feat(earn): add function for preparing supply transaction (#5405)

### Description

Mostly based off of swap transaction preparation

### Test plan

Unit tests, manually preparing a tx

### Related issues

- Part of ACT-1178

### Backwards compatibility

Yes

### Network scalability

If a new NetworkId and/or Network are added in the future, the changes
in this PR will:

- [x] Continue to work without code changes, OR trigger a compilation
error (guaranteeing we find it when a new network is added)

src/earn/prepareTransactions.test.ts

@@ -0,0 +1,272 @@
+import BigNumber from 'bignumber.js'
+import { FetchMock } from 'jest-fetch-mock/types'
+import aavePool from 'src/abis/AavePoolV3'
+import erc20 from 'src/abis/IERC20'
+import { prepareSupplyTransactions } from 'src/earn/prepareTransactions'
+import { TokenBalance } from 'src/tokens/slice'
+import { Network, NetworkId } from 'src/transactions/types'
+import { publicClient } from 'src/viem'
+import { prepareTransactions } from 'src/viem/prepareTransactions'
+import { Address, encodeFunctionData } from 'viem'
+
+const mockFeeCurrency: TokenBalance = {
+  address: null,
+  balance: new BigNumber(100), // 10k units, 100.0 decimals
+  decimals: 2,
+  priceUsd: null,
+  lastKnownPriceUsd: null,
+  tokenId: 'arbitrum-sepolia:native',
+  symbol: 'FEE1',
+  name: 'Fee token 1',
+  networkId: NetworkId['arbitrum-sepolia'],
+  isNative: true,
+}
+
+const mockTokenAddress: Address = '0x1234567890abcdef1234567890abcdef12345678'
+
+const mockToken: TokenBalance = {
+  address: mockTokenAddress,
+  balance: new BigNumber(10),
+  decimals: 6,
+  priceUsd: null,
+  lastKnownPriceUsd: null,
+  tokenId: `arbitrum-sepolia:${mockTokenAddress}`,
+  symbol: 'USDC',
+  name: 'USD Coin',
+  networkId: NetworkId['arbitrum-sepolia'],
+}
+
+jest.mock('src/viem/prepareTransactions')
+jest.mock('viem', () => ({
+  ...jest.requireActual('viem'),
+  encodeFunctionData: jest.fn(),
+}))
+
+describe('prepareTransactions', () => {
+  beforeEach(() => {
+    jest.clearAllMocks()
+    jest.mocked(prepareTransactions).mockImplementation(async ({ baseTransactions }) => ({
+      transactions: baseTransactions,
+      type: 'possible',
+      feeCurrency: mockFeeCurrency,
+    }))
+    jest.spyOn(publicClient[Network.Arbitrum], 'readContract').mockResolvedValue(BigInt(0))
+    jest.mocked(encodeFunctionData).mockReturnValue('0xencodedData')
+  })
+
+  describe('prepareSupplyTransactions', () => {
+    const mockFetch = fetch as FetchMock
+    beforeEach(() => {
+      mockFetch.resetMocks()
+    })
+
+    it('prepares transactions with approve and supply if not already approved', async () => {
+      mockFetch.mockResponseOnce(
+        JSON.stringify({
+          status: 'OK',
+          simulatedTransactions: [
+            {
+              status: 'success',
+              blockNumber: '1',
+              gasNeeded: 3000,
+              gasUsed: 2800,
+              gasPrice: '1',
+            },
+            {
+              status: 'success',
+              blockNumber: '1',
+              gasNeeded: 50000,
+              gasUsed: 49800,
+              gasPrice: '1',
+            },
+          ],
+        })
+      )
+
+      const result = await prepareSupplyTransactions({
+        amount: '5',
+        token: mockToken,
+        walletAddress: '0x1234',
+        feeCurrencies: [mockFeeCurrency],
+        poolContractAddress: '0x5678',
+      })
+
+      const expectedTransactions = [
+        {
+          from: '0x1234',
+          to: mockTokenAddress,
+          data: '0xencodedData',
+        },
+        {
+          from: '0x1234',
+          to: '0x5678',
+          data: '0xencodedData',
+          gas: BigInt(50000),
+          _estimatedGasUse: BigInt(49800),
+        },
+      ]
+      expect(result).toEqual({
+        type: 'possible',
+        feeCurrency: mockFeeCurrency,
+        transactions: expectedTransactions,
+      })
+      expect(publicClient[Network.Arbitrum].readContract).toHaveBeenCalledWith({
+        address: mockTokenAddress,
+        abi: erc20.abi,
+        functionName: 'allowance',
+        args: ['0x1234', '0x5678'],
+      })
+      expect(encodeFunctionData).toHaveBeenNthCalledWith(1, {
+        abi: erc20.abi,
+        functionName: 'approve',
+        args: ['0x5678', BigInt(5e6)],
+      })
+      expect(encodeFunctionData).toHaveBeenNthCalledWith(2, {
+        abi: aavePool,
+        functionName: 'supply',
+        args: [mockTokenAddress, BigInt(5e6), '0x1234', 0],
+      })
+      expect(prepareTransactions).toHaveBeenCalledWith({
+        baseTransactions: expectedTransactions,
+        feeCurrencies: [mockFeeCurrency],
+        spendToken: mockToken,
+        spendTokenAmount: new BigNumber(5),
+      })
+    })
+
+    it('prepares transactions with supply if already approved', async () => {
+      jest.spyOn(publicClient[Network.Arbitrum], 'readContract').mockResolvedValue(BigInt(5e6))
+      mockFetch.mockResponseOnce(
+        JSON.stringify({
+          status: 'OK',
+          simulatedTransactions: [
+            {
+              status: 'success',
+              blockNumber: '1',
+              gasNeeded: 50000,
+              gasUsed: 49800,
+              gasPrice: '1',
+            },
+          ],
+        })
+      )
+
+      const result = await prepareSupplyTransactions({
+        amount: '5',
+        token: mockToken,
+        walletAddress: '0x1234',
+        feeCurrencies: [mockFeeCurrency],
+        poolContractAddress: '0x5678',
+      })
+
+      const expectedTransactions = [
+        {
+          from: '0x1234',
+          to: '0x5678',
+          data: '0xencodedData',
+          gas: BigInt(50000),
+          _estimatedGasUse: BigInt(49800),
+        },
+      ]
+      expect(result).toEqual({
+        type: 'possible',
+        feeCurrency: mockFeeCurrency,
+        transactions: expectedTransactions,
+      })
+      expect(publicClient[Network.Arbitrum].readContract).toHaveBeenCalledWith({
+        address: mockTokenAddress,
+        abi: erc20.abi,
+        functionName: 'allowance',
+        args: ['0x1234', '0x5678'],
+      })
+      expect(encodeFunctionData).toHaveBeenNthCalledWith(1, {
+        abi: aavePool,
+        functionName: 'supply',
+        args: [mockTokenAddress, BigInt(5e6), '0x1234', 0],
+      })
+      expect(prepareTransactions).toHaveBeenCalledWith({
+        baseTransactions: expectedTransactions,
+        feeCurrencies: [mockFeeCurrency],
+        spendToken: mockToken,
+        spendTokenAmount: new BigNumber(5),
+      })
+    })
+
+    it('throws if simulate transactions sends a non 200 response', async () => {
+      mockFetch.mockResponseOnce(
+        JSON.stringify({
+          status: 'ERROR',
+          error: 'something went wrong',
+        }),
+        { status: 500 }
+      )
+
+      await expect(
+        prepareSupplyTransactions({
+          amount: '5',
+          token: mockToken,
+          walletAddress: '0x1234',
+          feeCurrencies: [mockFeeCurrency],
+          poolContractAddress: '0x5678',
+        })
+      ).rejects.toThrow('Failed to simulate transactions')
+    })
+
+    it('throws if supply transaction simulation status is failure', async () => {
+      mockFetch.mockResponseOnce(
+        JSON.stringify({
+          status: 'OK',
+          simulatedTransactions: [
+            {
+              status: 'success',
+              blockNumber: '1',
+              gasNeeded: 3000,
+              gasUsed: 2800,
+              gasPrice: '1',
+            },
+            {
+              status: 'failure',
+            },
+          ],
+        })
+      )
+
+      await expect(
+        prepareSupplyTransactions({
+          amount: '5',
+          token: mockToken,
+          walletAddress: '0x1234',
+          feeCurrencies: [mockFeeCurrency],
+          poolContractAddress: '0x5678',
+        })
+      ).rejects.toThrow('Failed to simulate supply transaction')
+    })
+
+    it('throws if simulated transactions length does not match base transactions length', async () => {
+      mockFetch.mockResponseOnce(
+        JSON.stringify({
+          status: 'OK',
+          simulatedTransactions: [
+            {
+              status: 'success',
+              blockNumber: '1',
+              gasNeeded: 3000,
+              gasUsed: 2800,
+              gasPrice: '1',
+            },
+          ],
+        })
+      )
+
+      await expect(
+        prepareSupplyTransactions({
+          amount: '5',
+          token: mockToken,
+          walletAddress: '0x1234',
+          feeCurrencies: [mockFeeCurrency],
+          poolContractAddress: '0x5678',
+        })
+      ).rejects.toThrow('Expected 2 simulated transactions, got 1')
+    })
+  })
+})

src/earn/prepareTransactions.ts

@@ -0,0 +1,124 @@
+import BigNumber from 'bignumber.js'
+import aavePool from 'src/abis/AavePoolV3'
+import erc20 from 'src/abis/IERC20'
+import { TokenBalance } from 'src/tokens/slice'
+import { fetchWithTimeout } from 'src/utils/fetchWithTimeout'
+import { publicClient } from 'src/viem'
+import { TransactionRequest, prepareTransactions } from 'src/viem/prepareTransactions'
+import networkConfig, { networkIdToNetwork } from 'src/web3/networkConfig'
+import { Address, encodeFunctionData, isAddress, parseUnits } from 'viem'
+
+type SimulatedTransactionResponse = {
+  status: 'OK'
+  simulatedTransactions: {
+    status: 'success' | 'failure'
+    blockNumber: string
+    gasNeeded: number
+    gasUsed: number
+    gasPrice: string
+  }[]
+}
+
+export async function prepareSupplyTransactions({
+  amount,
+  token,
+  walletAddress,
+  feeCurrencies,
+  poolContractAddress,
+}: {
+  amount: string
+  token: TokenBalance
+  walletAddress: Address
+  feeCurrencies: TokenBalance[]
+  poolContractAddress: Address
+}) {
+  const baseTransactions: TransactionRequest[] = []
+
+  // amount in smallest unit
+  const amountToSupply = parseUnits(amount, token.decimals)
+
+  if (!token.address || !isAddress(token.address)) {
+    // should never happen
+    throw new Error(`Cannot use a token without address. Token id: ${token.tokenId}`)
+  }
+
+  const approvedAllowanceForSpender = await publicClient[
+    networkIdToNetwork[token.networkId]
+  ].readContract({
+    address: token.address,
+    abi: erc20.abi,
+    functionName: 'allowance',
+    args: [walletAddress, poolContractAddress],
+  })
+
+  if (approvedAllowanceForSpender < amountToSupply) {
+    const data = encodeFunctionData({
+      abi: erc20.abi,
+      functionName: 'approve',
+      args: [poolContractAddress, amountToSupply],
+    })
+
+    const approveTx: TransactionRequest = {
+      from: walletAddress,
+      to: token.address,
+      data,
+    }
+    baseTransactions.push(approveTx)
+  }
+
+  const supplyTx: TransactionRequest = {
+    from: walletAddress,
+    to: poolContractAddress,
+    data: encodeFunctionData({
+      abi: aavePool,
+      functionName: 'supply',
+      args: [token.address, amountToSupply, walletAddress, 0],
+    }),
+  }
+
+  baseTransactions.push(supplyTx)
+
+  const response = await fetchWithTimeout(networkConfig.simulateTransactionsUrl, {
+    method: 'POST',
+    headers: {
+      'Content-Type': 'application/json',
+    },
+    body: JSON.stringify({
+      transactions: baseTransactions,
+      networkId: token.networkId,
+    }),
+  })
+
+  if (!response.ok) {
+    throw new Error(
+      `Failed to simulate transactions. status ${response.status}, text: ${await response.text()}`
+    )
+  }
+
+  // extract fee of the supply transaction and set gas fields
+  const { simulatedTransactions }: SimulatedTransactionResponse = await response.json()
+
+  if (simulatedTransactions.length !== baseTransactions.length) {
+    throw new Error(
+      `Expected ${baseTransactions.length} simulated transactions, got ${simulatedTransactions.length}, response: ${JSON.stringify(simulatedTransactions)}`
+    )
+  }
+
+  const supplySimulatedTx = simulatedTransactions[simulatedTransactions.length - 1]
+
+  if (supplySimulatedTx.status !== 'success') {
+    throw new Error(
+      `Failed to simulate supply transaction. response: ${JSON.stringify(simulatedTransactions)}`
+    )
+  }
+
+  baseTransactions[baseTransactions.length - 1].gas = BigInt(supplySimulatedTx.gasNeeded)
+  baseTransactions[baseTransactions.length - 1]._estimatedGasUse = BigInt(supplySimulatedTx.gasUsed)
+
+  return prepareTransactions({
+    feeCurrencies,
+    baseTransactions,
+    spendToken: token,
+    spendTokenAmount: new BigNumber(amount),
+  })
+}