Exit borrow at maturity

import {
  createWalletClient,
  http,
  parseUnits,
  zeroAddress,
  type Address,
} from "viem";
import { base } from "viem/chains";
import { privateKeyToAccount } from "viem/accounts";

// The existing borrower (your wallet address)
const borrower: Address = "0xYourWalletAddress";

// Create a wallet client connected to Base
// This example uses a simple EOA with a private key for brevity 
// You can substitute in any wallet solution that fits your setup
const walletClient = createWalletClient({
  account: privateKeyToAccount("0xYourPrivateKey"),  
  chain: base,
  transport: http(),
});

GET https://api.morpho.org/v0/midnight/markets
  /{marketId}/users/{userAddress}/position

// Response
{
  "data": {
    "chain_id":           8453,
    "market_id":          "0xd92de5e7fbb...7614",                // market the borrower borrowed from
    "user_address":       "0xYourWalletAddress",
    "last_indexed_block": "47457420",
    "loan_token":         "0x8335...2913",                       // USDC
    "maturity":           "1798761600",
    "type":               "borrow",                              // "lend" | "borrow" | "collateral_only"
    "credit":             "0",                                   // lender side (0 for a borrower)
    "debt":               "10527000000",                         // outstanding debt to clear
    "pending_fee":        "0",                                   // relevant for type: "credit" (over the defined maturity date, here's what you'll owe as a lender)
    "last_loss_factor":   "0",
    "loss_factor":        "0",
    "collaterals": [                                             // each entry is { token, amount }
      {
        "token":  "0x4200000000000000000000000000000000000006",  // WETH
        "amount": "5000000000000000000"                          // 5 WETH (18 dec)
      }
    ]
  }
}

import {
  erc20Abi, createPublicClient, encodeAbiParameters, parseAbiParameters, parseSignature, parseUnits, http,
} from "viem";
import { base } from "viem/chains";

const MIDNIGHT_BUNDLES = "0x6688dEc8878f43905e11B3C6Bc025E098133144f";   // MidnightBundles contract
const USDC            = "0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913";    // USDC on Base

// Full obligation = debt + accrued pending_fee
const debtAssets = BigInt(position.debt) + BigInt(position.pending_fee);

// Approve a bit more than the debtAssets. Any accrual between reading and executing could leave dust that blocks full collateral release.
const approveAmount = debtAssets + parseUnits("1", 6);

// Path 1: approve()
// 1. Let MidnightBundles pull USDC 
// 2. Set limit based on approveAmount computed above
await walletClient.writeContract({
  account: borrower, address: USDC, abi: erc20Abi,
  functionName: "approve", args: [MIDNIGHT_BUNDLES, approveAmount],
});

// Variable to set loanTokenPermit later in bundler argument
const tokenPermitNone = { kind: 0, data: "0x" } as const;

// --------------------------------------------------------------

// Path 2: EIP-2612
// Authorize exactly the USDC you'll spend buying units
const publicClient = createPublicClient({ chain: base, transport: http() });

// Ceiling you authorize via the permit (covers fee accruing before the tx lands) 
// Same as "approvedAmount" defined above for the approval flow
const permitValue = BigInt(position.debt) + BigInt(position.pending_fee)
                  + parseUnits("1", 6);
const deadline = BigInt(Math.floor(Date.now() / 1000) + 3600);

// Read the owner's current EIP-2612 nonce from the token.
const nonce = await publicClient.readContract({
  address: USDC,
  abi: [{ name: "nonces", type: "function", stateMutability: "view",
          inputs: [{ name: "owner", type: "address" }],
          outputs: [{ type: "uint256" }] }],
  functionName: "nonces",
  args: [borrower],
});

// Offchain signature (no transaction, no gas)
const sig = await walletClient.signTypedData({
  account: borrower,
  domain: { name: "USD Coin", version: "2", chainId: 8453, verifyingContract: USDC },
  types: { Permit: [
    { name: "owner",    type: "address" },
    { name: "spender",  type: "address" },
    { name: "value",    type: "uint256" },
    { name: "nonce",    type: "uint256" },
    { name: "deadline", type: "uint256" },
  ] },
  primaryType: "Permit",
  message: { owner: borrower, spender: MIDNIGHT_BUNDLES,
             value: permitValue, nonce, deadline },
});

const { r, s, v } = parseSignature(sig);

// Variable to set the loanTokenPermit variable to (bundler argument) in the Execute step that follows 
const loanTokenPermitEIP2612 = {
  kind: 1,                                                                 // 1 = ERC2612
  data: encodeAbiParameters(
    parseAbiParameters("uint256 deadline, uint8 v, bytes32 r, bytes32 s"),
    [deadline, Number(v), r, s],
  ),
} as const;

// --------------------------------------------------------------

// Path 3: Permit2
// One-time setup (once per token, ever): approve Permit2 on USDC
const PERMIT2 = "0x000000000022D473030F116dDEE9F6B43aC78BA3";              // canonical, same on every chain
const repayCeiling = BigInt(position.debt) + BigInt(position.pending_fee)
                   + parseUnits("1", 6);

// One-time setup (once per token, ever): approve Permit2 on USDC.
await walletClient.writeContract({
  account: borrower, address: USDC, abi: erc20Abi,
  functionName: "approve", args: [PERMIT2, maxUint256],
});

// Per-repay: sign a Permit2 SignatureTransfer (offchain, no gas).
const nonce    = BigInt(Date.now());                                       // unordered nonce (Permit2 uses a bitmap)
const deadline = BigInt(Math.floor(Date.now() / 1000) + 3600);

const sig = await walletClient.signTypedData({
  account: borrower,
  domain: { name: "Permit2", chainId: 8453, verifyingContract: PERMIT2 },  
  types: {
    PermitTransferFrom: [
      { name: "permitted", type: "TokenPermissions" },
      { name: "spender",   type: "address" },
      { name: "nonce",     type: "uint256" },
      { name: "deadline",  type: "uint256" },
    ],
    TokenPermissions: [
      { name: "token",  type: "address" },
      { name: "amount", type: "uint256" },
    ],
  },
  primaryType: "PermitTransferFrom",
  message: {
    permitted: { token: USDC, amount: repayCeiling },
    spender: MIDNIGHT_BUNDLES,
    nonce,
    deadline,
  },
});

// Variable to set the loanTokenPermit variable to (bundler argument) in the Execute step that follows 
const loanTokenPermit2 = {
  kind: 2,                                                                 // 2 = Permit2
  data: encodeAbiParameters(
    parseAbiParameters("uint256 nonce, uint256 deadline, bytes signature"),
    [nonce, deadline, sig],
  ),
} as const;

// --------------------------------------------------------------

// Authorize MidnightBundles to act on your position (one-time boolean, persists across future actions)
await walletClient.writeContract({
  account: borrower,
  address: MIDNIGHT,
  abi: midnightAbi,
  functionName: "setIsAuthorized",
  args: [MIDNIGHT_BUNDLES, true, borrower],
});

import { midnightBundlesAbi } from "@morpho-org/midnight-sdk";

// Release the full balance of each collateral:
// The position lists collateral by { token, amount } and the contract wants an INDEX into market.collateralParams[], so resolve token → index here.
const collateralWithdrawals = position.collaterals.map((c: any) => ({
  collateralIndex: BigInt(
    market.collateralParams.findIndex(
      (cp: any) => cp.token.toLowerCase() === c.token.toLowerCase()
    )
  ),
  assets: BigInt(c.amount),
}));

const repayAssets = BigInt(position.debt) + BigInt(position.pending_fee);

// Deadline: the transaction reverts if not included before this timestamp
const deadline = BigInt(Math.floor(Date.now() / 1000) + 3600);               // 1 hour from now

const hash = await walletClient.writeContract({
  account: borrower,
  address: MIDNIGHT_BUNDLES,
  abi: midnightBundlesAbi,
  functionName: "midnightBundlesV1RepayAndWithdrawCollateral",
  args: [
    market,                 // Market struct (Step 1)
    repayAssets,            // loan tokens to repay (full debt)
    borrower,               // onBehalf — whose position is repaid
    tokenPermitNone,        // if Permit EIP-2612 or Permit2 is used use loanTokenPermitEIP2612 or loanTokenPermit2, respectively
    collateralWithdrawals,  // CollateralWithdrawal[] (release all collateral)
    borrower,               // collateralReceiver (where the WETH is sent)
    0n,                     // referralFeePct (0 = none)
    zeroAddress,            // referralFeeRecipient (none)
    deadline               // deadline (reverts if tx is included after this timestamp)
  ],
});

console.log("Repay + withdraw tx:", hash);