import “../arrays/range”; import “../arrays/sum”; import “../math/trigonometry”; import “layout”;

d3.layout.pie = function() {

var value = Number,
    sort = d3_layout_pieSortByValue,
    startAngle = 0,
    endAngle = 2 * π;

function pie(data) {

  // Compute the numeric values for each data element.
  var values = data.map(function(d, i) { return +value.call(pie, d, i); });

  // Compute the start angle.
  var a = +(typeof startAngle === "function"
      ? startAngle.apply(this, arguments)
      : startAngle);

  // Compute the angular scale factor: from value to radians.
  var k = ((typeof endAngle === "function"
      ? endAngle.apply(this, arguments)
      : endAngle) - a)
      / d3.sum(values);

  // Optionally sort the data.
  var index = d3.range(data.length);
  if (sort != null) index.sort(sort === d3_layout_pieSortByValue
      ? function(i, j) { return values[j] - values[i]; }
      : function(i, j) { return sort(data[i], data[j]); });

  // Compute the arcs!
  // They are stored in the original data's order.
  var arcs = [];
  index.forEach(function(i) {
    var d;
    arcs[i] = {
      data: data[i],
      value: d = values[i],
      startAngle: a,
      endAngle: a += d * k
    };
  });
  return arcs;
}

/**
 * Specifies the value function *x*, which returns a nonnegative numeric value
 * for each datum. The default value function is `Number`. The value function
 * is passed two arguments: the current datum and the current index.
 */
pie.value = function(x) {
  if (!arguments.length) return value;
  value = x;
  return pie;
};

/**
 * Specifies a sort comparison operator *x*. The comparator is passed two data
 * elements from the data array, a and b; it returns a negative value if a is
 * less than b, a positive value if a is greater than b, and zero if a equals
 * b.
 */
pie.sort = function(x) {
  if (!arguments.length) return sort;
  sort = x;
  return pie;
};

/**
 * Specifies the overall start angle of the pie chart. Defaults to 0. The
 * start angle can be specified either as a constant or as a function; in the
 * case of a function, it is evaluated once per array (as opposed to per
 * element).
 */
pie.startAngle = function(x) {
  if (!arguments.length) return startAngle;
  startAngle = x;
  return pie;
};

/**
 * Specifies the overall end angle of the pie chart. Defaults to 2π. The
 * end angle can be specified either as a constant or as a function; in the
 * case of a function, it is evaluated once per array (as opposed to per
 * element).
 */
pie.endAngle = function(x) {
  if (!arguments.length) return endAngle;
  endAngle = x;
  return pie;
};

return pie;

};

var d3_layout_pieSortByValue = {};