////////////////////////////////////////////////////////////
//////////////////////// Set-up ////////////////////////////
////////////////////////////////////////////////////////////
var screenWidth = $(window).width();

var margin = {left: 50, top: 10, right: 50, bottom: 10},
	width = Math.min(screenWidth, 800) - margin.left - margin.right,
	height = Math.min(screenWidth, 800)*5/6 - margin.top - margin.bottom;
			
var svg = d3.select("#chart").append("svg")
			.attr("width", (width + margin.left + margin.right))
			.attr("height", (height + margin.top + margin.bottom));
			
var wrapper = svg.append("g").attr("class", "chordWrapper")
			.attr("transform", "translate(" + (width / 2 + margin.left) + "," + (height / 2 + margin.top) + ")");;
			
var outerRadius = Math.min(width, height) / 2  - 100,
	innerRadius = outerRadius * 0.95,
	opacityDefault = 0.7; //default opacity of chords
	
////////////////////////////////////////////////////////////
////////////////////////// Data ////////////////////////////
////////////////////////////////////////////////////////////

var Names = ["X","Y","Z","","C","B","A",""];

var respondents = 95, //Total number of respondents (i.e. the number that makes up the group)
	emptyPerc = 0.4, //What % of the circle should become empty in comparison to the visible arcs
	emptyStroke = Math.round(respondents*emptyPerc); //How many "units" would define this empty percentage
var matrix = [
	[0,0,0,0,10,5,15,0], //X
	[0,0,0,0,5,15,20,0], //Y
	[0,0,0,0,15,5,5,0], //Z
	[0,0,0,0,0,0,0,emptyStroke], //Dummy stroke
	[10,5,15,0,0,0,0,0], //C
	[5,15,5,0,0,0,0,0], //B
	[15,20,5,0,0,0,0,0], //A
	[0,0,0,emptyStroke,0,0,0,0] //Dummy stroke
];
//Calculate how far the Chord Diagram needs to be rotated clockwise
//to make the dummy invisible chord center vertically
var offset = Math.PI * (emptyStroke/(respondents + emptyStroke)) / 2;

var chord = d3.layout.chord()
	.padding(.02)
	.sortSubgroups(d3.descending) //sort the chords inside an arc from high to low
	.sortChords(d3.descending) //which chord should be shown on top when chords cross. Now the biggest chord is at the bottom
	.matrix(matrix);

var arc = d3.svg.arc()
	.innerRadius(innerRadius)
	.outerRadius(outerRadius)
	.startAngle(startAngle) //startAngle and endAngle now include the offset in degrees
	.endAngle(endAngle);

var path = d3.svg.chord()
	.radius(innerRadius)
	.startAngle(startAngle)
	.endAngle(endAngle);
	
var fill = d3.scale.ordinal()
    .domain(d3.range(Names.length))
    .range(["#C4C4C4","#C4C4C4","#C4C4C4","#E0E0E0","#EDC951","#CC333F","#00A0B0","#E0E0E0"]);

////////////////////////////////////////////////////////////
//////////////////// Draw outer Arcs ///////////////////////
////////////////////////////////////////////////////////////

var g = wrapper.selectAll("g.group")
	.data(chord.groups)
	.enter().append("g")
	.attr("class", "group");;

g.append("path")
	.style("stroke", function(d,i) { return (Names[i] === "" ? "none" : "#00A1DE"); })
	.style("fill", function(d,i) { return (Names[i] === "" ? "none" : "#00A1DE"); })
	.attr("d", arc);

////////////////////////////////////////////////////////////
////////////////////// Append Names ////////////////////////
////////////////////////////////////////////////////////////

//The text needs to be rotated with the offset in the clockwise direction
g.append("text")
	.each(function(d) { d.angle = ((d.startAngle + d.endAngle) / 2) + offset;}) //Slightly altered function
	.attr("dy", ".35em")
	.attr("class", "titles")
	.attr("text-anchor", function(d) { return d.angle > Math.PI ? "end" : null; })
	.attr("transform", function(d,i) { 
		var c = arc.centroid(d);
		return "rotate(" + (d.angle * 180 / Math.PI - 90) + ")"
		+ "translate(" + (innerRadius + 55) + ")"
		+ (d.angle > Math.PI ? "rotate(180)" : "")
	})
	.text(function(d,i) { return Names[i]; });

//+ "translate(" + (innerRadius + 55) + ")"

////////////////////////////////////////////////////////////
//////////////////// Draw inner chords /////////////////////
////////////////////////////////////////////////////////////
 
var chords = wrapper.selectAll("path.chord")
	.data(chord.chords)
	.enter().append("path")
	.attr("class", "chord")
	.style("stroke", "none")
	.style("fill", "#C4C4C4")
	.style("opacity", function(d) { return (Names[d.source.index] === "" ? 0 : opacityDefault); }) //Make the dummy strokes have a zero opacity (invisible)
	.attr("d", path);	

////////////////////////////////////////////////////////////
///////////////////////// Tooltip //////////////////////////
////////////////////////////////////////////////////////////

//Arcs
g.append("title")	
	.text(function(d, i) {return Math.round(d.value) + " people in " + Names[i];});
	
//Chords
chords.append("title")
	.text(function(d) {
		return [Math.round(d.source.value), " people from ", Names[d.target.index], " to ", Names[d.source.index]].join(""); 
	});
	
////////////////////////////////////////////////////////////
////////////////// Extra Functions /////////////////////////
////////////////////////////////////////////////////////////

//Include the offset in de start and end angle to rotate the Chord diagram clockwise
function startAngle(d) { return d.startAngle + offset; }
function endAngle(d) { return d.endAngle + offset; }