Best-pool swap

import { IERC20 } from "./IERC20.json";
import { IV3SwapRouter } from "./IV3SwapRouter.json";
import { IQuoterV2 } from "./IQuoterV2.json";
import { IUniswapV3Pool } from "./IUniswapV3Pool.json";

// Quote two Uniswap V3 pools on-chain and swap through whichever gives the
// better output, via SwapRouter02 — all decided inside one transaction.
// Router and Quoter are fixed (Base mainnet); the tokens, amount, caller and
// the two pools and minimum output are parameters.

function main(
  tokenIn: Address, tokenOut: Address, amountIn: Uint256, caller: Address,
  pool1Addr: Address, pool2Addr: Address, minOut: Uint256,
): Uint256 {
  const router: Address = 0x2626664c2603336E57B271c5C0b26F421741e481;
  const quoter: Address = 0x3d4e44Eb1374240CE5F1B871ab261CD16335B76a;

  // Pull the input tokens in and let the router spend them.
  const token = IERC20.at(tokenIn);
  token.transferFrom(caller, ctx.self(), amountIn);
  token.approve(router, amountIn);

  // Read each pool's fee tier on-chain.
  const feeA: Uint256 = IUniswapV3Pool.at(pool1Addr).fee();
  const feeB: Uint256 = IUniswapV3Pool.at(pool2Addr).fee();

  // Quote both pools. Keys a-e map positionally onto QuoteExactInputSingleParams:
  //   a=tokenIn, b=tokenOut, c=amountIn, d=fee, e=sqrtPriceLimitX96
  const q = IQuoterV2.at(quoter);
  const outA: Uint256 = q.quoteExactInputSingle({ a: tokenIn, b: tokenOut, c: amountIn, d: feeA, e: 0 })[0];
  const outB: Uint256 = q.quoteExactInputSingle({ a: tokenIn, b: tokenOut, c: amountIn, d: feeB, e: 0 })[0];

  // Swap through the better pool. Keys a-g map positionally onto ExactInputSingleParams:
  //   a=tokenIn, b=tokenOut, c=fee, d=recipient, e=amountIn, f=amountOutMinimum, g=sqrtPriceLimitX96
  const r = IV3SwapRouter.at(router);
  if (outA >= outB) {
    r.exactInputSingle({ a: tokenIn, b: tokenOut, c: feeA, d: caller, e: amountIn, f: minOut, g: 0 });
  } else {
    r.exactInputSingle({ a: tokenIn, b: tokenOut, c: feeB, d: caller, e: amountIn, f: minOut, g: 0 });
  }

  // Output tokens were sent straight to the caller by the router.
  return IERC20.at(tokenOut).balanceOf(caller);
}