const express = require('express');
const { ethers } = require('ethers');

const app = express();
app.use(express.json());

const PORT = process.env.PORT || 2015;

// Connect to an Ethereum provider
const provider = new ethers.JsonRpcProvider(process.env.INFURA_URL || 'https://mainnet.infura.io/v3/25c9f1810f234c278a4f13736a897836');

// ERC-20 token contract address
const tokenAddress = '0x22b6c31c2beb8f2d0d5373146eed41ab9ede3caf';

// ERC-20 token ABI (Application Binary Interface)
const tokenABI = [
  // Only the part of the ABI we need: balanceOf and decimals
  "function balanceOf(address owner) view returns (uint256)",
  "function decimals() view returns (uint8)"
];

// Create a contract instance
const tokenContract = new ethers.Contract(tokenAddress, tokenABI, provider);

app.listen(PORT, () => {
  console.log("started listening on localhost:" + PORT);
});

app.get("/status", (request, response) => {
  const status = {
    "Status": "Running"
  };

  response.send(status);
});

/* ------------------------------------------------------------------------------- */

app.get("/getBalance", async (request, response) => {
  try {
    const { address } = request.query;

    if (!address) {
      return response.status(400).json({ error: "Missing wallet address in the query parameters" });
    }

    // Check if the provided address is a valid Ethereum address
    if (!ethers.isAddress(address)) {
      return response.status(400).json({ error: "Invalid Ethereum address" });
    }

    // Get the token balance of the wallet address
    const balanceRaw = await tokenContract.balanceOf(address);

    // Get the number of decimals used by the token
    const decimals = await tokenContract.decimals();

    // Convert the balance to a human-readable format
    const balance = ethers.formatUnits(balanceRaw, decimals);

    response.json({ address, tokenAddress, balance});
  } catch (error) {
    console.error("Error fetching token balance:", error);
    response.status(500).json({ error: "Failed to fetch token balance", trace: error });
  }
});