/* coding: utf-8 */

var SvgBbox = function (svg) {
    this.svg = svg;
    this.width = document.body.clientWidth;
    this.height = null;
    this.fringe = 0;
    this.scale1px = null;
    this.vaspOption = 1;
};

SvgBbox.prototype.calc = function (id) {
    var chd = this.svg.getElementById(id).childNodes,
        aryX = Array(),
        aryY = Array();

    for (var i = 0, len = chd.length; i < len; i++) {
        var ele = chd[i],
            tgn = ele.tagName;

        if (tgn === 'ellipse') {
            aryX.push(Number(ele.getAttribute('cx')));
            aryY.push(Number(ele.getAttribute('cy')));

        } else if (tgn === 'text') {
            aryX.push(Number(ele.getAttribute('x')));
            aryY.push(Number(ele.getAttribute('y')));

        } else if (tgn === 'path') {
            var seg = ele.pathSegList;
            for (var j = 0, len2 = seg.length; j < len2; j++) {
                var s = seg[j];
                if (s.pathSegType === 2 || s.pathSegType === 4) {
                    // only SVGPathSegMovetoAbs or SVGPathSegLinetoAbs
                    aryX.push(s.x);
                    aryY.push(s.y);
                }
            }
        }
    }

    var x1 = Math.min.apply(null, aryX),
        y1 = Math.min.apply(null, aryY),
        x2 = Math.max.apply(null, aryX),
        y2 = Math.max.apply(null, aryY),
        hh = y2 - y1,
        ww = x2 - x1;

    this.scale1px = ww / this.width;
    this.height = hh / this.scale1px;

    var fgx = this.fringe * this.scale1px,
        fgy = this.fringe * this.scale1px / this.vaspOption;
        fg2x = this.fringe * 2,
        fg2y = this.fringe * 2 / this.vaspOption;

    this.svg.setAttribute('preserveAspectRatio', 'none');
    this.svg.setAttribute('height', this.height * this.vaspOption + fg2y);
    this.svg.setAttribute('width', this.width + fg2x);
    this.svg.setAttribute('viewBox', Array(
        x1 - fgx, y1 - fgy, x2 - x1 + fgx * 2, y2 - y1 + fgy * 2).join(' '));
};