(function() {
  var arc_g, arc_gen, c, ctrls, drag, l, offset, pinch_offset, q, redraw, svg;

  svg = d3.select('svg');

  q = 3;

  offset = 0;

  c = 40;

  l = 70;

  arc_gen = d3.svg.arc().innerRadius(100).outerRadius(200);

  arc_g = svg.append('g').attr('transform', 'rotate(90)');

  pinch_offset = null;

  drag = d3.behavior.drag().on('drag', function() {
    var angle;
    if (!(pinch_offset != null)) {
      pinch_offset = 180 / Math.PI * Math.atan2(d3.event.y, d3.event.x) + 180 - offset;
    }
    angle = 180 / Math.PI * Math.atan2(d3.event.y, d3.event.x) + 180;
    offset = angle - pinch_offset;
    return redraw();
  }).on('dragend', function() {
    return pinch_offset = null;
  });

  redraw = function() {
    var arcs, colors, delta, h;
    delta = 360 / q;
    colors = (function() {
      var _results;
      _results = [];
      for (h = 0; 0 <= q ? h < q : h > q; 0 <= q ? h++ : h--) {
        _results.push(d3.hcl((h * delta + offset) % 360, c, l));
      }
      return _results;
    })();
    arc_gen.startAngle(function(d) {
      return (d.h - delta / 2 + 270) * Math.PI / 180;
    }).endAngle(function(d) {
      return (d.h + delta / 2 + 270) * Math.PI / 180;
    });
    arcs = arc_g.selectAll('.arc').data(colors);
    arcs.enter().append('path').attr('class', 'arc').call(drag);
    arcs.exit().remove();
    arc_g.selectAll('.arc').attr('d', arc_gen).attr('fill', function(d) {
      return d;
    });
    return svg.select('#q').text(q);
  };

  svg.append('text').attr('class', 'label').attr('id', 'q').attr('dy', '0.30em').text(q);

  ctrls = svg.append('g').attr('id', 'controls');

  ctrls.append('circle').attr('r', 100).attr('fill', 'transparent');

  ctrls.append('text').attr('class', 'label control').attr('dx', '70px').attr('dy', '0.30em').text('+').on('click', function() {
    q = q === 36 ? 1 : q + 1;
    return redraw();
  });

  ctrls.append('text').attr('class', 'label control').attr('dx', '-70px').attr('dy', '0.30em').text('-').on('click', function() {
    q = q === 1 ? 36 : q - 1;
    return redraw();
  });

  redraw();

}).call(this);