/* ------------------------------------------------------------------------------
 *
 *  # D3.js - basic chord diagram
 *
 *  Demo chord diagram setup with mouseover interaction
 *
 * ---------------------------------------------------------------------------- */


// Setup module
// ------------------------------

var D3ChordBasic = function() {


    //
    // Setup module components
    //

    // Chart
    var _chordBasic = function() {
        if (typeof d3 == 'undefined') {
            console.warn('Warning - d3.min.js is not loaded.');
            return;
        }

        // Main variables
        var element = document.getElementById('d3-chord-basic');


        // Initialize chart only if element exsists in the DOM
        if(element) {

            // Basic setup
            // ------------------------------

            // Data set
            var data = [
                [6,32,47,81,31,89,24,68,50,39],
                [37,83,57,80,87,7,85,7,68,17],
                [50,15,31,3,1,85,36,95,83,99],
                [37,25,37,81,72,98,32,13,70,25],
                [19,99,97,79,74,43,78,18,4,57],
                [77,2,87,41,93,52,6,42,11,76],
                [44,54,60,69,36,44,76,58,50,16]
            ];



            // Construct layout
            // ------------------------------

            d3.chart = d3.chart || {};

            d3.chart.chord = function(container) {
                var self = {};

                // Main variables
                var w = 400,
                    h = 400,
                    r0 = Math.min(w, h) * .37,
                    r1 = r0 * 1.1;

                // Colors
                var fill = d3.scale.category20c();

                // Add chord layout
                var chord = d3.layout.chord()
                    .padding(.05)
                    .sortSubgroups(d3.descending)

                // Update chart
                self.update = function(data) {
                  chord.matrix(data);
                  self.render();
                };

                // Clear chart
                self.clear = function() {
                    d3.select(container).selectAll('svg').remove();
                };

                // Render chart
                self.render = function() {
                    self.clear();

                    // Create chart
                    var svg = d3.select(container)
                        .append("svg")
                            .attr("width", w)
                            .attr("height", h)
                            .append("g")
                                .attr("transform", "translate(" + w / 2 + "," + h / 2 + ")");

                    // Bind data and add chord path
                    svg.append("g")
                        .selectAll(".chord-path")
                        .data(chord.groups)
                        .enter()
                        .append("path")
                            .attr("class", "chord-path")
                            .style("fill", function(d) { return fill(d.index); })
                            .style("stroke", function(d) { return fill(d.index); })
                            .attr("d", d3.svg.arc().innerRadius(r0).outerRadius(r1))
                            .on("mouseover", fade(.1, svg))
                            .on("mouseout", fade(1, svg));


                    // Add ticks
                    // ------------------------------

                    // Group
                    var ticks = svg.append("g")
                        .selectAll("g")
                        .data(chord.groups)
                        .enter()
                        .append("g")
                            .selectAll("g")
                            .data(groupTicks)
                            .enter()
                            .append("g")
                                .attr("transform", function(d) {
                                    return "rotate(" + (d.angle * 180 / Math.PI - 90) + ")"
                                    + "translate(" + r1 + ",0)";
                                });

                    // Add tick lines
                    ticks.append("line")
                        .attr("x1", 1)
                        .attr("y1", 0)
                        .attr("x2", 5)
                        .attr("y2", 0)
                        .style("stroke", "#000");

                    // Add tick text
                    ticks.append("text")
                        .attr("x", 8)
                        .attr("dy", ".35em")
                        .attr("text-anchor", function(d) {
                            return d.angle > Math.PI ? "end" : null;
                        })
                        .attr("transform", function(d) {
                            return d.angle > Math.PI ? "rotate(180)translate(-16)" : null;
                        })
                        .style("font-size", 12)
                        .text(function(d) { return d.label; });


                    // Add chord
                    // ------------------------------

                    svg.append("g")
                        .attr("class", "d3-chord")
                        .selectAll("path")
                        .data(chord.chords)
                        .enter()
                        .append("path")
                            .style("fill", function(d) { return fill(d.target.index); })
                            .style("stroke", "#000")
                            .style("stroke-width", 0.5)
                            .style("fill-opacity", 0.7)
                            .attr("d", d3.svg.chord().radius(r0))
                            .style("opacity", 1);
                };

                return self;
            };



            // Utility functions
            // ------------------------------

            // Returns an array of tick angles and labels, given a group
            function groupTicks(d) {
                var k = (d.endAngle - d.startAngle) / d.value;
                return d3.range(0, d.value, 50).map(function(v, i) {
                    return {
                        angle: v * k + d.startAngle,
                        label: i % 2 ? null : v
                    };
                });
            }

            // Returns an event handler for fading a given chord group
            function fade(opacity, svg) {
                return function(g, i) {
                    svg.selectAll(".d3-chord path").filter(function(d) {
                        return d.source.index != i && d.target.index != i;
                    })
                    .transition()
                    .style("opacity", opacity);
                };
            }



            // Initialize chart
            // ------------------------------

            initChord();

            function initChord() {
                var chord = d3.chart.chord(element);
                chord.update(data);

                d3.select("#clear-basic").on("click", function() {
                    chord.clear();
                });
                d3.select("#render-basic").on("click", function() {
                    chord.render();
                });
            }
        }
    };


    //
    // Return objects assigned to module
    //

    return {
        init: function() {
            _chordBasic();
        }
    }
}();


// Initialize module
// ------------------------------

document.addEventListener('DOMContentLoaded', function() {
    D3ChordBasic.init();
});
