import “../core/document”; import “selection”;

d3_selectionPrototype.style = function(name, value, priority) {

var n = arguments.length;
if (n < 3) {

  // For style(object) or style(object, string), the object specifies the
  // names and values of the attributes to set or remove. The values may be
  // functions that are evaluated for each element. The optional string
  // specifies the priority.
  if (typeof name !== "string") {
    if (n < 2) value = "";
    for (priority in name) this.each(d3_selection_style(priority, name[priority], value));
    return this;
  }

  // For style(string), return the computed style value for the first node.
  if (n < 2) return d3_window.getComputedStyle(this.node(), null).getPropertyValue(name);

  // For style(string, string) or style(string, function), use the default
  // priority. The priority is ignored for style(string, null).
  priority = "";
}

// Otherwise, a name, value and priority are specified, and handled as below.
return this.each(d3_selection_style(name, value, priority));

};

function d3_selection_style(name, value, priority) {

// For style(name, null) or style(name, null, priority), remove the style
// property with the specified name. The priority is ignored.
function styleNull() {
  this.style.removeProperty(name);
}

// For style(name, string) or style(name, string, priority), set the style
// property with the specified name, using the specified priority.
function styleConstant() {
  this.style.setProperty(name, value, priority);
}

// For style(name, function) or style(name, function, priority), evaluate the
// function for each element, and set or remove the style property as
// appropriate. When setting, use the specified priority.
function styleFunction() {
  var x = value.apply(this, arguments);
  if (x == null) this.style.removeProperty(name);
  else this.style.setProperty(name, x, priority);
}

return value == null
    ? styleNull : (typeof value === "function"
    ? styleFunction : styleConstant);

}