Build a Crypto Price Alert Bot

require('dotenv').config();
const axios = require('axios');
const TelegramBot = require('node-telegram-bot-api');

// Configuration from .env file
const TELEGRAM_BOT_TOKEN = process.env.TELEGRAM_BOT_TOKEN;
const TELEGRAM_CHAT_ID = process.env.TELEGRAM_CHAT_ID;
const CRYPTO_TOKEN_ID = process.env.CRYPTO_TOKEN_ID;
const CRYPTO_NETWORK = process.env.CRYPTO_NETWORK;
const TARGET_PRICE = parseFloat(process.env.TARGET_PRICE);
const ALERT_TYPE = process.env.ALERT_TYPE.toLowerCase();
const CHECK_INTERVAL = parseInt(process.env.CHECK_INTERVAL) * 60 * 1000; // Convert minutes to milliseconds

// Initialize Telegram Bot
const bot = new TelegramBot(TELEGRAM_BOT_TOKEN);

// Validate configuration
if (!TELEGRAM_BOT_TOKEN || !TELEGRAM_CHAT_ID || !CRYPTO_TOKEN_ID || !CRYPTO_NETWORK || 
    isNaN(TARGET_PRICE) || !ALERT_TYPE || isNaN(CHECK_INTERVAL)) {
  console.error('Invalid configuration. Please check your .env file.');
  process.exit(1);
}

// Send startup message
bot.sendMessage(TELEGRAM_CHAT_ID, 
  `🤖 Crypto Alert Bot Started!\n\n` +
  `Monitoring: ${CRYPTO_TOKEN_ID} on ${CRYPTO_NETWORK}\n` +
  `Alert when price goes ${ALERT_TYPE} $${TARGET_PRICE}\n` +
  `Checking every ${CHECK_INTERVAL / 60000} minute(s)`
);

// Variables to track alert state
let alertSent = false;
let lastPrice = 0;

// Main function to check price and send alerts
async function checkPrice() {
  try {
    // Fetch current price from DexPaprika API
    const response = await axios.get(
      `https://api.dexpaprika.com/networks/${CRYPTO_NETWORK}/tokens/${CRYPTO_TOKEN_ID}`
    );

    // Extract price from response
    const currentPrice = response.data.summary.price_usd;
    lastPrice = currentPrice;
    
    console.log(`Current price of ${CRYPTO_TOKEN_ID}: $${currentPrice}`);
    
    // Check if alert condition is met
    let shouldAlert = false;
    
    if (ALERT_TYPE === 'above' && currentPrice > TARGET_PRICE) {
      shouldAlert = true;
    } else if (ALERT_TYPE === 'below' && currentPrice < TARGET_PRICE) {
      shouldAlert = true;
    }
    
    // Send alert if condition is met and no alert was sent before
    if (shouldAlert && !alertSent) {
      const message = 
        `🚨 PRICE ALERT 🚨\n\n` +
        `${response.data.name} (${response.data.symbol})\n` +
        `Current Price: $${currentPrice}\n` +
        `Target: ${ALERT_TYPE} $${TARGET_PRICE}\n\n` +
        `Condition met! 🎯`;
      
      bot.sendMessage(TELEGRAM_CHAT_ID, message);
      alertSent = true;
      console.log('Alert sent!');
    }
    
    // Reset alert flag if price goes back on the other side of the threshold
    if ((ALERT_TYPE === 'above' && currentPrice < TARGET_PRICE) || 
        (ALERT_TYPE === 'below' && currentPrice > TARGET_PRICE)) {
      alertSent = false;
    }
    
  } catch (error) {
    console.error('Error checking price:', error.message);
    
    // Send error notification if API fails
    if (error.response) {
      bot.sendMessage(TELEGRAM_CHAT_ID, 
        `⚠️ Error checking price: ${error.response.status} - ${error.response.statusText}`);
    } else {
      bot.sendMessage(TELEGRAM_CHAT_ID, 
        `⚠️ Error checking price: ${error.message}`);
    }
  }
}

// Run the price check immediately
checkPrice();

// Then set up interval to check regularly
setInterval(checkPrice, CHECK_INTERVAL);

console.log(`Bot is running. Checking ${CRYPTO_TOKEN_ID} every ${CHECK_INTERVAL / 60000} minute(s).`);