kkkmeet/public/app.js

const localVideo = document.querySelector("#local-video");
const localNameLabel = document.querySelector("#local-name");
const remoteGrid = document.querySelector("#remote-grid");
const remoteTemplate = document.querySelector("#remote-template");
const nameForm = document.querySelector("#name-form");
const nameInput = document.querySelector("#name-input");
const statusText = document.querySelector("#status");
const youtubeForm = document.querySelector("#youtube-form");
const youtubeInput = document.querySelector("#youtube-input");
const youtubeShell = document.querySelector("#youtube-shell");
const cameraSelect = document.querySelector("#camera-select");
const micSelect = document.querySelector("#mic-select");
const cameraButton = document.querySelector("#camera-button");
const micButton = document.querySelector("#mic-button");
const shareButton = document.querySelector("#share-button");

const roomId = "main";
const nameStorageKey = "kkkmeet.displayName";
const cameraStorageKey = "kkkmeet.cameraDeviceId";
const micStorageKey = "kkkmeet.micDeviceId";
const rtcConfig = {
  iceServers: [{ urls: "stun:stun.l.google.com:19302" }]
};

let peerId = "";
let displayName = "";
let localStream;
let screenStream;
let events;
let youtubePlayer;
let youtubeReady = false;
let currentYoutubeVideoId = "";
let applyingWatchStateUntil = 0;
const peers = new Map();

function setStatus(message) {
  statusText.textContent = message;
}

function normalizeName(name) {
  return name.trim().replace(/\s+/g, " ").slice(0, 48);
}

function setDisplayName(nextName) {
  displayName = normalizeName(nextName);
  localStorage.setItem(nameStorageKey, displayName);
  nameInput.value = displayName;
  localNameLabel.textContent = displayName ? `${displayName} (you)` : "You";
}

function labelForPeer(peer) {
  return peer?.name || `Participant ${peer?.id?.slice(0, 4) || ""}`.trim();
}

function parseYoutubeId(value) {
  const raw = value.trim();
  if (/^[a-zA-Z0-9_-]{11}$/.test(raw)) return raw;

  try {
    const url = new URL(raw);
    if (url.hostname.includes("youtu.be")) {
      return url.pathname.split("/").filter(Boolean)[0] || "";
    }
    if (url.hostname.includes("youtube.com")) {
      if (url.pathname.startsWith("/shorts/") || url.pathname.startsWith("/embed/")) {
        return url.pathname.split("/").filter(Boolean)[1] || "";
      }
      return url.searchParams.get("v") || "";
    }
  } catch {
    return "";
  }

  return "";
}

function loadYoutubeApi() {
  return new Promise((resolve) => {
    if (window.YT?.Player) {
      resolve();
      return;
    }

    const previousReady = window.onYouTubeIframeAPIReady;
    window.onYouTubeIframeAPIReady = () => {
      previousReady?.();
      resolve();
    };

    if (!document.querySelector('script[src="https://www.youtube.com/iframe_api"]')) {
      const script = document.createElement("script");
      script.src = "https://www.youtube.com/iframe_api";
      document.head.append(script);
    }
  });
}

async function ensureYoutubePlayer() {
  await loadYoutubeApi();
  if (youtubePlayer) return youtubePlayer;

  youtubePlayer = new YT.Player("youtube-player", {
    playerVars: {
      controls: 1,
      disablekb: 0,
      modestbranding: 1,
      rel: 0
    },
    events: {
      onReady: () => {
        youtubeReady = true;
      },
      onStateChange: handleYoutubeStateChange
    }
  });
  return youtubePlayer;
}

async function sendWatchState({ videoId, position, playing }) {
  if (!peerId || !videoId) return;

  await fetch(`/watch/${encodeURIComponent(roomId)}`, {
    method: "POST",
    headers: { "content-type": "application/json" },
    body: JSON.stringify({
      type: "watch-state",
      from: peerId,
      name: displayName,
      videoId,
      position,
      playing,
      updatedAt: Date.now()
    })
  });
}

function currentWatchState(playing) {
  if (!youtubeReady || !currentYoutubeVideoId) return null;
  return {
    videoId: currentYoutubeVideoId,
    position: youtubePlayer.getCurrentTime?.() || 0,
    playing
  };
}

function handleYoutubeStateChange(event) {
  if (Date.now() < applyingWatchStateUntil) return;
  if (![YT.PlayerState.PLAYING, YT.PlayerState.PAUSED].includes(event.data)) return;

  const state = currentWatchState(event.data === YT.PlayerState.PLAYING);
  if (state) {
    sendWatchState(state).catch((error) => {
      console.error(error);
      setStatus("Could not sync YouTube playback.");
    });
  }
}

async function applyWatchState(state) {
  if (!state?.videoId) return;

  youtubeShell.classList.add("is-active");
  const player = await ensureYoutubePlayer();
  currentYoutubeVideoId = state.videoId;
  applyingWatchStateUntil = Date.now() + 1200;

  const elapsed = state.playing ? Math.max(0, (Date.now() - state.updatedAt) / 1000) : 0;
  const position = Math.max(0, Number(state.position || 0) + elapsed);

  if (youtubeReady) {
    if (player.getVideoData?.().video_id !== state.videoId) {
      player.loadVideoById(state.videoId, position);
    } else {
      player.seekTo(position, true);
    }

    if (state.playing) {
      player.playVideo();
    } else {
      player.pauseVideo();
    }
  } else {
    const interval = setInterval(() => {
      if (!youtubeReady) return;
      clearInterval(interval);
      applyWatchState(state).catch(console.error);
    }, 100);
  }
}

function mediaConstraints() {
  const cameraDeviceId = localStorage.getItem(cameraStorageKey);
  const micDeviceId = localStorage.getItem(micStorageKey);

  return {
    audio: micDeviceId ? { deviceId: { exact: micDeviceId } } : true,
    video: {
      width: { ideal: 1280 },
      height: { ideal: 720 },
      ...(cameraDeviceId ? { deviceId: { exact: cameraDeviceId } } : {})
    }
  };
}

async function ensureLocalStream() {
  if (localStream) return localStream;

  try {
    localStream = await navigator.mediaDevices.getUserMedia(mediaConstraints());
  } catch (error) {
    localStorage.removeItem(cameraStorageKey);
    localStorage.removeItem(micStorageKey);
    localStream = await navigator.mediaDevices.getUserMedia(mediaConstraints());
  }
  localVideo.srcObject = localStream;
  await refreshDeviceLists();
  return localStream;
}

function trackDeviceId(kind) {
  return localStream?.getTracks().find((track) => track.kind === kind)?.getSettings().deviceId || "";
}

function fillDeviceSelect(select, devices, selectedDeviceId, fallbackLabel) {
  select.replaceChildren();

  if (devices.length === 0) {
    const option = new Option(`No ${fallbackLabel.toLowerCase()} found`, "");
    select.add(option);
    select.disabled = true;
    return;
  }

  select.disabled = false;
  devices.forEach((device, index) => {
    const label = device.label || `${fallbackLabel} ${index + 1}`;
    select.add(new Option(label, device.deviceId));
  });
  select.value = selectedDeviceId && devices.some((device) => device.deviceId === selectedDeviceId)
    ? selectedDeviceId
    : devices[0].deviceId;
}

async function refreshDeviceLists() {
  if (!navigator.mediaDevices?.enumerateDevices) return;

  const devices = await navigator.mediaDevices.enumerateDevices();
  fillDeviceSelect(
    cameraSelect,
    devices.filter((device) => device.kind === "videoinput"),
    trackDeviceId("video") || localStorage.getItem(cameraStorageKey),
    "Camera"
  );
  fillDeviceSelect(
    micSelect,
    devices.filter((device) => device.kind === "audioinput"),
    trackDeviceId("audio") || localStorage.getItem(micStorageKey),
    "Microphone"
  );
}

async function replaceLocalTrack(kind, deviceId) {
  if (!deviceId) return;

  if (!localStream) {
    localStorage.setItem(kind === "video" ? cameraStorageKey : micStorageKey, deviceId);
    return;
  }

  const oldTrack = localStream?.getTracks().find((track) => track.kind === kind);
  const wasEnabled = oldTrack?.enabled ?? true;
  const constraints = kind === "video"
    ? { video: { deviceId: { exact: deviceId }, width: { ideal: 1280 }, height: { ideal: 720 } } }
    : { audio: { deviceId: { exact: deviceId } } };
  const stream = await navigator.mediaDevices.getUserMedia(constraints);
  const newTrack = stream.getTracks()[0];
  newTrack.enabled = wasEnabled;

  if (!localStream) {
    localStream = new MediaStream([newTrack]);
  } else {
    if (oldTrack) {
      localStream.removeTrack(oldTrack);
      oldTrack.stop();
    }
    localStream.addTrack(newTrack);
  }

  if (kind === "audio" || !screenStream) {
    for (const { connection } of peers.values()) {
      const sender = connection.getSenders().find((item) => item.track?.kind === kind);
      await sender?.replaceTrack(newTrack);
    }
  }

  if (kind === "video" && !screenStream) {
    localVideo.srcObject = localStream;
  }

  localStorage.setItem(kind === "video" ? cameraStorageKey : micStorageKey, deviceId);
  await refreshDeviceLists();
}

function updateRemoteLabel(id, name) {
  const label = document.querySelector(`[data-peer-id="${id}"] span`);
  if (label) label.textContent = name || `Participant ${id.slice(0, 4)}`;
}

function createRemoteTile(peer) {
  const id = typeof peer === "string" ? peer : peer.id;
  const fragment = remoteTemplate.content.cloneNode(true);
  const tile = fragment.querySelector(".tile");
  const video = fragment.querySelector("video");
  const label = fragment.querySelector("span");
  tile.dataset.peerId = id;
  label.textContent = labelForPeer(typeof peer === "string" ? { id } : peer);
  remoteGrid.append(tile);
  return { tile, video };
}

function removeRemoteTile(id) {
  document.querySelector(`[data-peer-id="${id}"]`)?.remove();
}

async function sendSignal(to, payload) {
  await fetch(`/signal/${encodeURIComponent(roomId)}`, {
    method: "POST",
    headers: { "content-type": "application/json" },
    body: JSON.stringify({ ...payload, from: peerId, to, name: displayName })
  });
}

function createPeerConnection(remotePeer) {
  const remotePeerId = typeof remotePeer === "string" ? remotePeer : remotePeer.id;
  if (peers.has(remotePeerId)) {
    updateRemoteLabel(remotePeerId, remotePeer.name);
    return peers.get(remotePeerId).connection;
  }

  const connection = new RTCPeerConnection(rtcConfig);
  const remoteStream = new MediaStream();
  const { video } = createRemoteTile(remotePeer);
  video.srcObject = remoteStream;

  localStream.getTracks().forEach((track) => {
    connection.addTrack(track, localStream);
  });

  connection.ontrack = (event) => {
    event.streams[0].getTracks().forEach((track) => {
      remoteStream.addTrack(track);
    });
  };

  connection.onicecandidate = (event) => {
    if (event.candidate) {
      sendSignal(remotePeerId, { type: "ice-candidate", candidate: event.candidate });
    }
  };

  connection.onconnectionstatechange = () => {
    if (["closed", "disconnected", "failed"].includes(connection.connectionState)) {
      closePeer(remotePeerId);
    }
  };

  peers.set(remotePeerId, { connection, remoteStream, name: remotePeer.name });
  return connection;
}

async function callPeer(remotePeer) {
  const remotePeerId = typeof remotePeer === "string" ? remotePeer : remotePeer.id;
  const connection = createPeerConnection(remotePeer);
  const offer = await connection.createOffer();
  await connection.setLocalDescription(offer);
  await sendSignal(remotePeerId, { type: "offer", description: connection.localDescription });
}

async function answerPeer(message) {
  const connection = createPeerConnection({ id: message.from, name: message.name });
  await connection.setRemoteDescription(message.description);
  const answer = await connection.createAnswer();
  await connection.setLocalDescription(answer);
  await sendSignal(message.from, { type: "answer", description: connection.localDescription });
}

async function handleSignal(message) {
  if (message.type === "welcome") {
    peerId = message.peerId;
    setStatus(`Joined the call as ${displayName}. ${message.peers.length} other participant(s).`);
    if (message.watchState) {
      await applyWatchState(message.watchState);
    }
    for (const existingPeer of message.peers) {
      await callPeer(existingPeer);
    }
    return;
  }

  if (message.type === "peer-joined") {
    updateRemoteLabel(message.peerId, message.name);
    setStatus(`${message.name || "A participant"} joined.`);
    return;
  }

  if (message.type === "peer-left") {
    closePeer(message.peerId);
    setStatus("A participant left.");
    return;
  }

  if (message.type === "offer") {
    await answerPeer(message);
    return;
  }

  if (message.type === "watch-state") {
    await applyWatchState(message);
    setStatus(`${message.name || "Someone"} synced YouTube playback.`);
    return;
  }

  const connection = peers.get(message.from)?.connection;
  if (!connection) return;

  if (message.type === "answer") {
    await connection.setRemoteDescription(message.description);
  }

  if (message.type === "ice-candidate") {
    await connection.addIceCandidate(message.candidate);
  }
}

function closePeer(remotePeerId) {
  const peer = peers.get(remotePeerId);
  if (!peer) return;

  peer.connection.close();
  peers.delete(remotePeerId);
  removeRemoteTile(remotePeerId);
}

async function joinCall() {
  if (!displayName) {
    setStatus("Enter your name to join the call.");
    nameInput.focus();
    return;
  }

  leaveCall();
  await ensureLocalStream();

  const params = new URLSearchParams({ name: displayName });
  events = new EventSource(`/events/${encodeURIComponent(roomId)}?${params}`);
  events.onmessage = (event) => handleSignal(JSON.parse(event.data)).catch(console.error);
  events.onerror = () => setStatus("Connection to signaling server was interrupted.");
  setStatus(`Joining as ${displayName}...`);
}

function leaveCall() {
  events?.close();
  events = undefined;
  peerId = "";
  for (const remotePeerId of peers.keys()) closePeer(remotePeerId);
  setStatus(displayName ? `Ready as ${displayName}.` : "Enter your name to join the call.");
}

function setTrackEnabled(kind, enabled) {
  localStream?.getTracks().forEach((track) => {
    if (track.kind === kind) track.enabled = enabled;
  });
}

function updateToggleButton(button, enabled, enabledLabel, disabledLabel) {
  button.setAttribute("aria-pressed", String(enabled));
  button.setAttribute("aria-label", enabled ? enabledLabel : disabledLabel);
  button.title = enabled ? enabledLabel : disabledLabel;
  button.textContent = enabled ? "●" : "○";
}

nameForm.addEventListener("submit", (event) => {
  event.preventDefault();
  setDisplayName(nameInput.value);
  joinCall().catch((error) => {
    console.error(error);
    setStatus("Could not start camera or join the call.");
  });
});

nameInput.addEventListener("change", () => {
  setDisplayName(nameInput.value);
  if (events) {
    joinCall().catch((error) => {
      console.error(error);
      setStatus("Could not rejoin with the updated name.");
    });
  }
});

cameraButton.addEventListener("click", () => {
  const enabled = cameraButton.getAttribute("aria-pressed") !== "true";
  updateToggleButton(cameraButton, enabled, "Turn camera off", "Turn camera on");
  setTrackEnabled("video", enabled);
});

micButton.addEventListener("click", () => {
  const enabled = micButton.getAttribute("aria-pressed") !== "true";
  updateToggleButton(micButton, enabled, "Mute microphone", "Unmute microphone");
  setTrackEnabled("audio", enabled);
});

cameraSelect.addEventListener("change", () => {
  replaceLocalTrack("video", cameraSelect.value).catch((error) => {
    console.error(error);
    setStatus("Could not switch camera.");
  });
});

micSelect.addEventListener("change", () => {
  replaceLocalTrack("audio", micSelect.value).catch((error) => {
    console.error(error);
    setStatus("Could not switch microphone.");
  });
});

youtubeForm.addEventListener("submit", async (event) => {
  event.preventDefault();
  const videoId = parseYoutubeId(youtubeInput.value);

  if (!videoId) {
    setStatus("Enter a valid YouTube URL.");
    youtubeInput.focus();
    return;
  }

  currentYoutubeVideoId = videoId;
  await applyWatchState({
    videoId,
    position: 0,
    playing: true,
    updatedAt: Date.now()
  });
  await sendWatchState({ videoId, position: 0, playing: true });
});

shareButton.addEventListener("click", async () => {
  if (!localStream) return;

  screenStream = await navigator.mediaDevices.getDisplayMedia({ video: true });
  const screenTrack = screenStream.getVideoTracks()[0];

  for (const { connection } of peers.values()) {
    const sender = connection.getSenders().find((item) => item.track?.kind === "video");
    await sender?.replaceTrack(screenTrack);
  }

  localVideo.srcObject = screenStream;
  screenTrack.onended = async () => {
    const cameraTrack = localStream.getVideoTracks()[0];
    for (const { connection } of peers.values()) {
      const sender = connection.getSenders().find((item) => item.track?.kind === "video");
      await sender?.replaceTrack(cameraTrack);
    }
    localVideo.srcObject = localStream;
    screenStream = undefined;
  };
});

const savedName = localStorage.getItem(nameStorageKey);
if (savedName) {
  setDisplayName(savedName);
  joinCall().catch((error) => {
    console.error(error);
    setStatus("Could not start camera or join the call.");
  });
} else {
  nameInput.focus();
  refreshDeviceLists().catch(console.error);
}

navigator.mediaDevices?.addEventListener?.("devicechange", () => {
  refreshDeviceLists().catch(console.error);
});