import 'dart:html' as html;

import 'package:rules_of_living/Cell.dart';
import 'package:rules_of_living/Grid.dart';

class App {
  // Elapsed Time Counter - useful for Safety Timeout
  Stopwatch _elapsed = new Stopwatch();
  num lastNow = 0;

  // Game Tick Rate - *does* impact game speed
  final int _MS_PER_STEP = 1000;

  // Max Frame (i.e. Rendering) rate - does *not* impact game speed
  final int _MS_PER_FRAME = 1000;

  // ms stuck in updateloop after which game will declare itself unresponsive
  final int SAFETY_TIMEOUT = 2000;

  num _updateLag = 0.0;
  num _drawLag = 0.0;


  final html.CanvasElement canvas;
  final Grid grid = new Grid(20,20);
  List<List<Cell>> map;

  App(this.canvas) {
    this.map = this.grid.map;
  }

  void process(num now) {
    _drawLag = now - lastNow;
    print(_drawLag);
    lastNow = now;

    _updateLag += _drawLag;
    _elapsed.reset();

    while (_updateLag >= _MS_PER_STEP) {
      if (_elapsed.elapsedMilliseconds > SAFETY_TIMEOUT) {
        // TODO stub - give warning etc when this occurs
        print("ERROR STUCK IN UPDATE LOOP");
        break;
      }
      update();
      _updateLag -= _MS_PER_STEP;
    }

    if (_drawLag >= _MS_PER_FRAME) {
      render(_updateLag / _MS_PER_STEP);
      _drawLag = 0;
    }
  }

  void update() {
    print("updating");
    grid.update();
  }


  void render([num interp]) {
    html.CanvasRenderingContext2D ctx = canvas.getContext('2d');
    int brickW = (canvas.width ~/ map[0].length);
    int brickH = (canvas.height ~/ map.length);
    ctx.clearRect(0, 0, canvas.width, canvas.height);
    for (int y = 0; y < map.length; y++) {
      for (int x = 0; x < map[y].length; x++) {
        Cell c = map[y][x];
        if (c.state == true)
          ctx.setFillColorRgb(155, 155, 255);
        else
          ctx.setFillColorRgb(0, 0, 0);
        ctx.fillRect(x * brickW, y * brickH, brickW, brickH);
      }
    }
  }
}