var width = 960,
    height = 500;

var color = d3.scale.category20();

var d3cola = cola.d3adaptor()
    .avoidOverlaps(true)
    .size([width, height]);

jQuery(function () {
    draw_graph();
});

function draw_graph () {
    var svg = d3.select("body").append("svg")
        .attr("width", width)
        .attr("height", height);

    d3.json("test.json", function (error, graph) {
        var nodeRadius = 5;

        graph.nodes.forEach(function (v) { v.height = v.width = 2 * nodeRadius; });

        d3cola
            .nodes(graph.nodes)
            .links(graph.links)
            .flowLayout("y", 30)
            .symmetricDiffLinkLengths(6)
            .start(10,20,20);

        // define arrow markers for graph links
        svg.append('svg:defs').append('svg:marker')
            .attr('id', 'end-arrow')
            .attr('viewBox', '0 -5 10 10')
            .attr('refX', 6)
            .attr('markerWidth', 3)
            .attr('markerHeight', 3)
            .attr('orient', 'auto')
          .append('svg:path')
            .attr('d', 'M0,-5L10,0L0,5')
            .attr('fill', '#000');

        var path = svg.selectAll(".link")
            .data(graph.links)
          .enter().append('svg:path')
            .attr('class', 'link');

        var node = svg.selectAll(".node")
            .data(graph.nodes)
          .enter().append("circle")
            .attr("class", "node")
            .attr("r", nodeRadius)
            .style("fill", function (d) { return color(d.group); })
            .call(d3cola.drag);

        node.append("title")
            .text(function (d) { return d.name; });

        d3cola.on("tick", function () {
            path.each(function (d) {
                if (isIE()) this.parentNode.insertBefore(this, this);
            });
            // draw directed edges with proper padding from node centers
            path.attr('d', function (d) {
                var deltaX = d.target.x - d.source.x,
                    deltaY = d.target.y - d.source.y,
                    dist = Math.sqrt(deltaX * deltaX + deltaY * deltaY),
                    normX = deltaX / dist,
                    normY = deltaY / dist,
                    sourcePadding = nodeRadius,
                    targetPadding = nodeRadius + 2,
                    sourceX = d.source.x + (sourcePadding * normX),
                    sourceY = d.source.y + (sourcePadding * normY),
                    targetX = d.target.x - (targetPadding * normX),
                    targetY = d.target.y - (targetPadding * normY);
                return 'M' + sourceX + ',' + sourceY + 'L' + targetX + ',' + targetY;
            });

            node.attr("cx", function (d) { return d.x; })
                .attr("cy", function (d) { return d.y; });
        });
        // turn on overlap avoidance after first convergence
        //cola.on("end", function () {
        //    if (!cola.avoidOverlaps()) {
        //        graph.nodes.forEach(function (v) {
        //            v.width = v.height = 10;
        //        });
        //        cola.avoidOverlaps(true);
        //        cola.start();
        //    }
        //});
    });
}

function isIE() {
    return (navigator.appName == 'Microsoft Internet Explorer') ||
            ((navigator.appName == 'Netscape') &&
             (new RegExp("Trident/.*rv:([0-9]{1,}[\.0-9]{0,})").exec(navigator.userAgent)
              != null));
}