import simd

struct Instance {
  let position: SIMD3<Float>
  let scale: SIMD3<Float>
  let rotation: simd_quatf
  let color: Color<Float16>

  init(
    position: SIMD3<Float> = .zero,
    scale: SIMD3<Float> = .one,
    rotation: simd_quatf = .identity,
    color: Color<Float16> = .white
  ) {
    self.position = position
    self.scale = scale
    self.rotation = rotation
    self.color = color
  }
}

class Game: GameDelegate {
  private var fpsCalculator = FPSCalculator()
  var camera = Camera(fov: 60, size: .one, range: 0.06...900)
  var player = Player()
  var projection: matrix_float4x4 = .identity
  var world = World()

  func create(_ renderer: Renderer) {
    self.resetPlayer()
    self.generateWorld()

    renderer.clearColor = Color<Double>.black.mix(.white, 0.1).linear
  }

  private func resetPlayer() {
    self.player.position = .init(repeating: 0.5) + .init(0, Float(Chunk.size), 0)
    self.player.velocity = .zero
    self.player.rotation = .init(.pi, 0)
  }

  private func generateWorld() {
    var random: any RandomProvider
#if true
    let newSeed = UInt64(Arc4Random.instance.next()) | UInt64(Arc4Random.instance.next()) << 32
    printErr(newSeed)
    random = Xoroshiro128PlusPlus(seed: newSeed)
#else
    random = PCG32Random(state: (
        UInt64(Arc4Random.instance.next()) | UInt64(Arc4Random.instance.next()) << 32,
        UInt64(Arc4Random.instance.next()) | UInt64(Arc4Random.instance.next()) << 32))
#endif
#if DEBUG
      self.world.generate(width: 2, height: 1, depth: 1, random: &random)
#else
      self.world.generate(width: 5, height: 3, depth: 5, random: &random)
#endif
  }

  func fixedUpdate(_ time: GameTime) {
    
  }

  func update(_ time: GameTime) {
    fpsCalculator.frame(deltaTime: time.delta) { fps in
      print("FPS: \(fps)")
    }

    let deltaTime = min(Float(time.delta.asFloat), 1.0 / 15)

    var reset = false, generate = false
    if let pad = GameController.current?.state {
      if pad.pressed(.back) { reset = true }
      if pad.pressed(.start) { generate = true }
    }
    if Keyboard.pressed(.r) { reset = true }
    if Keyboard.pressed(.g) { generate = true }

    // Player reset
    if reset {
      self.resetPlayer()
    }
    // Regenerate
    if generate {
      self.generateWorld()
    }

    self.player.update(deltaTime: deltaTime, world: world)
    self.camera.position = player.eyePosition
    self.camera.rotation = player.eyeRotation
  }

  func draw(_ renderer: Renderer, _ time: GameTime) {
    let totalTime = Float(time.total.asFloat)

    let env = Environment(
      cullFace: .back,
      lightDirection: .init(0.75, -1, 0.5))
    let material = Material(
      ambient:  Color(rgba8888: 0x4F4F4F00).linear,
      diffuse:  Color(rgba8888: 0xDFDFDF00).linear,
      specular: Color(rgba8888: 0x2F2F2F00).linear,
      gloss: 75)

    var instances = world.instances
    instances.append(
      Instance(
        position: player.rayhitPos,
        scale:    .init(repeating: 0.0725 * 0.5),
        rotation:
          .init(angle: totalTime * 3.0, axis: .init(0, 1, 0)) *
          .init(angle: totalTime * 1.5, axis: .init(1, 0, 0)) *
          .init(angle: totalTime * 0.7, axis: .init(0, 0, 1)),
        color:    .init(r: 0.5, g: 0.5, b: 1).linear))
    if !instances.isEmpty {
      renderer.batch(instances: instances, material: material, environment: env, camera: self.camera)
    }
  }

  func resize(_ size: Size<Int>) {
    self.camera.setSize(size)
  }
}