//================= Canvas elements
let staticLayer = document.getElementById('static');
staticLayer.width = window.innerWidth;
staticLayer.height = window.innerHeight;

let beamLineLayer = document.getElementById('beamLine');

let colors = ["red", "orange", "yellow", "green", "blue", "indigo", "violet"];
let colorIndex = 0;

function rotate(xy, center, rad){
  let haha = [xy[0]-center[0], xy[1]-center[1]];
  let kaka = [ haha[0]*Math.cos(rad) - haha[1]*Math.sin(rad),
               haha[0]*Math.sin(rad) + haha[1]*Math.cos(rad)];
  return [ kaka[0] + center[0],
           kaka[1] + center[1]];
}

function translate(xy, t){
  return [xy[0] + t[0], xy[1] + t[1]];
}

function distance(xy1, xy2){
  return Math.sqrt( Math.pow(xy1[0]-xy2[0],2) + Math.pow(xy1[1]-xy2[1],2));
}

class basicShape{
  constructor(layer){
    this.layer = layer;
    this.shape = new Path2D();
    this.entracePos = [0,0];
    this.exitPos  = [0,0];
  }
  clear(){
    let ctx = this.layer.getContext('2d');
    ctx.save();
    ctx.globalCompositeOperation = 'destination-out';
    ctx.fill(this.shape);
    ctx.stroke(this.shape);
    ctx.restore();
  }
}

class tandemClass extends basicShape{
  
  constructor(xy, l, w){
    super(staticLayer);
    this.exitPos = [ xy[0], xy[1] - w - l];

    this.shape.rect(xy[0] - w/2, xy[1] - l - w/2, w, l);
    this.shape.arc(xy[0], xy[1]-w/2, w/2, 0, Math.PI);
    this.shape.arc(xy[0], xy[1]-w/2 - l, w/2, Math.PI, 2* Math.PI);
  }
  
  draw(color){
    let ctx = this.layer.getContext('2d');
    ctx.fillStyle = color;    
    ctx.fill(this.shape);
  }
  
}

class beamLine extends basicShape{
  constructor(xy, rad, l){
    super(beamLineLayer);
    this.offset = 0;
    this.lineWidth = 10;
    
    this.exitPos = [xy[0] + l, xy[1]]; 
    this.exitPos = rotate(this.exitPos, xy, rad);

    this.shape.moveTo(xy[0], xy[1]);
    this.shape.lineTo(this.exitPos[0], this.exitPos[1]);
  }

  draw(color){
    this.clear();
    let ctx = this.layer.getContext('2d');
    ctx.setLineDash([10,6]);
    ctx.lineDashOffset = -this.offset;
    ctx.lineWidth = 10;
    ctx.strokeStyle = color;
    ctx.stroke(this.shape);
  }

  march(color){
    this.offset++;
    if( this.offset > 16) this.offset = 0;
    this.draw(color);
    //setTimeout(this.march.bind(this), 20);
  }

}

class beamRectElement extends basicShape{
  constructor(xy, rad, l, w){
    super(staticLayer);

    let A = [xy[0]-w/2, xy[1]];
    let B = [xy[0]+w/2, xy[1]];
    let C = [xy[0]+w/2, xy[1] - l];
    let D = [xy[0]-w/2, xy[1] - l];

    A = rotate(A, xy, rad);
    B = rotate(B, xy, rad);
    C = rotate(C, xy, rad);
    D = rotate(D, xy, rad);

    this.shape.moveTo(A[0], A[1]);
    this.shape.lineTo(B[0], B[1]);
    this.shape.lineTo(C[0], C[1]);
    this.shape.lineTo(D[0], D[1]);
    this.shape.closePath();

    this.exitPos = [xy[0], xy[1] - l]
  }

  draw(color){
    let ctx = this.layer.getContext('2d');
    ctx.fillStyle = color; 
    ctx.fill(this.shape);
  }

}

class beamCircleElement extends basicShape{
  constructor(xy, r, rad0, rad1){
    super(staticLayer);

    this.shape.moveTo(xy[0], xy[1]);
    this.shape.arc(xy[0], xy[1], r, rad0, rad1);
    
    let rad = (rad0 + rad1)/2;
    let l = [r*Math.cos(rad), r*Math.sin(rad)];
    this.exitPos = [xy[0] + l[0], xy[1] + l[1]]; // the middle of the arc
  }

  GetExitPos(frac){
    let rad = rad0 + Math.abs(rad0 - rad1) * frac;
    let l = [r*Math.cos(rad), r*Math.sin(rad)];
    return [xy[0] + l[0], xy[1] + l[1]]; 
  }

  draw(color){
    let ctx = this.layer.getContext('2d');
    ctx.fillStyle = color; 
    ctx.fill(this.shape);
  }
}

class BeamSpilter extends basicShape{
  constructor(xy, r, rad){
    super(staticLayer);

    this.entracePos = xy;
    this.r = r;

    let w = r;
    let l = r/2;

    let A = [xy[0]+w/2, xy[1] - l];
    let B = [xy[0]+w/2, xy[1]];
    let C = [xy[0]-w/2, xy[1]];
    let D = [xy[0]-w/2, xy[1] - l];

    A = rotate(A, xy, rad);
    B = rotate(B, xy, rad);
    C = rotate(C, xy, rad);
    D = rotate(D, xy, rad);

    this.shape.moveTo(A[0], A[1]);
    this.shape.lineTo(B[0], B[1]);
    this.shape.lineTo(C[0], C[1]);
    this.shape.lineTo(D[0], D[1]);

    this.rad0 = rad -  Math.PI*3/4;
    this.rad1 = rad - Math.PI/4;
    this.shape.arc(xy[0], xy[1], r, this.rad0 , this.rad1);
  }

  GetExitPos(frac){
    let rad = this.rad0 + Math.abs(this.rad0 - this.rad1) * frac;
    let l = [this.r*Math.cos(rad), this.r*Math.sin(rad)];
    return translate(this.entracePos, l);
  }

  draw(color){
    let ctx = this.layer.getContext('2d');
    ctx.fillStyle = color; 
    ctx.fill(this.shape);
  }

}

///========================= Sand Box;

let windowSize = [staticLayer.width, staticLayer.height];

let RFSource1 = new beamRectElement([windowSize[0]*0.9, windowSize[1]*0.8], 0, 40, 100);
let RFSource2 = new beamRectElement(RFSource1.exitPos, 0, 40, 20);

let s1 = new BeamSpilter(translate(RFSource2.exitPos, [0, -100]), 50, Math.PI);

let b1S = new beamLine(RFSource2.exitPos, Math.PI *3/2, 200);

let tandem = new tandemClass(b1S.exitPos, 100, 100);
let b10 = new beamLine(tandem.exitPos, Math.PI *3/2, 100); b10.offset = 8;


RFSource1.draw('Olivedrab');
RFSource2.draw('Olivedrab');
b1S.draw('red');
s1.draw('gold');
tandem.draw('#782F40');
b10.draw('red');


function lineMotion(){
  b1S.march('red');
  b10.march('red');
  setTimeout(lineMotion, 20);
}
lineMotion();