/* -*- Mode: Java; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/* vim: set shiftwidth=2 tabstop=2 autoindent cindent expandtab: */
/* Copyright 2015 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.
 */
/* globals PDFViewer, PDFHistory, Promise, parseQueryString */

'use strict';

/**
 * Performs navigation functions inside PDF, such as opening specified page,
 * or destination.
 * @class
 * @implements {IPDFLinkService}
 */
var PDFLinkService = (function () {
  /**
   * @constructs PDFLinkService
   */
  function PDFLinkService() {
    this.baseUrl = null;
    this.pdfDocument = null;
    this.pdfViewer = null;
    this.pdfHistory = null;

    this._pagesRefCache = null;
  }

  PDFLinkService.prototype = {
    setDocument: function PDFLinkService_setDocument(pdfDocument, baseUrl) {
      this.baseUrl = baseUrl;
      this.pdfDocument = pdfDocument;
      this._pagesRefCache = Object.create(null);
    },

    setViewer: function PDFLinkService_setViewer(pdfViewer) {
      this.pdfViewer = pdfViewer;
    },

    setHistory: function PDFLinkService_setHistory(pdfHistory) {
      this.pdfHistory = pdfHistory;
    },

    /**
     * @returns {number}
     */
    get pagesCount() {
      return this.pdfDocument.numPages;
    },

    /**
     * @returns {number}
     */
    get page() {
      return this.pdfViewer.currentPageNumber;
    },

    /**
     * @param {number} value
     */
    set page(value) {
      this.pdfViewer.currentPageNumber = value;
    },

    /**
     * @param dest - The PDF destination object.
     */
    navigateTo: function PDFLinkService_navigateTo(dest) {
      var destString = '';
      var self = this;

      var goToDestination = function(destRef) {
        // dest array looks like that: <page-ref> </XYZ|FitXXX> <args..>
        var pageNumber = destRef instanceof Object ?
          self._pagesRefCache[destRef.num + ' ' + destRef.gen + ' R'] :
          (destRef + 1);
        if (pageNumber) {
          if (pageNumber > self.pagesCount) {
            pageNumber = self.pagesCount;
          }
          self.pdfViewer.scrollPageIntoView(pageNumber, dest);

          if (self.pdfHistory) {
            // Update the browsing history.
            self.pdfHistory.push({
              dest: dest,
              hash: destString,
              page: pageNumber
            });
          }
        } else {
          self.pdfDocument.getPageIndex(destRef).then(function (pageIndex) {
            var pageNum = pageIndex + 1;
            var cacheKey = destRef.num + ' ' + destRef.gen + ' R';
            self._pagesRefCache[cacheKey] = pageNum;
            goToDestination(destRef);
          });
        }
      };

      var destinationPromise;
      if (typeof dest === 'string') {
        destString = dest;
        destinationPromise = this.pdfDocument.getDestination(dest);
      } else {
        destinationPromise = Promise.resolve(dest);
      }
      destinationPromise.then(function(destination) {
        dest = destination;
        if (!(destination instanceof Array)) {
          return; // invalid destination
        }
        goToDestination(destination[0]);
      });
    },

    /**
     * @param dest - The PDF destination object.
     * @returns {string} The hyperlink to the PDF object.
     */
    getDestinationHash: function PDFLinkService_getDestinationHash(dest) {
      if (typeof dest === 'string') {
        return this.getAnchorUrl('#' + escape(dest));
      }
      if (dest instanceof Array) {
        var destRef = dest[0]; // see navigateTo method for dest format
        var pageNumber = destRef instanceof Object ?
          this._pagesRefCache[destRef.num + ' ' + destRef.gen + ' R'] :
          (destRef + 1);
        if (pageNumber) {
          var pdfOpenParams = this.getAnchorUrl('#page=' + pageNumber);
          var destKind = dest[1];
          if (typeof destKind === 'object' && 'name' in destKind &&
              destKind.name === 'XYZ') {
            var scale = (dest[4] || this.pdfViewer.currentScaleValue);
            var scaleNumber = parseFloat(scale);
            if (scaleNumber) {
              scale = scaleNumber * 100;
            }
            pdfOpenParams += '&zoom=' + scale;
            if (dest[2] || dest[3]) {
              pdfOpenParams += ',' + (dest[2] || 0) + ',' + (dest[3] || 0);
            }
          }
          return pdfOpenParams;
        }
      }
      return '';
    },

    /**
     * Prefix the full url on anchor links to make sure that links are resolved
     * relative to the current URL instead of the one defined in <base href>.
     * @param {String} anchor The anchor hash, including the #.
     * @returns {string} The hyperlink to the PDF object.
     */
    getAnchorUrl: function PDFLinkService_getAnchorUrl(anchor) {
      return (this.baseUrl || '') + anchor;
    },

    /**
     * @param {string} hash
     */
    setHash: function PDFLinkService_setHash(hash) {
      if (hash.indexOf('=') >= 0) {
        var params = parseQueryString(hash);
        // borrowing syntax from "Parameters for Opening PDF Files"
        if ('nameddest' in params) {
          if (this.pdfHistory) {
            this.pdfHistory.updateNextHashParam(params.nameddest);
          }
          this.navigateTo(params.nameddest);
          return;
        }
        var pageNumber, dest;
        if ('page' in params) {
          pageNumber = (params.page | 0) || 1;
        }
        if ('zoom' in params) {
          // Build the destination array.
          var zoomArgs = params.zoom.split(','); // scale,left,top
          var zoomArg = zoomArgs[0];
          var zoomArgNumber = parseFloat(zoomArg);

          if (zoomArg.indexOf('Fit') === -1) {
            // If the zoomArg is a number, it has to get divided by 100. If it's
            // a string, it should stay as it is.
            dest = [null, { name: 'XYZ' },
                    zoomArgs.length > 1 ? (zoomArgs[1] | 0) : null,
                    zoomArgs.length > 2 ? (zoomArgs[2] | 0) : null,
                    (zoomArgNumber ? zoomArgNumber / 100 : zoomArg)];
          } else {
            if (zoomArg === 'Fit' || zoomArg === 'FitB') {
              dest = [null, { name: zoomArg }];
            } else if ((zoomArg === 'FitH' || zoomArg === 'FitBH') ||
                       (zoomArg === 'FitV' || zoomArg === 'FitBV')) {
              dest = [null, { name: zoomArg },
                      zoomArgs.length > 1 ? (zoomArgs[1] | 0) : null];
            } else if (zoomArg === 'FitR') {
              if (zoomArgs.length !== 5) {
                console.error('PDFLinkService_setHash: ' +
                              'Not enough parameters for \'FitR\'.');
              } else {
                dest = [null, { name: zoomArg },
                        (zoomArgs[1] | 0), (zoomArgs[2] | 0),
                        (zoomArgs[3] | 0), (zoomArgs[4] | 0)];
              }
            } else {
              console.error('PDFLinkService_setHash: \'' + zoomArg +
                            '\' is not a valid zoom value.');
            }
          }
        }
        if (dest) {
          this.pdfViewer.scrollPageIntoView(pageNumber || this.page, dest);
        } else if (pageNumber) {
          this.page = pageNumber; // simple page
        }
        if ('pagemode' in params) {
          var event = document.createEvent('CustomEvent');
          event.initCustomEvent('pagemode', true, true, {
            mode: params.pagemode,
          });
          this.pdfViewer.container.dispatchEvent(event);
        }
      } else if (/^\d+$/.test(hash)) { // page number
        this.page = hash;
      } else { // named destination
        if (this.pdfHistory) {
          this.pdfHistory.updateNextHashParam(unescape(hash));
        }
        this.navigateTo(unescape(hash));
      }
    },

    /**
     * @param {string} action
     */
    executeNamedAction: function PDFLinkService_executeNamedAction(action) {
      // See PDF reference, table 8.45 - Named action
      switch (action) {
        case 'GoBack':
          if (this.pdfHistory) {
            this.pdfHistory.back();
          }
          break;

        case 'GoForward':
          if (this.pdfHistory) {
            this.pdfHistory.forward();
          }
          break;

        case 'NextPage':
          this.page++;
          break;

        case 'PrevPage':
          this.page--;
          break;

        case 'LastPage':
          this.page = this.pagesCount;
          break;

        case 'FirstPage':
          this.page = 1;
          break;

        default:
          break; // No action according to spec
      }

      var event = document.createEvent('CustomEvent');
      event.initCustomEvent('namedaction', true, true, {
        action: action
      });
      this.pdfViewer.container.dispatchEvent(event);
    },

    /**
     * @param {number} pageNum - page number.
     * @param {Object} pageRef - reference to the page.
     */
    cachePageRef: function PDFLinkService_cachePageRef(pageNum, pageRef) {
      var refStr = pageRef.num + ' ' + pageRef.gen + ' R';
      this._pagesRefCache[refStr] = pageNum;
    }
  };

  return PDFLinkService;
})();