CaffGeek/MBACNationals

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Web.Admin/2014/wordpress/wp-admin/js/revisions.js

Summary

Maintainability
F
3 days
Test Coverage
/* global _wpRevisionsSettings, isRtl */
window.wp = window.wp || {};

(function($) {
    var revisions;

    revisions = wp.revisions = { model: {}, view: {}, controller: {} };

    // Link settings.
    revisions.settings = _.isUndefined( _wpRevisionsSettings ) ? {} : _wpRevisionsSettings;

    // For debugging
    revisions.debug = false;

    revisions.log = function() {
        if ( window.console && revisions.debug ) {
            window.console.log.apply( window.console, arguments );
        }
    };

    // Handy functions to help with positioning
    $.fn.allOffsets = function() {
        var offset = this.offset() || {top: 0, left: 0}, win = $(window);
        return _.extend( offset, {
            right:  win.width()  - offset.left - this.outerWidth(),
            bottom: win.height() - offset.top  - this.outerHeight()
        });
    };

    $.fn.allPositions = function() {
        var position = this.position() || {top: 0, left: 0}, parent = this.parent();
        return _.extend( position, {
            right:  parent.outerWidth()  - position.left - this.outerWidth(),
            bottom: parent.outerHeight() - position.top  - this.outerHeight()
        });
    };

    // wp_localize_script transforms top-level numbers into strings. Undo that.
    if ( revisions.settings.to ) {
        revisions.settings.to = parseInt( revisions.settings.to, 10 );
    }
    if ( revisions.settings.from ) {
        revisions.settings.from = parseInt( revisions.settings.from, 10 );
    }

    // wp_localize_script does not allow for top-level booleans. Fix that.
    if ( revisions.settings.compareTwoMode ) {
        revisions.settings.compareTwoMode = revisions.settings.compareTwoMode === '1';
    }

    /**
     * ========================================================================
     * MODELS
     * ========================================================================
     */
    revisions.model.Slider = Backbone.Model.extend({
        defaults: {
            value: null,
            values: null,
            min: 0,
            max: 1,
            step: 1,
            range: false,
            compareTwoMode: false
        },

        initialize: function( options ) {
            this.frame = options.frame;
            this.revisions = options.revisions;

            // Listen for changes to the revisions or mode from outside
            this.listenTo( this.frame, 'update:revisions', this.receiveRevisions );
            this.listenTo( this.frame, 'change:compareTwoMode', this.updateMode );

            // Listen for internal changes
            this.listenTo( this, 'change:from', this.handleLocalChanges );
            this.listenTo( this, 'change:to', this.handleLocalChanges );
            this.listenTo( this, 'change:compareTwoMode', this.updateSliderSettings );
            this.listenTo( this, 'update:revisions', this.updateSliderSettings );

            // Listen for changes to the hovered revision
            this.listenTo( this, 'change:hoveredRevision', this.hoverRevision );

            this.set({
                max:   this.revisions.length - 1,
                compareTwoMode: this.frame.get('compareTwoMode'),
                from: this.frame.get('from'),
                to: this.frame.get('to')
            });
            this.updateSliderSettings();
        },

        getSliderValue: function( a, b ) {
            return isRtl ? this.revisions.length - this.revisions.indexOf( this.get(a) ) - 1 : this.revisions.indexOf( this.get(b) );
        },

        updateSliderSettings: function() {
            if ( this.get('compareTwoMode') ) {
                this.set({
                    values: [
                        this.getSliderValue( 'to', 'from' ),
                        this.getSliderValue( 'from', 'to' )
                    ],
                    value: null,
                    range: true // ensures handles cannot cross
                });
            } else {
                this.set({
                    value: this.getSliderValue( 'to', 'to' ),
                    values: null,
                    range: false
                });
            }
            this.trigger( 'update:slider' );
        },

        // Called when a revision is hovered
        hoverRevision: function( model, value ) {
            this.trigger( 'hovered:revision', value );
        },

        // Called when `compareTwoMode` changes
        updateMode: function( model, value ) {
            this.set({ compareTwoMode: value });
        },

        // Called when `from` or `to` changes in the local model
        handleLocalChanges: function() {
            this.frame.set({
                from: this.get('from'),
                to: this.get('to')
            });
        },

        // Receives revisions changes from outside the model
        receiveRevisions: function( from, to ) {
            // Bail if nothing changed
            if ( this.get('from') === from && this.get('to') === to ) {
                return;
            }

            this.set({ from: from, to: to }, { silent: true });
            this.trigger( 'update:revisions', from, to );
        }

    });

    revisions.model.Tooltip = Backbone.Model.extend({
        defaults: {
            revision: null,
            offset: {},
            hovering: false, // Whether the mouse is hovering
            scrubbing: false // Whether the mouse is scrubbing
        },

        initialize: function( options ) {
            this.frame = options.frame;
            this.revisions = options.revisions;
            this.slider = options.slider;

            this.listenTo( this.slider, 'hovered:revision', this.updateRevision );
            this.listenTo( this.slider, 'change:hovering', this.setHovering );
            this.listenTo( this.slider, 'change:scrubbing', this.setScrubbing );
        },


        updateRevision: function( revision ) {
            this.set({ revision: revision });
        },

        setHovering: function( model, value ) {
            this.set({ hovering: value });
        },

        setScrubbing: function( model, value ) {
            this.set({ scrubbing: value });
        }
    });

    revisions.model.Revision = Backbone.Model.extend({});

    revisions.model.Revisions = Backbone.Collection.extend({
        model: revisions.model.Revision,

        initialize: function() {
            _.bindAll( this, 'next', 'prev' );
        },

        next: function( revision ) {
            var index = this.indexOf( revision );

            if ( index !== -1 && index !== this.length - 1 ) {
                return this.at( index + 1 );
            }
        },

        prev: function( revision ) {
            var index = this.indexOf( revision );

            if ( index !== -1 && index !== 0 ) {
                return this.at( index - 1 );
            }
        }
    });

    revisions.model.Field = Backbone.Model.extend({});

    revisions.model.Fields = Backbone.Collection.extend({
        model: revisions.model.Field
    });

    revisions.model.Diff = Backbone.Model.extend({
        initialize: function() {
            var fields = this.get('fields');
            this.unset('fields');

            this.fields = new revisions.model.Fields( fields );
        }
    });

    revisions.model.Diffs = Backbone.Collection.extend({
        initialize: function( models, options ) {
            _.bindAll( this, 'getClosestUnloaded' );
            this.loadAll = _.once( this._loadAll );
            this.revisions = options.revisions;
            this.requests  = {};
        },

        model: revisions.model.Diff,

        ensure: function( id, context ) {
            var diff     = this.get( id ),
                request  = this.requests[ id ],
                deferred = $.Deferred(),
                ids      = {},
                from     = id.split(':')[0],
                to       = id.split(':')[1];
            ids[id] = true;

            wp.revisions.log( 'ensure', id );

            this.trigger( 'ensure', ids, from, to, deferred.promise() );

            if ( diff ) {
                deferred.resolveWith( context, [ diff ] );
            } else {
                this.trigger( 'ensure:load', ids, from, to, deferred.promise() );
                _.each( ids, _.bind( function( id ) {
                    // Remove anything that has an ongoing request
                    if ( this.requests[ id ] ) {
                        delete ids[ id ];
                    }
                    // Remove anything we already have
                    if ( this.get( id ) ) {
                        delete ids[ id ];
                    }
                }, this ) );
                if ( ! request ) {
                    // Always include the ID that started this ensure
                    ids[ id ] = true;
                    request   = this.load( _.keys( ids ) );
                }

                request.done( _.bind( function() {
                    deferred.resolveWith( context, [ this.get( id ) ] );
                }, this ) ).fail( _.bind( function() {
                    deferred.reject();
                }) );
            }

            return deferred.promise();
        },

        // Returns an array of proximal diffs
        getClosestUnloaded: function( ids, centerId ) {
            var self = this;
            return _.chain([0].concat( ids )).initial().zip( ids ).sortBy( function( pair ) {
                return Math.abs( centerId - pair[1] );
            }).map( function( pair ) {
                return pair.join(':');
            }).filter( function( diffId ) {
                return _.isUndefined( self.get( diffId ) ) && ! self.requests[ diffId ];
            }).value();
        },

        _loadAll: function( allRevisionIds, centerId, num ) {
            var self = this, deferred = $.Deferred(),
                diffs = _.first( this.getClosestUnloaded( allRevisionIds, centerId ), num );
            if ( _.size( diffs ) > 0 ) {
                this.load( diffs ).done( function() {
                    self._loadAll( allRevisionIds, centerId, num ).done( function() {
                        deferred.resolve();
                    });
                }).fail( function() {
                    if ( 1 === num ) { // Already tried 1. This just isn't working. Give up.
                        deferred.reject();
                    } else { // Request fewer diffs this time
                        self._loadAll( allRevisionIds, centerId, Math.ceil( num / 2 ) ).done( function() {
                            deferred.resolve();
                        });
                    }
                });
            } else {
                deferred.resolve();
            }
            return deferred;
        },

        load: function( comparisons ) {
            wp.revisions.log( 'load', comparisons );
            // Our collection should only ever grow, never shrink, so remove: false
            return this.fetch({ data: { compare: comparisons }, remove: false }).done( function() {
                wp.revisions.log( 'load:complete', comparisons );
            });
        },

        sync: function( method, model, options ) {
            if ( 'read' === method ) {
                options = options || {};
                options.context = this;
                options.data = _.extend( options.data || {}, {
                    action: 'get-revision-diffs',
                    post_id: revisions.settings.postId
                });

                var deferred = wp.ajax.send( options ),
                    requests = this.requests;

                // Record that we're requesting each diff.
                if ( options.data.compare ) {
                    _.each( options.data.compare, function( id ) {
                        requests[ id ] = deferred;
                    });
                }

                // When the request completes, clear the stored request.
                deferred.always( function() {
                    if ( options.data.compare ) {
                        _.each( options.data.compare, function( id ) {
                            delete requests[ id ];
                        });
                    }
                });

                return deferred;

            // Otherwise, fall back to `Backbone.sync()`.
            } else {
                return Backbone.Model.prototype.sync.apply( this, arguments );
            }
        }
    });


    revisions.model.FrameState = Backbone.Model.extend({
        defaults: {
            loading: false,
            error: false,
            compareTwoMode: false
        },

        initialize: function( attributes, options ) {
            var properties = {};

            _.bindAll( this, 'receiveDiff' );
            this._debouncedEnsureDiff = _.debounce( this._ensureDiff, 200 );

            this.revisions = options.revisions;
            this.diffs = new revisions.model.Diffs( [], { revisions: this.revisions });

            // Set the initial diffs collection provided through the settings
            this.diffs.set( revisions.settings.diffData );

            // Set up internal listeners
            this.listenTo( this, 'change:from', this.changeRevisionHandler );
            this.listenTo( this, 'change:to', this.changeRevisionHandler );
            this.listenTo( this, 'change:compareTwoMode', this.changeMode );
            this.listenTo( this, 'update:revisions', this.updatedRevisions );
            this.listenTo( this.diffs, 'ensure:load', this.updateLoadingStatus );
            this.listenTo( this, 'update:diff', this.updateLoadingStatus );

            // Set the initial revisions, baseUrl, and mode as provided through settings
            properties.to = this.revisions.get( revisions.settings.to );
            properties.from = this.revisions.get( revisions.settings.from );
            properties.compareTwoMode = revisions.settings.compareTwoMode;
            properties.baseUrl = revisions.settings.baseUrl;
            this.set( properties );

            // Start the router if browser supports History API
            if ( window.history && window.history.pushState ) {
                this.router = new revisions.Router({ model: this });
                Backbone.history.start({ pushState: true });
            }
        },

        updateLoadingStatus: function() {
            this.set( 'error', false );
            this.set( 'loading', ! this.diff() );
        },

        changeMode: function( model, value ) {
            // If we were on the first revision before switching, we have to bump them over one
            if ( value && 0 === this.revisions.indexOf( this.get('to') ) ) {
                this.set({
                    from: this.revisions.at(0),
                    to: this.revisions.at(1)
                });
            }
        },

        updatedRevisions: function( from, to ) {
            if ( this.get( 'compareTwoMode' ) ) {
                // TODO: compare-two loading strategy
            } else {
                this.diffs.loadAll( this.revisions.pluck('id'), to.id, 40 );
            }
        },

        // Fetch the currently loaded diff.
        diff: function() {
            return this.diffs.get( this._diffId );
        },

        // So long as `from` and `to` are changed at the same time, the diff
        // will only be updated once. This is because Backbone updates all of
        // the changed attributes in `set`, and then fires the `change` events.
        updateDiff: function( options ) {
            var from, to, diffId, diff;

            options = options || {};
            from = this.get('from');
            to = this.get('to');
            diffId = ( from ? from.id : 0 ) + ':' + to.id;

            // Check if we're actually changing the diff id.
            if ( this._diffId === diffId ) {
                return $.Deferred().reject().promise();
            }

            this._diffId = diffId;
            this.trigger( 'update:revisions', from, to );

            diff = this.diffs.get( diffId );

            // If we already have the diff, then immediately trigger the update.
            if ( diff ) {
                this.receiveDiff( diff );
                return $.Deferred().resolve().promise();
            // Otherwise, fetch the diff.
            } else {
                if ( options.immediate ) {
                    return this._ensureDiff();
                } else {
                    this._debouncedEnsureDiff();
                    return $.Deferred().reject().promise();
                }
            }
        },

        // A simple wrapper around `updateDiff` to prevent the change event's
        // parameters from being passed through.
        changeRevisionHandler: function() {
            this.updateDiff();
        },

        receiveDiff: function( diff ) {
            // Did we actually get a diff?
            if ( _.isUndefined( diff ) || _.isUndefined( diff.id ) ) {
                this.set({
                    loading: false,
                    error: true
                });
            } else if ( this._diffId === diff.id ) { // Make sure the current diff didn't change
                this.trigger( 'update:diff', diff );
            }
        },

        _ensureDiff: function() {
            return this.diffs.ensure( this._diffId, this ).always( this.receiveDiff );
        }
    });


    /**
     * ========================================================================
     * VIEWS
     * ========================================================================
     */

    // The frame view. This contains the entire page.
    revisions.view.Frame = wp.Backbone.View.extend({
        className: 'revisions',
        template: wp.template('revisions-frame'),

        initialize: function() {
            this.listenTo( this.model, 'update:diff', this.renderDiff );
            this.listenTo( this.model, 'change:compareTwoMode', this.updateCompareTwoMode );
            this.listenTo( this.model, 'change:loading', this.updateLoadingStatus );
            this.listenTo( this.model, 'change:error', this.updateErrorStatus );

            this.views.set( '.revisions-control-frame', new revisions.view.Controls({
                model: this.model
            }) );
        },

        render: function() {
            wp.Backbone.View.prototype.render.apply( this, arguments );

            $('html').css( 'overflow-y', 'scroll' );
            $('#wpbody-content .wrap').append( this.el );
            this.updateCompareTwoMode();
            this.renderDiff( this.model.diff() );
            this.views.ready();

            return this;
        },

        renderDiff: function( diff ) {
            this.views.set( '.revisions-diff-frame', new revisions.view.Diff({
                model: diff
            }) );
        },

        updateLoadingStatus: function() {
            this.$el.toggleClass( 'loading', this.model.get('loading') );
        },

        updateErrorStatus: function() {
            this.$el.toggleClass( 'diff-error', this.model.get('error') );
        },

        updateCompareTwoMode: function() {
            this.$el.toggleClass( 'comparing-two-revisions', this.model.get('compareTwoMode') );
        }
    });

    // The control view.
    // This contains the revision slider, previous/next buttons, the meta info and the compare checkbox.
    revisions.view.Controls = wp.Backbone.View.extend({
        className: 'revisions-controls',

        initialize: function() {
            _.bindAll( this, 'setWidth' );

            // Add the button view
            this.views.add( new revisions.view.Buttons({
                model: this.model
            }) );

            // Add the checkbox view
            this.views.add( new revisions.view.Checkbox({
                model: this.model
            }) );

            // Prep the slider model
            var slider = new revisions.model.Slider({
                frame: this.model,
                revisions: this.model.revisions
            }),

            // Prep the tooltip model
            tooltip = new revisions.model.Tooltip({
                frame: this.model,
                revisions: this.model.revisions,
                slider: slider
            });

            // Add the tooltip view
            this.views.add( new revisions.view.Tooltip({
                model: tooltip
            }) );

            // Add the tickmarks view
            this.views.add( new revisions.view.Tickmarks({
                model: tooltip
            }) );

            // Add the slider view
            this.views.add( new revisions.view.Slider({
                model: slider
            }) );

            // Add the Metabox view
            this.views.add( new revisions.view.Metabox({
                model: this.model
            }) );
        },

        ready: function() {
            this.top = this.$el.offset().top;
            this.window = $(window);
            this.window.on( 'scroll.wp.revisions', {controls: this}, function(e) {
                var controls  = e.data.controls,
                    container = controls.$el.parent(),
                    scrolled  = controls.window.scrollTop(),
                    frame     = controls.views.parent;

                if ( scrolled >= controls.top ) {
                    if ( ! frame.$el.hasClass('pinned') ) {
                        controls.setWidth();
                        container.css('height', container.height() + 'px' );
                        controls.window.on('resize.wp.revisions.pinning click.wp.revisions.pinning', {controls: controls}, function(e) {
                            e.data.controls.setWidth();
                        });
                    }
                    frame.$el.addClass('pinned');
                } else if ( frame.$el.hasClass('pinned') ) {
                    controls.window.off('.wp.revisions.pinning');
                    controls.$el.css('width', 'auto');
                    frame.$el.removeClass('pinned');
                    container.css('height', 'auto');
                    controls.top = controls.$el.offset().top;
                } else {
                    controls.top = controls.$el.offset().top;
                }
            });
        },

        setWidth: function() {
            this.$el.css('width', this.$el.parent().width() + 'px');
        }
    });

    // The tickmarks view
    revisions.view.Tickmarks = wp.Backbone.View.extend({
        className: 'revisions-tickmarks',
        direction: isRtl ? 'right' : 'left',

        initialize: function() {
            this.listenTo( this.model, 'change:revision', this.reportTickPosition );
        },

        reportTickPosition: function( model, revision ) {
            var offset, thisOffset, parentOffset, tick, index = this.model.revisions.indexOf( revision );
            thisOffset = this.$el.allOffsets();
            parentOffset = this.$el.parent().allOffsets();
            if ( index === this.model.revisions.length - 1 ) {
                // Last one
                offset = {
                    rightPlusWidth: thisOffset.left - parentOffset.left + 1,
                    leftPlusWidth: thisOffset.right - parentOffset.right + 1
                };
            } else {
                // Normal tick
                tick = this.$('div:nth-of-type(' + (index + 1) + ')');
                offset = tick.allPositions();
                _.extend( offset, {
                    left: offset.left + thisOffset.left - parentOffset.left,
                    right: offset.right + thisOffset.right - parentOffset.right
                });
                _.extend( offset, {
                    leftPlusWidth: offset.left + tick.outerWidth(),
                    rightPlusWidth: offset.right + tick.outerWidth()
                });
            }
            this.model.set({ offset: offset });
        },

        ready: function() {
            var tickCount, tickWidth;
            tickCount = this.model.revisions.length - 1;
            tickWidth = 1 / tickCount;
            this.$el.css('width', ( this.model.revisions.length * 50 ) + 'px');

            _(tickCount).times( function( index ){
                this.$el.append( '<div style="' + this.direction + ': ' + ( 100 * tickWidth * index ) + '%"></div>' );
            }, this );
        }
    });

    // The metabox view
    revisions.view.Metabox = wp.Backbone.View.extend({
        className: 'revisions-meta',

        initialize: function() {
            // Add the 'from' view
            this.views.add( new revisions.view.MetaFrom({
                model: this.model,
                className: 'diff-meta diff-meta-from'
            }) );

            // Add the 'to' view
            this.views.add( new revisions.view.MetaTo({
                model: this.model
            }) );
        }
    });

    // The revision meta view (to be extended)
    revisions.view.Meta = wp.Backbone.View.extend({
        template: wp.template('revisions-meta'),

        events: {
            'click .restore-revision': 'restoreRevision'
        },

        initialize: function() {
            this.listenTo( this.model, 'update:revisions', this.render );
        },

        prepare: function() {
            return _.extend( this.model.toJSON()[this.type] || {}, {
                type: this.type
            });
        },

        restoreRevision: function() {
            document.location = this.model.get('to').attributes.restoreUrl;
        }
    });

    // The revision meta 'from' view
    revisions.view.MetaFrom = revisions.view.Meta.extend({
        className: 'diff-meta diff-meta-from',
        type: 'from'
    });

    // The revision meta 'to' view
    revisions.view.MetaTo = revisions.view.Meta.extend({
        className: 'diff-meta diff-meta-to',
        type: 'to'
    });

    // The checkbox view.
    revisions.view.Checkbox = wp.Backbone.View.extend({
        className: 'revisions-checkbox',
        template: wp.template('revisions-checkbox'),

        events: {
            'click .compare-two-revisions': 'compareTwoToggle'
        },

        initialize: function() {
            this.listenTo( this.model, 'change:compareTwoMode', this.updateCompareTwoMode );
        },

        ready: function() {
            if ( this.model.revisions.length < 3 ) {
                $('.revision-toggle-compare-mode').hide();
            }
        },

        updateCompareTwoMode: function() {
            this.$('.compare-two-revisions').prop( 'checked', this.model.get('compareTwoMode') );
        },

        // Toggle the compare two mode feature when the compare two checkbox is checked.
        compareTwoToggle: function() {
            // Activate compare two mode?
            this.model.set({ compareTwoMode: $('.compare-two-revisions').prop('checked') });
        }
    });

    // The tooltip view.
    // Encapsulates the tooltip.
    revisions.view.Tooltip = wp.Backbone.View.extend({
        className: 'revisions-tooltip',
        template: wp.template('revisions-meta'),

        initialize: function() {
            this.listenTo( this.model, 'change:offset', this.render );
            this.listenTo( this.model, 'change:hovering', this.toggleVisibility );
            this.listenTo( this.model, 'change:scrubbing', this.toggleVisibility );
        },

        prepare: function() {
            if ( _.isNull( this.model.get('revision') ) ) {
                return;
            } else {
                return _.extend( { type: 'tooltip' }, {
                    attributes: this.model.get('revision').toJSON()
                });
            }
        },

        render: function() {
            var otherDirection,
                direction,
                directionVal,
                flipped,
                css      = {},
                position = this.model.revisions.indexOf( this.model.get('revision') ) + 1;

            flipped = ( position / this.model.revisions.length ) > 0.5;
            if ( isRtl ) {
                direction = flipped ? 'left' : 'right';
                directionVal = flipped ? 'leftPlusWidth' : direction;
            } else {
                direction = flipped ? 'right' : 'left';
                directionVal = flipped ? 'rightPlusWidth' : direction;
            }
            otherDirection = 'right' === direction ? 'left': 'right';
            wp.Backbone.View.prototype.render.apply( this, arguments );
            css[direction] = this.model.get('offset')[directionVal] + 'px';
            css[otherDirection] = '';
            this.$el.toggleClass( 'flipped', flipped ).css( css );
        },

        visible: function() {
            return this.model.get( 'scrubbing' ) || this.model.get( 'hovering' );
        },

        toggleVisibility: function() {
            if ( this.visible() ) {
                this.$el.stop().show().fadeTo( 100 - this.el.style.opacity * 100, 1 );
            } else {
                this.$el.stop().fadeTo( this.el.style.opacity * 300, 0, function(){ $(this).hide(); } );
            }
            return;
        }
    });

    // The buttons view.
    // Encapsulates all of the configuration for the previous/next buttons.
    revisions.view.Buttons = wp.Backbone.View.extend({
        className: 'revisions-buttons',
        template: wp.template('revisions-buttons'),

        events: {
            'click .revisions-next .button': 'nextRevision',
            'click .revisions-previous .button': 'previousRevision'
        },

        initialize: function() {
            this.listenTo( this.model, 'update:revisions', this.disabledButtonCheck );
        },

        ready: function() {
            this.disabledButtonCheck();
        },

        // Go to a specific model index
        gotoModel: function( toIndex ) {
            var attributes = {
                to: this.model.revisions.at( toIndex )
            };
            // If we're at the first revision, unset 'from'.
            if ( toIndex ) {
                attributes.from = this.model.revisions.at( toIndex - 1 );
            } else {
                this.model.unset('from', { silent: true });
            }

            this.model.set( attributes );
        },

        // Go to the 'next' revision
        nextRevision: function() {
            var toIndex = this.model.revisions.indexOf( this.model.get('to') ) + 1;
            this.gotoModel( toIndex );
        },

        // Go to the 'previous' revision
        previousRevision: function() {
            var toIndex = this.model.revisions.indexOf( this.model.get('to') ) - 1;
            this.gotoModel( toIndex );
        },

        // Check to see if the Previous or Next buttons need to be disabled or enabled.
        disabledButtonCheck: function() {
            var maxVal   = this.model.revisions.length - 1,
                minVal   = 0,
                next     = $('.revisions-next .button'),
                previous = $('.revisions-previous .button'),
                val      = this.model.revisions.indexOf( this.model.get('to') );

            // Disable "Next" button if you're on the last node.
            next.prop( 'disabled', ( maxVal === val ) );

            // Disable "Previous" button if you're on the first node.
            previous.prop( 'disabled', ( minVal === val ) );
        }
    });


    // The slider view.
    revisions.view.Slider = wp.Backbone.View.extend({
        className: 'wp-slider',
        direction: isRtl ? 'right' : 'left',

        events: {
            'mousemove' : 'mouseMove'
        },

        initialize: function() {
            _.bindAll( this, 'start', 'slide', 'stop', 'mouseMove', 'mouseEnter', 'mouseLeave' );
            this.listenTo( this.model, 'update:slider', this.applySliderSettings );
        },

        ready: function() {
            this.$el.css('width', ( this.model.revisions.length * 50 ) + 'px');
            this.$el.slider( _.extend( this.model.toJSON(), {
                start: this.start,
                slide: this.slide,
                stop:  this.stop
            }) );

            this.$el.hoverIntent({
                over: this.mouseEnter,
                out: this.mouseLeave,
                timeout: 800
            });

            this.applySliderSettings();
        },

        mouseMove: function( e ) {
            var zoneCount         = this.model.revisions.length - 1, // One fewer zone than models
                sliderFrom        = this.$el.allOffsets()[this.direction], // "From" edge of slider
                sliderWidth       = this.$el.width(), // Width of slider
                tickWidth         = sliderWidth / zoneCount, // Calculated width of zone
                actualX           = ( isRtl ? $(window).width() - e.pageX : e.pageX ) - sliderFrom, // Flipped for RTL - sliderFrom;
                currentModelIndex = Math.floor( ( actualX  + ( tickWidth / 2 )  ) / tickWidth ); // Calculate the model index

            // Ensure sane value for currentModelIndex.
            if ( currentModelIndex < 0 ) {
                currentModelIndex = 0;
            } else if ( currentModelIndex >= this.model.revisions.length ) {
                currentModelIndex = this.model.revisions.length - 1;
            }

            // Update the tooltip mode
            this.model.set({ hoveredRevision: this.model.revisions.at( currentModelIndex ) });
        },

        mouseLeave: function() {
            this.model.set({ hovering: false });
        },

        mouseEnter: function() {
            this.model.set({ hovering: true });
        },

        applySliderSettings: function() {
            this.$el.slider( _.pick( this.model.toJSON(), 'value', 'values', 'range' ) );
            var handles = this.$('a.ui-slider-handle');

            if ( this.model.get('compareTwoMode') ) {
                // in RTL mode the 'left handle' is the second in the slider, 'right' is first
                handles.first()
                    .toggleClass( 'to-handle', !! isRtl )
                    .toggleClass( 'from-handle', ! isRtl );
                handles.last()
                    .toggleClass( 'from-handle', !! isRtl )
                    .toggleClass( 'to-handle', ! isRtl );
            } else {
                handles.removeClass('from-handle to-handle');
            }
        },

        start: function( event, ui ) {
            this.model.set({ scrubbing: true });

            // Track the mouse position to enable smooth dragging,
            // overrides default jQuery UI step behavior.
            $( window ).on( 'mousemove.wp.revisions', { view: this }, function( e ) {
                var handles,
                    view              = e.data.view,
                    leftDragBoundary  = view.$el.offset().left,
                    sliderOffset      = leftDragBoundary,
                    sliderRightEdge   = leftDragBoundary + view.$el.width(),
                    rightDragBoundary = sliderRightEdge,
                    leftDragReset     = '0',
                    rightDragReset    = '100%',
                    handle            = $( ui.handle );

                // In two handle mode, ensure handles can't be dragged past each other.
                // Adjust left/right boundaries and reset points.
                if ( view.model.get('compareTwoMode') ) {
                    handles = handle.parent().find('.ui-slider-handle');
                    if ( handle.is( handles.first() ) ) { // We're the left handle
                        rightDragBoundary = handles.last().offset().left;
                        rightDragReset    = rightDragBoundary - sliderOffset;
                    } else { // We're the right handle
                        leftDragBoundary = handles.first().offset().left + handles.first().width();
                        leftDragReset    = leftDragBoundary - sliderOffset;
                    }
                }

                // Follow mouse movements, as long as handle remains inside slider.
                if ( e.pageX < leftDragBoundary ) {
                    handle.css( 'left', leftDragReset ); // Mouse to left of slider.
                } else if ( e.pageX > rightDragBoundary ) {
                    handle.css( 'left', rightDragReset ); // Mouse to right of slider.
                } else {
                    handle.css( 'left', e.pageX - sliderOffset ); // Mouse in slider.
                }
            } );
        },

        getPosition: function( position ) {
            return isRtl ? this.model.revisions.length - position - 1: position;
        },

        // Responds to slide events
        slide: function( event, ui ) {
            var attributes, movedRevision;
            // Compare two revisions mode
            if ( this.model.get('compareTwoMode') ) {
                // Prevent sliders from occupying same spot
                if ( ui.values[1] === ui.values[0] ) {
                    return false;
                }
                if ( isRtl ) {
                    ui.values.reverse();
                }
                attributes = {
                    from: this.model.revisions.at( this.getPosition( ui.values[0] ) ),
                    to: this.model.revisions.at( this.getPosition( ui.values[1] ) )
                };
            } else {
                attributes = {
                    to: this.model.revisions.at( this.getPosition( ui.value ) )
                };
                // If we're at the first revision, unset 'from'.
                if ( this.getPosition( ui.value ) > 0 ) {
                    attributes.from = this.model.revisions.at( this.getPosition( ui.value ) - 1 );
                } else {
                    attributes.from = undefined;
                }
            }
            movedRevision = this.model.revisions.at( this.getPosition( ui.value ) );

            // If we are scrubbing, a scrub to a revision is considered a hover
            if ( this.model.get('scrubbing') ) {
                attributes.hoveredRevision = movedRevision;
            }

            this.model.set( attributes );
        },

        stop: function() {
            $( window ).off('mousemove.wp.revisions');
            this.model.updateSliderSettings(); // To snap us back to a tick mark
            this.model.set({ scrubbing: false });
        }
    });

    // The diff view.
    // This is the view for the current active diff.
    revisions.view.Diff = wp.Backbone.View.extend({
        className: 'revisions-diff',
        template:  wp.template('revisions-diff'),

        // Generate the options to be passed to the template.
        prepare: function() {
            return _.extend({ fields: this.model.fields.toJSON() }, this.options );
        }
    });

    // The revisions router.
    // Maintains the URL routes so browser URL matches state.
    revisions.Router = Backbone.Router.extend({
        initialize: function( options ) {
            this.model = options.model;

            // Maintain state and history when navigating
            this.listenTo( this.model, 'update:diff', _.debounce( this.updateUrl, 250 ) );
            this.listenTo( this.model, 'change:compareTwoMode', this.updateUrl );
        },

        baseUrl: function( url ) {
            return this.model.get('baseUrl') + url;
        },

        updateUrl: function() {
            var from = this.model.has('from') ? this.model.get('from').id : 0,
                to   = this.model.get('to').id;
            if ( this.model.get('compareTwoMode' ) ) {
                this.navigate( this.baseUrl( '?from=' + from + '&to=' + to ), { replace: true } );
            } else {
                this.navigate( this.baseUrl( '?revision=' + to ), { replace: true } );
            }
        },

        handleRoute: function( a, b ) {
            var compareTwo = _.isUndefined( b );

            if ( ! compareTwo ) {
                b = this.model.revisions.get( a );
                a = this.model.revisions.prev( b );
                b = b ? b.id : 0;
                a = a ? a.id : 0;
            }
        }
    });

    // Initialize the revisions UI.
    revisions.init = function() {
        revisions.view.frame = new revisions.view.Frame({
            model: new revisions.model.FrameState({}, {
                revisions: new revisions.model.Revisions( revisions.settings.revisionData )
            })
        }).render();
    };

    $( revisions.init );
}(jQuery));