import JSBI from 'jsbi'
import { BigNumber } from '@ethersproject/bignumber'
import { Router, Trade as V2Trade } from '@uniswap/v2-sdk'
import { SwapRouter, Trade as V3Trade } from '@uniswap/v3-sdk'
import { ChainId, Percent, TradeType } from '@uniswap/sdk-core'
import { useMemo } from 'react'
import { BIPS_BASE, INITIAL_ALLOWED_SLIPPAGE } from '../constants'
import { SWAP_ROUTER_ADDRESSES } from '../constants/v3'
import { getTradeVersion } from '../utils/getTradeVersion'
import { useTransactionAdder } from '../state/transactions/hooks'
import { calculateGasMargin, isAddress, shortenAddress } from '../utils'
import isZero from '../utils/isZero'
import { useActiveWeb3React } from './index'
import { useV2RouterContract } from './useContract'
import useTransactionDeadline from './useTransactionDeadline'
import useENS from './useENS'
import { Version } from './useToggledVersion'

export enum SwapCallbackState {
  INVALID,
  LOADING,
  VALID,
}

interface SwapCall {
  address: string
  calldata: string
  value: string
}

interface SwapCallEstimate {
  call: SwapCall
}

interface SuccessfulCall extends SwapCallEstimate {
  call: SwapCall
  gasEstimate: BigNumber
}

interface FailedCall extends SwapCallEstimate {
  call: SwapCall
  error: Error
}

/**
 * Returns the swap calls that can be used to make the trade
 * @param trade trade to execute
 * @param allowedSlippage user allowed slippage
 * @param recipientAddressOrName
 */
function useSwapCallArguments(
  trade: V2Trade | V3Trade | undefined, // trade to execute, required
  allowedSlippage: number = INITIAL_ALLOWED_SLIPPAGE, // in bips
  recipientAddressOrName: string | null // the ENS name or address of the recipient of the trade, or null if swap should be returned to sender
): SwapCall[] {
  const { account, chainId, library } = useActiveWeb3React()

  const { address: recipientAddress } = useENS(recipientAddressOrName)
  const recipient = recipientAddressOrName === null ? account : recipientAddress
  const deadline = useTransactionDeadline()
  const routerContract = useV2RouterContract()

  return useMemo(() => {
    if (!trade || !recipient || !library || !account || !chainId || !deadline) return []

    if (trade instanceof V2Trade) {
      if (!routerContract) return []
      const swapMethods = []
      swapMethods.push(
        Router.swapCallParameters(trade, {
          feeOnTransfer: false,
          allowedSlippage: new Percent(JSBI.BigInt(allowedSlippage), BIPS_BASE),
          recipient,
          deadline: deadline.toNumber(),
        })
      )

      if (trade.tradeType === TradeType.EXACT_INPUT) {
        swapMethods.push(
          Router.swapCallParameters(trade, {
            feeOnTransfer: true,
            allowedSlippage: new Percent(JSBI.BigInt(allowedSlippage), BIPS_BASE),
            recipient,
            deadline: deadline.toNumber(),
          })
        )
      }
      return swapMethods.map(({ methodName, args, value }) => ({
        address: routerContract.address,
        calldata: routerContract.interface.encodeFunctionData(methodName, args),
        value,
      }))
    } else {
      // trade is V3Trade
      const swapRouterAddress = SWAP_ROUTER_ADDRESSES[chainId as ChainId]
      if (!swapRouterAddress) return []

      const { value, calldata } = SwapRouter.swapCallParameters(trade, {
        recipient,
        slippageTolerance: new Percent(JSBI.BigInt(allowedSlippage), BIPS_BASE),
        deadline: deadline.toString(),
      })

      return [
        {
          address: swapRouterAddress,
          calldata,
          value,
        },
      ]
    }
  }, [account, allowedSlippage, chainId, deadline, library, recipient, routerContract, trade])
}

// returns a function that will execute a swap, if the parameters are all valid
// and the user has approved the slippage adjusted input amount for the trade
export function useSwapCallback(
  trade: V2Trade | V3Trade | undefined, // trade to execute, required
  allowedSlippage: number = INITIAL_ALLOWED_SLIPPAGE, // in bips
  recipientAddressOrName: string | null // the ENS name or address of the recipient of the trade, or null if swap should be returned to sender
): { state: SwapCallbackState; callback: null | (() => Promise<string>); error: string | null } {
  const { account, chainId, library } = useActiveWeb3React()

  const swapCalls = useSwapCallArguments(trade, allowedSlippage, recipientAddressOrName)

  const addTransaction = useTransactionAdder()

  const { address: recipientAddress } = useENS(recipientAddressOrName)
  const recipient = recipientAddressOrName === null ? account : recipientAddress

  return useMemo(() => {
    if (!trade || !library || !account || !chainId) {
      return { state: SwapCallbackState.INVALID, callback: null, error: 'Missing dependencies' }
    }
    if (!recipient) {
      if (recipientAddressOrName !== null) {
        return { state: SwapCallbackState.INVALID, callback: null, error: 'Invalid recipient' }
      } else {
        return { state: SwapCallbackState.LOADING, callback: null, error: null }
      }
    }

    return {
      state: SwapCallbackState.VALID,
      callback: async function onSwap(): Promise<string> {
        const estimatedCalls: SwapCallEstimate[] = await Promise.all(
          swapCalls.map((call) => {
            const { address, calldata, value } = call

            const tx =
              !value || isZero(value)
                ? { to: address, data: calldata }
                : {
                    to: address,
                    data: calldata,
                    value,
                  }

            return library
              .estimateGas(tx)
              .then((gasEstimate) => {
                return {
                  call,
                  gasEstimate,
                }
              })
              .catch((gasError) => {
                console.debug('Gas estimate failed, trying eth_call to extract error', call)

                return library
                  .call(tx)
                  .then((result) => {
                    console.debug('Unexpected successful call after failed estimate gas', call, gasError, result)
                    return { call, error: new Error('Unexpected issue with estimating the gas. Please try again.') }
                  })
                  .catch((callError) => {
                    console.debug('Call threw error', call, callError)
                    let errorMessage: string
                    switch (callError.reason) {
                      case 'UniswapV2Router: EXPIRED':
                        errorMessage =
                          'The transaction could not be sent because the deadline has passed. Please check that your transaction deadline is not too low.'
                        break
                      case 'UniswapV2Router: INSUFFICIENT_OUTPUT_AMOUNT':
                      case 'UniswapV2Router: EXCESSIVE_INPUT_AMOUNT':
                        errorMessage =
                          'This transaction will not succeed either due to price movement or fee on transfer. Try increasing your slippage tolerance.'
                        break
                      case 'UniswapV2: TRANSFER_FAILED':
                        errorMessage = 'The token could not be transferred. There may be an issue with the token.'
                        break
                      case 'UniswapV2: K':
                        errorMessage =
                          'The Uniswap invariant x*y=k was not satisfied by the swap. This usually means one of the tokens you are swapping incorporates custom behavior on transfer.'
                        break
                      default:
                        return { call }
                    }
                    return { call, error: new Error(errorMessage) }
                  })
              })
          })
        )

        // a successful estimation is a bignumber gas estimate and the next call is also a bignumber gas estimate
        let bestCallOption: SuccessfulCall | SwapCallEstimate | undefined = estimatedCalls.find(
          (el, ix, list): el is SuccessfulCall =>
            'gasEstimate' in el && (ix === list.length - 1 || 'gasEstimate' in list[ix + 1])
        )

        // check if any calls errored with a recognizable error
        if (!bestCallOption) {
          const errorCalls = estimatedCalls.filter((call): call is FailedCall => 'error' in call)
          if (errorCalls.length > 0) throw errorCalls[errorCalls.length - 1].error
          const firstNoErrorCall = estimatedCalls.find<SwapCallEstimate>(
            (call): call is SwapCallEstimate => !('error' in call)
          )
          if (!firstNoErrorCall) throw new Error('Unexpected error. Could not estimate gas for the swap.')
          bestCallOption = firstNoErrorCall
        }

        const {
          call: { address, calldata, value },
        } = bestCallOption

        return library
          .getSigner()
          .sendTransaction({
            from: account,
            to: address,
            data: calldata,
            // let the wallet try if we can't estimate the gas
            ...('gasEstimate' in bestCallOption
              ? { gasLimit: calculateGasMargin(bestCallOption.gasEstimate) }
              : { gasLimit: 1_000_000 }),
            ...(value && !isZero(value) ? { value } : {}),
          })
          .then((response) => {
            const inputSymbol = trade.inputAmount.currency.symbol
            const outputSymbol = trade.outputAmount.currency.symbol
            const slippageTolerancePercent = new Percent(allowedSlippage)
            const inputAmount = trade.maximumAmountIn(slippageTolerancePercent).toSignificant(3)
            const outputAmount = trade.minimumAmountOut(slippageTolerancePercent).toSignificant(3)

            const base = `Swap ${inputAmount} ${inputSymbol} for ${outputAmount} ${outputSymbol}`
            const withRecipient =
              recipient === account
                ? base
                : `${base} to ${
                    recipientAddressOrName && isAddress(recipientAddressOrName)
                      ? shortenAddress(recipientAddressOrName)
                      : recipientAddressOrName
                  }`

            const tradeVersion = getTradeVersion(trade)

            const withVersion = tradeVersion === Version.v3 ? withRecipient : `${withRecipient} on ${tradeVersion}`

            addTransaction(response, {
              summary: withVersion,
            })

            return response.hash
          })
          .catch((error) => {
            // if the user rejected the tx, pass this along
            if (error?.code === 4001) {
              throw new Error('Transaction rejected.')
            } else {
              // otherwise, the error was unexpected and we need to convey that
              console.error(`Swap failed`, error, address, calldata, value)
              throw new Error(`Swap failed: ${error.message}`)
            }
          })
      },
      error: null,
    }
  }, [trade, library, account, chainId, recipient, recipientAddressOrName, swapCalls, allowedSlippage, addTransaction])
}
