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 {
    assert, MissingPDFException, UnexpectedResponseException
  } from '../shared/util';
  import {
    getFilenameFromContentDispositionHeader
  } from './content_disposition';
  
  function validateRangeRequestCapabilities({ getResponseHeader, isHttp,
                                              rangeChunkSize, disableRange, }) {
    assert(rangeChunkSize > 0, 'Range chunk size must be larger than zero');
    let returnValues = {
      allowRangeRequests: false,
      suggestedLength: undefined,
    };
    if (disableRange || !isHttp) {
      return returnValues;
    }
    if (getResponseHeader('Accept-Ranges') !== 'bytes') {
      return returnValues;
    }
  
    let contentEncoding = getResponseHeader('Content-Encoding') || 'identity';
    if (contentEncoding !== 'identity') {
      return returnValues;
    }
  
    let length = parseInt(getResponseHeader('Content-Length'), 10);
    if (!Number.isInteger(length)) {
      return returnValues;
    }
  
    returnValues.suggestedLength = length;
    if (length <= 2 * rangeChunkSize) {
      // The file size is smaller than the size of two chunks, so it does not
      // make any sense to abort the request and retry with a range request.
      return returnValues;
    }
  
    returnValues.allowRangeRequests = true;
    return returnValues;
  }
  
  function extractFilenameFromHeader(getResponseHeader) {
    const contentDisposition = getResponseHeader('Content-Disposition');
    if (contentDisposition) {
      let filename = getFilenameFromContentDispositionHeader(contentDisposition);
      if (/\.pdf$/i.test(filename)) {
        return filename;
      }
    }
    return null;
  }
  
  function createResponseStatusError(status, url) {
    if (status === 404 || status === 0 && /^file:/.test(url)) {
      return new MissingPDFException('Missing PDF "' + url + '".');
    }
    return new UnexpectedResponseException(
      'Unexpected server response (' + status +
      ') while retrieving PDF "' + url + '".', status);
  }
  
  function validateResponseStatus(status) {
    return status === 200 || status === 206;
  }
  
  export {
    createResponseStatusError,
    extractFilenameFromHeader,
    validateRangeRequestCapabilities,
    validateResponseStatus,
  };
  