function getTransformation(transform) {
    /*
     * This code comes from a StackOverflow answer to a question looking
     * to replace the d3.transform() functionality from v3.
     * http://stackoverflow.com/questions/38224875/replacing-d3-transform-in-d3-v4
     */
    var g = document.createElementNS("http://www.w3.org/2000/svg", "g");

    g.setAttributeNS(null, "transform", transform);
    var matrix = g.transform.baseVal.consolidate()
        .matrix;

    var {
        a,
        b,
        c,
        d,
        e,
        f
    } = matrix;
    var scaleX, scaleY, skewX;
    if (scaleX = Math.sqrt(a * a + b * b)) a /= scaleX, b /= scaleX;
    if (skewX = a * c + b * d) c -= a * skewX, d -= b * skewX;
    if (scaleY = Math.sqrt(c * c + d * d)) c /= scaleY, d /= scaleY, skewX /= scaleY;
    if (a * d < b * c) a = -a, b = -b, skewX = -skewX, scaleX = -scaleX;
    return {
        translateX: e,
        translateY: f,
        rotate: Math.atan2(b, a) * Math.PI / 180,
        skewX: Math.atan(skewX) * Math.PI / 180,
        scaleX: scaleX,
        scaleY: scaleY
    };
}


function arrangeLabels(selection, label_class) {
    var move = 1;
    while (move > 0) {
        move = 0;
        selection.selectAll(label_class)
            .each(function() {
                var that = this;
                var a = this.getBoundingClientRect();
                selection.selectAll(label_class)
                    .each(function() {
                        if (this != that) {
                            var b = this.getBoundingClientRect();
                            if ((Math.abs(a.left - b.left) * 2 < (a.width + b.width)) && (Math.abs(a.top - b.top) * 2 < (a.height + b.height))) {
                                var dx = (Math.max(0, a.right - b.left) + Math.min(0, a.left - b.right)) * 0.01;
                                var dy = (Math.max(0, a.bottom - b.top) + Math.min(0, a.top - b.bottom)) * 0.02;
                                var tt = getTransformation(d3.select(this)
                                    .attr("transform"));
                                var to = getTransformation(d3.select(that)
                                    .attr("transform"));
                                move += Math.abs(dx) + Math.abs(dy);

                                to.translate = [to.translateX + dx, to.translateY + dy];
                                tt.translate = [tt.translateX - dx, tt.translateY - dy];
                                d3.select(this)
                                    .attr("transform", "translate(" + tt.translate + ")");
                                d3.select(that)
                                    .attr("transform", "translate(" + to.translate + ")");
                                a = this.getBoundingClientRect();
                            }
                        }
                    });
            });
    }
}

function wrap(text, width) {
    text.each(function() {
        var text = d3.select(this);
        var words = text.text()
            .split(/\s+/)
            .reverse();
        var word;
        var line = [];
        var lineHeight = 1;
        var y = 0 //text.attr("y");
        var x = 0;
        var dy = parseFloat(text.attr("dy"));
        var dx = parseFloat(text.attr("dx"));
        var tspan = text.text(null)
            .append("tspan")
            .attr("x", x)
            .attr("y", y);
        while (word = words.pop()) {
            line.push(word);
            tspan.text(line.join(" "));
            if (tspan.node()
                .getComputedTextLength() > width - x) {
                line.pop();
                tspan.text(line.join(" "));
                line = [word];
                tspan = text.append("tspan")
                    .attr("x", x)
                    .attr("dy", lineHeight + "em")
                    .attr("dx", dx + "em")
                    .text(word);
            }
        }
    });
}