/**
 * Adds support for the <code>curve</code> property for the <code>to</code>
 * attribute.  A curve is zero or more control points and an end point.
 * @module anim
 * @submodule anim-curve
 */

Y.Anim.behaviors.curve = {
    set: function(anim, att, from, to, elapsed, duration, fn) {
        from = from.slice.call(from);
        to = to.slice.call(to);
        var t = fn(elapsed, 0, 100, duration) / 100;
        to.unshift(from);
        anim._node.setXY(Y.Anim.getBezier(to, t));
    },

    get: function(anim) {
        return anim._node.getXY();
    }
};

/**
 * Get the current position of the animated element based on t.
 * Each point is an array of "x" and "y" values (0 = x, 1 = y)
 * At least 2 points are required (start and end).
 * First point is start. Last point is end.
 * Additional control points are optional.
 * @for Anim
 * @method getBezier
 * @static
 * @param {Array} points An array containing Bezier points
 * @param {Number} t A number between 0 and 1 which is the basis for determining current position
 * @return {Array} An array containing int x and y member data
 */
Y.Anim.getBezier = function(points, t) {
    var n = points.length,
        tmp = [],
        i,
        j;

    for (i = 0; i < n; ++i){
        tmp[i] = [points[i][0], points[i][1]]; // save input
    }

    for (j = 1; j < n; ++j) {
        for (i = 0; i < n - j; ++i) {
            tmp[i][0] = (1 - t) * tmp[i][0] + t * tmp[parseInt(i + 1, 10)][0];
            tmp[i][1] = (1 - t) * tmp[i][1] + t * tmp[parseInt(i + 1, 10)][1];
        }
    }

    return [ tmp[0][0], tmp[0][1] ];

};