const ApeECS = require('ape-ecs');

class Gravity extends ApeECS.System {
  init() {
    this.mainQuery = this.createQuery().fromAll('Position', 'Physics');
  }

  update(tick) {
    const entities = this.mainQuery.execute();
    const frameInfo = this.world.getEntity('frame');
    for (const entity of entities) {
      const point = entity.getOne('Position');
      if (!entity.has('Vector')) {
        entity.addComponent({
          type: 'Vector',
          mx: 0,
          my: 0
        })
      }
      const vector = entity.getOne('Vector');
      vector.my += 9.807 * frame.time.deltaTime * .01;
      vector.update();
    }
  }
}

class Position extends ApeECS.Component {}
Position.properties = {
  x: 0,
  y: 0
};

class Vector extends ApeECS.Component {

  get speed() {
    return Math.sqrt(this.mx**2 + this.my**2);
  }
}
Vector.properties = {
  mx: 0,
  my: 0,
  speed: 0
};

class FrameInfo extends ApeECS.Component {}
FrameInfo.properties = {
  deltaTime: 0,
  deltaFrame: 0,
  time: 0
};

const world = new ApeECS.World();
world.registerComponent(Position);
world.registerComponent(Vectory);
world.registerComponent(FrameInfo);
world.registerTags('Physics');
world.registerSystem('frame', Gravity);

const frame = world.createEntity({
  id: 'frame',
  c: {
    time: {
      type: 'FrameInfo',
    }
  }
})

// see world.creatEntity and world.createEntities
// in docs/World.md for more details
world.registerSystem('frame', require('./move.js'));
world.createEntities(require('./saveGame.json'));

let lastTime = 0;

function update(time) {
  const delta = time - lastTime;
  time = lastTime;
  frame.time.update({
    time: time,
    deltaTime: delta,
    deltaFrame: delta / 16.667
  });
  world.runSystems('frame');
  // run update again the next browser render call
  // every 16ms or so
  window.requestAnimationFrame(update);
}
update(0);