has('RF')) {
        warn('Related file specifications are not supported');
      }
      this.contentAvailable = true;
      if (!root.has('EF')) {
        this.contentAvailable = false;
        warn('Non-embedded file specifications are not supported');
      }
    }
  
    function pickPlatformItem(dict) {
      // Look for the filename in this order:
      // UF, F, Unix, Mac, DOS
      if (dict.has('UF')) {
        return dict.get('UF');
      } else if (dict.has('F')) {
        return dict.get('F');
      } else if (dict.has('Unix')) {
        return dict.get('Unix');
      } else if (dict.has('Mac')) {
        return dict.get('Mac');
      } else if (dict.has('DOS')) {
        return dict.get('DOS');
      }
      return null;
    }
  
    FileSpec.prototype = {
      get filename() {
        if (!this._filename && this.root) {
          var filename = pickPlatformItem(this.root) || 'unnamed';
          this._filename = stringToPDFString(filename).
            replace(/\\\\/g, '\\').
            replace(/\\\//g, '/').
            replace(/\\/g, '/');
        }
        return this._filename;
      },
      get content() {
        if (!this.contentAvailable) {
          return null;
        }
        if (!this.contentRef && this.root) {
          this.contentRef = pickPlatformItem(this.root.get('EF'));
        }
        var content = null;
        if (this.contentRef) {
          var xref = this.xref;
          var fileObj = xref.fetchIfRef(this.contentRef);
          if (fileObj && isStream(fileObj)) {
            content = fileObj.getBytes();
          } else {
            warn('Embedded file specification points to non-existing/invalid ' +
              'content');
          }
        } else {
          warn('Embedded file specification does not have a content');
        }
        return content;
      },
      get serializable() {
        return {
          filename: this.filename,
          content: this.content,
        };
      },
    };
    return FileSpec;
  })();
  
  /**
   * A helper for loading missing data in `Dict` graphs. It traverses the graph
   * depth first and queues up any objects that have missing data. Once it has
   * has traversed as many objects that are available it attempts to bundle the
   * missing data requests and then resume from the nodes that weren't ready.
   *
   * NOTE: It provides protection from circular references by keeping track of
   * loaded references. However, you must be careful not to load any graphs
   * that have references to the catalog or other pages since that will cause the
   * entire PDF document object graph to be traversed.
   */
  let ObjectLoader = (function() {
    function mayHaveChildren(value) {
      return isRef(value) || isDict(value) || Array.isArray(value) ||
             isStream(value);
    }
  
    function addChildren(node, nodesToVisit) {
      if (isDict(node) || isStream(node)) {
        let dict = isDict(node) ? node : node.dict;
        let dictKeys = dict.getKeys();
        for (let i = 0, ii = dictKeys.length; i < ii; i++) {
          let rawValue = dict.getRaw(dictKeys[i]);
          if (mayHaveChildren(rawValue)) {
            nodesToVisit.push(rawValue);
          }
        }
      } else if (Array.isArray(node)) {
        for (let i = 0, ii = node.length; i < ii; i++) {
          let value = node[i];
          if (mayHaveChildren(value)) {
            nodesToVisit.push(value);
          }
        }
      }
    }
  
    function ObjectLoader(dict, keys, xref) {
      this.dict = dict;
      this.keys = keys;
      this.xref = xref;
      this.refSet = null;
      this.capability = null;
    }
  
    ObjectLoader.prototype = {
      load() {
        this.capability = createPromiseCapability();
        // Don't walk the graph if all the data is already loaded.
        if (!(this.xref.stream instanceof ChunkedStream) ||
            this.xref.stream.getMissingChunks().length === 0) {
          this.capability.resolve();
          return this.capability.promise;
        }
  
        let { keys, dict, } = this;
        this.refSet = new RefSet();
        // Setup the initial nodes to visit.
        let nodesToVisit = [];
        for (let i = 0, ii = keys.length; i < ii; i++) {
          let rawValue = dict.getRaw(keys[i]);
          // Skip nodes that are guaranteed to be empty.
          if (rawValue !== undefined) {
            nodesToVisit.push(rawValue);
          }
        }
  
        this._walk(nodesToVisit);
        return this.capability.promise;
      },
  
      _walk(nodesToVisit) {
        let nodesToRevisit = [];
        let pendingRequests = [];
        // DFS walk of the object graph.
        while (nodesToVisit.length) {
          let currentNode = nodesToVisit.pop();
  
          // Only references or chunked streams can cause missing data exceptions.
          if (isRef(currentNode)) {
            // Skip nodes that have already been visited.
            if (this.refSet.has(currentNode)) {
              continue;
            }
            try {
              this.refSet.put(currentNode);
              currentNode = this.xref.fetch(currentNode);
            } catch (ex) {
              if (!(ex instanceof MissingDataException)) {
                throw ex;
              }
              nodesToRevisit.push(currentNode);
              pendingRequests.push({ begin: ex.begin, end: ex.end, });
            }
          }
          if (currentNode && currentNode.getBaseStreams) {
            let baseStreams = currentNode.getBaseStreams();
            let foundMissingData = false;
            for (let i = 0, ii = baseStreams.length; i < ii; i++) {
              let stream = baseStreams[i];
              if (stream.getMissingChunks && stream.getMissingChunks().length) {
                foundMissingData = true;
                pendingRequests.push({ begin: stream.start, end: stream.end, });
              }
            }
            if (foundMissingData) {
              nodesToRevisit.push(currentNode);
            }
          }
  
          addChildren(currentNode, nodesToVisit);
        }
  
        if (pendingRequests.length) {
          this.xref.stream.manager.requestRanges(pendingRequests).then(() => {
            for (let i = 0, ii = nodesToRevisit.length; i < ii; i++) {
              let node = nodesToRevisit[i];
              // Remove any reference nodes from the current `RefSet` so they
              // aren't skipped when we revist them.
              if (isRef(node)) {
                this.refSet.remove(node);
              }
            }
            this._walk(nodesToRevisit);
          }, this.capability.reject);
          return;
        }
        // Everything is loaded.
        this.refSet = null;
        this.capability.resolve();
      },
    };
  
    return ObjectLoader;
  })();
  
  export {
    Catalog,
    ObjectLoader,
    XRef,
    FileSpec,
  };
  