/* 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, createPromiseCapability, globalScope, isInt, MissingPDFException,
  UnexpectedResponseException
} from '../shared/util';
import { setPDFNetworkStreamClass } from './api';

if (typeof PDFJSDev !== 'undefined' && PDFJSDev.test('FIREFOX || MOZCENTRAL')) {
  throw new Error('Module "./network" shall not ' +
                  'be used with FIREFOX or MOZCENTRAL build.');
}

var OK_RESPONSE = 200;
var PARTIAL_CONTENT_RESPONSE = 206;

function NetworkManager(url, args) {
  this.url = url;
  args = args || {};
  this.isHttp = /^https?:/i.test(url);
  this.httpHeaders = (this.isHttp && args.httpHeaders) || {};
  this.withCredentials = args.withCredentials || false;
  this.getXhr = args.getXhr ||
    function NetworkManager_getXhr() {
      return new XMLHttpRequest();
    };

  this.currXhrId = 0;
  this.pendingRequests = Object.create(null);
  this.loadedRequests = Object.create(null);
}

function getArrayBuffer(xhr) {
  var data = xhr.response;
  if (typeof data !== 'string') {
    return data;
  }
  var length = data.length;
  var array = new Uint8Array(length);
  for (var i = 0; i < length; i++) {
    array[i] = data.charCodeAt(i) & 0xFF;
  }
  return array.buffer;
}

var supportsMozChunked =
  typeof PDFJSDev !== 'undefined' && PDFJSDev.test('CHROME') ? false :
    (function supportsMozChunkedClosure() {
  try {
    var x = new XMLHttpRequest();
    // Firefox 37- required .open() to be called before setting responseType.
    // https://bugzilla.mozilla.org/show_bug.cgi?id=707484
    // Even though the URL is not visited, .open() could fail if the URL is
    // blocked, e.g. via the connect-src CSP directive or the NoScript addon.
    // When this error occurs, this feature detection method will mistakenly
    // report that moz-chunked-arraybuffer is not supported in Firefox 37-.
    x.open('GET', globalScope.location.href);
    x.responseType = 'moz-chunked-arraybuffer';
    return x.responseType === 'moz-chunked-arraybuffer';
  } catch (e) {
    return false;
  }
})();

NetworkManager.prototype = {
  requestRange: function NetworkManager_requestRange(begin, end, listeners) {
    var args = {
      begin,
      end,
    };
    for (var prop in listeners) {
      args[prop] = listeners[prop];
    }
    return this.request(args);
  },

  requestFull: function NetworkManager_requestFull(listeners) {
    return this.request(listeners);
  },

  request: function NetworkManager_request(args) {
    var xhr = this.getXhr();
    var xhrId = this.currXhrId++;
    var pendingRequest = this.pendingRequests[xhrId] = {
      xhr,
    };

    xhr.open('GET', this.url);
    xhr.withCredentials = this.withCredentials;
    for (var property in this.httpHeaders) {
      var value = this.httpHeaders[property];
      if (typeof value === 'undefined') {
        continue;
      }
      xhr.setRequestHeader(property, value);
    }
    if (this.isHttp && 'begin' in args && 'end' in args) {
      var rangeStr = args.begin + '-' + (args.end - 1);
      xhr.setRequestHeader('Range', 'bytes=' + rangeStr);
      pendingRequest.expectedStatus = 206;
    } else {
      pendingRequest.expectedStatus = 200;
    }

    var useMozChunkedLoading = supportsMozChunked && !!args.onProgressiveData;
    if (useMozChunkedLoading) {
      xhr.responseType = 'moz-chunked-arraybuffer';
      pendingRequest.onProgressiveData = args.onProgressiveData;
      pendingRequest.mozChunked = true;
    } else {
      xhr.responseType = 'arraybuffer';
    }

    if (args.onError) {
      xhr.onerror = function(evt) {
        args.onError(xhr.status);
      };
    }
    xhr.onreadystatechange = this.onStateChange.bind(this, xhrId);
    xhr.onprogress = this.onProgress.bind(this, xhrId);

    pendingRequest.onHeadersReceived = args.onHeadersReceived;
    pendingRequest.onDone = args.onDone;
    pendingRequest.onError = args.onError;
    pendingRequest.onProgress = args.onProgress;

    xhr.send(null);

    return xhrId;
  },

  onProgress: function NetworkManager_onProgress(xhrId, evt) {
    var pendingRequest = this.pendingRequests[xhrId];
    if (!pendingRequest) {
      // Maybe abortRequest was called...
      return;
    }

    if (pendingRequest.mozChunked) {
      var chunk = getArrayBuffer(pendingRequest.xhr);
      pendingRequest.onProgressiveData(chunk);
    }

    var onProgress = pendingRequest.onProgress;
    if (onProgress) {
      onProgress(evt);
    }
  },

  onStateChange: function NetworkManager_onStateChange(xhrId, evt) {
    var pendingRequest = this.pendingRequests[xhrId];
    if (!pendingRequest) {
      // Maybe abortRequest was called...
      return;
    }

    var xhr = pendingRequest.xhr;
    if (xhr.readyState >= 2 && pendingRequest.onHeadersReceived) {
      pendingRequest.onHeadersReceived();
      delete pendingRequest.onHeadersReceived;
    }

    if (xhr.readyState !== 4) {
      return;
    }

    if (!(xhrId in this.pendingRequests)) {
      // The XHR request might have been aborted in onHeadersReceived()
      // callback, in which case we should abort request
      return;
    }

    delete this.pendingRequests[xhrId];

    // success status == 0 can be on ftp, file and other protocols
    if (xhr.status === 0 && this.isHttp) {
      if (pendingRequest.onError) {
        pendingRequest.onError(xhr.status);
      }
      return;
    }
    var xhrStatus = xhr.status || OK_RESPONSE;

    // From http://www.w3.org/Protocols/rfc2616/rfc2616-sec14.html#sec14.35.2:
    // "A server MAY ignore the Range header". This means it's possible to
    // get a 200 rather than a 206 response from a range request.
    var ok_response_on_range_request =
        xhrStatus === OK_RESPONSE &&
        pendingRequest.expectedStatus === PARTIAL_CONTENT_RESPONSE;

    if (!ok_response_on_range_request &&
        xhrStatus !== pendingRequest.expectedStatus) {
      if (pendingRequest.onError) {
        pendingRequest.onError(xhr.status);
      }
      return;
    }

    this.loadedRequests[xhrId] = true;

    var chunk = getArrayBuffer(xhr);
    if (xhrStatus === PARTIAL_CONTENT_RESPONSE) {
      var rangeHeader = xhr.getResponseHeader('Content-Range');
      var matches = /bytes (\d+)-(\d+)\/(\d+)/.exec(rangeHeader);
      var begin = parseInt(matches[1], 10);
      pendingRequest.onDone({
        begin,
        chunk,
      });
    } else if (pendingRequest.onProgressiveData) {
      pendingRequest.onDone(null);
    } else if (chunk) {
      pendingRequest.onDone({
        begin: 0,
        chunk,
      });
    } else if (pendingRequest.onError) {
      pendingRequest.onError(xhr.status);
    }
  },

  hasPendingRequests: function NetworkManager_hasPendingRequests() {
    for (var xhrId in this.pendingRequests) {
      return true;
    }
    return false;
  },

  getRequestXhr: function NetworkManager_getXhr(xhrId) {
    return this.pendingRequests[xhrId].xhr;
  },

  isStreamingRequest: function NetworkManager_isStreamingRequest(xhrId) {
    return !!(this.pendingRequests[xhrId].onProgressiveData);
  },

  isPendingRequest: function NetworkManager_isPendingRequest(xhrId) {
    return xhrId in this.pendingRequests;
  },

  isLoadedRequest: function NetworkManager_isLoadedRequest(xhrId) {
    return xhrId in this.loadedRequests;
  },

  abortAllRequests: function NetworkManager_abortAllRequests() {
    for (var xhrId in this.pendingRequests) {
      this.abortRequest(xhrId | 0);
    }
  },

  abortRequest: function NetworkManager_abortRequest(xhrId) {
    var xhr = this.pendingRequests[xhrId].xhr;
    delete this.pendingRequests[xhrId];
    xhr.abort();
  },
};

/** @implements {IPDFStream} */
function PDFNetworkStream(options) {
  this._options = options;
  var source = options.source;
  this._manager = new NetworkManager(source.url, {
    httpHeaders: source.httpHeaders,
    withCredentials: source.withCredentials,
  });
  this._rangeChunkSize = source.rangeChunkSize;
  this._fullRequestReader = null;
  this._rangeRequestReaders = [];
}

PDFNetworkStream.prototype = {
  _onRangeRequestReaderClosed:
      function PDFNetworkStream_onRangeRequestReaderClosed(reader) {
    var i = this._rangeRequestReaders.indexOf(reader);
    if (i >= 0) {
      this._rangeRequestReaders.splice(i, 1);
    }
  },

  getFullReader: function PDFNetworkStream_getFullReader() {
    assert(!this._fullRequestReader);
    this._fullRequestReader =
      new PDFNetworkStreamFullRequestReader(this._manager, this._options);
    return this._fullRequestReader;
  },

  getRangeReader: function PDFNetworkStream_getRangeReader(begin, end) {
    var reader = new PDFNetworkStreamRangeRequestReader(this._manager,
                                                        begin, end);
    reader.onClosed = this._onRangeRequestReaderClosed.bind(this);
    this._rangeRequestReaders.push(reader);
    return reader;
  },

  cancelAllRequests: function PDFNetworkStream_cancelAllRequests(reason) {
    if (this._fullRequestReader) {
      this._fullRequestReader.cancel(reason);
    }
    var readers = this._rangeRequestReaders.slice(0);
    readers.forEach(function (reader) {
      reader.cancel(reason);
    });
  },
};

/** @implements {IPDFStreamReader} */
function PDFNetworkStreamFullRequestReader(manager, options) {
  this._manager = manager;

  var source = options.source;
  var args = {
    onHeadersReceived: this._onHeadersReceived.bind(this),
    onProgressiveData: source.disableStream ? null :
                       this._onProgressiveData.bind(this),
    onDone: this._onDone.bind(this),
    onError: this._onError.bind(this),
    onProgress: this._onProgress.bind(this),
  };
  this._url = source.url;
  this._fullRequestId = manager.requestFull(args);
  this._headersReceivedCapability = createPromiseCapability();
  this._disableRange = options.disableRange || false;
  this._contentLength = source.length; // optional
  this._rangeChunkSize = source.rangeChunkSize;
  if (!this._rangeChunkSize && !this._disableRange) {
    this._disableRange = true;
  }

  this._isStreamingSupported = false;
  this._isRangeSupported = false;

  this._cachedChunks = [];
  this._requests = [];
  this._done = false;
  this._storedError = undefined;

  this.onProgress = null;
}

PDFNetworkStreamFullRequestReader.prototype = {
  _validateRangeRequestCapabilities: function
      PDFNetworkStreamFullRequestReader_validateRangeRequestCapabilities() {

    if (this._disableRange) {
      return false;
    }

    var networkManager = this._manager;
    if (!networkManager.isHttp) {
      return false;
    }
    var fullRequestXhrId = this._fullRequestId;
    var fullRequestXhr = networkManager.getRequestXhr(fullRequestXhrId);
    if (fullRequestXhr.getResponseHeader('Accept-Ranges') !== 'bytes') {
      return false;
    }

    var contentEncoding =
      fullRequestXhr.getResponseHeader('Content-Encoding') || 'identity';
    if (contentEncoding !== 'identity') {
      return false;
    }

    var length = fullRequestXhr.getResponseHeader('Content-Length');
    length = parseInt(length, 10);
    if (!isInt(length)) {
      return false;
    }

    this._contentLength = length; // setting right content length

    if (length <= 2 * this._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 false;
    }

    return true;
  },

  _onHeadersReceived:
      function PDFNetworkStreamFullRequestReader_onHeadersReceived() {

    if (this._validateRangeRequestCapabilities()) {
      this._isRangeSupported = true;
    }

    var networkManager = this._manager;
    var fullRequestXhrId = this._fullRequestId;
    if (networkManager.isStreamingRequest(fullRequestXhrId)) {
      // We can continue fetching when progressive loading is enabled,
      // and we don't need the autoFetch feature.
      this._isStreamingSupported = true;
    } else if (this._isRangeSupported) {
      // NOTE: by cancelling the full request, and then issuing range
      // requests, there will be an issue for sites where you can only
      // request the pdf once. However, if this is the case, then the
      // server should not be returning that it can support range
      // requests.
      networkManager.abortRequest(fullRequestXhrId);
    }

    this._headersReceivedCapability.resolve();
  },

  _onProgressiveData:
      function PDFNetworkStreamFullRequestReader_onProgressiveData(chunk) {
    if (this._requests.length > 0) {
      var requestCapability = this._requests.shift();
      requestCapability.resolve({ value: chunk, done: false, });
    } else {
      this._cachedChunks.push(chunk);
    }
  },

  _onDone: function PDFNetworkStreamFullRequestReader_onDone(args) {
    if (args) {
      this._onProgressiveData(args.chunk);
    }
    this._done = true;
    if (this._cachedChunks.length > 0) {
      return;
    }
    this._requests.forEach(function (requestCapability) {
      requestCapability.resolve({ value: undefined, done: true, });
    });
    this._requests = [];
  },

  _onError: function PDFNetworkStreamFullRequestReader_onError(status) {
    var url = this._url;
    var exception;
    if (status === 404 || status === 0 && /^file:/.test(url)) {
      exception = new MissingPDFException('Missing PDF "' + url + '".');
    } else {
      exception = new UnexpectedResponseException(
        'Unexpected server response (' + status +
        ') while retrieving PDF "' + url + '".', status);
    }
    this._storedError = exception;
    this._headersReceivedCapability.reject(exception);
    this._requests.forEach(function (requestCapability) {
      requestCapability.reject(exception);
    });
    this._requests = [];
    this._cachedChunks = [];
  },

  _onProgress: function PDFNetworkStreamFullRequestReader_onProgress(data) {
    if (this.onProgress) {
      this.onProgress({
        loaded: data.loaded,
        total: data.lengthComputable ? data.total : this._contentLength,
      });
    }
  },

  get isRangeSupported() {
    return this._isRangeSupported;
  },

  get isStreamingSupported() {
    return this._isStreamingSupported;
  },

  get contentLength() {
    return this._contentLength;
  },

  get headersReady() {
    return this._headersReceivedCapability.promise;
  },

  read: function PDFNetworkStreamFullRequestReader_read() {
    if (this._storedError) {
      return Promise.reject(this._storedError);
    }
    if (this._cachedChunks.length > 0) {
      var chunk = this._cachedChunks.shift();
      return Promise.resolve({ value: chunk, done: false, });
    }
    if (this._done) {
      return Promise.resolve({ value: undefined, done: true, });
    }
    var requestCapability = createPromiseCapability();
    this._requests.push(requestCapability);
    return requestCapability.promise;
  },

  cancel: function PDFNetworkStreamFullRequestReader_cancel(reason) {
    this._done = true;
    this._headersReceivedCapability.reject(reason);
    this._requests.forEach(function (requestCapability) {
      requestCapability.resolve({ value: undefined, done: true, });
    });
    this._requests = [];
    if (this._manager.isPendingRequest(this._fullRequestId)) {
      this._manager.abortRequest(this._fullRequestId);
    }
    this._fullRequestReader = null;
  },
};

/** @implements {IPDFStreamRangeReader} */
function PDFNetworkStreamRangeRequestReader(manager, begin, end) {
  this._manager = manager;
  var args = {
    onDone: this._onDone.bind(this),
    onProgress: this._onProgress.bind(this),
  };
  this._requestId = manager.requestRange(begin, end, args);
  this._requests = [];
  this._queuedChunk = null;
  this._done = false;

  this.onProgress = null;
  this.onClosed = null;
}

PDFNetworkStreamRangeRequestReader.prototype = {
  _close: function PDFNetworkStreamRangeRequestReader_close() {
    if (this.onClosed) {
      this.onClosed(this);
    }
  },

  _onDone: function PDFNetworkStreamRangeRequestReader_onDone(data) {
    var chunk = data.chunk;
    if (this._requests.length > 0) {
      var requestCapability = this._requests.shift();
      requestCapability.resolve({ value: chunk, done: false, });
    } else {
      this._queuedChunk = chunk;
    }
    this._done = true;
    this._requests.forEach(function (requestCapability) {
      requestCapability.resolve({ value: undefined, done: true, });
    });
    this._requests = [];
    this._close();
  },

  _onProgress: function PDFNetworkStreamRangeRequestReader_onProgress(evt) {
    if (!this.isStreamingSupported && this.onProgress) {
      this.onProgress({
        loaded: evt.loaded,
      });
    }
  },

  get isStreamingSupported() {
    return false; // TODO allow progressive range bytes loading
  },

  read: function PDFNetworkStreamRangeRequestReader_read() {
    if (this._queuedChunk !== null) {
      var chunk = this._queuedChunk;
      this._queuedChunk = null;
      return Promise.resolve({ value: chunk, done: false, });
    }
    if (this._done) {
      return Promise.resolve({ value: undefined, done: true, });
    }
    var requestCapability = createPromiseCapability();
    this._requests.push(requestCapability);
    return requestCapability.promise;
  },

  cancel: function PDFNetworkStreamRangeRequestReader_cancel(reason) {
    this._done = true;
    this._requests.forEach(function (requestCapability) {
      requestCapability.resolve({ value: undefined, done: true, });
    });
    this._requests = [];
    if (this._manager.isPendingRequest(this._requestId)) {
      this._manager.abortRequest(this._requestId);
    }
    this._close();
  },
};

setPDFNetworkStreamClass(PDFNetworkStream);

export {
  PDFNetworkStream,
  NetworkManager,
};
