/**
 * Telegram Bot for showing rules to new members in a Supergroup
 * The bot can be hosted on Cloudflare Workers
 * This bot automatically sends a welcome message with group rules when a new user joins the supergroup.
 * - The welcome message includes an "Accept" button.
 * - Only the mentioned user can click the button to accept the rules.
 * - When accepted, the bot deletes the welcome message to keep the chat clean.
 * - If another user clicks the button, they receive an alert message.
 *
 * The bot is deployed on Cloudflare Workers and listens for updates via Telegram Webhook.
 * More information about setting webhook here: https://core.telegram.org/bots/api#setwebhook
 * This is my first experience developing a Telegram bot.
 * Feel free to share your feedback with me! 😊
 * Reza Zarchi https://t.me/rezaZarchi
 */

export default {
    async fetch(request) {
        const TOKEN = "YOUR_BOT_TOKEN"; // Replace with your bot token
        const API_URL = `https://api.telegram.org/bot${TOKEN}/`;
        const WELCOME_TEXT = "YOUR_RULES_OR_WELCOME_HERE";
        const DEFAULT_USER_NAME = "Dear new member";
        const updates = await request.json();

        if (updates.message) {
            const chatId = updates.message.chat.id;

            // Detect new user joined
            if (updates.message.new_chat_members) {

                for (const user of updates.message.new_chat_members) {
                    const userId = user.id;
                    const userMention = user.username
                        ? `@${user.username}`
                        : user.first_name
                            ? user.first_name
                            : DEFAULT_USER_NAME;

                    // Send welcome message with "Accept" button
                    const response = await fetch(`${API_URL}sendMessage`, {
                        method: "POST",
                        headers: { "Content-Type": "application/json" },
                        body: JSON.stringify({
                            chat_id: chatId,
                            text: "Hey " + userMention + WELCOME_TEXT,
                            reply_markup: {
                                inline_keyboard: [[
                                    { text: "✅ Accept", callback_data: `accept_rules_${userId}` }
                                ]]
                            }
                        })
                    });

                    const responseBody = await response.json();

                    if (responseBody.ok) {
                        const messageId = responseBody.result.message_id;
                        return new Response(JSON.stringify({ chat_id: chatId, message_id: messageId }));
                    }
                }
            }
        }

        // Handle "Accept" button click
        if (updates.callback_query) {
            const callbackQuery = updates.callback_query;
            const chatId = callbackQuery.message.chat.id;
            const messageId = callbackQuery.message.message_id;
            const userId = callbackQuery.from.id;
            const callbackData = callbackQuery.data;

            // Extract the user ID from callback data
            if (callbackData.startsWith("accept_rules_")) {
                const originalUserId = parseInt(callbackData.split("_")[2], 10);

                if (userId === originalUserId) {
                    // Delete the welcome message if the correct user clicked
                     await fetch(`${API_URL}deleteMessage`, {
                        method: "POST",
                        headers: { "Content-Type": "application/json" },
                        body: JSON.stringify({
                            chat_id: chatId,
                            message_id: messageId
                        })
                    });

                    // Respond to the user
                    await fetch(`${API_URL}answerCallbackQuery`, {
                        method: "POST",
                        headers: { "Content-Type": "application/json" },
                        body: JSON.stringify({
                            callback_query_id: callbackQuery.id,
                            show_alert: false,
                            text: "✅ You have accepted the rules! Welcome to the club! 🎉"
                        })
                    });
                } else {
                    // If another user clicks, show an alert message
                    await fetch(`${API_URL}answerCallbackQuery`, {
                        method: "POST",
                        headers: { "Content-Type": "application/json" },
                        body: JSON.stringify({
                            callback_query_id: callbackQuery.id,
                            text: "⛔ You can not accept this message!",
                            show_alert: true
                        })
                    });
                }
            }
        }

        return new Response("OK", { status: 200 });
    }
};