lib/display/fetch_stream.js

/**
 * @licstart The following is the entire license notice for the
 * Javascript code in this page
 *
 * Copyright 2020 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.
 *
 * @licend The above is the entire license notice for the
 * Javascript code in this page
 */
"use strict";

Object.defineProperty(exports, "__esModule", {
  value: true
});
exports.PDFFetchStream = void 0;

var _util = require("../shared/util.js");

var _network_utils = require("./network_utils.js");

;

function createFetchOptions(headers, withCredentials, abortController) {
  return {
    method: "GET",
    headers,
    signal: abortController && abortController.signal,
    mode: "cors",
    credentials: withCredentials ? "include" : "same-origin",
    redirect: "follow"
  };
}

function createHeaders(httpHeaders) {
  const headers = new Headers();

  for (const property in httpHeaders) {
    const value = httpHeaders[property];

    if (typeof value === "undefined") {
      continue;
    }

    headers.append(property, value);
  }

  return headers;
}

class PDFFetchStream {
  constructor(source) {
    this.source = source;
    this.isHttp = /^https?:/i.test(source.url);
    this.httpHeaders = this.isHttp && source.httpHeaders || {};
    this._fullRequestReader = null;
    this._rangeRequestReaders = [];
  }

  get _progressiveDataLength() {
    return this._fullRequestReader ? this._fullRequestReader._loaded : 0;
  }

  getFullReader() {
    (0, _util.assert)(!this._fullRequestReader, "PDFFetchStream.getFullReader can only be called once.");
    this._fullRequestReader = new PDFFetchStreamReader(this);
    return this._fullRequestReader;
  }

  getRangeReader(begin, end) {
    if (end <= this._progressiveDataLength) {
      return null;
    }

    const reader = new PDFFetchStreamRangeReader(this, begin, end);

    this._rangeRequestReaders.push(reader);

    return reader;
  }

  cancelAllRequests(reason) {
    if (this._fullRequestReader) {
      this._fullRequestReader.cancel(reason);
    }

    const readers = this._rangeRequestReaders.slice(0);

    readers.forEach(function (reader) {
      reader.cancel(reason);
    });
  }

}

exports.PDFFetchStream = PDFFetchStream;

class PDFFetchStreamReader {
  constructor(stream) {
    this._stream = stream;
    this._reader = null;
    this._loaded = 0;
    this._filename = null;
    const source = stream.source;
    this._withCredentials = source.withCredentials || false;
    this._contentLength = source.length;
    this._headersCapability = (0, _util.createPromiseCapability)();
    this._disableRange = source.disableRange || false;
    this._rangeChunkSize = source.rangeChunkSize;

    if (!this._rangeChunkSize && !this._disableRange) {
      this._disableRange = true;
    }

    if (typeof AbortController !== "undefined") {
      this._abortController = new AbortController();
    }

    this._isStreamingSupported = !source.disableStream;
    this._isRangeSupported = !source.disableRange;
    this._headers = createHeaders(this._stream.httpHeaders);
    const url = source.url;
    fetch(url, createFetchOptions(this._headers, this._withCredentials, this._abortController)).then(response => {
      if (!(0, _network_utils.validateResponseStatus)(response.status)) {
        throw (0, _network_utils.createResponseStatusError)(response.status, url);
      }

      this._reader = response.body.getReader();

      this._headersCapability.resolve();

      const getResponseHeader = name => {
        return response.headers.get(name);
      };

      const {
        allowRangeRequests,
        suggestedLength
      } = (0, _network_utils.validateRangeRequestCapabilities)({
        getResponseHeader,
        isHttp: this._stream.isHttp,
        rangeChunkSize: this._rangeChunkSize,
        disableRange: this._disableRange
      });
      this._isRangeSupported = allowRangeRequests;
      this._contentLength = suggestedLength || this._contentLength;
      this._filename = (0, _network_utils.extractFilenameFromHeader)(getResponseHeader);

      if (!this._isStreamingSupported && this._isRangeSupported) {
        this.cancel(new _util.AbortException("Streaming is disabled."));
      }
    }).catch(this._headersCapability.reject);
    this.onProgress = null;
  }

  get headersReady() {
    return this._headersCapability.promise;
  }

  get filename() {
    return this._filename;
  }

  get contentLength() {
    return this._contentLength;
  }

  get isRangeSupported() {
    return this._isRangeSupported;
  }

  get isStreamingSupported() {
    return this._isStreamingSupported;
  }

  async read() {
    await this._headersCapability.promise;
    const {
      value,
      done
    } = await this._reader.read();

    if (done) {
      return {
        value,
        done
      };
    }

    this._loaded += value.byteLength;

    if (this.onProgress) {
      this.onProgress({
        loaded: this._loaded,
        total: this._contentLength
      });
    }

    const buffer = new Uint8Array(value).buffer;
    return {
      value: buffer,
      done: false
    };
  }

  cancel(reason) {
    if (this._reader) {
      this._reader.cancel(reason);
    }

    if (this._abortController) {
      this._abortController.abort();
    }
  }

}

class PDFFetchStreamRangeReader {
  constructor(stream, begin, end) {
    this._stream = stream;
    this._reader = null;
    this._loaded = 0;
    const source = stream.source;
    this._withCredentials = source.withCredentials || false;
    this._readCapability = (0, _util.createPromiseCapability)();
    this._isStreamingSupported = !source.disableStream;

    if (typeof AbortController !== "undefined") {
      this._abortController = new AbortController();
    }

    this._headers = createHeaders(this._stream.httpHeaders);

    this._headers.append("Range", `bytes=${begin}-${end - 1}`);

    const url = source.url;
    fetch(url, createFetchOptions(this._headers, this._withCredentials, this._abortController)).then(response => {
      if (!(0, _network_utils.validateResponseStatus)(response.status)) {
        throw (0, _network_utils.createResponseStatusError)(response.status, url);
      }

      this._readCapability.resolve();

      this._reader = response.body.getReader();
    }).catch(reason => {
      if (reason && reason.name === "AbortError") {
        return;
      }

      throw reason;
    });
    this.onProgress = null;
  }

  get isStreamingSupported() {
    return this._isStreamingSupported;
  }

  async read() {
    await this._readCapability.promise;
    const {
      value,
      done
    } = await this._reader.read();

    if (done) {
      return {
        value,
        done
      };
    }

    this._loaded += value.byteLength;

    if (this.onProgress) {
      this.onProgress({
        loaded: this._loaded
      });
    }

    const buffer = new Uint8Array(value).buffer;
    return {
      value: buffer,
      done: false
    };
  }

  cancel(reason) {
    if (this._reader) {
      this._reader.cancel(reason);
    }

    if (this._abortController) {
      this._abortController.abort();
    }
  }

}