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.js";
  import { getFilenameFromContentDispositionHeader } from "./content_disposition.js";
  import { isPdfFile } from "./display_utils.js";
  
  function validateRangeRequestCapabilities({
    getResponseHeader,
    isHttp,
    rangeChunkSize,
    disableRange,
  }) {
    assert(rangeChunkSize > 0, "Range chunk size must be larger than zero");
    const returnValues = {
      allowRangeRequests: false,
      suggestedLength: undefined,
    };
  
    const 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;
    }
  
    if (disableRange || !isHttp) {
      return returnValues;
    }
    if (getResponseHeader("Accept-Ranges") !== "bytes") {
      return returnValues;
    }
  
    const contentEncoding = getResponseHeader("Content-Encoding") || "identity";
    if (contentEncoding !== "identity") {
      return returnValues;
    }
  
    returnValues.allowRangeRequests = true;
    return returnValues;
  }
  
  function extractFilenameFromHeader(getResponseHeader) {
    const contentDisposition = getResponseHeader("Content-Disposition");
    if (contentDisposition) {
      let filename = getFilenameFromContentDispositionHeader(contentDisposition);
      if (filename.includes("%")) {
        try {
          filename = decodeURIComponent(filename);
        } catch (ex) {}
      }
      if (isPdfFile(filename)) {
        return filename;
      }
    }
    return null;
  }
  
  function createResponseStatusError(status, url) {
    if (status === 404 || (status === 0 && url.startsWith("file:"))) {
      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,
  };
  