let socket;
let username;
let sessionToken;
let nextId = 0;
let pendingMessages = {};

async function init() {
    try {
        const res = await fetch("/api/session");
        const data = await res.json();
        if (data.authenticated) {
            username = data.username;
            sessionToken = data.token;
            showChat();
            connectWebSocket();
        } else {
            showLogin();
        }
    } catch {
        showLogin();
    }
}

function showLogin() {
    document.getElementById("auth-container").style.display = "block";
    document.getElementById("login-form").style.display = "block";
    document.getElementById("signup-form").style.display = "none";
    document.getElementById("chat-app").style.display = "none";
    document.getElementById("login-error").textContent = "";
}

function showSignup() {
    document.getElementById("auth-container").style.display = "block";
    document.getElementById("login-form").style.display = "none";
    document.getElementById("signup-form").style.display = "block";
    document.getElementById("chat-app").style.display = "none";
    document.getElementById("signup-error").textContent = "";
}

function showChat() {
    document.getElementById("auth-container").style.display = "none";
    document.getElementById("chat-app").style.display = "block";
    document.getElementById("display-username").textContent = username;
    document.getElementById("chat-window").innerHTML = "";
}

async function handleLogin(e) {
    e.preventDefault();
    const login = e.target.login.value;
    const password = e.target.password.value;
    const error = document.getElementById("login-error");

    try {
        const res = await fetch("/api/login", {
            method: "POST",
            headers: { "Content-Type": "application/json" },
            body: JSON.stringify({ login, password }),
        });
        const data = await res.json();
        if (res.ok) {
            username = data.username;
            sessionToken = data.token;
            showChat();
            connectWebSocket();
        } else {
            error.textContent = data.error;
            e.target.password.value = "";
        }
    } catch {
        error.textContent = "Network error.";
    }
}

async function handleSignup(e) {
    e.preventDefault();
    const email = e.target.email.value;
    const usernameVal = e.target.username.value;
    const password = e.target.password.value;
    const confirm = e.target.confirm_password.value;
    const error = document.getElementById("signup-error");

    if (password !== confirm) {
        error.textContent = "Passwords do not match.";
        return;
    }

    try {
        const res = await fetch("/api/signup", {
            method: "POST",
            headers: { "Content-Type": "application/json" },
            body: JSON.stringify({ email, username: usernameVal, password }),
        });
        const data = await res.json();
        if (res.ok) {
            username = data.username;
            sessionToken = data.token;
            showChat();
            connectWebSocket();
        } else {
            error.textContent = data.error;
        }
    } catch {
        error.textContent = "Network error.";
    }
}

async function logout() {
    if (socket) { socket.close(); socket = null; }
    try { await fetch("/api/logout", { method: "POST" }); } catch {}
    username = "";
    sessionToken = "";
    showLogin();
}

function connectWebSocket() {
    const protocol = window.location.protocol === "https:" ? "wss:" : "ws:";
    const url = protocol + "//" + window.location.host + "/ws?token=" + encodeURIComponent(sessionToken);
    socket = new WebSocket(url);

    socket.onmessage = function (event) {
        const data = JSON.parse(event.data);
        const now = Date.now();
        const win = document.getElementById("chat-window");
        const el = document.createElement("div");

        if (data.is_system) {
            el.style.fontStyle = "italic";
            el.style.color = "#ffcc00";
            el.textContent = "[System] " + data.msg;
        } else {
            let text = data.user + ": " + data.msg;
            if (data.user === username && pendingMessages[data.id] !== undefined) {
                const rtt = now - pendingMessages[data.id];
                text += " (rtt: " + rtt + "ms)";
                delete pendingMessages[data.id];
            } else if (data.server_time) {
                const sp = now - data.server_time;
                text += " (sping: " + sp + "ms)";
            }
            el.textContent = text;
        }
        win.appendChild(el);
        win.scrollTop = win.scrollHeight;
    };

    socket.onclose = function (event) {
        if (event.code === 4002) {
            location.reload();
            return;
        }
        const win = document.getElementById("chat-window");
        if (win) {
            const el = document.createElement("div");
            el.style.fontStyle = "italic";
            el.style.color = "#e94560";
            if (event.code === 4001) {
                el.textContent = "Session expired. Logging out...";
                setTimeout(() => { logout(); }, 1500);
            } else {
                el.textContent = "Connection lost. Refresh the page.";
            }
            win.appendChild(el);
        }
    };
}

function sendMessage() {
    if (!socket || socket.readyState !== WebSocket.OPEN) return;
    const input = document.getElementById("message-input");
    const msg = input.value.trim();
    if (!msg) return;

    const id = nextId++;
    pendingMessages[id] = Date.now();
    socket.send(JSON.stringify({ msg, id }));
    input.value = "";
    input.focus();
}

init();