// examples/telegram-bot-nodejs/bot.js  (excerpt)
import crypto from 'node:crypto';
import { Telegraf, Markup } from 'telegraf';

const bot = new Telegraf(process.env.BOT_TOKEN);

const sign = (body, secretKey) =>
    crypto.createHmac('sha256', secretKey).update(body).digest('hex');

async function createInvoice(orderId, priceFiat) {
    const body = JSON.stringify({
        order_id: orderId,
        price_fiat: priceFiat,
        fiat_currency: 'USD',
        callback_url: CALLBACK_URL,
    });
    const res = await fetch(`${BASE_URL}/api/v1/invoices`, {
        method: 'POST',
        headers: {
            'Content-Type': 'application/json',
            'X-API-Key': PUBLIC_KEY,
            'X-Signature': sign(body, SECRET_KEY),
            'Idempotency-Key': crypto.randomUUID(),
        },
        body,
    });
    return res.json();
}

// /buy  →  inline keyboard with the price tiers
bot.command('buy', async (ctx) => {
    const tiers = [
        ['🥉 Bronze — 5 USDT', '5.00'],
        ['🥈 Silver — 15 USDT', '15.00'],
        ['🥇 Gold — 50 USDT', '50.00'],
    ];
    await ctx.reply('Choose a VIP tier:',
        Markup.inlineKeyboard(tiers.map(([label, amount]) =>
            [Markup.button.callback(label, `buy:${amount}`)]
        )),
    );
});

// tapping a tier creates an invoice and posts the hosted checkout link
bot.action(/^buy:(.+)$/, async (ctx) => {
    await ctx.answerCbQuery();
    const invoice = await createInvoice(`tg-${ctx.from.id}-${Date.now()}`, ctx.match[1]);
    await ctx.reply(`Pay ${ctx.match[1]} USD within 15 minutes.\n\n🔗 [Open checkout](${invoice.checkout_url})`,
        Markup.inlineKeyboard([Markup.button.callback('✅ I paid', 'check')]),
    );
});

// Webhook verification for the Telegram bot (point callback_url here)
export function verifyWebhook(rawBody, signatureHeader) {
    const expected = crypto.createHmac('sha256', SECRET_KEY)
        .update(rawBody).digest('hex');
    return signatureHeader === expected;
}