/*

YUI 3.10.3 (build 2fb5187)

Copyright 2013 Yahoo! Inc. All rights reserved.

Licensed under the BSD License.

http://yuilibrary.com/license/

*/

YUI.add('series-curve-util', function (Y, NAME) {

/**

 * Provides functionality for drawing curves in a series.

 *

 * @module charts

 * @submodule series-curve-util

 */

/**

 * Utility class used for calculating curve points.

 *

 * @class CurveUtil

 * @constructor

 * @submodule series-curve-util

 */

function CurveUtil()

{

}

CurveUtil.prototype = {

    /**

     * Creates an array of start, end and control points for splines.

     *

     * @method getCurveControlPoints

     * @param {Array} xcoords Collection of x-coordinates used for calculate the curves

     * @param {Array} ycoords Collection of y-coordinates used for calculate the curves

     * @return Object

     * @protected

     */

    getCurveControlPoints: function(xcoords, ycoords)

    {

		var outpoints = [],

            i = 1,

            l = xcoords.length - 1,

            xvals = [],

            yvals = [];

		// Too few points, need at least two

		if (l < 1)

        {

			return null;

		}

        outpoints[0] = {

            startx: xcoords[0],

            starty: ycoords[0],

            endx: xcoords[1],

            endy: ycoords[1]

        };

		// Special case, the Bezier should be a straight line

        if (l === 1)

        {

			outpoints[0].ctrlx1 = (2.0*xcoords[0] + xcoords[1])/3.0;

			outpoints[0].ctrly2 = (2.0*ycoords[0] + ycoords[1])/3.0;

			outpoints[0].ctrlx2 = 2.0*outpoints[0].ctrlx1 - xcoords[0];

            outpoints[0].ctrly2 = 2.0*outpoints[0].ctrly1 - ycoords[0];

            return outpoints;

		}

		for (; i < l; ++i)

        {

			outpoints.push({

                startx: Math.round(xcoords[i]),

                starty: Math.round(ycoords[i]),

                endx: Math.round(xcoords[i+1]),

                endy: Math.round(ycoords[i+1])

            });

			xvals[i] = 4.0 * xcoords[i] + 2*xcoords[i+1];

			yvals[i] = 4.0*ycoords[i] + 2*ycoords[i+1];

		}

		xvals[0] = xcoords[0] + (2.0 * xcoords[1]);

		xvals[l-1] = (8.0 * xcoords[l-1] + xcoords[l]) / 2.0;

		xvals = this.getControlPoints(xvals.concat());

        yvals[0] = ycoords[0] + (2.0 * ycoords[1]);

		yvals[l-1] = (8.0 * ycoords[l-1] + ycoords[l]) / 2.0;

		yvals = this.getControlPoints(yvals.concat());

        for (i = 0; i < l; ++i)

        {

			outpoints[i].ctrlx1 = Math.round(xvals[i]);

            outpoints[i].ctrly1 = Math.round(yvals[i]);

			if (i < l-1)

            {

				outpoints[i].ctrlx2 = Math.round(2*xcoords[i+1] - xvals[i+1]);

                outpoints[i].ctrly2 = Math.round(2*ycoords[i+1] - yvals[i+1]);

			}

			else

            {

				outpoints[i].ctrlx2 = Math.round((xcoords[l] + xvals[l-1])/2);

                outpoints[i].ctrly2 = Math.round((ycoords[l] + yvals[l-1])/2);

			}

		}

		return outpoints;

	},

    /**

     * Gets the control points for the curve.

     *

     * @method getControlPoints

     * @param {Array} vals Collection of values coords used to generate control points.

     * @return Array

     * @private

     */

	getControlPoints: function(vals)

    {

		var l = vals.length,

            x = [],

            tmp = [],

            b = 2.0,

            i = 1;

		x[0] = vals[0] / b;

		for (; i < l; ++i)

        {

			tmp[i] = 1/b;

			b = (i < l-1 ? 4.0 : 3.5) - tmp[i];

			x[i] = (vals[i] - x[i-1]) / b;

		}

		for (i = 1; i < l; ++i)

        {

			x[l-i-1] -= tmp[l-i] * x[l-i];

		}

		return x;

	}

};

Y.CurveUtil = CurveUtil;

}, '3.10.3');