Swapping - Fixed Input

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  const { decimalsToken0, decimalsToken1 } = await getTokenDecimals(
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    client,
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    testnetPair,
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  );
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  // We define the exact amount of tokens that we would like to provide (in token1 Units)
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  const amountIn = 1000n * 10n ** BigInt(decimalsToken1);
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  console.log("Desired amount In ", amountIn);

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Desired amountIn (raw AUSD): 1000000000n

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/**
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 * Quote how much token0 is output for a fixed token1 input
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 * Returns `[amountIn, amountOutMin]`
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 */
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async function getQuoteForAmountOut(
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  pair: `0x${string}`,
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  amountIn: bigint,
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  swapPath: `0x${string}`[],
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) {
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  return await client.readContract({
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    address: pair,
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    abi: stableSwapAbi,
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    functionName: "getAmountsOut",
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    args: [amountIn, swapPath],
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  });
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}

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const [, amountOutMin] = await getQuoteForAmountOut(
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  TESTNET_PAIR_AUSD_CTK,
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  amountIn,
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  swapPath,
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);
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console.log("Quoted amountOutMin (raw CTK):", amountOutMin);

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Quoted amountOutMin (raw CTK): 999800000000000000000n

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/*
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 * Give `pair` permission to spend `amount` of `tokenToApprove`.
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 * Returns the transaction hash of the on-chain approval.
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 */
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async function approveAllowance(
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  tokenToApprove: `0x${string}`,
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  pair: `0x${string}`,
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  amount: bigint,
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) {
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  // 1) Dry-run to catch reverts & obtain gas estimate
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  const { request } = await client.simulateContract({
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    address: tokenToApprove,
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    abi: ausdImplementationAbi, // standard ERC-20 ABI
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    functionName: "approve",
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    args: [pair, amount],
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  });
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  // 2) Send the real transaction
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  return await client.writeContract(request);
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}

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   // Step 4. ─ approve AUSD allowance
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  console.log(`Approving pair to spend ${amountIn} units of AUSD...`);
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  const approveAllowanceTxHash = await approveAllowance(
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    swapPath[0],
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    TESTNET_PAIR_AUSD_CTK,
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    amountIn,
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  );
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  console.log("Approve transaction hash:", approveAllowanceTxHash);

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Approving pair to spend 1000000000 units of AUSD..
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Approve transaction hash: 0x360753e44c0be192cf633a9888c5cb31dc0a599c49197d7e969150d2f8f9824f

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// Step 5. Execute the swap.
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// Set a deadline for the swap (e.g. current time + 300 seconds)
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const deadline = BigInt(Math.floor(Date.now() / 1000) + 300);
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console.log("Executing swapExactTokensForTokens...");
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const { request: swapRequest } = await client.simulateContract({
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  address: TESTNET_PAIR_AUSD_CTK,
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  abi: stableSwapAbi,
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  functionName: "swapExactTokensForTokens",
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  args: [amountIn, amountOutMin, swapPath, callerAddress, BigInt(deadline)],
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});
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const swapRequestTxHash = await client.writeContract(swapRequest);
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console.log("Swap transaction hash:", swapRequestTxHash);

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Executing swapExactTokensForTokens...
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Swap transaction hash: 0x5693db026af155e5ce9a6678d2e0aa27ba62a0b15e91979b6bcd1c3731f7151c