import "../core/document";

import "../core/rebind";

import "../event/drag";

import "../event/event";

import "../event/mouse";

import "../event/touches";

import "behavior";

d3.behavior.drag = function() {

var event = d3_eventDispatch(drag, "drag", "dragstart", "dragend"),

origin = null,

mousedown = dragstart(d3_noop, d3.mouse, "mousemove", "mouseup"),

touchstart = dragstart(touchid, touchposition, "touchmove", "touchend");

function drag() {

this.on("mousedown.drag", mousedown)

.on("touchstart.drag", touchstart);

}

function touchid() {

return d3.event.changedTouches[0].identifier;

}

function touchposition(parent, id) {

return d3.touches(parent).filter(function(p) { return p.identifier === id; })[0];

}

function dragstart(id, position, move, end) {

return function() {

var target = this,

parent = target.parentNode,

event_ = event.of(target, arguments),

eventTarget = d3.event.target,

eventId = id(),

drag = eventId == null ? "drag" : "drag-" + eventId,

origin_ = position(parent, eventId),

dragged = 0,

offset,

w = d3.select(d3_window).on(move + "." + drag, moved).on(end + "." + drag, ended),

dragRestore = d3_event_dragSuppress();

if (origin) {

offset = origin.apply(target, arguments);

offset = [offset.x - origin_[0], offset.y - origin_[1]];

} else {

offset = [0, 0];

}

event_({type: "dragstart"});

function moved() {

var p = position(parent, eventId),

dx = p[0] - origin_[0],

dy = p[1] - origin_[1];

dragged |= dx | dy;

origin_ = p;

event_({type: "drag", x: p[0] + offset[0], y: p[1] + offset[1], dx: dx, dy: dy});

}

function ended() {

w.on(move + "." + drag, null).on(end + "." + drag, null);

dragRestore(dragged && d3.event.target === eventTarget);

event_({type: "dragend"});

}

};

}

drag.origin = function(x) {

if (!arguments.length) return origin;

origin = x;

return drag;

};

return d3.rebind(drag, event, "on");

};