/*

mouse.register({
  down: (x, y) => {
  },
  move: (x, y, dx, dy) => {
  },
  up: (x, y) => {
  },
})

*/


let fns = {
  down: [],
  move: [],
  up: [],
}

export default {
  register: (callbacks) => {
    callbacks.down && fns.down.push(callbacks.down)
    callbacks.move && fns.move.push(callbacks.move)
    callbacks.up && fns.up.push(callbacks.up)
  }
}

let x, y, dragging = false

function down(e){
  x = e.pageX
  y = e.pageY
  dragging = true
  fns.down.map(f => f(x, y))
}
function move(e){
  if (!dragging) return
  let dx = e.pageX - x
  let dy = e.pageY - y
  x = e.pageX
  y = e.pageY
  dragging = true
  fns.move.map(f => f(x, y, dx, dy))
}
function up(e){
  dragging = false
  fns.up.map(f => f(x, y))
}

function touch(f){ return (e) => e.preventDefault() && f(e.touches[0]) }
document.body.addEventListener("mousedown", down)
document.body.addEventListener("mousemove", move)
document.body.addEventListener("mouseup", up)
document.body.addEventListener("touchstart", touch(down))
document.body.addEventListener("touchmove", touch(move))
document.body.addEventListener("touchup", touch(up))