/// CONFIG
var FPS=30; //How often tick() is called each second

//Width and height of the canvas. -1 = maximum possible (whole window)
var WIDTH = -1;
var HEIGHT = -1;

var HIDDEN = false;

var LEFT = 0.5;
var TOP = 0.5;

var BORDER = 0;
var BORDER_COLOR = "black";
var FULLSCREEN = false;

var PAGE_TITLE = "Empty.js";

var PAUSED = false; //set to true to pause calling tick().

var CURSOR = "default" //set cursor on canvas

//EMPTYJS
var cv, c;
var empty_keys = [];
var empty_mouse_x = -1;
var empty_mouse_y = -1;
var empty_mouse_keys= [false, false, false];

var empty_new_mouse_x = -1;
var empty_new_mouse_y = -1;

document.addEventListener("DOMContentLoaded",function() {              //ONLOAD
  cv = document.getElementById("cv");
  if (cv == null) {
    cv = document.createElement("canvas");
    cv.id = "cv";
    document.body.appendChild(cv);
  }
  c = cv.getContext("2d");

  document.body.style.margin="0";

  window.addEventListener("resize",empty_resize);

  document.addEventListener("fullscreenchange",function() {
    cv.focus();
    empty_fullscreen();
  });

  document.addEventListener("mousemove",function(e) {  //MOUSE MOVEMENT
      var box = cv.getBoundingClientRect();
      var boxX = box.top;
      var boxY = box.left;
      var x = e.clientX - boxX;
      var y = e.clientY - boxY;
      empty_new_mouse_x = e.clientX;
      empty_new_mouse_y = e.clientY;
    if (typeof onMouseMove == "function") {
      onMouseMove(x,y);
    }
  });

  document.addEventListener("keydown", function(e) {  //KEY DOWN
    if (e.isComposing || e.keyCode === 229) { return; }
    empty_setKey(e.code, true);
    if (typeof onKeyDown == "function") {
      onKeyDown(e);
    }
    empty_fullscreen();
  });

  document.addEventListener("keyup", function(e) {   //KEY UP
    if (e.isComposing || e.keyCode === 229) {return;}
    empty_setKey(e.code, false);
    if (typeof onKeyUp == "function") {
      onKeyUp(e);
    }
  });

  document.addEventListener("click", function(e) { //CLICK
    empty_fullscreen();
    if (!HIDDEN && !PAUSED) {
      cv.focus();
    }
  });

  document.addEventListener("mousedown", function(e) {  //MOUSEDOWN
    if (e.button==0) {
      empty_fullscreen();
    }
    if (!HIDDEN && !PAUSED) {
      cv.focus();
    }
    empty_new_mouse_x = e.clientX;
    empty_new_mouse_y = e.clientY;
    empty_mouse_keys[e.button]=true;
    if (typeof onMouseDown == "function") {
      onMouseDown(getMousePos().x, getMousePos().y, e.button);
    }
  });

  document.addEventListener("mouseup",function(e) {     //MOUSEUP
    if (e.button==0) {
      empty_fullscreen();
    }
    empty_new_mouse_x = e.clientX;
    empty_new_mouse_y = e.clientY;
    empty_mouse_keys[e.button]=false;
    if (typeof onMouseUp == "function") {
      onMouseUp(getMousePos().x, getMousePos().y, e.button);
    }
  });

  document.addEventListener("contextmenu",function(e) {    //CONTEXTMENU
    if (!HIDDEN && !PAUSED) {
      cv.focus();
      e.preventDefault();
    }
    cv.focus();
  });

  document.addEventListener("touchmove",function(e) {
    empty_new_mouse_x = e.touches[0].clientX;
    empty_new_mouse_y = e.touches[0].clientY;
    var box = cv.getBoundingClientRect();
    var boxX = box.top;
    var boxY = box.left;
    var x = empty_new_mouse_x - boxX;
    var y = empty_new_mouse_y - boxY;
    if (typeof onMouseMove == "function") {
      onMouseMove(x,y);
    }
  })

  document.addEventListener("touchstart",function(e) {
    empty_new_mouse_x = e.touches[0].clientX;
    empty_new_mouse_y = e.touches[0].clientY;
    var box = cv.getBoundingClientRect();
    var boxX = box.top;
    var boxY = box.left;
    var x = empty_new_mouse_x - boxX;
    var y = empty_new_mouse_y - boxY;
    if (typeof onMouseDown == "function") {
      onMouseDown(x,y,0);
    }
  })

  document.addEventListener("touchstart",function(e) {
    empty_new_mouse_x = e.touches[0].clientX;
    empty_new_mouse_y = e.touches[0].clientY;
    var box = cv.getBoundingClientRect();
    var boxX = box.top;
    var boxY = box.left;
    var x = empty_new_mouse_x - boxX;
    var y = empty_new_mouse_y - boxY;
    empty_mouse_keys[0] = true;
    if (typeof onMouseDown == "function") {
      onMouseDown(x,y,0);
    }
  })
  document.addEventListener("touchend",function(e) {
    var box = cv.getBoundingClientRect();
    var boxX = box.top;
    var boxY = box.left;
    var x = empty_new_mouse_x - boxX;
    var y = empty_new_mouse_y - boxY;
    empty_mouse_keys[0] = false;
    if (typeof onMouseUp == "function") {
      onMouseUp(x,y,0);
    }
  })

  empty_resize();
  if (typeof init == "function") {
    init();
  }
  setTimeout(empty_tick,1000/FPS);
});

function empty_tick() {                            //TICK
  window.document.title=PAGE_TITLE;

  if (HIDDEN && cv.style.display!="hidden") {
    cv.style.display="none";
  }
  if (!HIDDEN && cv.style.display!="inline-block") {
    cv.style.display="inline-block";
  }

  if (BORDER>0) {
    cv.style.borderStyle="solid";
  } else {
    cv.style.borderStyle="none";
  }
  cv.style.borderWidth=BORDER;
  cv.style.borderColor=BORDER_COLOR;
  if (typeof tick == "function" && !PAUSED) {
    tick();
  }
  document.body.style.cursor = CURSOR;
  empty_mouse_x = empty_new_mouse_x;
  empty_mouse_y = empty_new_mouse_y;
  setTimeout(empty_tick,1000/FPS);
}

function empty_fullscreen() {
  if (FULLSCREEN) {
    FULLSCREEN=false;
    if(document.body.requestFullscreen) {
      document.body.requestFullscreen();
    } else if(document.body.mozRequestFullScreen) {
      document.body.mozRequestFullScreen();
    } else if(document.body.msRequestFullscreen) {
      document.body.msRequestFullscreen();
    } else if(document.body.webkitRequestFullscreen) {
      document.body.webkitRequestFullscreen();
    } else {
      FULLSCREEN=true;
    }
  }
}

function empty_resize() {                                           //WINDOW RESIZE
  if (typeof onresize=="function") {
    onresize(window.innerWidth, window.innerHeight);
  }
}

function empty_setKey(code, value) {                         //SET KEYSTATE
  empty_keys[code] = value;
}


// DATA FUNCTIONS

function getMouseKey(key) {                     //GET MOUSE KEY
  return empty_mouse_keys[key];
}

function getKey(code) {                       //GET KEYSTATE
  if (code in empty_keys) return empty_keys[code];
  return false;
}

function getMousePosGobal() {                         //MOUSE POSITION
  return {x: empty_mouse_x, y: empty_mouse_y};
}

function getMousePos() {
  var box = cv.getBoundingClientRect();
  var boxX = box.top;
  var boxY = box.left;
  var x = empty_new_mouse_x - box.top;
  var y = empty_new_mouse_y - box.left;
  return {x: x, y: y};
}

function getLastMousePos() {
  var box = cv.getBoundingClientRect();
  var boxX = box.top;
  var boxY = box.left;
  var x = empty_mouse_x - box.top;
  var y = empty_mouse_y - box.left;
  return {x: x, y: y};
}

function getRelativeMouseMovement() {
  var m1=getMousePos();
  var m2=getLastMousePos();
  var ret={x: m1.x - m2.x, y: m1.y - m2.y};
  return ret;
}


// DRAWING FUNCTIONS

function fillBackground() {
  c.fillRect(0,0,cv.width,cv.height);
}

function fillCircle(x,y,r) {
  c.beginPath();
  c.moveTo(x,y);
  c.arc(x,y,r,0,Math.PI*2);
  c.fill();
}

function strokeCircle(x,y,r) {
  c.beginPath();
  c.moveTo(x+r,y);
  c.arc(x,y,r,0,Math.PI*2);
  c.stroke();
}

function line(x1,y1,x2,y2) {
  c.beginPath();
  c.moveTo(x1,y1);
  c.lineTo(x2,y2);
  c.stroke();
}

function drawRotatedImage(image,x,y,angle,width,height) {
  var origin = {x: width/2, y: height/2};
  c.save();
  c.translate(x,y);
  c.rotate(angle);
  c.drawImage(image,-origin.x,-origin.y,width,height);
  c.restore();
}


// CALCULATION FUNCTIONS

function distance(x1,y1,x2,y2) {                      //DISTANCE
  return Math.sqrt(Math.pow(x1-x2,2) + Math.pow(y1-y2,2));
}

function randomRange(min,max) {                                     //RANDOM RANGE
  return Math.floor(Math.random() * (max-min+1) + min);
}

function range(j) {
  var arr=[];
  for (var i=0; i<j; i++) {
    arr.push(i);
  }
  return arr;
}

function minmax(num, min, max) {
  if (num>max) return max;
  if (num<min) return min;
  return num;
}

function rgb(r,g,b) {                                               //COLOR FUNCTIONS
  return "rgb(" + r + "," + g + "," + b +")";
}

function rgba(r,g,b,a) {
  return "rgba(" + r + "," + g + "," + b +"," + a + ")";
}

function hsl(h,s,l) {
  return "hsl(" + h + "," + s + "%," + l +"%)";
}

function hsla(h,s,l,a) {
  return "hsla(" + h + "," + s + "%," + l +"%," + a +")";
}

function closestPointOnLine(l1x, l1y, l2x, l2y, px, py) {
  var bb = Math.atan2(py - l1y, px - l1x);
  var ll = Math.atan2(l2y - l1y, l2x - l1x);
  var ab=ll-bb;
  var d=Math.cos(ab)*distance(l1x, l1y, px, py);
  d = minmax(d, 0, distance(l1x, l1y, l2x, l2y));
  var x=Math.cos(ll)*d + l1x;
  var y=Math.sin(ll)*d + l1y;
  return {x:x, y:y};
}

function lineCircleIntersect(l1x, l1y, l2x, l2y, cx, cy, cr) {
  var p =closestPointOnLine(l1x, l1y, l2x, l2y, cx, cy)
  return pointInCircle(p.x,p.y,cx,cy,cr);
}

function pointInRect(px,py,rx,ry,rw,rh) {
  return px>=rx && py>=ry && px<=rx+rw && py<=ry+rh;
}

function pointInCircle(px,py,cx,cy,cr) {
	return distance(px,py,cx,cy)<=cr;
}

function rectsCollide(x1,y1,dx1,dy1,x2,y2,dx2,dy2) {
  return (empty_1dcollide(x1,dx1,x2,dx2) && empty_1dcollide(y1,dy1,y2,dy2))
}

function empty_1dcollide(x1,dx1,x2,dx2) {
  if (x2 >= x1 && x2 < x1+dx1) {
    return true;
  }
  if (x1 >= x2 && x1 < x2+dx2) {
    return true;
  }
  return false;
}