interface Interaction {
  target: string;   // Contract address to invoke
  value: BigNumberish; // Native Ether amount in wei (defaults to 0)
  callData: string;    // Encoded function data (defaults to "0x")
}

interface InteractionLike {
  target: string;
  value?: BigNumberish;
  callData?: string;
}

function normalizeInteraction(interaction: InteractionLike): Interaction;

function normalizeInteractions(interactions: InteractionLike[]): Interaction[];

enum InteractionStage {
  PRE = 0,   // Setup operations before token transfers
  INTRA = 1, // Swaps after sell tokens arrive (default)
  POST = 2,  // Cleanup after all trading concludes
}

import { ethers } from "ethers";

// EIP-2612 permit (PRE stage)
const permitInteraction = {
  target: tokenAddress,
  value: 0,
  callData: tokenContract.interface.encodeFunctionData("permit", [
    owner, spender, value, deadline, v, r, s
  ]),
};

// Uniswap swap (INTRA stage)
const swapInteraction = {
  target: uniswapRouterAddress,
  value: 0,
  callData: router.interface.encodeFunctionData("exactInputSingle", [params]),
};

// WETH unwrap (POST stage)
const unwrapInteraction = {
  target: wethAddress,
  value: 0,
  callData: weth.interface.encodeFunctionData("withdraw", [amount]),
};