/**
 * @private
 * @class Ext.slider.Thumb
 * @extends Ext.Base
 * @private
 * Represents a single thumb element on a Slider. This would not usually be created manually and would instead
 * be created internally by an {@link Ext.slider.Multi Ext.Slider}.
 */
Ext.define('Ext.slider.Thumb', {
    requires: ['Ext.dd.DragTracker', 'Ext.util.Format'],
    /**
     * @private
     * @property topThumbZIndex
     * @type Number
     * The number used internally to set the z index of the top thumb (see promoteThumb for details)
     */
    topZIndex: 10000,
    /**
     * @constructor
     * @cfg {Ext.slider.MultiSlider} slider The Slider to render to (required)
     */
    constructor: function(config) {
        var me = this;
        
        /**
         * @property slider
         * @type Ext.slider.MultiSlider
         * The slider this thumb is contained within
         */
        Ext.apply(me, config || {}, {
            cls: Ext.baseCSSPrefix + 'slider-thumb',

            /**
             * @cfg {Boolean} constrain True to constrain the thumb so that it cannot overlap its siblings
             */
            constrain: false
        });
        me.callParent([config]);

        if (me.slider.vertical) {
            Ext.apply(me, Ext.slider.Thumb.Vertical);
        }
    },

    /**
     * Renders the thumb into a slider
     */
    render: function() {
        var me = this;
        
        me.el = me.slider.innerEl.insertFirst({cls: me.cls});
        if (me.disabled) {
            me.disable();
        }
        me.initEvents();
    },
    
    /**
     * @private
     * move the thumb
     */
    move: function(v, animate){
        if(!animate){
            this.el.setLeft(v);
        }else{
            Ext.create('Ext.fx.Anim', {
                target: this.el,
                duration: 350,
                to: {
                    left: v
                }
            });
        }
    },

    /**
     * @private
     * Bring thumb dom element to front.
     */
    bringToFront: function() {
        this.el.setStyle('zIndex', this.topZIndex);
    },
    
    /**
     * @private
     * Send thumb dom element to back.
     */
    sendToBack: function() {
        this.el.setStyle('zIndex', '');
    },
    
    /**
     * Enables the thumb if it is currently disabled
     */
    enable: function() {
        var me = this;
        
        me.disabled = false;
        if (me.el) {
            me.el.removeCls(me.slider.disabledCls);
        }
    },

    /**
     * Disables the thumb if it is currently enabled
     */
    disable: function() {
        var me = this;
        
        me.disabled = true;
        if (me.el) {
            me.el.addCls(me.slider.disabledCls);
        }
    },

    /**
     * Sets up an Ext.dd.DragTracker for this thumb
     */
    initEvents: function() {
        var me = this,
            el = me.el;

        me.tracker = Ext.create('Ext.dd.DragTracker', {
            onBeforeStart: Ext.Function.bind(me.onBeforeDragStart, me),
            onStart      : Ext.Function.bind(me.onDragStart, me),
            onDrag       : Ext.Function.bind(me.onDrag, me),
            onEnd        : Ext.Function.bind(me.onDragEnd, me),
            tolerance    : 3,
            autoStart    : 300,
            overCls      : Ext.baseCSSPrefix + 'slider-thumb-over'
        });

        me.tracker.initEl(el);
    },

    /**
     * @private
     * This is tied into the internal Ext.dd.DragTracker. If the slider is currently disabled,
     * this returns false to disable the DragTracker too.
     * @return {Boolean} False if the slider is currently disabled
     */
    onBeforeDragStart : function(e) {
        if (this.disabled) {
            return false;
        } else {
            this.slider.promoteThumb(this);
            return true;
        }
    },

    /**
     * @private
     * This is tied into the internal Ext.dd.DragTracker's onStart template method. Adds the drag CSS class
     * to the thumb and fires the 'dragstart' event
     */
    onDragStart: function(e){
        var me = this;
        
        me.el.addCls(Ext.baseCSSPrefix + 'slider-thumb-drag');
        me.dragging = true;
        me.dragStartValue = me.value;

        me.slider.fireEvent('dragstart', me.slider, e, me);
    },

    /**
     * @private
     * This is tied into the internal Ext.dd.DragTracker's onDrag template method. This is called every time
     * the DragTracker detects a drag movement. It updates the Slider's value using the position of the drag
     */
    onDrag: function(e) {
        var me       = this,
            slider   = me.slider,
            index    = me.index,
            newValue = me.getNewValue(),
            above,
            below;

        if (me.constrain) {
            above = slider.thumbs[index + 1];
            below = slider.thumbs[index - 1];

            if (below !== undefined && newValue <= below.value) {
                newValue = below.value;
            }
            
            if (above !== undefined && newValue >= above.value) {
                newValue = above.value;
            }
        }

        slider.setValue(index, newValue, false);
        slider.fireEvent('drag', slider, e, me);
    },

    getNewValue: function() {
        var slider = this.slider,
            pos = slider.innerEl.translatePoints(this.tracker.getXY());

        return Ext.util.Format.round(slider.reverseValue(pos.left), slider.decimalPrecision);
    },

    /**
     * @private
     * This is tied to the internal Ext.dd.DragTracker's onEnd template method. Removes the drag CSS class and
     * fires the 'changecomplete' event with the new value
     */
    onDragEnd: function(e) {
        var me     = this,
            slider = me.slider,
            value  = me.value;

        me.el.removeCls(Ext.baseCSSPrefix + 'slider-thumb-drag');

        me.dragging = false;
        slider.fireEvent('dragend', slider, e);

        if (me.dragStartValue != value) {
            slider.fireEvent('changecomplete', slider, value, me);
        }
    },

    destroy: function() {
        Ext.destroy(this.tracker);
    },
    statics: {
        // Method overrides to support vertical dragging of thumb within slider
        Vertical: {
            getNewValue: function() {
                var slider   = this.slider,
                    innerEl  = slider.innerEl,
                    pos      = innerEl.translatePoints(this.tracker.getXY()),
                    bottom   = innerEl.getHeight() - pos.top;

                return Ext.util.Format.round(slider.reverseValue(bottom), slider.decimalPrecision);
            },
            move: function(v, animate) {
                if (!animate) {
                    this.el.setBottom(v);
                } else {
                    Ext.create('Ext.fx.Anim', {
                        target: this.el,
                        duration: 350,
                        to: {
                            bottom: v
                        }
                    });
                }
            }
        }
    }
});
