CocoRoboDesktop/pdf.js/src/core/document.js

/* 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 { AnnotationFactory, PopupAnnotation } from "./annotation.js";
import {
  assert,
  FormatError,
  info,
  InvalidPDFException,
  isArrayEqual,
  PageActionEventType,
  RenderingIntentFlag,
  shadow,
  stringToBytes,
  stringToPDFString,
  stringToUTF8String,
  unreachable,
  UNSUPPORTED_FEATURES,
  Util,
  warn,
} from "../shared/util.js";
import {
  collectActions,
  getInheritableProperty,
  getNewAnnotationsMap,
  isWhiteSpace,
  MissingDataException,
  PDF_VERSION_REGEXP,
  validateCSSFont,
  XRefEntryException,
  XRefParseException,
} from "./core_utils.js";
import { Dict, isName, Name, Ref } from "./primitives.js";
import { getXfaFontDict, getXfaFontName } from "./xfa_fonts.js";
import { BaseStream } from "./base_stream.js";
import { calculateMD5 } from "./crypto.js";
import { Catalog } from "./catalog.js";
import { clearGlobalCaches } from "./cleanup_helper.js";
import { DatasetReader } from "./dataset_reader.js";
import { Linearization } from "./parser.js";
import { NullStream } from "./stream.js";
import { ObjectLoader } from "./object_loader.js";
import { OperatorList } from "./operator_list.js";
import { PartialEvaluator } from "./evaluator.js";
import { StreamsSequenceStream } from "./decode_stream.js";
import { StructTreePage } from "./struct_tree.js";
import { writeObject } from "./writer.js";
import { XFAFactory } from "./xfa/factory.js";
import { XRef } from "./xref.js";

const DEFAULT_USER_UNIT = 1.0;
const LETTER_SIZE_MEDIABOX = [0, 0, 612, 792];

class Page {
  constructor({
    pdfManager,
    xref,
    pageIndex,
    pageDict,
    ref,
    globalIdFactory,
    fontCache,
    builtInCMapCache,
    standardFontDataCache,
    globalImageCache,
    nonBlendModesSet,
    xfaFactory,
  }) {
    this.pdfManager = pdfManager;
    this.pageIndex = pageIndex;
    this.pageDict = pageDict;
    this.xref = xref;
    this.ref = ref;
    this.fontCache = fontCache;
    this.builtInCMapCache = builtInCMapCache;
    this.standardFontDataCache = standardFontDataCache;
    this.globalImageCache = globalImageCache;
    this.nonBlendModesSet = nonBlendModesSet;
    this.evaluatorOptions = pdfManager.evaluatorOptions;
    this.resourcesPromise = null;
    this.xfaFactory = xfaFactory;

    const idCounters = {
      obj: 0,
    };
    this._localIdFactory = class extends globalIdFactory {
      static createObjId() {
        return `p${pageIndex}_${++idCounters.obj}`;
      }

      static getPageObjId() {
        return `page${ref.toString()}`;
      }
    };
  }

  /**
   * @private
   */
  _getInheritableProperty(key, getArray = false) {
    const value = getInheritableProperty({
      dict: this.pageDict,
      key,
      getArray,
      stopWhenFound: false,
    });
    if (!Array.isArray(value)) {
      return value;
    }
    if (value.length === 1 || !(value[0] instanceof Dict)) {
      return value[0];
    }
    return Dict.merge({ xref: this.xref, dictArray: value });
  }

  get content() {
    return this.pageDict.getArray("Contents");
  }

  get resources() {
    // For robustness: The spec states that a \Resources entry has to be
    // present, but can be empty. Some documents still omit it; in this case
    // we return an empty dictionary.
    const resources = this._getInheritableProperty("Resources");

    return shadow(
      this,
      "resources",
      resources instanceof Dict ? resources : Dict.empty
    );
  }

  _getBoundingBox(name) {
    if (this.xfaData) {
      return this.xfaData.bbox;
    }
    let box = this._getInheritableProperty(name, /* getArray = */ true);

    if (Array.isArray(box) && box.length === 4) {
      box = Util.normalizeRect(box);
      if (box[2] - box[0] > 0 && box[3] - box[1] > 0) {
        return box;
      }
      warn(`Empty, or invalid, /${name} entry.`);
    }
    return null;
  }

  get mediaBox() {
    // Reset invalid media box to letter size.
    return shadow(
      this,
      "mediaBox",
      this._getBoundingBox("MediaBox") || LETTER_SIZE_MEDIABOX
    );
  }

  get cropBox() {
    // Reset invalid crop box to media box.
    return shadow(
      this,
      "cropBox",
      this._getBoundingBox("CropBox") || this.mediaBox
    );
  }

  get userUnit() {
    let obj = this.pageDict.get("UserUnit");
    if (typeof obj !== "number" || obj <= 0) {
      obj = DEFAULT_USER_UNIT;
    }
    return shadow(this, "userUnit", obj);
  }

  get view() {
    // From the spec, 6th ed., p.963:
    // "The crop, bleed, trim, and art boxes should not ordinarily
    // extend beyond the boundaries of the media box. If they do, they are
    // effectively reduced to their intersection with the media box."
    const { cropBox, mediaBox } = this;

    if (cropBox !== mediaBox && !isArrayEqual(cropBox, mediaBox)) {
      const box = Util.intersect(cropBox, mediaBox);
      if (box && box[2] - box[0] > 0 && box[3] - box[1] > 0) {
        return shadow(this, "view", box);
      }
      warn("Empty /CropBox and /MediaBox intersection.");
    }
    return shadow(this, "view", mediaBox);
  }

  get rotate() {
    let rotate = this._getInheritableProperty("Rotate") || 0;

    // Normalize rotation so it's a multiple of 90 and between 0 and 270.
    if (rotate % 90 !== 0) {
      rotate = 0;
    } else if (rotate >= 360) {
      rotate %= 360;
    } else if (rotate < 0) {
      // The spec doesn't cover negatives. Assume it's counterclockwise
      // rotation. The following is the other implementation of modulo.
      rotate = ((rotate % 360) + 360) % 360;
    }
    return shadow(this, "rotate", rotate);
  }

  /**
   * @private
   */
  _onSubStreamError(handler, reason, objId) {
    if (this.evaluatorOptions.ignoreErrors) {
      // Error(s) when reading one of the /Contents sub-streams -- sending
      // unsupported feature notification and allow parsing to continue.
      handler.send("UnsupportedFeature", {
        featureId: UNSUPPORTED_FEATURES.errorContentSubStream,
      });
      warn(`getContentStream - ignoring sub-stream (${objId}): "${reason}".`);
      return;
    }
    throw reason;
  }

  /**
   * @returns {Promise<BaseStream>}
   */
  getContentStream(handler) {
    return this.pdfManager.ensure(this, "content").then(content => {
      if (content instanceof BaseStream) {
        return content;
      }
      if (Array.isArray(content)) {
        return new StreamsSequenceStream(
          content,
          this._onSubStreamError.bind(this, handler)
        );
      }
      // Replace non-existent page content with empty content.
      return new NullStream();
    });
  }

  get xfaData() {
    return shadow(
      this,
      "xfaData",
      this.xfaFactory
        ? { bbox: this.xfaFactory.getBoundingBox(this.pageIndex) }
        : null
    );
  }

  async saveNewAnnotations(handler, task, annotations) {
    if (this.xfaFactory) {
      throw new Error("XFA: Cannot save new annotations.");
    }

    const partialEvaluator = new PartialEvaluator({
      xref: this.xref,
      handler,
      pageIndex: this.pageIndex,
      idFactory: this._localIdFactory,
      fontCache: this.fontCache,
      builtInCMapCache: this.builtInCMapCache,
      standardFontDataCache: this.standardFontDataCache,
      globalImageCache: this.globalImageCache,
      options: this.evaluatorOptions,
    });

    const pageDict = this.pageDict;
    const annotationsArray = this.annotations.slice();
    const newData = await AnnotationFactory.saveNewAnnotations(
      partialEvaluator,
      task,
      annotations
    );

    for (const { ref } of newData.annotations) {
      annotationsArray.push(ref);
    }

    const savedDict = pageDict.get("Annots");
    pageDict.set("Annots", annotationsArray);
    const buffer = [];

    let transform = null;
    if (this.xref.encrypt) {
      transform = this.xref.encrypt.createCipherTransform(
        this.ref.num,
        this.ref.gen
      );
    }

    writeObject(this.ref, pageDict, buffer, transform);
    if (savedDict) {
      pageDict.set("Annots", savedDict);
    }

    const objects = newData.dependencies;
    objects.push(
      { ref: this.ref, data: buffer.join("") },
      ...newData.annotations
    );

    return objects;
  }

  save(handler, task, annotationStorage) {
    const partialEvaluator = new PartialEvaluator({
      xref: this.xref,
      handler,
      pageIndex: this.pageIndex,
      idFactory: this._localIdFactory,
      fontCache: this.fontCache,
      builtInCMapCache: this.builtInCMapCache,
      standardFontDataCache: this.standardFontDataCache,
      globalImageCache: this.globalImageCache,
      options: this.evaluatorOptions,
    });

    // Fetch the page's annotations and save the content
    // in case of interactive form fields.
    return this._parsedAnnotations.then(function (annotations) {
      const newRefsPromises = [];
      for (const annotation of annotations) {
        if (!annotation.mustBePrinted(annotationStorage)) {
          continue;
        }
        newRefsPromises.push(
          annotation
            .save(partialEvaluator, task, annotationStorage)
            .catch(function (reason) {
              warn(
                "save - ignoring annotation data during " +
                  `"${task.name}" task: "${reason}".`
              );
              return null;
            })
        );
      }

      return Promise.all(newRefsPromises).then(function (newRefs) {
        return newRefs.filter(newRef => !!newRef);
      });
    });
  }

  loadResources(keys) {
    if (!this.resourcesPromise) {
      // TODO: add async `_getInheritableProperty` and remove this.
      this.resourcesPromise = this.pdfManager.ensure(this, "resources");
    }
    return this.resourcesPromise.then(() => {
      const objectLoader = new ObjectLoader(this.resources, keys, this.xref);
      return objectLoader.load();
    });
  }

  getOperatorList({
    handler,
    sink,
    task,
    intent,
    cacheKey,
    annotationStorage = null,
  }) {
    const contentStreamPromise = this.getContentStream(handler);
    const resourcesPromise = this.loadResources([
      "ColorSpace",
      "ExtGState",
      "Font",
      "Pattern",
      "Properties",
      "Shading",
      "XObject",
    ]);

    const partialEvaluator = new PartialEvaluator({
      xref: this.xref,
      handler,
      pageIndex: this.pageIndex,
      idFactory: this._localIdFactory,
      fontCache: this.fontCache,
      builtInCMapCache: this.builtInCMapCache,
      standardFontDataCache: this.standardFontDataCache,
      globalImageCache: this.globalImageCache,
      options: this.evaluatorOptions,
    });

    const newAnnotationsByPage = !this.xfaFactory
      ? getNewAnnotationsMap(annotationStorage)
      : null;

    let newAnnotationsPromise = Promise.resolve(null);
    if (newAnnotationsByPage) {
      const newAnnotations = newAnnotationsByPage.get(this.pageIndex);
      if (newAnnotations) {
        newAnnotationsPromise = AnnotationFactory.printNewAnnotations(
          partialEvaluator,
          task,
          newAnnotations
        );
      }
    }
    const dataPromises = Promise.all([contentStreamPromise, resourcesPromise]);
    const pageListPromise = dataPromises.then(([contentStream]) => {
      const opList = new OperatorList(intent, sink);

      handler.send("StartRenderPage", {
        transparency: partialEvaluator.hasBlendModes(
          this.resources,
          this.nonBlendModesSet
        ),
        pageIndex: this.pageIndex,
        cacheKey,
      });

      return partialEvaluator
        .getOperatorList({
          stream: contentStream,
          task,
          resources: this.resources,
          operatorList: opList,
        })
        .then(function () {
          return opList;
        });
    });

    // Fetch the page's annotations and add their operator lists to the
    // page's operator list to render them.
    return Promise.all([
      pageListPromise,
      this._parsedAnnotations,
      newAnnotationsPromise,
    ]).then(function ([pageOpList, annotations, newAnnotations]) {
      if (newAnnotations) {
        annotations = annotations.concat(newAnnotations);
      }
      if (
        annotations.length === 0 ||
        intent & RenderingIntentFlag.ANNOTATIONS_DISABLE
      ) {
        pageOpList.flush(/* lastChunk = */ true);
        return { length: pageOpList.totalLength };
      }
      const renderForms = !!(intent & RenderingIntentFlag.ANNOTATIONS_FORMS),
        intentAny = !!(intent & RenderingIntentFlag.ANY),
        intentDisplay = !!(intent & RenderingIntentFlag.DISPLAY),
        intentPrint = !!(intent & RenderingIntentFlag.PRINT);

      // Collect the operator list promises for the annotations. Each promise
      // is resolved with the complete operator list for a single annotation.
      const opListPromises = [];
      for (const annotation of annotations) {
        if (
          intentAny ||
          (intentDisplay && annotation.mustBeViewed(annotationStorage)) ||
          (intentPrint && annotation.mustBePrinted(annotationStorage))
        ) {
          opListPromises.push(
            annotation
              .getOperatorList(
                partialEvaluator,
                task,
                intent,
                renderForms,
                annotationStorage
              )
              .catch(function (reason) {
                warn(
                  "getOperatorList - ignoring annotation data during " +
                    `"${task.name}" task: "${reason}".`
                );
                return {
                  opList: null,
                  separateForm: false,
                  separateCanvas: false,
                };
              })
          );
        }
      }

      return Promise.all(opListPromises).then(function (opLists) {
        let form = false,
          canvas = false;

        for (const { opList, separateForm, separateCanvas } of opLists) {
          pageOpList.addOpList(opList);

          if (separateForm) {
            form = separateForm;
          }
          if (separateCanvas) {
            canvas = separateCanvas;
          }
        }
        pageOpList.flush(
          /* lastChunk = */ true,
          /* separateAnnots = */ { form, canvas }
        );
        return { length: pageOpList.totalLength };
      });
    });
  }

  extractTextContent({
    handler,
    task,
    includeMarkedContent,
    sink,
    combineTextItems,
  }) {
    const contentStreamPromise = this.getContentStream(handler);
    const resourcesPromise = this.loadResources([
      "ExtGState",
      "Font",
      "Properties",
      "XObject",
    ]);

    const dataPromises = Promise.all([contentStreamPromise, resourcesPromise]);
    return dataPromises.then(([contentStream]) => {
      const partialEvaluator = new PartialEvaluator({
        xref: this.xref,
        handler,
        pageIndex: this.pageIndex,
        idFactory: this._localIdFactory,
        fontCache: this.fontCache,
        builtInCMapCache: this.builtInCMapCache,
        standardFontDataCache: this.standardFontDataCache,
        globalImageCache: this.globalImageCache,
        options: this.evaluatorOptions,
      });

      return partialEvaluator.getTextContent({
        stream: contentStream,
        task,
        resources: this.resources,
        includeMarkedContent,
        combineTextItems,
        sink,
        viewBox: this.view,
      });
    });
  }

  async getStructTree() {
    const structTreeRoot = await this.pdfManager.ensureCatalog(
      "structTreeRoot"
    );
    if (!structTreeRoot) {
      return null;
    }
    const structTree = await this.pdfManager.ensure(this, "_parseStructTree", [
      structTreeRoot,
    ]);
    return structTree.serializable;
  }

  /**
   * @private
   */
  _parseStructTree(structTreeRoot) {
    const tree = new StructTreePage(structTreeRoot, this.pageDict);
    tree.parse();
    return tree;
  }

  async getAnnotationsData(handler, task, intent) {
    const annotations = await this._parsedAnnotations;
    if (annotations.length === 0) {
      return [];
    }

    const textContentPromises = [];
    const annotationsData = [];
    let partialEvaluator;

    const intentAny = !!(intent & RenderingIntentFlag.ANY),
      intentDisplay = !!(intent & RenderingIntentFlag.DISPLAY),
      intentPrint = !!(intent & RenderingIntentFlag.PRINT);

    for (const annotation of annotations) {
      // Get the annotation even if it's hidden because
      // JS can change its display.
      const isVisible = intentAny || (intentDisplay && annotation.viewable);
      if (isVisible || (intentPrint && annotation.printable)) {
        annotationsData.push(annotation.data);
      }

      if (annotation.hasTextContent && isVisible) {
        if (!partialEvaluator) {
          partialEvaluator = new PartialEvaluator({
            xref: this.xref,
            handler,
            pageIndex: this.pageIndex,
            idFactory: this._localIdFactory,
            fontCache: this.fontCache,
            builtInCMapCache: this.builtInCMapCache,
            standardFontDataCache: this.standardFontDataCache,
            globalImageCache: this.globalImageCache,
            options: this.evaluatorOptions,
          });
        }
        textContentPromises.push(
          annotation
            .extractTextContent(partialEvaluator, task, this.view)
            .catch(function (reason) {
              warn(
                `getAnnotationsData - ignoring textContent during "${task.name}" task: "${reason}".`
              );
            })
        );
      }
    }

    await Promise.all(textContentPromises);
    return annotationsData;
  }

  get annotations() {
    const annots = this._getInheritableProperty("Annots");
    return shadow(this, "annotations", Array.isArray(annots) ? annots : []);
  }

  get _parsedAnnotations() {
    const parsedAnnotations = this.pdfManager
      .ensure(this, "annotations")
      .then(() => {
        const annotationPromises = [];
        for (const annotationRef of this.annotations) {
          annotationPromises.push(
            AnnotationFactory.create(
              this.xref,
              annotationRef,
              this.pdfManager,
              this._localIdFactory,
              /* collectFields */ false
            ).catch(function (reason) {
              warn(`_parsedAnnotations: "${reason}".`);
              return null;
            })
          );
        }

        return Promise.all(annotationPromises).then(function (annotations) {
          if (annotations.length === 0) {
            return annotations;
          }

          const sortedAnnotations = [];
          let popupAnnotations;
          // Ensure that PopupAnnotations are handled last, since they depend on
          // their parent Annotation in the display layer; fixes issue 11362.
          for (const annotation of annotations) {
            if (!annotation) {
              continue;
            }
            if (annotation instanceof PopupAnnotation) {
              if (!popupAnnotations) {
                popupAnnotations = [];
              }
              popupAnnotations.push(annotation);
              continue;
            }
            sortedAnnotations.push(annotation);
          }
          if (popupAnnotations) {
            sortedAnnotations.push(...popupAnnotations);
          }

          return sortedAnnotations;
        });
      });

    return shadow(this, "_parsedAnnotations", parsedAnnotations);
  }

  get jsActions() {
    const actions = collectActions(
      this.xref,
      this.pageDict,
      PageActionEventType
    );
    return shadow(this, "jsActions", actions);
  }
}

const PDF_HEADER_SIGNATURE = new Uint8Array([0x25, 0x50, 0x44, 0x46, 0x2d]);
const STARTXREF_SIGNATURE = new Uint8Array([
  0x73, 0x74, 0x61, 0x72, 0x74, 0x78, 0x72, 0x65, 0x66,
]);
const ENDOBJ_SIGNATURE = new Uint8Array([0x65, 0x6e, 0x64, 0x6f, 0x62, 0x6a]);

const FINGERPRINT_FIRST_BYTES = 1024;
const EMPTY_FINGERPRINT =
  "\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00";

function find(stream, signature, limit = 1024, backwards = false) {
  if (
    typeof PDFJSDev === "undefined" ||
    PDFJSDev.test("!PRODUCTION || TESTING")
  ) {
    assert(limit > 0, 'The "limit" must be a positive integer.');
  }
  const signatureLength = signature.length;

  const scanBytes = stream.peekBytes(limit);
  const scanLength = scanBytes.length - signatureLength;

  if (scanLength <= 0) {
    return false;
  }
  if (backwards) {
    const signatureEnd = signatureLength - 1;

    let pos = scanBytes.length - 1;
    while (pos >= signatureEnd) {
      let j = 0;
      while (
        j < signatureLength &&
        scanBytes[pos - j] === signature[signatureEnd - j]
      ) {
        j++;
      }
      if (j >= signatureLength) {
        // `signature` found.
        stream.pos += pos - signatureEnd;
        return true;
      }
      pos--;
    }
  } else {
    // forwards
    let pos = 0;
    while (pos <= scanLength) {
      let j = 0;
      while (j < signatureLength && scanBytes[pos + j] === signature[j]) {
        j++;
      }
      if (j >= signatureLength) {
        // `signature` found.
        stream.pos += pos;
        return true;
      }
      pos++;
    }
  }
  return false;
}

/**
 * The `PDFDocument` class holds all the (worker-thread) data of the PDF file.
 */
class PDFDocument {
  constructor(pdfManager, stream) {
    if (
      typeof PDFJSDev === "undefined" ||
      PDFJSDev.test("!PRODUCTION || TESTING")
    ) {
      assert(
        stream instanceof BaseStream,
        'PDFDocument: Invalid "stream" argument.'
      );
    }
    if (stream.length <= 0) {
      throw new InvalidPDFException(
        "The PDF file is empty, i.e. its size is zero bytes."
      );
    }

    this.pdfManager = pdfManager;
    this.stream = stream;
    this.xref = new XRef(stream, pdfManager);
    this._pagePromises = new Map();
    this._version = null;

    const idCounters = {
      font: 0,
    };
    this._globalIdFactory = class {
      static getDocId() {
        return `g_${pdfManager.docId}`;
      }

      static createFontId() {
        return `f${++idCounters.font}`;
      }

      static createObjId() {
        unreachable("Abstract method `createObjId` called.");
      }

      static getPageObjId() {
        unreachable("Abstract method `getPageObjId` called.");
      }
    };
  }

  parse(recoveryMode) {
    this.xref.parse(recoveryMode);
    this.catalog = new Catalog(this.pdfManager, this.xref);
  }

  get linearization() {
    let linearization = null;
    try {
      linearization = Linearization.create(this.stream);
    } catch (err) {
      if (err instanceof MissingDataException) {
        throw err;
      }
      info(err);
    }
    return shadow(this, "linearization", linearization);
  }

  get startXRef() {
    const stream = this.stream;
    let startXRef = 0;

    if (this.linearization) {
      // Find the end of the first object.
      stream.reset();
      if (find(stream, ENDOBJ_SIGNATURE)) {
        startXRef = stream.pos + 6 - stream.start;
      }
    } else {
      // Find `startxref` by checking backwards from the end of the file.
      const step = 1024;
      const startXRefLength = STARTXREF_SIGNATURE.length;
      let found = false,
        pos = stream.end;

      while (!found && pos > 0) {
        pos -= step - startXRefLength;
        if (pos < 0) {
          pos = 0;
        }
        stream.pos = pos;
        found = find(stream, STARTXREF_SIGNATURE, step, true);
      }

      if (found) {
        stream.skip(9);
        let ch;
        do {
          ch = stream.getByte();
        } while (isWhiteSpace(ch));
        let str = "";
        while (ch >= /* Space = */ 0x20 && ch <= /* '9' = */ 0x39) {
          str += String.fromCharCode(ch);
          ch = stream.getByte();
        }
        startXRef = parseInt(str, 10);
        if (isNaN(startXRef)) {
          startXRef = 0;
        }
      }
    }
    return shadow(this, "startXRef", startXRef);
  }

  // Find the header, get the PDF format version and setup the
  // stream to start from the header.
  checkHeader() {
    const stream = this.stream;
    stream.reset();

    if (!find(stream, PDF_HEADER_SIGNATURE)) {
      // May not be a PDF file, but don't throw an error and let
      // parsing continue.
      return;
    }
    stream.moveStart();

    // Skip over the "%PDF-" prefix, since it was found above.
    stream.skip(PDF_HEADER_SIGNATURE.length);
    // Read the PDF format version.
    let version = "",
      ch;
    while (
      (ch = stream.getByte()) > /* Space = */ 0x20 &&
      version.length < /* MAX_PDF_VERSION_LENGTH = */ 7
    ) {
      version += String.fromCharCode(ch);
    }

    if (PDF_VERSION_REGEXP.test(version)) {
      this._version = version;
    } else {
      warn(`Invalid PDF header version: ${version}`);
    }
  }

  parseStartXRef() {
    this.xref.setStartXRef(this.startXRef);
  }

  get numPages() {
    let num = 0;
    if (this.catalog.hasActualNumPages) {
      num = this.catalog.numPages;
    } else if (this.xfaFactory) {
      // num is a Promise.
      num = this.xfaFactory.getNumPages();
    } else if (this.linearization) {
      num = this.linearization.numPages;
    } else {
      num = this.catalog.numPages;
    }
    return shadow(this, "numPages", num);
  }

  /**
   * @private
   */
  _hasOnlyDocumentSignatures(fields, recursionDepth = 0) {
    const RECURSION_LIMIT = 10;

    if (!Array.isArray(fields)) {
      return false;
    }
    return fields.every(field => {
      field = this.xref.fetchIfRef(field);
      if (!(field instanceof Dict)) {
        return false;
      }
      if (field.has("Kids")) {
        if (++recursionDepth > RECURSION_LIMIT) {
          warn("_hasOnlyDocumentSignatures: maximum recursion depth reached");
          return false;
        }
        return this._hasOnlyDocumentSignatures(
          field.get("Kids"),
          recursionDepth
        );
      }
      const isSignature = isName(field.get("FT"), "Sig");
      const rectangle = field.get("Rect");
      const isInvisible =
        Array.isArray(rectangle) && rectangle.every(value => value === 0);
      return isSignature && isInvisible;
    });
  }

  get _xfaStreams() {
    const acroForm = this.catalog.acroForm;
    if (!acroForm) {
      return null;
    }

    const xfa = acroForm.get("XFA");
    const entries = {
      "xdp:xdp": "",
      template: "",
      datasets: "",
      config: "",
      connectionSet: "",
      localeSet: "",
      stylesheet: "",
      "/xdp:xdp": "",
    };
    if (xfa instanceof BaseStream && !xfa.isEmpty) {
      entries["xdp:xdp"] = xfa;
      return entries;
    }

    if (!Array.isArray(xfa) || xfa.length === 0) {
      return null;
    }

    for (let i = 0, ii = xfa.length; i < ii; i += 2) {
      let name;
      if (i === 0) {
        name = "xdp:xdp";
      } else if (i === ii - 2) {
        name = "/xdp:xdp";
      } else {
        name = xfa[i];
      }

      if (!entries.hasOwnProperty(name)) {
        continue;
      }
      const data = this.xref.fetchIfRef(xfa[i + 1]);
      if (!(data instanceof BaseStream) || data.isEmpty) {
        continue;
      }
      entries[name] = data;
    }
    return entries;
  }

  get xfaDatasets() {
    const streams = this._xfaStreams;
    if (!streams) {
      return shadow(this, "xfaDatasets", null);
    }
    for (const key of ["datasets", "xdp:xdp"]) {
      const stream = streams[key];
      if (!stream) {
        continue;
      }
      try {
        const str = stringToUTF8String(stream.getString());
        const data = { [key]: str };
        return shadow(this, "xfaDatasets", new DatasetReader(data));
      } catch (_) {
        warn("XFA - Invalid utf-8 string.");
        break;
      }
    }
    return shadow(this, "xfaDatasets", null);
  }

  get xfaData() {
    const streams = this._xfaStreams;
    if (!streams) {
      return null;
    }
    const data = Object.create(null);
    for (const [key, stream] of Object.entries(streams)) {
      if (!stream) {
        continue;
      }
      try {
        data[key] = stringToUTF8String(stream.getString());
      } catch (_) {
        warn("XFA - Invalid utf-8 string.");
        return null;
      }
    }
    return data;
  }

  get xfaFactory() {
    let data;
    if (
      this.pdfManager.enableXfa &&
      this.catalog.needsRendering &&
      this.formInfo.hasXfa &&
      !this.formInfo.hasAcroForm
    ) {
      data = this.xfaData;
    }
    return shadow(this, "xfaFactory", data ? new XFAFactory(data) : null);
  }

  get isPureXfa() {
    return this.xfaFactory ? this.xfaFactory.isValid() : false;
  }

  get htmlForXfa() {
    return this.xfaFactory ? this.xfaFactory.getPages() : null;
  }

  async loadXfaImages() {
    const xfaImagesDict = await this.pdfManager.ensureCatalog("xfaImages");
    if (!xfaImagesDict) {
      return;
    }

    const keys = xfaImagesDict.getKeys();
    const objectLoader = new ObjectLoader(xfaImagesDict, keys, this.xref);
    await objectLoader.load();

    const xfaImages = new Map();
    for (const key of keys) {
      const stream = xfaImagesDict.get(key);
      if (stream instanceof BaseStream) {
        xfaImages.set(key, stream.getBytes());
      }
    }

    this.xfaFactory.setImages(xfaImages);
  }

  async loadXfaFonts(handler, task) {
    const acroForm = await this.pdfManager.ensureCatalog("acroForm");
    if (!acroForm) {
      return;
    }
    const resources = await acroForm.getAsync("DR");
    if (!(resources instanceof Dict)) {
      return;
    }
    const objectLoader = new ObjectLoader(resources, ["Font"], this.xref);
    await objectLoader.load();

    const fontRes = resources.get("Font");
    if (!(fontRes instanceof Dict)) {
      return;
    }

    const options = Object.assign(
      Object.create(null),
      this.pdfManager.evaluatorOptions
    );
    options.useSystemFonts = false;

    const partialEvaluator = new PartialEvaluator({
      xref: this.xref,
      handler,
      pageIndex: -1,
      idFactory: this._globalIdFactory,
      fontCache: this.catalog.fontCache,
      builtInCMapCache: this.catalog.builtInCMapCache,
      standardFontDataCache: this.catalog.standardFontDataCache,
      options,
    });
    const operatorList = new OperatorList();
    const pdfFonts = [];
    const initialState = {
      get font() {
        return pdfFonts.at(-1);
      },
      set font(font) {
        pdfFonts.push(font);
      },
      clone() {
        return this;
      },
    };

    const fonts = new Map();
    fontRes.forEach((fontName, font) => {
      fonts.set(fontName, font);
    });
    const promises = [];

    for (const [fontName, font] of fonts) {
      const descriptor = font.get("FontDescriptor");
      if (!(descriptor instanceof Dict)) {
        continue;
      }
      let fontFamily = descriptor.get("FontFamily");
      // For example, "Wingdings 3" is not a valid font name in the css specs.
      fontFamily = fontFamily.replace(/[ ]+(\d)/g, "$1");
      const fontWeight = descriptor.get("FontWeight");

      // Angle is expressed in degrees counterclockwise in PDF
      // when it's clockwise in CSS
      // (see https://drafts.csswg.org/css-fonts-4/#valdef-font-style-oblique-angle)
      const italicAngle = -descriptor.get("ItalicAngle");
      const cssFontInfo = { fontFamily, fontWeight, italicAngle };

      if (!validateCSSFont(cssFontInfo)) {
        continue;
      }
      promises.push(
        partialEvaluator
          .handleSetFont(
            resources,
            [Name.get(fontName), 1],
            /* fontRef = */ null,
            operatorList,
            task,
            initialState,
            /* fallbackFontDict = */ null,
            /* cssFontInfo = */ cssFontInfo
          )
          .catch(function (reason) {
            warn(`loadXfaFonts: "${reason}".`);
            return null;
          })
      );
    }

    await Promise.all(promises);
    const missingFonts = this.xfaFactory.setFonts(pdfFonts);

    if (!missingFonts) {
      return;
    }

    options.ignoreErrors = true;
    promises.length = 0;
    pdfFonts.length = 0;

    const reallyMissingFonts = new Set();
    for (const missing of missingFonts) {
      if (!getXfaFontName(`${missing}-Regular`)) {
        // No substitution available: we'll fallback on Myriad.
        reallyMissingFonts.add(missing);
      }
    }

    if (reallyMissingFonts.size) {
      missingFonts.push("PdfJS-Fallback");
    }

    for (const missing of missingFonts) {
      if (reallyMissingFonts.has(missing)) {
        continue;
      }
      for (const fontInfo of [
        { name: "Regular", fontWeight: 400, italicAngle: 0 },
        { name: "Bold", fontWeight: 700, italicAngle: 0 },
        { name: "Italic", fontWeight: 400, italicAngle: 12 },
        { name: "BoldItalic", fontWeight: 700, italicAngle: 12 },
      ]) {
        const name = `${missing}-${fontInfo.name}`;
        const dict = getXfaFontDict(name);

        promises.push(
          partialEvaluator
            .handleSetFont(
              resources,
              [Name.get(name), 1],
              /* fontRef = */ null,
              operatorList,
              task,
              initialState,
              /* fallbackFontDict = */ dict,
              /* cssFontInfo = */ {
                fontFamily: missing,
                fontWeight: fontInfo.fontWeight,
                italicAngle: fontInfo.italicAngle,
              }
            )
            .catch(function (reason) {
              warn(`loadXfaFonts: "${reason}".`);
              return null;
            })
        );
      }
    }

    await Promise.all(promises);
    this.xfaFactory.appendFonts(pdfFonts, reallyMissingFonts);
  }

  async serializeXfaData(annotationStorage) {
    return this.xfaFactory
      ? this.xfaFactory.serializeData(annotationStorage)
      : null;
  }

  /**
   * The specification states in section 7.5.2 that the version from
   * the catalog, if present, should overwrite the version from the header.
   */
  get version() {
    return this.catalog.version || this._version;
  }

  get formInfo() {
    const formInfo = {
      hasFields: false,
      hasAcroForm: false,
      hasXfa: false,
      hasSignatures: false,
    };
    const acroForm = this.catalog.acroForm;
    if (!acroForm) {
      return shadow(this, "formInfo", formInfo);
    }

    try {
      const fields = acroForm.get("Fields");
      const hasFields = Array.isArray(fields) && fields.length > 0;
      formInfo.hasFields = hasFields; // Used by the `fieldObjects` getter.

      // The document contains XFA data if the `XFA` entry is a non-empty
      // array or stream.
      const xfa = acroForm.get("XFA");
      formInfo.hasXfa =
        (Array.isArray(xfa) && xfa.length > 0) ||
        (xfa instanceof BaseStream && !xfa.isEmpty);

      // The document contains AcroForm data if the `Fields` entry is a
      // non-empty array and it doesn't consist of only document signatures.
      // This second check is required for files that don't actually contain
      // AcroForm data (only XFA data), but that use the `Fields` entry to
      // store (invisible) document signatures. This can be detected using
      // the first bit of the `SigFlags` integer (see Table 219 in the
      // specification).
      const sigFlags = acroForm.get("SigFlags");
      const hasSignatures = !!(sigFlags & 0x1);
      const hasOnlyDocumentSignatures =
        hasSignatures && this._hasOnlyDocumentSignatures(fields);
      formInfo.hasAcroForm = hasFields && !hasOnlyDocumentSignatures;
      formInfo.hasSignatures = hasSignatures;
    } catch (ex) {
      if (ex instanceof MissingDataException) {
        throw ex;
      }
      warn(`Cannot fetch form information: "${ex}".`);
    }
    return shadow(this, "formInfo", formInfo);
  }

  get documentInfo() {
    const docInfo = {
      PDFFormatVersion: this.version,
      Language: this.catalog.lang,
      EncryptFilterName: this.xref.encrypt
        ? this.xref.encrypt.filterName
        : null,
      IsLinearized: !!this.linearization,
      IsAcroFormPresent: this.formInfo.hasAcroForm,
      IsXFAPresent: this.formInfo.hasXfa,
      IsCollectionPresent: !!this.catalog.collection,
      IsSignaturesPresent: this.formInfo.hasSignatures,
    };

    let infoDict;
    try {
      infoDict = this.xref.trailer.get("Info");
    } catch (err) {
      if (err instanceof MissingDataException) {
        throw err;
      }
      info("The document information dictionary is invalid.");
    }
    if (!(infoDict instanceof Dict)) {
      return shadow(this, "documentInfo", docInfo);
    }

    for (const key of infoDict.getKeys()) {
      const value = infoDict.get(key);

      switch (key) {
        case "Title":
        case "Author":
        case "Subject":
        case "Keywords":
        case "Creator":
        case "Producer":
        case "CreationDate":
        case "ModDate":
          if (typeof value === "string") {
            docInfo[key] = stringToPDFString(value);
            continue;
          }
          break;
        case "Trapped":
          if (value instanceof Name) {
            docInfo[key] = value;
            continue;
          }
          break;
        default:
          // For custom values, only accept white-listed types to prevent
          // errors that would occur when trying to send non-serializable
          // objects to the main-thread (for example `Dict` or `Stream`).
          let customValue;
          switch (typeof value) {
            case "string":
              customValue = stringToPDFString(value);
              break;
            case "number":
            case "boolean":
              customValue = value;
              break;
            default:
              if (value instanceof Name) {
                customValue = value;
              }
              break;
          }

          if (customValue === undefined) {
            warn(`Bad value, for custom key "${key}", in Info: ${value}.`);
            continue;
          }
          if (!docInfo.Custom) {
            docInfo.Custom = Object.create(null);
          }
          docInfo.Custom[key] = customValue;
          continue;
      }
      warn(`Bad value, for key "${key}", in Info: ${value}.`);
    }
    return shadow(this, "documentInfo", docInfo);
  }

  get fingerprints() {
    function validate(data) {
      return (
        typeof data === "string" &&
        data.length > 0 &&
        data !== EMPTY_FINGERPRINT
      );
    }

    function hexString(hash) {
      const buf = [];
      for (const num of hash) {
        const hex = num.toString(16);
        buf.push(hex.padStart(2, "0"));
      }
      return buf.join("");
    }

    const idArray = this.xref.trailer.get("ID");
    let hashOriginal, hashModified;
    if (Array.isArray(idArray) && validate(idArray[0])) {
      hashOriginal = stringToBytes(idArray[0]);

      if (idArray[1] !== idArray[0] && validate(idArray[1])) {
        hashModified = stringToBytes(idArray[1]);
      }
    } else {
      hashOriginal = calculateMD5(
        this.stream.getByteRange(0, FINGERPRINT_FIRST_BYTES),
        0,
        FINGERPRINT_FIRST_BYTES
      );
    }

    return shadow(this, "fingerprints", [
      hexString(hashOriginal),
      hashModified ? hexString(hashModified) : null,
    ]);
  }

  async _getLinearizationPage(pageIndex) {
    const { catalog, linearization, xref } = this;
    if (
      typeof PDFJSDev === "undefined" ||
      PDFJSDev.test("!PRODUCTION || TESTING")
    ) {
      assert(
        linearization && linearization.pageFirst === pageIndex,
        "_getLinearizationPage - invalid pageIndex argument."
      );
    }

    const ref = Ref.get(linearization.objectNumberFirst, 0);
    try {
      const obj = await xref.fetchAsync(ref);
      // Ensure that the object that was found is actually a Page dictionary.
      if (obj instanceof Dict) {
        let type = obj.getRaw("Type");
        if (type instanceof Ref) {
          type = await xref.fetchAsync(type);
        }
        if (isName(type, "Page") || (!obj.has("Type") && !obj.has("Kids"))) {
          if (!catalog.pageKidsCountCache.has(ref)) {
            catalog.pageKidsCountCache.put(ref, 1); // Cache the Page reference.
          }
          // Help improve performance of the `Catalog.getPageIndex` method.
          if (!catalog.pageIndexCache.has(ref)) {
            catalog.pageIndexCache.put(ref, 0);
          }

          return [obj, ref];
        }
      }
      throw new FormatError(
        "The Linearization dictionary doesn't point to a valid Page dictionary."
      );
    } catch (reason) {
      warn(`_getLinearizationPage: "${reason.message}".`);
      return catalog.getPageDict(pageIndex);
    }
  }

  getPage(pageIndex) {
    const cachedPromise = this._pagePromises.get(pageIndex);
    if (cachedPromise) {
      return cachedPromise;
    }
    const { catalog, linearization, xfaFactory } = this;

    let promise;
    if (xfaFactory) {
      promise = Promise.resolve([Dict.empty, null]);
    } else if (linearization && linearization.pageFirst === pageIndex) {
      promise = this._getLinearizationPage(pageIndex);
    } else {
      promise = catalog.getPageDict(pageIndex);
    }
    promise = promise.then(([pageDict, ref]) => {
      return new Page({
        pdfManager: this.pdfManager,
        xref: this.xref,
        pageIndex,
        pageDict,
        ref,
        globalIdFactory: this._globalIdFactory,
        fontCache: catalog.fontCache,
        builtInCMapCache: catalog.builtInCMapCache,
        standardFontDataCache: catalog.standardFontDataCache,
        globalImageCache: catalog.globalImageCache,
        nonBlendModesSet: catalog.nonBlendModesSet,
        xfaFactory,
      });
    });

    this._pagePromises.set(pageIndex, promise);
    return promise;
  }

  async checkFirstPage(recoveryMode = false) {
    if (recoveryMode) {
      return;
    }
    try {
      await this.getPage(0);
    } catch (reason) {
      if (reason instanceof XRefEntryException) {
        // Clear out the various caches to ensure that we haven't stored any
        // inconsistent and/or incorrect state, since that could easily break
        // subsequent `this.getPage` calls.
        this._pagePromises.delete(0);
        await this.cleanup();

        throw new XRefParseException();
      }
    }
  }

  async checkLastPage(recoveryMode = false) {
    const { catalog, pdfManager } = this;

    catalog.setActualNumPages(); // Ensure that it's always reset.
    let numPages;

    try {
      await Promise.all([
        pdfManager.ensureDoc("xfaFactory"),
        pdfManager.ensureDoc("linearization"),
        pdfManager.ensureCatalog("numPages"),
      ]);

      if (this.xfaFactory) {
        return; // The Page count is always calculated for XFA-documents.
      } else if (this.linearization) {
        numPages = this.linearization.numPages;
      } else {
        numPages = catalog.numPages;
      }

      if (!Number.isInteger(numPages)) {
        throw new FormatError("Page count is not an integer.");
      } else if (numPages <= 1) {
        return;
      }
      await this.getPage(numPages - 1);
    } catch (reason) {
      // Clear out the various caches to ensure that we haven't stored any
      // inconsistent and/or incorrect state, since that could easily break
      // subsequent `this.getPage` calls.
      this._pagePromises.delete(numPages - 1);
      await this.cleanup();

      if (reason instanceof XRefEntryException && !recoveryMode) {
        throw new XRefParseException();
      }
      warn(`checkLastPage - invalid /Pages tree /Count: ${numPages}.`);

      let pagesTree;
      try {
        pagesTree = await catalog.getAllPageDicts(recoveryMode);
      } catch (reasonAll) {
        if (reasonAll instanceof XRefEntryException && !recoveryMode) {
          throw new XRefParseException();
        }
        catalog.setActualNumPages(1);
        return;
      }

      for (const [pageIndex, [pageDict, ref]] of pagesTree) {
        let promise;
        if (pageDict instanceof Error) {
          promise = Promise.reject(pageDict);

          // Prevent "uncaught exception: Object"-messages in the console.
          promise.catch(() => {});
        } else {
          promise = Promise.resolve(
            new Page({
              pdfManager,
              xref: this.xref,
              pageIndex,
              pageDict,
              ref,
              globalIdFactory: this._globalIdFactory,
              fontCache: catalog.fontCache,
              builtInCMapCache: catalog.builtInCMapCache,
              standardFontDataCache: catalog.standardFontDataCache,
              globalImageCache: catalog.globalImageCache,
              nonBlendModesSet: catalog.nonBlendModesSet,
              xfaFactory: null,
            })
          );
        }

        this._pagePromises.set(pageIndex, promise);
      }
      catalog.setActualNumPages(pagesTree.size);
    }
  }

  fontFallback(id, handler) {
    return this.catalog.fontFallback(id, handler);
  }

  async cleanup(manuallyTriggered = false) {
    return this.catalog
      ? this.catalog.cleanup(manuallyTriggered)
      : clearGlobalCaches();
  }

  /**
   * @private
   */
  _collectFieldObjects(name, fieldRef, promises) {
    const field = this.xref.fetchIfRef(fieldRef);
    if (field.has("T")) {
      const partName = stringToPDFString(field.get("T"));
      if (name === "") {
        name = partName;
      } else {
        name = `${name}.${partName}`;
      }
    }

    if (!promises.has(name)) {
      promises.set(name, []);
    }
    promises.get(name).push(
      AnnotationFactory.create(
        this.xref,
        fieldRef,
        this.pdfManager,
        this._localIdFactory,
        /* collectFields */ true
      )
        .then(annotation => annotation && annotation.getFieldObject())
        .catch(function (reason) {
          warn(`_collectFieldObjects: "${reason}".`);
          return null;
        })
    );

    if (field.has("Kids")) {
      const kids = field.get("Kids");
      for (const kid of kids) {
        this._collectFieldObjects(name, kid, promises);
      }
    }
  }

  get fieldObjects() {
    if (!this.formInfo.hasFields) {
      return shadow(this, "fieldObjects", Promise.resolve(null));
    }

    const allFields = Object.create(null);
    const fieldPromises = new Map();
    for (const fieldRef of this.catalog.acroForm.get("Fields")) {
      this._collectFieldObjects("", fieldRef, fieldPromises);
    }

    const allPromises = [];
    for (const [name, promises] of fieldPromises) {
      allPromises.push(
        Promise.all(promises).then(fields => {
          fields = fields.filter(field => !!field);
          if (fields.length > 0) {
            allFields[name] = fields;
          }
        })
      );
    }

    return shadow(
      this,
      "fieldObjects",
      Promise.all(allPromises).then(() => allFields)
    );
  }

  get hasJSActions() {
    const promise = this.pdfManager.ensureDoc("_parseHasJSActions");
    return shadow(this, "hasJSActions", promise);
  }

  /**
   * @private
   */
  async _parseHasJSActions() {
    const [catalogJsActions, fieldObjects] = await Promise.all([
      this.pdfManager.ensureCatalog("jsActions"),
      this.pdfManager.ensureDoc("fieldObjects"),
    ]);

    if (catalogJsActions) {
      return true;
    }
    if (fieldObjects) {
      return Object.values(fieldObjects).some(fieldObject =>
        fieldObject.some(object => object.actions !== null)
      );
    }
    return false;
  }

  get calculationOrderIds() {
    const acroForm = this.catalog.acroForm;
    if (!acroForm || !acroForm.has("CO")) {
      return shadow(this, "calculationOrderIds", null);
    }

    const calculationOrder = acroForm.get("CO");
    if (!Array.isArray(calculationOrder) || calculationOrder.length === 0) {
      return shadow(this, "calculationOrderIds", null);
    }

    const ids = [];
    for (const id of calculationOrder) {
      if (id instanceof Ref) {
        ids.push(id.toString());
      }
    }
    if (ids.length === 0) {
      return shadow(this, "calculationOrderIds", null);
    }
    return shadow(this, "calculationOrderIds", ids);
  }
}

export { Page, PDFDocument };