/* main.js - websnap */
import { HandLandmarker, FilesetResolver }
  from "https://cdn.jsdelivr.net/npm/@mediapipe/tasks-vision@latest";

/* set html elements */
const video   = document.getElementById("video");
const canvas  = document.getElementById("canvas");
const overlay = document.getElementById("overlay");
const octx    = overlay.getContext("2d");
const ctx     = canvas.getContext("2d");
const flash   = document.getElementById("flash");

let lastShot = 0;

/* function to request fullscreen */
function requestFS() {
  const el = document.documentElement;
  (el.requestFullscreen || el.webkitRequestFullscreen || el.mozRequestFullScreen)
    ?.call(el);
}
requestFS();

/* add listeners for fullscreen */
document.addEventListener("click",    requestFS, { once: true });
document.addEventListener("touchend", requestFS, { once: true });
document.addEventListener("dblclick", requestFS);

/* camera setup */
const stream = await navigator.mediaDevices.getUserMedia({
  /* ideal res: 4096x2160 ; 4k */
  video: { width: { ideal: 4096 }, height: { ideal: 2160 }, facingMode: "user" }
});
video.srcObject = stream;

/* import mediapipe for handgestures */
const vision = await FilesetResolver.forVisionTasks(
  "https://cdn.jsdelivr.net/npm/@mediapipe/tasks-vision/wasm"
);
const handLandmarker = await HandLandmarker.createFromOptions(vision, {
  baseOptions: {
    modelAssetPath:
      "https://storage.googleapis.com/mediapipe-models/hand_landmarker/hand_landmarker/float16/1/hand_landmarker.task"
  },
  runningMode: "VIDEO",
  numHands: 1
});

/* flash for when picture gets taken */
function triggerFlash() {
  flash.classList.add("pop");
  requestAnimationFrame(() => requestAnimationFrame(() => flash.classList.remove("pop")));
}

/* capture a picture */
function takePhoto() {
  triggerFlash();
  const w = video.videoWidth, h = video.videoHeight;
  canvas.width = w; canvas.height = h;
  ctx.drawImage(video, 0, 0, w, h);
  canvas.toBlob(blob => {
    if (!blob) return;
    saveAs(blob, "websnap-" + Date.now() + ".png");
  }, "image/png");
}

/* detect shit */
function detectLoop(timestamp) {
  const dw = overlay.offsetWidth, dh = overlay.offsetHeight;
  if (overlay.width !== dw || overlay.height !== dh) {
    overlay.width = dw; overlay.height = dh;
  }
  /* draw rect */
  octx.clearRect(0, 0, dw, dh);

  if (video.readyState < 2) { requestAnimationFrame(detectLoop); return; }

  const result = handLandmarker.detectForVideo(video, timestamp);

  if (result.landmarks.length) {
    const lm = result.landmarks[0];

    /* finger indexes, for peace sign */
    const indexUp   = lm[8].y  < lm[6].y;
    const middleUp  = lm[12].y < lm[10].y;
    const ringDown  = lm[16].y > lm[14].y;
    const pinkyDown = lm[20].y > lm[18].y;
    const fingerGap = Math.abs(lm[8].x - lm[12].x);
    const peace = 
      indexUp &&
      middleUp &&
      ringDown &&
      pinkyDown &&
      fingerGap > 0.05;

    if (peace && Date.now() - lastShot > 2500) { /* wait a bit */
      takePhoto();
      lastShot = Date.now();
    }
  }

  requestAnimationFrame(detectLoop);
}

requestAnimationFrame(detectLoop);