Swapr Uniswap V2 integration

index.ts

import {
  ChainId,
  Percent,
  Token,
  TokenAmount,
  UniswapV2RoutablePlatform,
  UniswapV2Trade,
} from '@swapr/sdk'
import { getAllCommonPairs } from '@swapr/sdk/dist/entities/trades/uniswap-v2/contracts'
import { utils, providers } from 'ethers'

// RPC provider must match the tokens' chainId
const provider = new providers.JsonRpcProvider('https://rpc.gnosischain.com/')

// Define the tokens
// This can be obtained in JSON from token lists
const tokenWXDAI = new Token(
  ChainId.XDAI,
  '0xe91D153E0b41518A2Ce8Dd3D7944Fa863463a97d',
  18,
  'WXDAI',
  'WXDAI',
)

const tokenUSDC = new Token(
  ChainId.XDAI,
  '0xDDAfbb505ad214D7b80b1f830fcCc89B60fb7A83',
  6,
  'USDC',
  'USDC',
)

const tokenWXDAIAmount = new TokenAmount(
  tokenWXDAI,
  utils.parseUnits('1', tokenWXDAI.decimals).toBigInt(),
)

const tokenUSDCAmount = new TokenAmount(
  tokenUSDC,
  utils.parseUnits('1', tokenUSDC.decimals).toBigInt(),
)

// Get all common pairs between WXDAI and USDC
getAllCommonPairs({
  currencyA: tokenWXDAI,
  currencyB: tokenUSDC,
  platform: UniswapV2RoutablePlatform.SWAPR,
  provider: provider as any,
})
  .then(async (pairs) => {
    // Compute list of routes between XWDAI and USDC such that
    // the input amount of WXDAI spend must equal 1
    const tradeListExactIn = UniswapV2Trade.computeTradesExactIn({
      currencyAmountIn: tokenWXDAIAmount,
      currencyOut: tokenUSDC,
      maximumSlippage: new Percent('30', '10000'), // 0.3%
      maxHops: {
        maxHops: 3,
        maxNumResults: 1,
      },
      pairs,
    })

    // Compute list of routes between XWDAI and USDC such that
    // the output amount of WXDAI spend must equal 1
    const tradeListExactOut = UniswapV2Trade.computeTradesExactOut({
      currencyAmountOut: tokenWXDAIAmount,
      currencyIn: tokenUSDC,
      maximumSlippage: new Percent('30', '10000'), // 0.3%
      maxHops: {
        maxHops: 3,
        maxNumResults: 1,
      },
      pairs,
    })

    const [bestTradeExactIn] = tradeListExactIn
    const [bestTradeExactOut] = tradeListExactOut

    // Get unsigned transaction
    const bestTradeExactInUnsignedTx = await bestTradeExactIn.swapTransaction({
      recipient: '0x0000000000000000000000000000000000000000', // Address of the recipient
      ttl: 60 * 30, // 30 minutes
    })

    // Get unsigned transaction
    const bestTradeExactOutUnsignedTx = await bestTradeExactOut.swapTransaction(
      {
        recipient: '0x0000000000000000000000000000000000000000', // Address of the recipient
        ttl: 60 * 30, // 30 minutes
      },
    )
  })
  .catch((error) => {
    console.error(error)
  })