library ball;

import 'dart:async';
import 'dart:html';
import 'dart:math';

void main() {
  CanvasElement canvas = querySelector("#area");
  scheduleMicrotask(new Game(canvas).start);
}

class Ball {
  num   x;
  num    y;
  num    radius;
  String color;

  Ball(this.x, this.y, this.radius, this.color) {
    this.X = x;
    this.Y = y;
    this.Color = color;
    this.Radius = radius;
  }

  void draw(CanvasRenderingContext2D context) {
    context..lineWidth = 0.5
           ..fillStyle = color
           ..strokeStyle = color;

    context
        ..beginPath()
        ..arc(x, y, radius, 0, PI * 2, false)
        ..fill()
        ..closePath();
  }

  num get X => this.x;
      set X(x) => this.x = x;

  num get Y => this.y;
      set Y(y) => this.y = y;

  num get Radius => radius;
      set Radius(r) => radius = r;

  String get Color => this.color;
         set Color(c) => this.color = c;
}

class Game {
  CanvasElement canvas;
  final List<Ball> balls = <Ball>[];

  var rng = new Random();

  num width;
  num height;

  Game(this.canvas);

  start() {
    Rectangle rect = canvas.parent.client;

    width = rect.width;
    height = rect.height;

    canvas.width = width;
    canvas.height = height;

    for (var i = 0; i < 100; ++i) {
      final Ball ball = new Ball(rng.nextInt(500) + 100, rng.nextInt(500) + 100, rng.nextInt(50), '#' + rng.nextInt(1000).toString());

      balls.add(ball);
    }

    requestDraw();
  }

  void drawBackground(CanvasRenderingContext2D context) {
    context.clearRect(0, 0, width, height);
  }

  void drawBalls(CanvasRenderingContext2D context) {
    for (var i in balls) {
      i.draw(context);
    }
  }

  void draw(num _) {
    var context = canvas.context2D;

    drawBackground(context);
    drawBalls(context);

    requestDraw();
  }

  void requestDraw() {
    window.requestAnimationFrame(draw);
  }
}