Build multi-hop calldata

Use this when your quote contains a non-empty multihop array and a path with 3+ tokens.

Endpoint POST /public/emigroswap/buildTransaction

Request (key differences vs single-hop)

• Include the exact path from the quote.

• Include multihop with per-hop params from the quote (e.g., feeTier or spacing).

• Keep using amountOut and minAmountIn from the quote (RAW values).

Sample request (Slipstream multi-hop)

{
  "fromTokenAddress": "0x60a3e35cc302bfa44cb288bc5a4f316fdb1adb42",
  "toTokenAddress":   "0xE9185Ee218cae427aF7B9764A011bb89FeA761B4",
  "chainId": 8453,
  "userWallet": "0x000000000000000000000000000000000000dEaD",
  "amountOut": "100000000",
  "minAmountIn": "618042428770765345237",
  "routerType": "aerodrome-slipstream",
  "path": [
    "0x60a3e35cc302bfa44cb288bc5a4f316fdb1adb42",
    "0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913",
    "0xE9185Ee218cae427aF7B9764A011bb89FeA761B4"
  ],
  "multihop": [
    { "fromTokenAddress": "0x60a3e35...", "toTokenAddress": "0x833589fC...", "feeTier": 50 },
    { "fromTokenAddress": "0x833589fC...", "toTokenAddress": "0xE9185Ee2...", "feeTier": 10 }
  ]
}

import axios from "axios";
import { ethers } from "ethers";

// ---- Config ----
const API_KEY = "esk_live.***";
const BASE_URL = "https://api.emigro.co";
const CHAIN_ID = 8453;
const USER_WALLET = "0x000000000000000000000000000000000000dEaD";

type Hop = { fromTokenAddress: string; toTokenAddress: string; feeTier?: number };
type Quote = {
  fromTokenAddress: string;
  toTokenAddress: string;
  chainId: number;
  amountOut: string;   // RAW input
  minAmountIn: string; // RAW min out
  routerType: string;  // e.g. "aerodrome-slipstream"
  multihop: Hop[];     // non-empty for multi-hop
  path: string[];      // 3+ tokens
};

type BuildTx = {
  success: boolean;
  chainId: number;
  routerAddress: string;
  abiFunctionSignature: string; // swapExactInputPathVia(...)
  abiParameters: any[];
  routerType: string;
  adapterAddress: string;
  adapterData: string;
};

// 1) Get a multi-hop quote (EURC -> USDC -> BRZ)
async function getMultiHopQuote() {
  const { data } = await axios.post<Quote>(
    `${BASE_URL}/public/emigroswap/quote`,
    {
      fromTokenAddress: "0x60a3e35cc302bfa44cb288bc5a4f316fdb1adb42", // EURC
      toTokenAddress:   "0xE9185Ee218cae427aF7B9764A011bb89FeA761B4", // BRZ
      amount: "100.00",
      chainId: CHAIN_ID,
      slippage: 0.5,
    },
    { headers: { "x-api-key": API_KEY, "Content-Type": "application/json" } }
  );
  if (!Array.isArray(data.multihop) || data.path.length < 3) {
    throw new Error("Expected multi-hop; quote returned single-hop.");
  }
  return data;
}

// 2) Build calldata (multi-hop)
async function buildMultiHopCalldata(q: Quote) {
  const body = {
    fromTokenAddress: q.fromTokenAddress,
    toTokenAddress: q.toTokenAddress,
    chainId: q.chainId,
    userWallet: USER_WALLET,
    amountOut: q.amountOut,
    minAmountIn: q.minAmountIn,
    routerType: q.routerType,
    path: q.path,           // EXACTLY from quote
    multihop: q.multihop,   // EXACTLY from quote
  };

  const { data } = await axios.post<BuildTx>(
    `${BASE_URL}/public/emigroswap/buildTransaction`,
    body,
    { headers: { "x-api-key": API_KEY, "Content-Type": "application/json" } }
  );
  return data;
}

// 3) (Optional) Encode & send using ethers v6
async function encodeCall(build: BuildTx) {
  const iface = new ethers.Interface([`function ${build.abiFunctionSignature}`]);
  const data = iface.encodeFunctionData(
    build.abiFunctionSignature.split("(")[0],
    build.abiParameters
  );
  return { to: build.routerAddress, data };
}

(async () => {
  const quote = await getMultiHopQuote();
  const build = await buildMultiHopCalldata(quote);
  console.log("build:", build);
  const tx = await encodeCall(build);
  console.log("tx payload:", tx);
})();

Response (shape)

{
    "success":  true,
    "chainId":  8453,
    "routerAddress":  "0x6b0e33f464dD297cf997DfA96D694aFC153e7F6F",
    "abiFunctionSignature":  "swapExactInputPathVia(address,address[],uint256,uint256,address,bytes)",
    "abiParameters":  [
                          "0x75eaef728727FaBc1C202d21aE9671C4619Df0C0",
                          [
                              "0x60a3e35cc302bfa44cb288bc5a4f316fdb1adb42",
                              "0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913",
                              "0xE9185Ee218cae427aF7B9764A011bb89FeA761B4"
                          ],
                          "100000000",
                          "618042428770765345237",
                          "0x000000000000000000000000000000000000dEaD",
                          "0x0000000000000000000000000000000000000000000000000000000000000040000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000020000000000000000000000000000000000000000000000000000000000000032000000000000000000000000000000000000000000000000000000000000000a"
                      ],
    "routerType":  "aerodrome-slipstream",
    "amountOut":  "100000000",
    "minAmountIn":  "618042428770765345237",
    "adapterAddress":  "0x75eaef728727FaBc1C202d21aE9671C4619Df0C0",
    "adapterData":  "0x0000000000000000000000000000000000000000000000000000000000000040000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000020000000000000000000000000000000000000000000000000000000000000032000000000000000000000000000000000000000000000000000000000000000a"
}

Per-router adapterData encoding

• Slipstream (Aerodrome V2 concentrated): abi.encode(int24[] tickSpacings, uint256 deadlineOrFlags) – the builder derives tickSpacings from multihop or uses safe fallbacks.

• Uniswap V3 (path-based): abi.encode(uint24[] feeTiers, uint256 deadlineOrFlags).

As with single-hop, execute the tx using the returned routerAddress, abiFunctionSignature, and abiParameters without modification.