@lifi/sdk/src/core/EVM/checkPermitSupport.ts

LI.FI Any-to-Any Cross-Chain-Swap SDK

import type { ExtendedChain } from '@lifi/types'
import { ChainType } from '@lifi/types'
import type { Address } from 'viem'
import { config } from '../../config.js'
import { getActionWithFallback } from './getActionWithFallback.js'
import { getAllowance } from './getAllowance.js'
import { getNativePermit } from './permits/getNativePermit.js'
import { getPublicClient } from './publicClient.js'
import type { EVMProvider } from './types.js'

export type PermitSupport = {
  /** Whether the token supports EIP-2612 native permits */
  nativePermitSupported: boolean
  /** Whether Permit2 is available and has sufficient allowance */
  permit2AllowanceSufficient: boolean
}

/**
 * Checks what permit types are supported for a token on a specific chain.
 * Checks in order:
 * 1. Native permit (EIP-2612) support
 * 2. Permit2 availability and allowance
 *
 * @param chain - The chain to check permit support on
 * @param tokenAddress - The token address to check
 * @param ownerAddress - The address that would sign the permit
 * @param amount - The amount to check allowance against for Permit2
 * @returns Object indicating which permit types are supported
 */
export const checkPermitSupport = async ({
  chain,
  tokenAddress,
  ownerAddress,
  amount,
}: {
  chain: ExtendedChain
  tokenAddress: Address
  ownerAddress: Address
  amount: bigint
}): Promise<PermitSupport> => {
  const provider = config.getProvider(ChainType.EVM) as EVMProvider | undefined

  let client = await provider?.getWalletClient?.()

  if (!client) {
    client = await getPublicClient(chain.id)
  }

  const nativePermit = await getActionWithFallback(
    client,
    getNativePermit,
    'getNativePermit',
    {
      chainId: chain.id,
      tokenAddress,
      spenderAddress: chain.permit2Proxy as Address,
      amount,
    }
  )

  let permit2Allowance: bigint | undefined
  // Check Permit2 allowance if available on chain
  if (chain.permit2) {
    permit2Allowance = await getAllowance(
      client,
      tokenAddress,
      ownerAddress,
      chain.permit2 as Address
    )
  }

  return {
    nativePermitSupported: !!nativePermit,
    permit2AllowanceSufficient:
      !!permit2Allowance && permit2Allowance >= amount,
  }
}