// JS
var d3 = window.d3 || require('d3');

// CSS
require('./directed_force.css');

/* Modified from http://bl.ocks.org/d3noob/5141278 */
function directedForceVis(slice) {
  var div = d3.select(slice.selector);

  var render = function () {
    var width = slice.width();
    var height = slice.height() - 25;
    d3.json(slice.jsonEndpoint(), function (error, json) {
      var link_length = json.form_data.link_length || 200;
      var charge = json.form_data.charge || -500;

      if (error !== null) {
        slice.error(error.responseText, error);
        return '';
      }
      var links = json.data;
      var nodes = {};
      // Compute the distinct nodes from the links.
      links.forEach(function (link) {
        link.source = nodes[link.source] || (nodes[link.source] = {
          name: link.source
        });
        link.target = nodes[link.target] || (nodes[link.target] = {
          name: link.target
        });
        link.value = Number(link.value);

        var target_name = link.target.name;
        var source_name = link.source.name;

        if (nodes[target_name].total === undefined) {
          nodes[target_name].total = link.value;
        }
        if (nodes[source_name].total === undefined) {
          nodes[source_name].total = 0;
        }
        if (nodes[target_name].max === undefined) {
          nodes[target_name].max = 0;
        }
        if (link.value > nodes[target_name].max) {
          nodes[target_name].max = link.value;
        }
        if (nodes[target_name].min === undefined) {
          nodes[target_name].min = 0;
        }
        if (link.value > nodes[target_name].min) {
          nodes[target_name].min = link.value;
        }

        nodes[target_name].total += link.value;
      });

      var force = d3.layout.force()
        .nodes(d3.values(nodes))
        .links(links)
        .size([width, height])
        .linkDistance(link_length)
        .charge(charge)
        .on("tick", tick)
        .start();

      var svg = div.append("svg")
        .attr("width", width)
        .attr("height", height);

      // build the arrow.
      svg.append("svg:defs").selectAll("marker")
        .data(["end"]) // Different link/path types can be defined here
        .enter().append("svg:marker") // This section adds in the arrows
        .attr("id", String)
        .attr("viewBox", "0 -5 10 10")
        .attr("refX", 15)
        .attr("refY", -1.5)
        .attr("markerWidth", 6)
        .attr("markerHeight", 6)
        .attr("orient", "auto")
        .append("svg:path")
        .attr("d", "M0,-5L10,0L0,5");

      var edgeScale = d3.scale.linear()
        .range([0.1, 0.5]);
      // add the links and the arrows
      var path = svg.append("svg:g").selectAll("path")
        .data(force.links())
        .enter().append("svg:path")
        .attr("class", "link")
        .style("opacity", function (d) {
          return edgeScale(d.value / d.target.max);
        })
        .attr("marker-end", "url(#end)");

      // define the nodes
      var node = svg.selectAll(".node")
        .data(force.nodes())
        .enter().append("g")
        .attr("class", "node")
        .on("mouseenter", function (d) {
          d3.select(this)
            .select("circle")
            .transition()
            .style('stroke-width', 5);

          d3.select(this)
            .select("text")
            .transition()
            .style('font-size', 25);
        })
        .on("mouseleave", function (d) {
          d3.select(this)
            .select("circle")
            .transition()
            .style('stroke-width', 1.5);
          d3.select(this)
            .select("text")
            .transition()
            .style('font-size', 12);
        })
        .call(force.drag);

      // add the nodes
      var ext = d3.extent(d3.values(nodes), function (d) {
        return Math.sqrt(d.total);
      });
      var circleScale = d3.scale.linear()
        .domain(ext)
        .range([3, 30]);

      node.append("circle")
        .attr("r", function (d) {
          return circleScale(Math.sqrt(d.total));
        });

      // add the text
      node.append("text")
        .attr("x", 6)
        .attr("dy", ".35em")
        .text(function (d) {
          return d.name;
        });

      // add the curvy lines
      function tick() {
        path.attr("d", function (d) {
          var dx = d.target.x - d.source.x,
            dy = d.target.y - d.source.y,
            dr = Math.sqrt(dx * dx + dy * dy);
          return "M" +
            d.source.x + "," +
            d.source.y + "A" +
            dr + "," + dr + " 0 0,1 " +
            d.target.x + "," +
            d.target.y;
        });

        node.attr("transform", function (d) {
          return "translate(" + d.x + "," + d.y + ")";
        });
      }

      slice.done(json);
    });
  };
  return {
    render: render,
    resize: render
  };
}

module.exports = directedForceVis;