3️⃣Estimate Router Data

To properly estimate the logics of the router results, closely follow the steps below.

Step 1: Build Router Data

First, you need to prepare the Router Data, which will include the chainId, account, and logics data.

import * as api from '@protocolink/api';

const routerData: api.RouterData = {
  chainId,
  account: '0xaAaAaAaaAaAaAaaAaAAAAAAAAaaaAaAaAaaAaaAa',
  logics: [swapLogic, supplyLogic],
};

Step 2: Estimate Router Data Result

Next, use api.estimateRouterData to estimate how much funds will be spent (funds) and how many balances will be obtained (balances) from this transaction. It will also identify any approvals that the user needs to execute (approvals) before the transaction.

In the current implementation of Permit2, users have two options for authorizing Agent to spend their assets: permit and approve. These methods provide distinct approaches to token authorization, allowing users to choose the one that best suits their needs. If not specified, permit is the default behavior.

type Permit2Type = 'permit' | 'approve';

The permit method involves obtaining authorization data (permitData) for the ERC20 tokens being spent in the router data. Users are required to sign this data. The permitData and the associated signature are then sent to the Protocolink API as part of the transaction.

import * as api from '@protocolink/api';

const estimateResult = await api.estimateRouterData(routerData);
// or
const estimateResult = await api.estimateRouterData(routerData, { permit2Type: 'permit'});

The approve method provides users with the necessary transactions to approve the expenditure of ERC20 tokens in the router data. Users must complete these approval transactions before sending the router transaction.

import * as api from '@protocolink/api';

const estimateResult = await api.estimateRouterData(routerData, { permit2Type: 'approve'});

The structure of the estimateResult obtained is roughly as follows:

{
  "funds": [         // How much initial funds are needed
    {
      "token": ...,  // USDC
      "amount": "1000"
    }
  ],
  "balances": [      // How many tokens you will receive
    {
      "token": ...,  // aEthWBTC
      "amount": "0.03579397"
    }
  ],
  "fees": [          // How many fees you will be charged
    {
      "rid": "permit2:pull-token",
      "feeAmount": {
        "token": {
          "chainId": 1,
          "address": "0x0000000000000000000000000000000000000000",
          "decimals": 18,
          "symbol": "ETH",
          "name": "Ethereum"
        },
        "amount": "0.001240475451939898"
      }
    }
  ],
  "approvals": [     // User approval before transaction if need
    {
      "to": "0xA0b86991c6218b36c1d19D4a2e9Eb0cE3606eB48",
      "data": "0x095ea7b3000000000000000000000000000000000022d473030f116ddee9f6b43ac78ba3ffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffff"
    }
  ],
  "permitData": {    // Token permit before transaction if need
    "domain": ...,
    "types": ...,
    "values": ...
  }
}

Funds: For this transaction, 1000 USDC will be spent, which can be displayed on the interface.

Balances: For this transaction, 0.03579397 aEthWBTC will be obtained, which can be displayed on the interface.

Fees: For this transaction, 0.001240475451939898 ETH will be charged, which can be displayed on the interface.

Step 3: Approvals (optional)

For this transaction, the user may need to perform one or more of the following approvals before proceeding:

• Approve the Permit2 contract to spend their assets.

• Approve the Agent to spend their assets.

• Authorize the Agent to execute protocol specific operations that require authorization.

If using ethers package, you can refer to the following code snippet to help the user send approval transactions:

const signer = provider.getSigner(account);
for (const approval of estimateResult.approvals) {
  const tx = await signer.sendTransaction(approval);
}

Step 4: PermitData (optional)

For this transaction, the user needs to sign to permit Protocolink contract to spend his USDC fist. If using ethers package, you can refer to the following code snippet to help the user sign the `permitData`:

const signer = provider.getSigner(account);
const permitSig = await signer._signTypedData(permitData.domain, permitData.types, permitData.values);

After signing, it is necessary to include permitData and permitSig into routerData. Without this step, the transaction will fail.

routerData.permitData = estimateResult.permitData;
routerData.permitSig = permitSig;