Add Platform Fees

import "dotenv/config";

import { Keypair } from "@solana/web3.js";
import bs58 from "bs58";

const DFLOW_TRADE_API_URL = process.env.DFLOW_TRADE_API_URL ?? "https://dev-quote-api.dflow.net";
const DFLOW_API_KEY = process.env.DFLOW_API_KEY; // optional; not needed for dev endpoints
const DFLOW_SETTLEMENT_MINT = process.env.DFLOW_SETTLEMENT_MINT ?? "EPjFWdd5AufqSSqeM2qN1xzybapC8G4wEGGkZwyTDt1v"; // USDC

const SOL_MINT = "So11111111111111111111111111111111111111112";

const keypair = Keypair.fromSecretKey(
  bs58.decode(process.env.SOLANA_PRIVATE_KEY ?? "")
);

const headers: HeadersInit = {};
if (DFLOW_API_KEY) headers["x-api-key"] = DFLOW_API_KEY;

const queryParams = new URLSearchParams();
queryParams.append("inputMint", SOL_MINT);
queryParams.append("outputMint", DFLOW_SETTLEMENT_MINT);
queryParams.append("amount", "1000000000");
queryParams.append("platformFeeBps", "50"); // 0.5% fee
queryParams.append("platformFeeMode", "outputMint"); // Collect from output (USDC)
queryParams.append("feeAccount", "YourUSDCTokenAccountAddress");
queryParams.append("userPublicKey", keypair.publicKey.toBase58());

const orderResponse = await fetch(
  `${DFLOW_TRADE_API_URL}/order?${queryParams.toString()}`,
  { headers }
).then((x) => x.json());

/// To collect fee from input mint instead, override the values from above with `.set()` (not `.append()`):
queryParams.set("platformFeeMode", "inputMint");
queryParams.set("feeAccount", "YourSOLTokenAccountAddress"); // Must match input mint

/// For /quote endpoint (imperative swaps)
const quoteResponse = await fetch(
  `${DFLOW_TRADE_API_URL}/quote?${queryParams.toString()}`,
  { headers }
).then((x) => x.json());

/// For /intent endpoint (declarative swaps)
const intentResponse = await fetch(
  `${DFLOW_TRADE_API_URL}/intent?${queryParams.toString()}`,
  { headers }
).then((x) => x.json());

// Reuses the `orderResponse` from the request step above.
if (orderResponse.platformFee) {
  console.log("Platform fee details:", {
    amount: orderResponse.platformFee.amount,
    feeBps: orderResponse.platformFee.feeBps,
    feeAccount: orderResponse.platformFee.feeAccount,
  });
}