let offlineMode = true; // Set this based on your application's state
let currentPublicKey, nextPublicKey;

function arrayBufferToBase64(buffer) {
    let binary = '';
    const bytes = new Uint8Array(buffer);
    for (let i = 0; i < bytes.byteLength; i++) {
        binary += String.fromCharCode(bytes[i]);
    }
    return window.btoa(binary);
}

function updatePublicKeys() {
    if (offlineMode) {
        console.log('Running in offline mode. Skipping public key update.');
        return;
    }
    // Fetch the current and next public keys from the server
    const xhr = new XMLHttpRequest();
    xhr.open('GET', 'http://localhost:9876/api/getPublicKeys', true);

    xhr.onreadystatechange = function() {
        if (xhr.readyState === 4 && xhr.status === 200) {
            const keys = JSON.parse(xhr.responseText);
            currentPublicKey = keys.currentPublicKey;
            nextPublicKey = keys.nextPublicKey;
        }
    };

    xhr.send();
}

function encryptWithPublicKey(plaintext, pubKey) {
    if (offlineMode) {
        console.log('Running in offline mode. Skipping encryption.');
        return Promise.resolve(plaintext);
    }
    // Implement RSA encryption with public key
    // Assuming pubKey is in PEM format
    const publicKey = new TextEncoder().encode(pubKey);
    const textBuffer = new TextEncoder().encode(plaintext);

    return window.crypto.subtle.importKey(
        'spki',
        publicKey,
        {
            name: 'RSA-OAEP',
            hash: 'SHA-256'
        },
        false,
        ['encrypt']
    ).then(key => {
        return window.crypto.subtle.encrypt(
            {
                name: 'RSA-OAEP'
            },
            key,
            textBuffer
        );
    }).then(encrypted => {
        return arrayBufferToBase64(encrypted);
    });
}

function sendMessage() {
    const xhr = new XMLHttpRequest();
    const message = {
        text: 'Hello, server!'
    };

    // Encrypt the message using the server's public key
    encryptWithPublicKey(message.text, currentPublicKey).then(encryptedMessage => {
        xhr.open('POST', 'http://localhost:9876/api/sendMessage', true);
        xhr.setRequestHeader('Content-Type', 'application/json;charset=UTF-8');

        xhr.onreadystatechange = function() {
            if (xhr.readyState === 4 && xhr.status === 200) {
                console.log('Message sent successfully:', xhr.responseText);
            }
        };

        xhr.send(JSON.stringify({text: encryptedMessage}));
    });
}

function addMessageToChat(message, sender) {
    const chatWindow = document.getElementById('chat-window');
    const messageDiv = document.createElement('div');

    messageDiv.className = sender; // 'user' or 'server'
    messageDiv.textContent = message;

    chatWindow.appendChild(messageDiv);
}

function pollForMessages() {
    if (offlineMode) {
        console.log('Running in offline mode. Skipping message polling.');
        return;
    }
    const xhr = new XMLHttpRequest();
    xhr.open('GET', 'http://localhost:9876/api/receiveMessage', true);

    xhr.onreadystatechange = function() {
        if (xhr.readyState === 4 && xhr.status === 200) {
            const receivedMsg = JSON.parse(xhr.responseText);
            addMessageToChat(receivedMsg.text, 'server');
        }
    };

    xhr.send();
}

// Start polling for messages
if (!offlineMode) {
    setInterval(pollForMessages, 2000);  // Poll every 2 seconds
}

function main() {
    if (!offlineMode) {
        updatePublicKeys(); // Before joining the channel
        setInterval(updatePublicKeys, 5 * 60 * 1000); // Check for new keys every 5 minutes
    }
}