// SecureChat App — Main Frontend Logic

const API = window.location.origin + "/api";
let token = null;
let me = null;
let privateKey = null;  // CryptoKey object
let ws = null;

// Cache of decrypted messages and public keys
const pubKeyCache = {};   // userId -> CryptoKey
const msgCache = {};      // convId -> [{...}]
const groupMsgCache = {}; // groupId -> [{...}]

let currentChat = null;   // { type: 'dm', id: conv_id, other_user } | { type: 'group', id: group_id, name, members }
let conversations = [];
let groups = [];
let typingTimeout = null;
let selectedGroupMembers = []; // for create group modal
let currentGroupData = null;

// ── Call State ────────────────────────────────────────────────────────────────
let callState = null;
let callType = null;
let callTarget = null;
let localStream = null;
let remoteStream = null;
let peerConnection = null;
let pendingCallOffer = null;

const ICE_SERVERS = {
  iceServers: [
    { urls: 'stun:stun.l.google.com:19302' },
    { urls: 'stun:stun1.l.google.com:19302' }
  ]
};



// ── Bootstrap ───────────────────────────────────────────────────────────────

window.addEventListener("DOMContentLoaded", async () => {
  const params = new URLSearchParams(window.location.search);
  const urlToken = params.get("token");
  const newUser = params.get("new_user") === "True";
  const googleSetup = params.get("google_setup");

  if (googleSetup) {
    pendingGoogleToken = googleSetup;
    window.history.replaceState({}, "", "/");
    showGoogleSetup();
    return;
  }

  if (urlToken) {
    localStorage.setItem("sc_token", urlToken);
    window.history.replaceState({}, "", "/");
    if (newUser) {
      await setupSession(urlToken, true);
      return;
    }
  }

  const stored = localStorage.getItem("sc_token");
  if (stored) {
    await setupSession(stored);
  }
});

async function setupSession(tok, generateKeys = false) {
  try {
    const res = await apiFetch("/auth/me", tok);
    if (!res) { showAuth(); return; }
    token = tok;
    me = res;

    // Load or generate private key
    const storedKeyJwk = Crypto.loadPrivateKey();
    if (storedKeyJwk && me.public_key) {
      privateKey = await Crypto.importPrivateKey(storedKeyJwk);
    } else if (!me.public_key || generateKeys) {
      // Generate new key pair
      const kp = await Crypto.generateKeyPair();
      privateKey = kp.keyPair.privateKey;
      Crypto.storePrivateKey(kp.privateKeyJwk);
      const pubKeyStr = JSON.stringify(kp.publicKeyJwk);
      await apiFetch("/auth/profile", token, "PUT", { public_key: pubKeyStr });
      me.public_key = pubKeyStr;
    }

    // Cache our own public key for group message encryption
    if (me.public_key) {
      try { pubKeyCache[me.id] = await Crypto.importPublicKey(me.public_key); } catch (e) {}
    }

    showApp();
    updateMyProfile();
    await loadChats();
    connectWebSocket();
  } catch (e) {
    showAuth();
  }
}

function showAuth() {
  document.getElementById("auth").style.display = "flex";
  document.getElementById("app").style.display = "none";
}

function showApp() {
  document.getElementById("auth").style.display = "none";
  document.getElementById("app").style.display = "flex";
}

// ── API Helper ───────────────────────────────────────────────────────────────

async function apiFetch(path, tok, method = "GET", body = null) {
  const opts = {
    method,
    headers: {
      "Content-Type": "application/json",
      "Authorization": `Bearer ${tok || token}`
    }
  };
  if (body) opts.body = JSON.stringify(body);
  const res = await fetch(API + path, opts);
  if (!res.ok) {
    const err = await res.json().catch(() => ({}));
    throw new Error(err.detail || res.statusText);
  }
  return res.json();
}

// ── Auth ─────────────────────────────────────────────────────────────────────

function showTab(tab) {
  document.getElementById("auth-tabs").classList.remove("hidden");
  document.getElementById("form-login").classList.toggle("hidden", tab !== "login");
  document.getElementById("form-register").classList.toggle("hidden", tab !== "register");
  document.getElementById("form-google-setup").classList.add("hidden");
  const active = "flex-1 py-2 rounded-lg text-sm font-medium transition-all glass-btn-active text-white";
  const inactive = "flex-1 py-2 rounded-lg text-sm font-medium transition-all text-gray-400";
  document.getElementById("tab-login").className = tab === "login" ? active : inactive;
  document.getElementById("tab-register").className = tab === "register" ? active : inactive;
}

async function doLogin() {
  const username = document.getElementById("login-username").value.trim();
  const password = document.getElementById("login-password").value;
  const errEl = document.getElementById("login-error");
  const btn = document.getElementById("login-btn");
  try {
    errEl.classList.add("hidden");
    if (!username || !password) throw new Error("Please fill in all required fields");
    btn.disabled = true;
    btn.textContent = "Signing in…";
    const data = await apiFetch("/auth/login", null, "POST", { username, password });
    localStorage.setItem("sc_token", data.token);
    await setupSession(data.token);
  } catch (e) {
    errEl.textContent = e.message;
    errEl.classList.remove("hidden");
    btn.disabled = false;
    btn.textContent = "Sign In";
  }
}

async function doRegister() {
  const display_name = document.getElementById("reg-display").value.trim();
  const username = document.getElementById("reg-username").value.trim();
  const email = document.getElementById("reg-email").value.trim();
  const password = document.getElementById("reg-password").value;
  const errEl = document.getElementById("reg-error");
  const btn = document.getElementById("reg-btn");
  try {
    errEl.classList.add("hidden");
    if (!display_name || !username || !password) throw new Error("Please fill in all required fields");
    if (password.length < 8) throw new Error("Password must be at least 8 characters");

    btn.disabled = true;
    btn.textContent = "Generating keys…";

    const kp = await Crypto.generateKeyPair();
    const publicKeyStr = JSON.stringify(kp.publicKeyJwk);
    Crypto.storePrivateKey(kp.privateKeyJwk);

    btn.textContent = "Creating account…";

    const data = await apiFetch("/auth/register", null, "POST", {
      username, display_name, password, email: email || null, public_key: publicKeyStr
    });
    localStorage.setItem("sc_token", data.token);
    token = data.token;
    me = data.user;
    privateKey = kp.keyPair.privateKey;
    showApp();
    updateMyProfile();
    try {
      await loadChats();
    } catch (e) {
      console.error("loadChats error:", e);
    }
    connectWebSocket();
  } catch (e) {
    console.error("Registration error:", e);
    errEl.textContent = e.message;
    errEl.classList.remove("hidden");
    btn.disabled = false;
    btn.textContent = "Create Account";
  }
}

function googleLogin() {
  window.location.href = "/api/auth/google";
}

function showGoogleSetup() {
  document.getElementById("auth-tabs").classList.add("hidden");
  document.getElementById("form-login").classList.add("hidden");
  document.getElementById("form-register").classList.add("hidden");
  document.getElementById("form-google-setup").classList.remove("hidden");
}

let pendingGoogleToken = null;

async function completeGoogleSetup() {
  const username = document.getElementById("gs-username").value.trim();
  const display_name = document.getElementById("gs-display").value.trim();
  const errEl = document.getElementById("gs-error");
  const btn = document.getElementById("gs-btn");
  if (!pendingGoogleToken) {
    pendingGoogleToken = new URLSearchParams(window.location.search).get("google_setup");
  }
  try {
    errEl.classList.add("hidden");
    if (!username || !display_name) throw new Error("Please fill in all fields");
    btn.disabled = true;
    btn.textContent = "Creating account…";
    const data = await apiFetch("/auth/register", null, "POST", {
      username,
      display_name,
      email: null,
      password: "",
      google_setup_token: pendingGoogleToken
    });
    localStorage.setItem("sc_token", data.token);
    token = data.token;
    me = data.user;
    pendingGoogleToken = null;
    const kp = await Crypto.generateKeyPair();
    privateKey = kp.keyPair.privateKey;
    Crypto.storePrivateKey(kp.privateKeyJwk);
    const pubKeyStr = JSON.stringify(kp.publicKeyJwk);
    await apiFetch("/auth/profile", token, "PUT", { public_key: pubKeyStr });
    me.public_key = pubKeyStr;
    if (me.public_key) {
      try { pubKeyCache[me.id] = await Crypto.importPublicKey(me.public_key); } catch (e) {}
    }
    showApp();
    updateMyProfile();
    try { await loadChats(); } catch (e) { console.error("loadChats error:", e); }
    connectWebSocket();
  } catch (e) {
    console.error("Google setup error:", e);
    errEl.textContent = e.message;
    errEl.classList.remove("hidden");
    btn.disabled = false;
    btn.textContent = "Create Account";
  }
}

function logout() {
  localStorage.removeItem("sc_token");
  Crypto.clearPrivateKey();
  if (ws) ws.close();
  showAuth();
}

// ── Profile ───────────────────────────────────────────────────────────────────

function updateMyProfile() {
  document.getElementById("my-display-name").textContent = me.display_name;
  document.getElementById("my-username").textContent = "@" + me.username;
  const av = document.getElementById("my-avatar");
  av.textContent = me.display_name[0].toUpperCase();
  av.style.background = me.avatar_color;
}

function showSettings() {
  document.getElementById("settings-display-name").value = me.display_name;
  document.getElementById("settings-username").value = "@" + me.username;
  document.getElementById("settings-msg").classList.add("hidden");
  document.getElementById("settings-password-section").classList.toggle("hidden", !!me.has_password);
  document.getElementById("settings-password").value = "";
  document.getElementById("settings-password-confirm").value = "";
  document.getElementById("settings-pw-error").classList.add("hidden");
  document.getElementById("modal-settings").classList.remove("hidden");
}

async function setPassword() {
  const password = document.getElementById("settings-password").value;
  const confirm = document.getElementById("settings-password-confirm").value;
  const errEl = document.getElementById("settings-pw-error");
  const btn = document.getElementById("settings-pw-btn");
  try {
    errEl.classList.add("hidden");
    if (!password || password.length < 8) throw new Error("Password must be at least 8 characters");
    if (password !== confirm) throw new Error("Passwords do not match");
    btn.disabled = true;
    btn.textContent = "Setting password…";
    await apiFetch("/auth/set-password", token, "POST", { password });
    me.has_password = true;
    btn.textContent = "Password set!";
    setTimeout(() => {
      document.getElementById("settings-password-section").classList.add("hidden");
    }, 1500);
  } catch (e) {
    errEl.textContent = e.message;
    errEl.classList.remove("hidden");
    btn.disabled = false;
    btn.textContent = "Set Password";
  }
}

async function saveSettings() {
  const newName = document.getElementById("settings-display-name").value.trim();
  if (!newName) return;
  await apiFetch("/auth/profile", token, "PUT", { display_name: newName });
  me.display_name = newName;
  updateMyProfile();
  document.getElementById("settings-msg").classList.remove("hidden");
  setTimeout(() => {
    document.getElementById("settings-msg").classList.add("hidden");
    closeModal("modal-settings");
  }, 1200);
}

// ── WebSocket ─────────────────────────────────────────────────────────────────

function connectWebSocket() {
  const proto = window.location.protocol === "https:" ? "wss" : "ws";
  ws = new WebSocket(`${proto}://${window.location.host}/ws/${token}`);
  ws.onmessage = handleWsMessage;
  ws.onclose = () => setTimeout(connectWebSocket, 3000);
}

async function handleWsMessage(evt) {
  const msg = JSON.parse(evt.data);
  if (msg.type === "dm") {
    await handleIncomingDm(msg);
  } else if (msg.type === "group") {
    await handleIncomingGroup(msg);
  } else if (msg.type === "typing") {
    showTyping(msg);
  } else if (msg.type === "read_receipt") {
    handleReadReceipt(msg);
  } else if (msg.type === "call_offer") {
    handleCallOffer(msg);
  } else if (msg.type === "call_answer") {
    handleCallAnswer(msg);
  } else if (msg.type === "ice_candidate") {
    handleIceCandidate(msg);
  } else if (msg.type === "call_end") {
    handleCallEnd(msg);
  } else if (msg.type === "video_toggle") {
    handleVideoToggle(msg);
  }
}

async function handleIncomingDm(msg) {
  const { conversation_id, message } = msg;

  // For pending DM (no id yet), link it when we get the echo or a reply
  if (currentChat && currentChat.type === "dm" && !currentChat.id) {
    const matchesEcho = message.sender_id === me.id;
    const matchesReply = message.sender_id === currentChat.other_user?.id;
    if (matchesEcho || matchesReply) {
      currentChat.id = conversation_id;
    }
  }

  // Skip our own messages — shown optimistically in sendDm
  if (message.sender_id === me.id) {
    await loadChats();
    return;
  }

  if (!msgCache[conversation_id]) msgCache[conversation_id] = [];

  let plaintext = null;
  if (privateKey) {
    try {
      plaintext = await Crypto.decryptWithPrivateKey(message.ciphertext, privateKey);
    } catch (e) {
      plaintext = "[Encrypted message]";
    }
  }
  const withPlain = { ...message, plaintext };
  msgCache[conversation_id].push(withPlain);

  if (currentChat && currentChat.type === "dm" && currentChat.id === conversation_id) {
    appendMessage(withPlain, currentChat.other_user);
    scrollToBottom();
    sendReadReceipt(conversation_id);
  }

  await loadChats();
}

async function handleIncomingGroup(msg) {
  const { group_id, message } = msg;
  if (!groupMsgCache[group_id]) groupMsgCache[group_id] = [];

  let plaintext = null;
  if (privateKey && message.encrypted_aes_key) {
    try {
      const aesKey = await Crypto.unwrapAesKey(message.encrypted_aes_key, privateKey);
      plaintext = await Crypto.decryptWithAes(message.ciphertext, message.iv, aesKey);
    } catch (e) {
      plaintext = "[Encrypted message]";
    }
  }
  const withPlain = { ...message, plaintext };
  groupMsgCache[group_id].push(withPlain);

  if (currentChat && currentChat.type === "group" && currentChat.id === group_id) {
    appendMessage(withPlain, null, true);
    scrollToBottom();
  }

  await loadChats();
}

function showTyping(msg) {
  if (!currentChat) return;
  const relevant = (currentChat.type === "dm" && msg.conversation_id === currentChat.id) ||
    (currentChat.type === "group" && msg.group_id === currentChat.id);
  if (!relevant && msg.user_id !== currentChat?.other_user?.id) return;

  const ind = document.getElementById("typing-indicator");
  const txt = document.getElementById("typing-text");
  if (msg.is_typing) {
    txt.textContent = `${msg.display_name} is typing…`;
    ind.classList.remove("hidden");
    clearTimeout(typingTimeout);
    typingTimeout = setTimeout(() => ind.classList.add("hidden"), 3000);
  } else {
    ind.classList.add("hidden");
  }
}

// ── Chats Loading ─────────────────────────────────────────────────────────────

let activeTab = "dms";

function setTab(tab) {
  activeTab = tab;
  const activeClass = "flex-1 text-xs py-1.5 rounded-lg glass-btn-active text-white font-medium";
  const inactiveClass = "flex-1 text-xs py-1.5 rounded-lg text-gray-400 hover:text-white transition-colors";
  document.getElementById("tab-dms").className = tab === "dms" ? activeClass : inactiveClass;
  document.getElementById("tab-groups").className = tab === "groups" ? activeClass : inactiveClass;
  renderChatList();
}

function sendReadReceipt(conversationId) {
  if (ws && ws.readyState === WebSocket.OPEN) {
    ws.send(JSON.stringify({ type: "read", conversation_id: conversationId }));
    setTimeout(() => loadChats(), 200);
  }
}

function handleReadReceipt(msg) {
  const { conversation_id } = msg;
  if (msgCache[conversation_id]) {
    let changed = false;
    for (const m of msgCache[conversation_id]) {
      if (m.sender_id === me.id && !m.is_read) {
        m.is_read = true;
        changed = true;
      }
    }
    if (changed && currentChat && currentChat.id === conversation_id) {
      const otherUser = currentChat.other_user;
      renderMessages(msgCache[conversation_id], otherUser);
    }
  }
}

// ── Call Functions ────────────────────────────────────────────────────────────

function showCallDropdown() {
  document.getElementById("call-dropdown").classList.toggle("hidden");
}

function showCallModal() {
  document.getElementById("modal-call").classList.remove("hidden");
}

function hideCallModal() {
  document.getElementById("modal-call").classList.add("hidden");
}

function showIncomingCall() {
  document.getElementById("incoming-call").classList.remove("hidden");
}

function hideIncomingCall() {
  document.getElementById("incoming-call").classList.add("hidden");
}

async function startCall(type) {
  if (!currentChat || currentChat.type !== "dm" || !currentChat.other_user) return;
  document.getElementById("call-dropdown").classList.add("hidden");
  callType = type;
  callTarget = currentChat.other_user;
  callState = "calling";
  try {
    const constraints = { audio: true, video: type === "video" };
    localStream = await navigator.mediaDevices.getUserMedia(constraints);
    peerConnection = new RTCPeerConnection(ICE_SERVERS);
    localStream.getTracks().forEach(t => peerConnection.addTrack(t, localStream));
    remoteStream = new MediaStream();
    peerConnection.ontrack = (event) => {
      event.streams[0].getTracks().forEach(t => remoteStream.addTrack(t));
      const el = document.getElementById("remote-video");
      if (el) el.srcObject = remoteStream;
    };
    peerConnection.onicecandidate = (event) => {
      if (event.candidate && ws && ws.readyState === WebSocket.OPEN) {
        ws.send(JSON.stringify({ type: "ice_candidate", target_id: callTarget.id, candidate: event.candidate }));
      }
    };
    peerConnection.oniceconnectionstatechange = () => {
      if (peerConnection.connectionState === "disconnected" || peerConnection.connectionState === "failed") {
        endCall();
      }
    };
    const offer = await peerConnection.createOffer();
    await peerConnection.setLocalDescription(offer);
    ws.send(JSON.stringify({ type: "call_offer", target_id: callTarget.id, call_type: type, sdp: peerConnection.localDescription }));
    showCallModal();
    document.getElementById("call-status").textContent = "Calling…";
    document.getElementById("call-peer-name").textContent = callTarget.display_name;
    setupCallMedia();
  } catch (e) {
    console.error("startCall error:", e);
    cleanupCall();
  }
}

function handleCallOffer(msg) {
  if (callState) {
    ws.send(JSON.stringify({ type: "call_end", target_id: msg.from }));
    return;
  }
  callType = msg.call_type;
  callTarget = { id: msg.from, display_name: msg.from_display_name, avatar_color: msg.from_avatar_color };
  pendingCallOffer = msg.sdp;
  callState = "ringing";
  document.getElementById("incoming-caller-name").textContent = msg.from_display_name;
  document.getElementById("incoming-call-type").textContent = msg.call_type === "video" ? "Video Call" : "Audio Call";
  const av = document.getElementById("incoming-avatar");
  av.textContent = msg.from_display_name[0].toUpperCase();
  av.style.background = msg.from_avatar_color || "#6366f1";
  document.getElementById("incoming-call-type-icon").textContent = msg.call_type === "video" ? "📹" : "📞";
  document.getElementById("call-dropdown").classList.add("hidden");
  showIncomingCall();
}

async function acceptCall() {
  hideIncomingCall();
  callState = "connected";
  try {
    const constraints = { audio: true, video: callType === "video" };
    localStream = await navigator.mediaDevices.getUserMedia(constraints);
    peerConnection = new RTCPeerConnection(ICE_SERVERS);
    localStream.getTracks().forEach(t => peerConnection.addTrack(t, localStream));
    remoteStream = new MediaStream();
    peerConnection.ontrack = (event) => {
      event.streams[0].getTracks().forEach(t => remoteStream.addTrack(t));
      const el = document.getElementById("remote-video");
      if (el) el.srcObject = remoteStream;
    };
    peerConnection.onicecandidate = (event) => {
      if (event.candidate && ws && ws.readyState === WebSocket.OPEN) {
        ws.send(JSON.stringify({ type: "ice_candidate", target_id: callTarget.id, candidate: event.candidate }));
      }
    };
    peerConnection.oniceconnectionstatechange = () => {
      if (peerConnection.connectionState === "disconnected" || peerConnection.connectionState === "failed") {
        endCall();
      }
    };
    await peerConnection.setRemoteDescription(new RTCSessionDescription(pendingCallOffer));
    pendingCallOffer = null;
    const answer = await peerConnection.createAnswer();
    await peerConnection.setLocalDescription(answer);
    ws.send(JSON.stringify({ type: "call_answer", target_id: callTarget.id, sdp: peerConnection.localDescription }));
    showCallModal();
    document.getElementById("call-status").textContent = "Connected";
    document.getElementById("call-peer-name").textContent = callTarget.display_name;
    setupCallMedia();
  } catch (e) {
    console.error("acceptCall error:", e);
    cleanupCall();
  }
}

function rejectCall() {
  hideIncomingCall();
  if (ws && ws.readyState === WebSocket.OPEN && callTarget) {
    ws.send(JSON.stringify({ type: "call_end", target_id: callTarget.id }));
  }
  cleanupCall();
}

function handleCallAnswer(msg) {
  if (!peerConnection || callState !== "calling") return;
  callState = "connected";
  document.getElementById("call-status").textContent = "Connected";
  peerConnection.setRemoteDescription(new RTCSessionDescription(msg.sdp)).catch(e => console.error("setRemoteDescription error:", e));
}

function handleIceCandidate(msg) {
  if (peerConnection && msg.candidate) {
    peerConnection.addIceCandidate(new RTCIceCandidate(msg.candidate)).catch(() => {});
  }
}

function handleCallEnd(msg) {
  if (callState === "ringing") hideIncomingCall();
  if (callState) {
    callState = null;
    const status = document.getElementById("call-status");
    if (status) {
      status.textContent = "Call ended";
      setTimeout(hideCallModal, 1500);
    }
    cleanupCall();
  }
}

function endCall() {
  if (ws && ws.readyState === WebSocket.OPEN && callTarget) {
    ws.send(JSON.stringify({ type: "call_end", target_id: callTarget.id }));
  }
  cleanupCall();
  hideCallModal();
  hideIncomingCall();
}

function cleanupCall() {
  if (peerConnection) { peerConnection.close(); peerConnection = null; }
  if (localStream) { localStream.getTracks().forEach(t => t.stop()); localStream = null; }
  remoteStream = null;
  callState = null;
  callType = null;
  callTarget = null;
  pendingCallOffer = null;
  const lv = document.getElementById("local-video");
  const rv = document.getElementById("remote-video");
  if (lv) lv.srcObject = null;
  if (rv) rv.srcObject = null;
  document.getElementById("local-video-avatar").classList.add("hidden");
  document.getElementById("remote-video-avatar").classList.add("hidden");
}

function setupCallMedia() {
  const lv = document.getElementById("local-video");
  if (lv) lv.srcObject = localStream;
  // Init local avatar (shows me when my camera is off)
  const localInner = document.getElementById("local-video-avatar-inner");
  if (localInner && me) {
    localInner.textContent = me.display_name[0].toUpperCase();
    localInner.style.background = me.avatar_color || "#6366f1";
  }
  // Init remote avatar (shows other person when their camera is off)
  const remoteInner = document.getElementById("remote-video-avatar-inner");
  if (remoteInner && callTarget) {
    remoteInner.textContent = callTarget.display_name[0].toUpperCase();
    remoteInner.style.background = callTarget.avatar_color || "#6366f1";
  }
  const videoContent = document.getElementById("call-video-content");
  const audioContent = document.getElementById("call-audio-content");
  const videoBtn = document.getElementById("call-video-btn");
  if (callType === "video") {
    if (videoContent) videoContent.classList.remove("hidden");
    if (audioContent) audioContent.classList.add("hidden");
    if (videoBtn) videoBtn.classList.remove("hidden");
  } else {
    if (videoContent) videoContent.classList.add("hidden");
    if (audioContent) audioContent.classList.remove("hidden");
    if (videoBtn) videoBtn.classList.add("hidden");
    const av = document.getElementById("call-audio-avatar");
    if (av) {
      av.textContent = callTarget.display_name[0].toUpperCase();
      av.style.background = callTarget.avatar_color || "#6366f1";
    }
  }
}

function toggleMute() {
  if (localStream) {
    const t = localStream.getAudioTracks()[0];
    if (t) {
      t.enabled = !t.enabled;
      document.getElementById("call-mute-btn").textContent = t.enabled ? "🔊 Mute" : "🔇 Unmute";
    }
  }
}

function toggleVideo() {
  if (localStream && callType === "video") {
    const t = localStream.getVideoTracks()[0];
    if (t) {
      t.enabled = !t.enabled;
      const isOn = t.enabled;
      document.getElementById("call-video-btn").textContent = isOn ? "📹 Video" : "🚫 Video Off";
      const overlay = document.getElementById("local-video-avatar");
      if (overlay) {
        overlay.classList.toggle("hidden", isOn);
      }
      if (ws && ws.readyState === WebSocket.OPEN && callTarget) {
        ws.send(JSON.stringify({ type: "video_toggle", target_id: callTarget.id, enabled: isOn }));
      }
    }
  }
}

function handleVideoToggle(msg) {
  const overlay = document.getElementById("remote-video-avatar");
  const inner = document.getElementById("remote-video-avatar-inner");
  if (!overlay || !inner) return;
  if (msg.enabled) {
    overlay.classList.add("hidden");
  } else {
    inner.textContent = (msg.display_name || "?")[0].toUpperCase();
    inner.style.background = msg.avatar_color || "#6366f1";
    overlay.classList.remove("hidden");
  }
}

async function loadChats() {
  [conversations, groups] = await Promise.all([
    apiFetch("/chat/conversations"),
    apiFetch("/chat/groups")
  ]);
  renderChatList();
}

function filterChats() {
  renderChatList();
}

async function deleteConversation(convId, event) {
  if (event) { event.stopPropagation(); }
  if (!confirm("Delete this conversation?")) return;
  try {
    await apiFetch(`/chat/conversations/${convId}`, token, "DELETE");
    if (currentChat && currentChat.type === "dm" && currentChat.id === convId) {
      currentChat = null;
      document.getElementById("chat-window").classList.add("hidden");
      document.getElementById("chat-window").classList.remove("flex");
      document.getElementById("empty-state").classList.remove("hidden");
      document.getElementById("call-btn").classList.add("hidden");
    }
    delete msgCache[convId];
    await loadChats();
  } catch (e) {
    console.error("deleteConversation error:", e);
  }
}

function renderChatList() {
  const q = document.getElementById("sidebar-search").value.toLowerCase();
  const list = document.getElementById("chat-list");
  list.innerHTML = "";

  if (activeTab === "dms") {
    let filtered = conversations;
    if (q) filtered = filtered.filter(c => c.other_user.display_name.toLowerCase().includes(q) || c.other_user.username.includes(q));
    filtered.forEach(conv => {
      const isActive = currentChat && currentChat.type === "dm" && currentChat.id === conv.id;
      const div = document.createElement("div");
      div.className = `sidebar-item flex items-center gap-3 px-3 py-2.5 rounded-xl cursor-pointer transition-all mx-1 mb-0.5 ${isActive ? "active" : ""}`;
      div.onclick = () => openDmChat(conv);
      div.innerHTML = `
        <div class="w-9 h-9 rounded-full flex items-center justify-center text-white text-sm font-semibold shrink-0" style="background:${conv.other_user.avatar_color}">
          ${conv.other_user.display_name[0].toUpperCase()}
        </div>
        <div class="flex-1 min-w-0">
          <p class="text-sm font-medium truncate">${escHtml(conv.other_user.display_name)}</p>
          <p class="text-xs text-gray-500 truncate">@${conv.other_user.username}</p>
        </div>
        ${conv.unread_count > 0 ? `<span class="w-5 h-5 rounded-full unread-badge text-white text-xs flex items-center justify-center font-medium">${conv.unread_count}</span>` : ""}
        <button onclick="deleteConversation(${conv.id}, event)" class="shrink-0 w-6 h-6 rounded-lg text-gray-600 hover:text-red-400 hover:bg-white/10 flex items-center justify-center text-xs transition-colors" title="Delete conversation">✕</button>
      `;
      list.appendChild(div);
    });
  } else {
    let filtered = groups;
    if (q) filtered = filtered.filter(g => g.name.toLowerCase().includes(q));
    filtered.forEach(group => {
      const isActive = currentChat && currentChat.type === "group" && currentChat.id === group.id;
      const div = document.createElement("div");
      div.className = `sidebar-item flex items-center gap-3 px-3 py-2.5 rounded-xl cursor-pointer transition-all mx-1 mb-0.5 ${isActive ? "active" : ""}`;
      div.onclick = () => openGroupChat(group);
      div.innerHTML = `
        <div class="w-9 h-9 rounded-full flex items-center justify-center text-white text-sm font-semibold shrink-0" style="background:${group.avatar_color}">
          ${group.name[0].toUpperCase()}
        </div>
        <div class="flex-1 min-w-0">
          <p class="text-sm font-medium truncate">${escHtml(group.name)}</p>
          <p class="text-xs text-gray-500">${group.member_count} members</p>
        </div>
      `;
      list.appendChild(div);
    });
  }
}

// ── Open Chats ────────────────────────────────────────────────────────────────

async function openDmChat(conv) {
  // Get full conversation with messages
  const full = await apiFetch(`/chat/conversations?target_user_id=${conv.other_user.id}`, token, "POST");
  currentChat = { type: "dm", id: full.id, other_user: full.other_user };

  // Show header
  document.getElementById("chat-avatar").textContent = full.other_user.display_name[0].toUpperCase();
  document.getElementById("chat-avatar").style.background = full.other_user.avatar_color;
  document.getElementById("chat-name").textContent = full.other_user.display_name;
  document.getElementById("chat-sub").textContent = "@" + full.other_user.username;
  document.getElementById("call-btn").classList.remove("hidden");
  document.getElementById("group-settings-btn").classList.add("hidden");

  document.getElementById("empty-state").classList.add("hidden");
  document.getElementById("chat-window").classList.remove("hidden");
  document.getElementById("chat-window").classList.add("flex");

  // Decrypt and cache messages
  const decrypted = await Promise.all(full.messages.map(async m => {
    if (!privateKey) return { ...m, plaintext: "[No key]" };
    try {
      const plain = await Crypto.decryptWithPrivateKey(m.ciphertext, privateKey);
      return { ...m, plaintext: plain };
    } catch {
      return { ...m, plaintext: "[Encrypted message]" };
    }
  }));
  msgCache[full.id] = decrypted;

  renderMessages(decrypted, full.other_user);
  renderChatList();
  document.getElementById("msg-input").focus();
  sendReadReceipt(full.id);
}

async function openGroupChat(group) {
  const full = await apiFetch(`/chat/groups/${group.id}`);
  currentGroupData = full;
  currentChat = { type: "group", id: full.id, name: full.name, members: full.members };

  document.getElementById("chat-avatar").textContent = full.name[0].toUpperCase();
  document.getElementById("chat-avatar").style.background = full.avatar_color;
  document.getElementById("chat-name").textContent = full.name;
  document.getElementById("chat-sub").textContent = `${full.members.length} members`;
  document.getElementById("call-btn").classList.add("hidden");
  document.getElementById("call-dropdown").classList.add("hidden");
  document.getElementById("group-settings-btn").classList.remove("hidden");

  document.getElementById("empty-state").classList.add("hidden");
  document.getElementById("chat-window").classList.remove("hidden");
  document.getElementById("chat-window").classList.add("flex");

  // Decrypt messages
  const decrypted = await Promise.all(full.messages.map(async m => {
    if (!privateKey || !m.encrypted_aes_key) return { ...m, plaintext: "[Encrypted message]" };
    try {
      const aesKey = await Crypto.unwrapAesKey(m.encrypted_aes_key, privateKey);
      const plain = await Crypto.decryptWithAes(m.ciphertext, m.iv, aesKey);
      return { ...m, plaintext: plain };
    } catch {
      return { ...m, plaintext: "[Encrypted message]" };
    }
  }));
  groupMsgCache[full.id] = decrypted;

  renderMessages(decrypted, null, true);
  renderChatList();
  document.getElementById("msg-input").focus();
}

// ── Render Messages ───────────────────────────────────────────────────────────

function renderMessages(messages, otherUser, isGroup = false) {
  const container = document.getElementById("messages");
  container.innerHTML = "";
  messages.forEach(m => appendMessage(m, otherUser, isGroup));
  scrollToBottom();
}

function appendMessage(m, otherUser, isGroup = false) {
  const container = document.getElementById("messages");
  const isMe = m.sender_id === me.id;

  const div = document.createElement("div");
  div.className = `flex ${isMe ? "justify-end" : "justify-start"} gap-2 fade-in`;

  const time = timeAgo(m.created_at);
  const text = m.plaintext || "[Encrypted message]";

  if (isGroup && !isMe) {
    div.innerHTML = `
      <div class="flex flex-col items-start gap-0.5 max-w-[72%]">
        <span class="text-xs text-gray-500 ml-1">${escHtml(m.sender_name)}</span>
        <div class="msg-bubble glass rounded-2xl rounded-tl-sm px-4 py-2.5 text-sm text-gray-100">${escHtml(text)}</div>
        <span class="text-xs text-gray-500 ml-1">${time}</span>
      </div>`;
  } else if (isMe) {
    const readIcon = m.is_read ? '<span class="text-[10px] text-white/40 ml-1">✓✓</span>' : '<span class="text-[10px] text-white/30">✓</span>';
    div.innerHTML = `
      <div class="flex flex-col items-end gap-0.5 max-w-[72%]">
        <div class="msg-bubble glass-btn rounded-2xl rounded-tr-sm px-4 py-2.5 text-sm text-white">${escHtml(text)}</div>
        <span class="text-xs text-gray-500 flex items-center gap-1">${time}${readIcon}</span>
      </div>`;
  } else {
    div.innerHTML = `
      <div class="flex flex-col items-start gap-0.5 max-w-[72%]">
        <div class="msg-bubble bg-white/8 rounded-2xl rounded-tl-sm px-4 py-2.5 text-sm text-gray-100">${escHtml(text)}</div>
        <span class="text-xs text-gray-600 ml-1">${time}</span>
      </div>`;
  }

  container.appendChild(div);
}

function scrollToBottom() {
  const m = document.getElementById("messages");
  m.scrollTop = m.scrollHeight;
}

// ── Send Message ──────────────────────────────────────────────────────────────

async function sendMessage() {
  const input = document.getElementById("msg-input");
  const text = input.value.trim();
  if (!text || !currentChat || !ws || ws.readyState !== WebSocket.OPEN) return;
  input.value = "";
  input.style.height = "auto";

  if (currentChat.type === "dm") {
    await sendDm(text);
  } else {
    await sendGroupMsg(text);
  }
}

async function sendDm(text) {
  const other = currentChat.other_user;

  // Get recipient's public key (cached or fetch)
  if (!pubKeyCache[other.id]) {
    if (other.public_key) {
      pubKeyCache[other.id] = await Crypto.importPublicKey(other.public_key);
    } else {
      const data = await apiFetch(`/chat/users/${other.id}/public_key`);
      pubKeyCache[other.id] = await Crypto.importPublicKey(data.public_key);
    }
  }

  // Also encrypt for self (so we can read our own messages)
  let myPubKey = pubKeyCache[me.id];
  if (!myPubKey && me.public_key) {
    myPubKey = await Crypto.importPublicKey(me.public_key);
    pubKeyCache[me.id] = myPubKey;
  }

  const ciphertextForRecipient = await Crypto.encryptForRecipient(text, pubKeyCache[other.id]);
  const ciphertextForSender = myPubKey ? await Crypto.encryptForRecipient(text, myPubKey) : ciphertextForRecipient;

  const payload = { type: "dm", ciphertext_for_recipient: ciphertextForRecipient, ciphertext_for_sender: ciphertextForSender };
  if (currentChat.id) {
    payload.conversation_id = currentChat.id;
  } else {
    payload.target_user_id = other.id;
  }
  ws.send(JSON.stringify(payload));

  // Show message immediately
  const optimistic = { id: Date.now(), sender_id: me.id, plaintext: text, created_at: new Date().toISOString(), is_read: false };
  if (currentChat.id) {
    if (!msgCache[currentChat.id]) msgCache[currentChat.id] = [];
    msgCache[currentChat.id].push(optimistic);
  }
  appendMessage(optimistic, other);
  scrollToBottom();
}

async function sendGroupMsg(text) {
  // Get all members' public keys
  const members = currentGroupData?.members || currentChat.members;
  const aesKey = await Crypto.generateAesKey();
  const { ciphertext, iv } = await Crypto.encryptWithAes(text, aesKey);

  const encrypted_aes_keys = {};
  for (const m of members) {
    const uid = m.user.id;
    if (!pubKeyCache[uid]) {
      if (m.user.public_key) {
        pubKeyCache[uid] = await Crypto.importPublicKey(m.user.public_key);
      } else {
        try {
          const data = await apiFetch(`/chat/users/${uid}/public_key`);
          if (data.public_key) pubKeyCache[uid] = await Crypto.importPublicKey(data.public_key);
        } catch {}
      }
    }
    if (pubKeyCache[uid]) {
      encrypted_aes_keys[uid] = await Crypto.wrapAesKey(aesKey, pubKeyCache[uid]);
    }
  }

  ws.send(JSON.stringify({
    type: "group",
    group_id: currentChat.id,
    ciphertext,
    iv,
    encrypted_aes_keys
  }));
}

function handleKey(e) {
  if (e.key === "Enter" && !e.shiftKey) {
    e.preventDefault();
    sendMessage();
  }
  // Auto resize
  const ta = e.target;
  ta.style.height = "auto";
  ta.style.height = Math.min(ta.scrollHeight, 128) + "px";
}

function handleTyping() {
  if (!currentChat || !ws || ws.readyState !== WebSocket.OPEN) return;
  if (currentChat.type === "dm") {
    ws.send(JSON.stringify({
      type: "typing",
      target_id: currentChat.other_user.id,
      conversation_id: currentChat.id,
      is_typing: true
    }));
    clearTimeout(typingTimeout);
    typingTimeout = setTimeout(() => {
      ws.send(JSON.stringify({ type: "typing", target_id: currentChat.other_user.id, conversation_id: currentChat.id, is_typing: false }));
    }, 2000);
  }
}

// ── New Chat ──────────────────────────────────────────────────────────────────

function showNewChat() {
  document.getElementById("modal-new-chat").classList.remove("hidden");
  document.getElementById("search-user-input").value = "";
  document.getElementById("user-search-results").innerHTML = "";
  setTimeout(() => document.getElementById("search-user-input").focus(), 100);
}

let searchTimeout = null;
async function searchUsers() {
  const q = document.getElementById("search-user-input").value.trim();
  clearTimeout(searchTimeout);
  if (!q) { document.getElementById("user-search-results").innerHTML = ""; return; }
  searchTimeout = setTimeout(async () => {
    const users = await apiFetch(`/chat/users/search?q=${encodeURIComponent(q)}`);
    const el = document.getElementById("user-search-results");
    el.innerHTML = users.map(u => `
      <div onclick="startDmWith(${u.id}, ${JSON.stringify(u).replace(/"/g, "&quot;")})" class="flex items-center gap-3 px-3 py-2 rounded-xl cursor-pointer hover:bg-white/5 transition-colors">
        <div class="w-8 h-8 rounded-full flex items-center justify-center text-white text-sm font-semibold" style="background:${u.avatar_color}">${u.display_name[0].toUpperCase()}</div>
        <div>
          <p class="text-sm font-medium">${escHtml(u.display_name)}</p>
          <p class="text-xs text-gray-500">@${u.username}</p>
        </div>
      </div>
    `).join("");
  }, 300);
}

function showChatHeader(user) {
  document.getElementById("chat-avatar").textContent = user.display_name[0].toUpperCase();
  document.getElementById("chat-avatar").style.background = user.avatar_color;
  document.getElementById("chat-name").textContent = user.display_name;
  document.getElementById("chat-sub").textContent = "@" + user.username;
  document.getElementById("call-btn").classList.remove("hidden");
  document.getElementById("call-dropdown").classList.add("hidden");
  document.getElementById("group-settings-btn").classList.add("hidden");
}

async function startDmWith(userId, user) {
  closeModal("modal-new-chat");
  setTab("dms");
  currentChat = { type: "dm", id: null, other_user: user };
  showChatHeader(user);
  document.getElementById("empty-state").classList.add("hidden");
  document.getElementById("chat-window").classList.remove("hidden");
  document.getElementById("chat-window").classList.add("flex");
  document.getElementById("messages").innerHTML = "";
  document.getElementById("msg-input").focus();
}

// ── New Group ─────────────────────────────────────────────────────────────────

function showNewGroup() {
  selectedGroupMembers = [];
  document.getElementById("group-name-input").value = "";
  document.getElementById("group-desc-input").value = "";
  document.getElementById("group-search-input").value = "";
  document.getElementById("group-search-results").innerHTML = "";
  document.getElementById("group-members-list").innerHTML = "";
  document.getElementById("modal-new-group").classList.remove("hidden");
}

async function searchGroupUsers() {
  const q = document.getElementById("group-search-input").value.trim();
  if (!q) { document.getElementById("group-search-results").innerHTML = ""; return; }
  const users = await apiFetch(`/chat/users/search?q=${encodeURIComponent(q)}`);
  const el = document.getElementById("group-search-results");
  el.innerHTML = users.filter(u => !selectedGroupMembers.find(m => m.id === u.id)).map(u => `
    <div onclick='addGroupMember(${JSON.stringify(u)})' class="flex items-center gap-3 px-3 py-2 rounded-xl cursor-pointer hover:bg-white/5 transition-colors">
      <div class="w-7 h-7 rounded-full flex items-center justify-center text-white text-xs font-semibold" style="background:${u.avatar_color}">${u.display_name[0].toUpperCase()}</div>
      <div class="text-sm">${escHtml(u.display_name)} <span class="text-gray-500">@${u.username}</span></div>
    </div>
  `).join("");
}

function addGroupMember(user) {
  if (!selectedGroupMembers.find(m => m.id === user.id)) {
    selectedGroupMembers.push(user);
  }
  document.getElementById("group-search-input").value = "";
  document.getElementById("group-search-results").innerHTML = "";
  renderGroupMemberChips();
}

function removeGroupMember(userId) {
  selectedGroupMembers = selectedGroupMembers.filter(m => m.id !== userId);
  renderGroupMemberChips();
}

function renderGroupMemberChips() {
  document.getElementById("group-members-list").innerHTML = selectedGroupMembers.map(u => `
    <div class="flex items-center gap-1 glass rounded-lg px-2 py-1 text-xs text-white/80">
      <span>${escHtml(u.display_name)}</span>
      <button onclick="removeGroupMember(${u.id})" class="ml-1 hover:text-white">✕</button>
    </div>
  `).join("");
}

async function createGroup() {
  const name = document.getElementById("group-name-input").value.trim();
  const description = document.getElementById("group-desc-input").value.trim();
  if (!name) return;
  const group = await apiFetch("/chat/groups", token, "POST", {
    name, description, member_ids: selectedGroupMembers.map(m => m.id)
  });
  closeModal("modal-new-group");
  setTab("groups");
  await loadChats();
  await openGroupChat(group);
}

// ── Group Settings ────────────────────────────────────────────────────────────

async function showGroupSettings() {
  if (!currentGroupData) return;
  const full = await apiFetch(`/chat/groups/${currentGroupData.id}`);
  currentGroupData = full;
  document.getElementById("gs-name").textContent = full.name;

  document.getElementById("gs-members").innerHTML = full.members.map(m => {
    const isMe = m.user.id === me.id;
    return `<div class="flex items-center gap-3 px-2 py-2 rounded-lg">
      <div class="w-8 h-8 rounded-full flex items-center justify-center text-white text-sm font-semibold" style="background:${m.user.avatar_color}">${m.user.display_name[0].toUpperCase()}</div>
      <div class="flex-1 min-w-0">
        <p class="text-sm font-medium">${escHtml(m.user.display_name)}${isMe ? ' <span class="text-xs text-gray-500">(You)</span>' : ''}</p>
        <p class="text-xs text-gray-500">@${m.user.username}</p>
      </div>
      <button onclick="removeFromGroup(${m.user.id})" class="text-red-400 hover:text-red-300 text-xs ml-2">${isMe ? 'Leave' : 'Remove'}</button>
    </div>`;
  }).join("");

  document.getElementById("gs-add-section").style.display = "block";
  document.getElementById("gs-search-input").value = "";
  document.getElementById("gs-search-results").innerHTML = "";
  document.getElementById("modal-group-settings").classList.remove("hidden");
}

async function searchGsUsers() {
  const q = document.getElementById("gs-search-input").value.trim();
  if (!q) { document.getElementById("gs-search-results").innerHTML = ""; return; }
  const users = await apiFetch(`/chat/users/search?q=${encodeURIComponent(q)}`);
  const currentIds = currentGroupData.members.map(m => m.user.id);
  const el = document.getElementById("gs-search-results");
  el.innerHTML = users.filter(u => !currentIds.includes(u.id)).map(u => `
    <div onclick="addToGroup(${u.id})" class="flex items-center gap-3 px-3 py-2 rounded-xl cursor-pointer hover:bg-white/5 transition-colors">
      <div class="w-7 h-7 rounded-full flex items-center justify-center text-white text-xs font-semibold" style="background:${u.avatar_color}">${u.display_name[0].toUpperCase()}</div>
      <div class="text-sm">${escHtml(u.display_name)}</div>
    </div>
  `).join("");
}

async function addToGroup(userId) {
  await apiFetch(`/chat/groups/${currentGroupData.id}/members`, token, "POST", { user_id: userId });
  await showGroupSettings();
}

async function removeFromGroup(userId) {
  try {
    await apiFetch(`/chat/groups/${currentGroupData.id}/members/${userId}`, token, "DELETE");
  } catch (e) {
    console.error("removeFromGroup error:", e);
    return;
  }
  if (userId === me.id) {
    closeModal("modal-group-settings");
    currentChat = null;
    currentGroupData = null;
    document.getElementById("chat-window").classList.add("hidden");
    document.getElementById("chat-window").classList.remove("flex");
    document.getElementById("empty-state").classList.remove("hidden");
    document.getElementById("call-btn").classList.add("hidden");
    await loadChats();
  } else {
    await showGroupSettings();
  }
}

// ── Modals ────────────────────────────────────────────────────────────────────

function closeModal(id) {
  document.getElementById(id).classList.add("hidden");
}

// Close on backdrop click
document.addEventListener("click", (e) => {
  ["modal-new-chat", "modal-new-group", "modal-settings", "modal-group-settings", "modal-call"].forEach(id => {
    const el = document.getElementById(id);
    if (e.target === el) el.classList.add("hidden");
  });
  // Close call dropdown when clicking outside
  const dd = document.getElementById("call-dropdown");
  const btn = document.getElementById("call-btn");
  if (dd && !dd.classList.contains("hidden") && !dd.contains(e.target) && !btn.contains(e.target)) {
    dd.classList.add("hidden");
  }
});

// ── Utils ─────────────────────────────────────────────────────────────────────

function timeAgo(dateStr) {
  const now = Date.now();
  const then = new Date(dateStr).getTime();
  const diff = now - then;
  const mins = Math.floor(diff / 60000);
  if (mins < 1) return "now";
  if (mins < 60) return mins + "m ago";
  const hrs = Math.floor(mins / 60);
  if (hrs < 24) return hrs + "h ago";
  const days = Math.floor(hrs / 24);
  if (days < 7) return days + "d ago";
  return new Date(dateStr).toLocaleDateString([], { month: "short", day: "numeric" });
}

function escHtml(str) {
  return String(str).replace(/&/g, "&amp;").replace(/</g, "&lt;").replace(/>/g, "&gt;").replace(/"/g, "&quot;");
}