diffux/diffux

define([
    "../core",
    "../css"
], function( jQuery ) {

function Tween( elem, options, prop, end, easing ) {
    return new Tween.prototype.init( elem, options, prop, end, easing );
}
jQuery.Tween = Tween;

Tween.prototype = {
    constructor: Tween,
    init: function( elem, options, prop, end, easing, unit ) {
        this.elem = elem;
        this.prop = prop;
        this.easing = easing || "swing";
        this.options = options;
        this.start = this.now = this.cur();
        this.end = end;
        this.unit = unit || ( jQuery.cssNumber[ prop ] ? "" : "px" );
    },
    cur: function() {
        var hooks = Tween.propHooks[ this.prop ];

        return hooks && hooks.get ?
            hooks.get( this ) :
            Tween.propHooks._default.get( this );
    },
    run: function( percent ) {
        var eased,
            hooks = Tween.propHooks[ this.prop ];

        if ( this.options.duration ) {
            this.pos = eased = jQuery.easing[ this.easing ](
                percent, this.options.duration * percent, 0, 1, this.options.duration
            );
        } else {
            this.pos = eased = percent;
        }
        this.now = ( this.end - this.start ) * eased + this.start;

        if ( this.options.step ) {
            this.options.step.call( this.elem, this.now, this );
        }

        if ( hooks && hooks.set ) {
            hooks.set( this );
        } else {
            Tween.propHooks._default.set( this );
        }
        return this;
    }
};

Tween.prototype.init.prototype = Tween.prototype;

Tween.propHooks = {
    _default: {
        get: function( tween ) {
            var result;

            if ( tween.elem[ tween.prop ] != null &&
                (!tween.elem.style || tween.elem.style[ tween.prop ] == null) ) {
                return tween.elem[ tween.prop ];
            }

            // Passing an empty string as a 3rd parameter to .css will automatically
            // attempt a parseFloat and fallback to a string if the parse fails.
            // Simple values such as "10px" are parsed to Float;
            // complex values such as "rotate(1rad)" are returned as-is.
            result = jQuery.css( tween.elem, tween.prop, "" );
            // Empty strings, null, undefined and "auto" are converted to 0.
            return !result || result === "auto" ? 0 : result;
        },
        set: function( tween ) {
            // Use step hook for back compat.
            // Use cssHook if its there.
            // Use .style if available and use plain properties where available.
            if ( jQuery.fx.step[ tween.prop ] ) {
                jQuery.fx.step[ tween.prop ]( tween );
            } else if ( tween.elem.style && ( tween.elem.style[ jQuery.cssProps[ tween.prop ] ] != null || jQuery.cssHooks[ tween.prop ] ) ) {
                jQuery.style( tween.elem, tween.prop, tween.now + tween.unit );
            } else {
                tween.elem[ tween.prop ] = tween.now;
            }
        }
    }
};

// Support: IE9
// Panic based approach to setting things on disconnected nodes
Tween.propHooks.scrollTop = Tween.propHooks.scrollLeft = {
    set: function( tween ) {
        if ( tween.elem.nodeType && tween.elem.parentNode ) {
            tween.elem[ tween.prop ] = tween.now;
        }
    }
};

jQuery.easing = {
    linear: function( p ) {
        return p;
    },
    swing: function( p ) {
        return 0.5 - Math.cos( p * Math.PI ) / 2;
    }
};

jQuery.fx = Tween.prototype.init;

// Back Compat <1.8 extension point
jQuery.fx.step = {};

});