import { cls, print, spr, use_texture, Texture } from "./graphics";
import { load_texture } from "./assets";
import { since_start } from "./time";
import { btn, Button } from "./input";
// import { load_string } from "./io";
import { new_v2, vadd, vmul, vnorm } from "./vector";

/// TODO: Support reload by saving and restoring state from init/update/restore.

/// A nice looping frame counter.
let clock = 0;

let bot_sprite: Texture | undefined = undefined;

// Note zelda overworld is 16x8 screens
//      zelda screen is 16x11 tiles
// from a feeling point of view this is sufficient, apparently :D

let loaded = false;

async function load_map(path: string) {
  // print("Loading map:", path);
  // const blob = await load_string(path);
  // const map = JSON.parse(blob);
  // print("Loaded map:", map);
}

function load_assets() {
  // Start this load, but then...
  let texture_load = load_texture("./bot.png").then((n) => {
    print("Bot loaded at", since_start());
    bot_sprite = n;
  });

  let map_load = load_map("./overworld.ldtk");

  Promise.all([texture_load, map_load]).then(() => {
    loaded = true;
    print("All are loaded.");
  });
}

export function init() {
  print("Hello world!");
  load_assets();
}

const friction = 0.6;
let robo_vel = new_v2(0);
let robo_pos = new_v2(10);

export function update() {
  clock = (clock + 1) % 20160;

  // Acceleration from input
  let a = new_v2(0);
  if (btn(Button.Up)) {
    a.y -= 1;
  }
  if (btn(Button.Down)) {
    a.y += 1;
  }
  if (btn(Button.Left)) {
    a.x -= 1;
  }
  if (btn(Button.Right)) {
    a.x += 1;
  }
  vnorm(a);
  a = vmul(a, 0.8); // Speed.

  // Friction
  let v = vmul(robo_vel, friction);
  v = vadd(v, a);

  // Zero if we're smaller than some epsilon.
  if (Math.abs(v.x) < 0.01) {
    v.x = 0;
  }
  if (Math.abs(v.y) < 0.01) {
    v.y = 0;
  }

  // Motion
  let np = vadd(robo_pos, v);

  // TODO: Collide.

  robo_pos = np;
  robo_vel = v;
}

// GARBAGE OBVIOUSLY
const robo_info = {
  width: 32,
  height: 32,
  animations: [
    { start: 0, length: 1, speed: 20 },
    { start: 1, length: 4, speed: 8 },
  ],
};

export function draw() {
  cls(0.1, 0.2, 0.3);
  if (!loaded) {
    return;
  }

  if (bot_sprite != undefined) {
    // ...it gets resolved here?
    use_texture(bot_sprite);

    const moving = robo_vel.x != 0 || robo_vel.y != 0;
    const anim = robo_info.animations[moving ? 1 : 0];
    const frame = (anim.start + ((clock / anim.speed) % anim.length)) >> 0;
    spr(robo_pos.x, robo_pos.y, 32, 32, frame * robo_info.width, 0, 32, 32);
  }
  // print("FRAME TIME:", since_last_frame());
}