import * as Color from './color.js';

export const WIDTH = 1000;
export const HEIGHT = 673;


export type Layer = 'static' | 'eyeshine' | Color.Layer;

// in compositing order
export const allLayers: Layer[] =
  ['static', 'outer', 'spines', 'stripes', 'cuffs', 'fins1', 'fins2', 'fins3',
   'belly1', 'belly2', 'masks', 'claws', 'vitiligo1', 'vitiligo2', 'vitiligo3',
   'vitiligo4', 'eyes', 'eyeshine', 'lines'];

export type Image = ImageData;
export type Images = Record<Layer, Image>;

export type ComposedImages = Images & {comp?: ImageData};

export type Side = 'front' | 'back';

export function flip(s: Side): Side {
  return s == 'front' ? 'back' : 'front';
}


let buffer = new OffscreenCanvas(WIDTH, HEIGHT);
let bufferCtx = buffer.getContext('2d')!;

type Positions = Record<Layer, [number, number]>;

const FRONT_POS: Positions = {
  belly1:    [187, 105],
  belly2:    [186, 91],
  claws:     [3,   168],
  cuffs:     [42,  160],
  eyes:      [223, 52],
  eyeshine:  [223, 52],
  fins1:     [381, 31],
  fins2:     [387, 35],
  fins3:     [495, 140],
  lines:     [1,   0],
  masks:     [173, 3],
  outer:     [28,  43],
  spines:    [372, 23],
  static:    [50,  52],
  stripes:   [50,  168],
  vitiligo1: [34,  23],
  vitiligo2: [198, 92],
  vitiligo3: [214, 312],
  vitiligo4: [647, 71],
};

const BACK_POS: Positions = {
  belly1:    [39,  67],
  belly2:    [92,  95],
  claws:     [191, 334],
  cuffs:     [221, 215],
  eyes:      [685, 42],
  eyeshine:  [685, 42],
  fins1:     [227, 60],
  fins2:     [226, 61],
  fins3:     [229, 195],
  lines:     [0,   0],
  masks:     [643, 1],
  outer:     [2,   22],
  spines:    [337, 50],
  static:    [219, 41],
  stripes:   [219, 221],
  vitiligo1: [4,   22],
  vitiligo2: [46,  48],
  vitiligo3: [101, 134],
  vitiligo4: [221, 56],
};


type Rgb = [number, number, number];
type Rgbs = Record<Color.Layer, Rgb>;

function toRgb(col: Color.Oklch): Rgb {
  // :)
  const prev = bufferCtx.getImageData(0, 0, 1, 1);

  bufferCtx.save();
  bufferCtx.fillStyle = Color.oklch(col);
  bufferCtx.fillRect(0, 0, 1, 1);
  bufferCtx.restore();

  const rgb = bufferCtx.getImageData(0, 0, 1, 1).data;
  bufferCtx.putImageData(prev, 0, 0);

  return [rgb[0]!, rgb[1]!, rgb[2]!];
}

function toRgbs(col: Color.Colors): Rgbs {
  return Color.makeColorInfo(l => toRgb(col[l]));
}


function setImageDataRgb([r, g, b]: Rgb, img: Image): void {
  let data = img.data;
  for (let i = 0; i < data.length; i += 4) {
    data[i] = r; data[i+1] = g; data[i+2] = b;
  }
}


async function wait(img: HTMLImageElement): Promise<HTMLImageElement> {
  if (img.complete) {
    return new Promise((r, _) => r(img));
  } else {
    return new Promise((r, _) => img.addEventListener('load', () => r(img)));
  }
}

async function load(side: Side, layer: Layer): Promise<Image> {
  if (layer == 'eyeshine') layer = 'eyes';
  let img = new Image; img.src = `./${side}/${layer}.png`;
  let bmp = await createImageBitmap(await wait(img));
  bufferCtx.clearRect(0, 0, WIDTH, HEIGHT); // ?
  bufferCtx.drawImage(bmp, 0, 0);
  return bufferCtx.getImageData(0, 0, WIDTH, HEIGHT);
}

async function loadSide(side: Side): Promise<ComposedImages> {
  const res: Partial<ComposedImages> = { };
  for (const l of allLayers) { res[l] = await load(side, l); }
  return res as ComposedImages;
}

function setColors(cols: Rgbs, layers: ComposedImages): void {
  bufferCtx.save();

  for (const l of allLayers) {
    if (l == 'static' || l == 'eyeshine') continue;
    setImageDataRgb(cols[l], layers[l]);
  }

  delete layers.comp;

  bufferCtx.restore();
}

async function compose(layers: Images, pos: Positions): Promise<ImageData> {
  bufferCtx.save();
  bufferCtx.clearRect(0, 0, WIDTH, HEIGHT);

  for (const l of allLayers) {
    const [x, y] = pos[l];
    bufferCtx.globalCompositeOperation =
      l == 'eyeshine' ? 'luminosity' : 'source-over';
    bufferCtx.drawImage(await createImageBitmap(layers[l]), x, y);
  }

  let res = bufferCtx.getImageData(0, 0, WIDTH, HEIGHT);
  bufferCtx.restore();

  return res;
}


async function redraw(ctx: CanvasRenderingContext2D,
                      layers: ComposedImages, pos: Positions) {
  let data = layers.comp ??= await compose(layers, pos);
  ctx.putImageData(data, 0, 0);
}


async function loadingMessage(): Promise<ImageBitmap> {
  bufferCtx.save();
  bufferCtx.clearRect(0, 0, WIDTH, HEIGHT);
  bufferCtx.font = 'bold 100px Muller, sans-serif';
  bufferCtx.textAlign = 'center';
  bufferCtx.fillText('loading layers…', WIDTH/2, HEIGHT/2);
  let res = createImageBitmap(buffer);
  bufferCtx.restore();
  return await res;
}


let pic:  HTMLCanvasElement;
let picCtx: CanvasRenderingContext2D;

let pic2: HTMLCanvasElement;
let pic2Ctx: CanvasRenderingContext2D;

let fronts: Images;
let backs:  Images;

let side: Side = 'front';

function startAnim(name: string) {
  document.documentElement.dataset.running = name;
}

function isRunning(): boolean {
  return !!document.documentElement.dataset.running;
}

function finishAnim() {
  delete document.documentElement.dataset.running;
}

function layers(): Images { return side == 'front' ? fronts : backs; }
function pos(): Positions { return side == 'front' ? FRONT_POS : BACK_POS; }


async function recolorOn(ctx: CanvasRenderingContext2D) {
  const cols = Color.colors();
  const rgbs = toRgbs(cols);
  setColors(rgbs, fronts);
  setColors(rgbs, backs);
  await redraw(ctx, layers(), pos());
  return cols.outer.h;
}

function setBg(hue: number) {
  document.documentElement.style.setProperty('--hue', `${hue}`);
}


async function animateReroll(_e: Event, done: () => void) {
  const duration = 400;
  const hue = await recolorOn(pic2Ctx);
  pic2.style.animation = `${duration}ms ease fade-in`;
  setBg(hue);
  setTimeout(finish, duration);

  async function finish() {
    await redraw(picCtx, layers(), pos()).then(() => {
      pic2.style.removeProperty('animation');
      pic2.style.removeProperty('opacity');
      done();
    });
  }
}


function animateSwap(_e: Event, done: () => void) {
  const duration = 1000;
  pic.style.animation = `${duration}ms ease swap`;
  setTimeout(swapImage, duration/2);
  setTimeout(finish, duration);

  async function swapImage() {
    side = flip(side);
    await redraw(picCtx, layers(), pos());
  }

  function finish() {
    pic.style.removeProperty('animation');
    done();
  }
}

document.addEventListener('DOMContentLoaded', async function() {
  pic = document.getElementById('pic') as HTMLCanvasElement;
  picCtx = pic.getContext('2d')!;

  pic2 = document.getElementById('pic2') as HTMLCanvasElement;
  pic2Ctx = pic2.getContext('2d')!;

  picCtx.drawImage(await loadingMessage(), 0, 0);

  fronts = await loadSide('front');
  backs  = await loadSide('back');
  side   = 'front';

  let hue = await recolorOn(picCtx);
  setBg(hue);
  await redraw(picCtx, layers(), pos());

  const reroll = document.getElementById('reroll')!;
  const swap   = document.getElementById('swap')!;

  addListeners();

  function addListeners() {
    reroll.addEventListener('click', handleReroll);
    swap.addEventListener('click', handleSwap);
  }

  function removeListeners() {
    reroll.removeEventListener('click', handleReroll);
    swap.removeEventListener('click', handleSwap);
  }

  function handleReroll(e: Event) { wrap(reroll, animateReroll, 'reroll', e); }
  function handleSwap(e: Event) { wrap(swap, animateSwap, 'swap', e); }

  type HandlerWithFinish = (e: Event, finish: () => void) => void;

  function wrap(elem: Element, f: HandlerWithFinish,
                name: string, e: Event) {
    if (elem != e.target) return;
    e.stopPropagation();
    if (isRunning()) return;
    removeListeners();
    startAnim(name);
    f(e, () => { finishAnim(); addListeners(); });
  }
});

export { load, loadSide };