/web/js/backbone.paginator.js

/*! backbone.paginator - v0.8.1 - 7/3/2013
* http://github.com/addyosmani/backbone.paginator
* Copyright (c) 2013 Addy Osmani; Licensed MIT */
/*globals Backbone:true, _:true, jQuery:true*/
Backbone.Paginator = (function ( Backbone, _, $ ) {
  "use strict";


  var bbVer = _.map(Backbone.VERSION.split('.'), function(digit) {
    return parseInt(digit, 10);
  });

  var Paginator = {};
  Paginator.version = "0.8.1";

  // @name: clientPager
  //
  // @tagline: Paginator for client-side data
  //
  // @description:
  // This paginator is responsible for providing pagination
  // and sort capabilities for a single payload of data
  // we wish to paginate by the UI for easier browsering.
  //
  Paginator.clientPager = Backbone.Collection.extend({

    // DEFAULTS FOR SORTING & FILTERING
    useDiacriticsPlugin: true, // use diacritics plugin if available
    useLevenshteinPlugin: true, // use levenshtein plugin if available
    sortColumn: "",
    sortDirection: "desc",
    lastSortColumn: "",
    fieldFilterRules: [],
    lastFieldFilterRules: [],
    filterFields: "",
    filterExpression: "",
    lastFilterExpression: "",

    //DEFAULT PAGINATOR UI VALUES
    defaults_ui: {
      firstPage: 0,
      currentPage: 1,
      perPage: 5,
      totalPages: 10,
      pagesInRange: 4
    },

    // Default values used when sorting and/or filtering.
    initialize: function(){
      //LISTEN FOR ADD & REMOVE EVENTS THEN REMOVE MODELS FROM ORGINAL MODELS
      this.on('add', this.addModel, this);
      this.on('remove', this.removeModel, this);

      // SET DEFAULT VALUES (ALLOWS YOU TO POPULATE PAGINATOR MAUNALLY)
      this.setDefaults();
    },


    setDefaults: function() {
      // SET DEFAULT UI SETTINGS
      var options = _.defaults(this.paginator_ui, this.defaults_ui);

      //UPDATE GLOBAL UI SETTINGS
      _.defaults(this, options);
    },

    addModel: function(model) {
      this.origModels.push(model);
    },

    removeModel: function(model) {
      var index = _.indexOf(this.origModels, model);

      this.origModels.splice(index, 1);
    },

    sync: function ( method, model, options ) {
      var self = this;

      // SET DEFAULT VALUES
      this.setDefaults();

      // Some values could be functions, let's make sure
      // to change their scope too and run them
      var queryAttributes = {};
      _.each(_.result(self, "server_api"), function(value, key){
        if( _.isFunction(value) ) {
          value = _.bind(value, self);
          value = value();
        }
        queryAttributes[key] = value;
      });

      var queryOptions = _.clone(self.paginator_core);
      _.each(queryOptions, function(value, key){
        if( _.isFunction(value) ) {
          value = _.bind(value, self);
          value = value();
        }
        queryOptions[key] = value;
      });

      // Create default values if no others are specified
      queryOptions = _.defaults(queryOptions, {
        timeout: 25000,
        cache: false,
        type: 'GET',
        dataType: 'jsonp'
      });

      queryOptions = _.extend(queryOptions, {
        data: decodeURIComponent($.param(queryAttributes)),
        processData: false,
        url: _.result(queryOptions, 'url')
      }, options);

      var promiseSuccessFormat = !(bbVer[0] === 0 &&
                                   bbVer[1] === 9 &&
                                   bbVer[2] === 10);

      var success = queryOptions.success;
      queryOptions.success = function ( resp, status, xhr ) {
        if ( success ) {
          // This is to keep compatibility with Backbone 0.9.10
          if (promiseSuccessFormat) {
            success( resp, status, xhr );
          } else {
            success( model, resp, queryOptions );
          }
        }
        if ( model && model.trigger ) {
          model.trigger( 'sync', model, resp, queryOptions );
        }
      };

      var error = queryOptions.error;
      queryOptions.error = function ( xhr ) {
        if ( error ) {
          error( model, xhr, queryOptions );
        }
        if ( model && model.trigger ) {
          model.trigger( 'error', model, xhr, queryOptions );
        }
      };

      var xhr = queryOptions.xhr = Backbone.ajax( queryOptions );
      if ( model && model.trigger ) {
        model.trigger('request', model, xhr, queryOptions);
      }
      return xhr;
    },

    nextPage: function (options) {
      if(this.currentPage < this.information.totalPages) {
        this.currentPage = ++this.currentPage;
        this.pager(options);
      }
    },

    previousPage: function (options) {
      if(this.currentPage > 1) {
        this.currentPage = --this.currentPage;
        this.pager(options);
      }
    },

    goTo: function ( page, options ) {
      if(page !== undefined){
        this.currentPage = parseInt(page, 10);
        this.pager(options);
      }
    },

    howManyPer: function ( perPage ) {
      if(perPage !== undefined){
        var lastPerPage = this.perPage;
        this.perPage = parseInt(perPage, 10);
        this.currentPage = Math.ceil( ( lastPerPage * ( this.currentPage - 1 ) + 1 ) / perPage);
        this.pager();
      }
    },


    // setSort is used to sort the current model. After
    // passing 'column', which is the model's field you want
    // to filter and 'direction', which is the direction
    // desired for the ordering ('asc' or 'desc'), pager()
    // and info() will be called automatically.
    setSort: function ( column, direction ) {
      if(column !== undefined && direction !== undefined){
        this.lastSortColumn = this.sortColumn;
        this.sortColumn = column;
        this.sortDirection = direction;
        this.pager();
        this.info();
      }
    },

    // setFieldFilter is used to filter each value of each model
    // according to `rules` that you pass as argument.
    // Example: You have a collection of books with 'release year' and 'author'.
    // You can filter only the books that were released between 1999 and 2003
    // And then you can add another `rule` that will filter those books only to
    // authors who's name start with 'A'.
    setFieldFilter: function ( fieldFilterRules ) {
      if( !_.isEmpty( fieldFilterRules ) ) {
        this.lastFieldFilterRules = this.fieldFilterRules;
        this.fieldFilterRules = fieldFilterRules;
        this.pager();
        this.info();
        // if all the filters are removed, we should save the last filter
        // and then let the list reset to it's original state.
      } else {
        this.lastFieldFilterRules = this.fieldFilterRules;
        this.fieldFilterRules = '';
        this.pager();
        this.info();
      }
    },

    // doFakeFieldFilter can be used to get the number of models that will remain
    // after calling setFieldFilter with a filter rule(s)
    doFakeFieldFilter: function ( rules ) {
      if( !_.isEmpty( rules ) ) {
        var testModels = this.origModels;
        if (testModels === undefined) {
          testModels = this.models;
        }

        testModels = this._fieldFilter(testModels, rules);

        // To comply with current behavior, also filter by any previously defined setFilter rules.
        if ( this.filterExpression !== "" ) {
          testModels = this._filter(testModels, this.filterFields, this.filterExpression);
        }

        // Return size
        return testModels.length;
      }

    },

    // setFilter is used to filter the current model. After
    // passing 'fields', which can be a string referring to
    // the model's field, an array of strings representing
    // each of the model's fields or an object with the name
    // of the model's field(s) and comparing options (see docs)
    // you wish to filter by and
    // 'filter', which is the word or words you wish to
    // filter by, pager() and info() will be called automatically.
    setFilter: function ( fields, filter ) {
      if( fields !== undefined && filter !== undefined ){
        this.filterFields = fields;
        this.lastFilterExpression = this.filterExpression;
        this.filterExpression = filter;
        this.pager();
        this.info();
      }
    },

    // doFakeFilter can be used to get the number of models that will
    // remain after calling setFilter with a `fields` and `filter` args.
    doFakeFilter: function ( fields, filter ) {
      if( fields !== undefined && filter !== undefined ){
        var testModels = this.origModels;
        if (testModels === undefined) {
          testModels = this.models;
        }

        // To comply with current behavior, first filter by any previously defined setFieldFilter rules.
        if ( !_.isEmpty( this.fieldFilterRules ) ) {
          testModels = this._fieldFilter(testModels, this.fieldFilterRules);
        }

        testModels = this._filter(testModels, fields, filter);

        // Return size
        return testModels.length;
      }
    },


    // pager is used to sort, filter and show the data
    // you expect the library to display.
    pager: function (options) {
      var self = this,
      disp = this.perPage,
      start = (self.currentPage - 1) * disp,
      stop = start + disp;
      // Saving the original models collection is important
      // as we could need to sort or filter, and we don't want
      // to loose the data we fetched from the server.
      if (self.origModels === undefined) {
        self.origModels = self.models;
      }

      self.models = self.origModels.slice();

      // Check if sorting was set using setSort.
      if ( this.sortColumn !== "" ) {
        self.models = self._sort(self.models, this.sortColumn, this.sortDirection);
      }

      // Check if field-filtering was set using setFieldFilter
      if ( !_.isEmpty( this.fieldFilterRules ) ) {
        self.models = self._fieldFilter(self.models, this.fieldFilterRules);
      }

      // Check if filtering was set using setFilter.
      if ( this.filterExpression !== "" ) {
        self.models = self._filter(self.models, this.filterFields, this.filterExpression);
      }

      // If the sorting or the filtering was changed go to the first page
      if ( this.lastSortColumn !== this.sortColumn || this.lastFilterExpression !== this.filterExpression || !_.isEqual(this.fieldFilterRules, this.lastFieldFilterRules) ) {
        start = 0;
        stop = start + disp;
        self.currentPage = 1;

        this.lastSortColumn = this.sortColumn;
        this.lastFieldFilterRules = this.fieldFilterRules;
        this.lastFilterExpression = this.filterExpression;
      }

      // We need to save the sorted and filtered models collection
      // because we'll use that sorted and filtered collection in info().
      self.sortedAndFilteredModels = self.models.slice();
      self.info();
      self.reset(self.models.slice(start, stop));

      // This is somewhat of a hack to get all the nextPage, prevPage, and goTo methods
      // to work with a success callback (as in the requestPager). Realistically there is no failure case here,
      // but maybe we could catch exception and trigger a failure callback?
      _.result(options, 'success');
    },

    // The actual place where the collection is sorted.
    // Check setSort for arguments explicacion.
    _sort: function ( models, sort, direction ) {
      models = models.sort(function (a, b) {
        var ac = a.get(sort),
        bc = b.get(sort);

        if ( _.isUndefined(ac) || _.isUndefined(bc) || ac === null || bc === null ) {
          return 0;
        } else {
          /* Make sure that both ac and bc are lowercase strings.
           * .toString() first so we don't have to worry if ac or bc
           * have other String-only methods.
           */
          ac = ac.toString().toLowerCase();
          bc = bc.toString().toLowerCase();
        }

        if (direction === 'desc') {

          // We need to know if there aren't any non-number characters
          // and that there are numbers-only characters and maybe a dot
          // if we have a float.
          // Oh, also a '-' for negative numbers!
          if((!ac.match(/[^\-\d\.]/) && ac.match(/-?[\d\.]+/)) &&
               (!bc.match(/[^\-\d\.]/) && bc.match(/-?[\d\.]+/))){

            if( (ac - 0) < (bc - 0) ) {
              return 1;
            }
            if( (ac - 0) > (bc - 0) ) {
              return -1;
            }
          } else {
            if (ac < bc) {
              return 1;
            }
            if (ac > bc) {
              return -1;
            }
          }

        } else {

          //Same as the regexp check in the 'if' part.
          if((!ac.match(/[^\-\d\.]/) && ac.match(/-?[\d\.]+/)) &&
             (!bc.match(/[^\-\d\.]/) && bc.match(/-?[\d\.]+/))){
            if( (ac - 0) < (bc - 0) ) {
              return -1;
            }
            if( (ac - 0) > (bc - 0) ) {
              return 1;
            }
          } else {
            if (ac < bc) {
              return -1;
            }
            if (ac > bc) {
              return 1;
            }
          }

        }

        if (a.cid && b.cid){
          var aId = a.cid,
          bId = b.cid;

          if (aId < bId) {
            return -1;
          }
          if (aId > bId) {
            return 1;
          }
        }

        return 0;
      });

      return models;
    },

    // The actual place where the collection is field-filtered.
    // Check setFieldFilter for arguments explicacion.
    _fieldFilter: function( models, rules ) {

      // Check if there are any rules
      if ( _.isEmpty(rules) ) {
        return models;
      }

      var filteredModels = [];

      // Iterate over each rule
      _.each(models, function(model){

        var should_push = true;

        // Apply each rule to each model in the collection
        _.each(rules, function(rule){

          // Don't go inside the switch if we're already sure that the model won't be included in the results
          if( !should_push ){
            return false;
          }

          should_push = false;

          // The field's value will be passed to a custom function, which should
          // return true (if model should be included) or false (model should be ignored)
          if(rule.type === "function"){
            var f = _.wrap(rule.value, function(func){
              return func( model.get(rule.field) );
            });
            if( f() ){
              should_push = true;
            }

            // The field's value is required to be non-empty
          }else if(rule.type === "required"){
            if( !_.isEmpty( model.get(rule.field).toString() ) ) {
              should_push = true;
            }

            // The field's value is required to be greater tan N (numbers only)
          }else if(rule.type === "min"){
            if( !_.isNaN( Number( model.get(rule.field) ) ) &&
               !_.isNaN( Number( rule.value ) ) &&
                 Number( model.get(rule.field) ) >= Number( rule.value ) ) {
              should_push = true;
            }

            // The field's value is required to be smaller tan N (numbers only)
          }else if(rule.type === "max"){
            if( !_.isNaN( Number( model.get(rule.field) ) ) &&
               !_.isNaN( Number( rule.value ) ) &&
                 Number( model.get(rule.field) ) <= Number( rule.value ) ) {
              should_push = true;
            }

            // The field's value is required to be between N and M (numbers only)
          }else if(rule.type === "range"){
            if( !_.isNaN( Number( model.get(rule.field) ) ) &&
               _.isObject( rule.value ) &&
                 !_.isNaN( Number( rule.value.min ) ) &&
                   !_.isNaN( Number( rule.value.max ) ) &&
                     Number( model.get(rule.field) ) >= Number( rule.value.min ) &&
                       Number( model.get(rule.field) ) <= Number( rule.value.max ) ) {
              should_push = true;
            }

            // The field's value is required to be more than N chars long
          }else if(rule.type === "minLength"){
            if( model.get(rule.field).toString().length >= rule.value ) {
              should_push = true;
            }

            // The field's value is required to be no more than N chars long
          }else if(rule.type === "maxLength"){
            if( model.get(rule.field).toString().length <= rule.value ) {
              should_push = true;
            }

            // The field's value is required to be more than N chars long and no more than M chars long
          }else if(rule.type === "rangeLength"){
            if( _.isObject( rule.value ) &&
               !_.isNaN( Number( rule.value.min ) ) &&
                 !_.isNaN( Number( rule.value.max ) ) &&
                   model.get(rule.field).toString().length >= rule.value.min &&
                     model.get(rule.field).toString().length <= rule.value.max ) {
              should_push = true;
            }

            // The field's value is required to be equal to one of the values in rules.value
          }else if(rule.type === "oneOf"){
            if( _.isArray( rule.value ) &&
               _.include( rule.value, model.get(rule.field) ) ) {
              should_push = true;
            }

            // The field's value is required to be equal to the value in rules.value
          }else if(rule.type === "equalTo"){
            if( rule.value === model.get(rule.field) ) {
              should_push = true;
            }

          }else if(rule.type === "containsAllOf"){
            if( _.isArray( rule.value ) &&
                _.isArray(model.get(rule.field)) &&
                _.intersection( rule.value, model.get(rule.field)).length === rule.value.length) {
              should_push = true;
            }

              // The field's value is required to match the regular expression
          }else if(rule.type === "pattern"){
            if( model.get(rule.field).toString().match(rule.value) ) {
              should_push = true;
            }

            //Unknown type
          }else{
            should_push = false;
          }

        });

        if( should_push ){
          filteredModels.push(model);
        }

      });

      return filteredModels;
    },

    // The actual place where the collection is filtered.
    // Check setFilter for arguments explicacion.
    _filter: function ( models, fields, filter ) {

      //  For example, if you had a data model containing cars like { color: '', description: '', hp: '' },
      //  your fields was set to ['color', 'description', 'hp'] and your filter was set
      //  to "Black Mustang 300", the word "Black" will match all the cars that have black color, then
      //  "Mustang" in the description and then the HP in the 'hp' field.
      //  NOTE: "Black Musta 300" will return the same as "Black Mustang 300"

      // We accept fields to be a string, an array or an object
      // but if string or array is passed we need to convert it
      // to an object.

      var self = this;

      var obj_fields = {};

      if( _.isString( fields ) ) {
        obj_fields[fields] = {cmp_method: 'regexp'};
      }else if( _.isArray( fields ) ) {
        _.each(fields, function(field){
          obj_fields[field] = {cmp_method: 'regexp'};
        });
      }else{
        _.each(fields, function( cmp_opts, field ) {
          obj_fields[field] = _.defaults(cmp_opts, { cmp_method: 'regexp' });
        });
      }

      fields = obj_fields;

      //Remove diacritic characters if diacritic plugin is loaded
      if( _.has(Backbone.Paginator, 'removeDiacritics') && self.useDiacriticsPlugin ){
        filter = Backbone.Paginator.removeDiacritics(filter);
      }

      // 'filter' can be only a string.
      // If 'filter' is string we need to convert it to
      // a regular expression.
      // For example, if 'filter' is 'black dog' we need
      // to find every single word, remove duplicated ones (if any)
      // and transform the result to '(black|dog)'
      if( filter === '' || !_.isString(filter) ) {
        return models;
      } else {
        var words = _.map(filter.match(/\w+/ig), function(element) { return element.toLowerCase(); });
        var pattern = "(" + _.uniq(words).join("|") + ")";
        var regexp = new RegExp(pattern, "igm");
      }

      var filteredModels = [];

      // We need to iterate over each model
      _.each( models, function( model ) {

        var matchesPerModel = [];

        // and over each field of each model
        _.each( fields, function( cmp_opts, field ) {

          var value = model.get( field );

          if( value ) {

            // The regular expression we created earlier let's us detect if a
            // given string contains each and all of the words in the regular expression
            // or not, but in both cases match() will return an array containing all
            // the words it matched.
            var matchesPerField = [];

            if( _.has(Backbone.Paginator, 'removeDiacritics') && self.useDiacriticsPlugin ){
              value = Backbone.Paginator.removeDiacritics(value.toString());
            }else{
              value = value.toString();
            }

            // Levenshtein cmp
            if( cmp_opts.cmp_method === 'levenshtein' && _.has(Backbone.Paginator, 'levenshtein') && self.useLevenshteinPlugin ) {
              var distance = Backbone.Paginator.levenshtein(value, filter);

              _.defaults(cmp_opts, { max_distance: 0 });

              if( distance <= cmp_opts.max_distance ) {
                matchesPerField = _.uniq(words);
              }

              // Default (RegExp) cmp
            }else{
              matchesPerField = value.match( regexp );
            }

            matchesPerField = _.map(matchesPerField, function(match) {
              return match.toString().toLowerCase();
            });

            _.each(matchesPerField, function(match){
              matchesPerModel.push(match);
            });

          }

        });

        // We just need to check if the returned array contains all the words in our
        // regex, and if it does, it means that we have a match, so we should save it.
        matchesPerModel = _.uniq( _.without(matchesPerModel, "") );

        if(  _.isEmpty( _.difference(words, matchesPerModel) ) ) {
          filteredModels.push(model);
        }

      });

      return filteredModels;
    },

    // You shouldn't need to call info() as this method is used to
    // calculate internal data as first/prev/next/last page...
    info: function () {
      var self = this,
      info = {},
      totalRecords = (self.sortedAndFilteredModels) ? self.sortedAndFilteredModels.length : self.length,
      totalPages = Math.ceil(totalRecords / self.perPage);

      info = {
        totalUnfilteredRecords: self.origModels.length,
        totalRecords: totalRecords,
        currentPage: self.currentPage,
        perPage: this.perPage,
        totalPages: totalPages,
        lastPage: totalPages,
        previous: false,
        next: false,
        startRecord: totalRecords === 0 ? 0 : (self.currentPage - 1) * this.perPage + 1,
        endRecord: Math.min(totalRecords, self.currentPage * this.perPage)
      };

      if (self.currentPage > 1) {
        info.previous = self.currentPage - 1;
      }

      if (self.currentPage < info.totalPages) {
        info.next = self.currentPage + 1;
      }

      info.pageSet = self.setPagination(info);

      self.information = info;
      return info;
    },


    // setPagination also is an internal function that shouldn't be called directly.
    // It will create an array containing the pages right before and right after the
    // actual page.
    setPagination: function ( info ) {

      var pages = [], i = 0, l = 0;

      // How many adjacent pages should be shown on each side?
      var ADJACENTx2 = this.pagesInRange * 2,
      LASTPAGE = Math.ceil(info.totalRecords / info.perPage);

      if (LASTPAGE > 1) {

        // not enough pages to bother breaking it up
        if (LASTPAGE <= (1 + ADJACENTx2)) {
          for (i = 1, l = LASTPAGE; i <= l; i++) {
            pages.push(i);
          }
        }

        // enough pages to hide some
        else {

          //close to beginning; only hide later pages
          if (info.currentPage <=  (this.pagesInRange + 1)) {
            for (i = 1, l = 2 + ADJACENTx2; i < l; i++) {
              pages.push(i);
            }
          }

          // in middle; hide some front and some back
          else if (LASTPAGE - this.pagesInRange > info.currentPage && info.currentPage > this.pagesInRange) {
            for (i = info.currentPage - this.pagesInRange; i <= info.currentPage + this.pagesInRange; i++) {
              pages.push(i);
            }
          }

          // close to end; only hide early pages
          else {
            for (i = LASTPAGE - ADJACENTx2; i <= LASTPAGE; i++) {
              pages.push(i);
            }
          }
        }

      }

      return pages;

    },

    bootstrap: function(options) {
      _.extend(this, options);
      this.goTo(1);
      this.info();
      return this;
    }

  });

  // function aliasing
  Paginator.clientPager.prototype.prevPage = Paginator.clientPager.prototype.previousPage;

  // Helper function to generate rejected Deferred
  var reject = function () {
    var response = new $.Deferred();
    response.reject();
    return response.promise();
  };

  // @name: requestPager
  //
  // Paginator for server-side data being requested from a backend/API
  //
  // @description:
  // This paginator is responsible for providing pagination
  // and sort capabilities for requests to a server-side
  // data service (e.g an API)
  //
  Paginator.requestPager = Backbone.Collection.extend({

    sync: function ( method, model, options ) {

      var self = this;

      self.setDefaults();

      // Some values could be functions, let's make sure
      // to change their scope too and run them
      var queryAttributes = {};
      _.each(_.result(self, "server_api"), function(value, key){
        if( _.isFunction(value) ) {
          value = _.bind(value, self);
          value = value();
        }
        queryAttributes[key] = value;
      });

      var queryOptions = _.clone(self.paginator_core);
      _.each(queryOptions, function(value, key){
        if( _.isFunction(value) ) {
          value = _.bind(value, self);
          value = value();
        }
        queryOptions[key] = value;
      });

      // Create default values if no others are specified
      queryOptions = _.defaults(queryOptions, {
        timeout: 25000,
        cache: false,
        type: 'GET',
        dataType: 'jsonp'
      });

      // Allows the passing in of {data: {foo: 'bar'}} at request time to overwrite server_api defaults
      if( options.data ){
        options.data = decodeURIComponent($.param(_.extend(queryAttributes,options.data)));
      }else{
        options.data = decodeURIComponent($.param(queryAttributes));
      }

      queryOptions = _.extend(queryOptions, {
        data: decodeURIComponent($.param(queryAttributes)),
        processData: false,
        url: _.result(queryOptions, 'url')
      }, options);

      var promiseSuccessFormat = !(bbVer[0] === 0 &&
                                   bbVer[1] === 9 &&
                                   bbVer[2] === 10);

      var success = queryOptions.success;
      queryOptions.success = function ( resp, status, xhr ) {

        if ( success ) {
          // This is to keep compatibility with Backbone 0.9.10
          if (promiseSuccessFormat) {
            success( resp, status, xhr );
          } else {
            success( model, resp, queryOptions );
          }
        }
        if (bbVer[0] < 1 && model && model.trigger ) {
          model.trigger( 'sync', model, resp, queryOptions );
        }
      };

      var error = queryOptions.error;
      queryOptions.error = function ( xhr ) {
        if ( error ) {
          error( xhr );
        }
        if ( model && model.trigger ) {
          model.trigger( 'error', model, xhr, queryOptions );
        }
      };

      var xhr = queryOptions.xhr = Backbone.ajax( queryOptions );
      if ( model && model.trigger ) {
        model.trigger('request', model, xhr, queryOptions);
      }
      return xhr;
    },

    setDefaults: function() {
      var self = this;

      // Create default values if no others are specified
      _.defaults(self.paginator_ui, {
        firstPage: 0,
        currentPage: 1,
        perPage: 5,
        totalPages: 10,
        pagesInRange: 4
      });

      // Change scope of 'paginator_ui' object values
      _.each(self.paginator_ui, function(value, key) {
        if (_.isUndefined(self[key])) {
          self[key] = self.paginator_ui[key];
        }
      });
    },

    requestNextPage: function ( options ) {
      if ( this.currentPage !== undefined ) {
        this.currentPage += 1;
        return this.pager( options );
      } else {
        return reject();
      }
    },

    requestPreviousPage: function ( options ) {
      if ( this.currentPage !== undefined ) {
        this.currentPage -= 1;
        return this.pager( options );
      } else {
        return reject();
      }
    },

    updateOrder: function ( column, options ) {
      if (column !== undefined) {
        this.sortField = column;
        return this.pager( options );
      } else {
        return reject();
      }
    },

    goTo: function ( page, options ) {
      if ( page !== undefined ) {
        this.currentPage = parseInt(page, 10);
        return this.pager( options );
      } else {
        return reject();
      }
    },

    howManyPer: function ( count, options ) {
      if ( count !== undefined ) {
        this.currentPage = this.firstPage;
        this.perPage = count;
        return this.pager( options );
      } else {
        return reject();
      }
    },

    info: function () {

      var info = {
        // If parse() method is implemented and totalRecords is set to the length
        // of the records returned, make it available. Else, default it to 0
        totalRecords: this.totalRecords || 0,

        currentPage: this.currentPage,
        firstPage: this.firstPage,
        totalPages: Math.ceil(this.totalRecords / this.perPage),
        lastPage: this.totalPages, // should use totalPages in template
        perPage: this.perPage,
        previous:false,
        next:false
      };

      if (this.currentPage > 1) {
        info.previous = this.currentPage - 1;
      }

      if (this.currentPage < info.totalPages) {
        info.next = this.currentPage + 1;
      }

      // left around for backwards compatibility
      info.hasNext = info.next;
      info.hasPrevious = info.next;

      info.pageSet = this.setPagination(info);

      this.information = info;
      return info;
    },

    setPagination: function ( info ) {

      var pages = [], i = 0, l = 0;

      // How many adjacent pages should be shown on each side?
      var ADJACENTx2 = this.pagesInRange * 2,
      LASTPAGE = Math.ceil(info.totalRecords / info.perPage);

      if (LASTPAGE > 1) {

        // not enough pages to bother breaking it up
        if (LASTPAGE <= (1 + ADJACENTx2)) {
          for (i = 1, l = LASTPAGE; i <= l; i++) {
            pages.push(i);
          }
        }

        // enough pages to hide some
        else {

          //close to beginning; only hide later pages
          if (info.currentPage <=  (this.pagesInRange + 1)) {
            for (i = 1, l = 2 + ADJACENTx2; i < l; i++) {
              pages.push(i);
            }
          }

          // in middle; hide some front and some back
          else if (LASTPAGE - this.pagesInRange > info.currentPage && info.currentPage > this.pagesInRange) {
            for (i = info.currentPage - this.pagesInRange; i <= info.currentPage + this.pagesInRange; i++) {
              pages.push(i);
            }
          }

          // close to end; only hide early pages
          else {
            for (i = LASTPAGE - ADJACENTx2; i <= LASTPAGE; i++) {
              pages.push(i);
            }
          }
        }

      }

      return pages;

    },

    // fetches the latest results from the server
    pager: function ( options ) {
      if ( !_.isObject(options) ) {
        options = {};
      }
      return this.fetch( options );
    },

    url: function(){
      // Expose url parameter enclosed in this.paginator_core.url to properly
      // extend Collection and allow Collection CRUD
      if(this.paginator_core !== undefined && this.paginator_core.url !== undefined){
        return this.paginator_core.url;
      } else {
        return null;
      }
    },

    bootstrap: function(options) {
      _.extend(this, options);
      this.setDefaults();
      this.info();
      return this;
    }
  });

  // function aliasing
  Paginator.requestPager.prototype.nextPage = Paginator.requestPager.prototype.requestNextPage;
  Paginator.requestPager.prototype.prevPage = Paginator.requestPager.prototype.requestPreviousPage;

  return Paginator;

}( Backbone, _, jQuery ));