import {
  encodeAbiParameters,
  keccak256,
  pad,
  parseAbiParameters,
  toBytes,
  toHex,
} from 'viem'
import type { Address, Client, Hex } from 'viem'
import type { TypedDataDomain } from 'viem'
import { multicall, readContract } from 'viem/actions'
import { eip2612Abi, eip2612Types } from '../abi.js'
import { getMulticallAddress } from '../utils.js'
import type { NativePermitData } from './types.js'

/**
 * EIP-712 domain typehash with chainId
 * @link https://eips.ethereum.org/EIPS/eip-712#specification
 *
 * keccak256(toBytes(
 *   'EIP712Domain(string name,string version,uint256 chainId,address verifyingContract)'
 * ))
 */
const EIP712_DOMAIN_TYPEHASH =
  '0x8b73c3c69bb8fe3d512ecc4cf759cc79239f7b179b0ffacaa9a75d522b39400f' as Hex

/**
 * EIP-712 domain typehash with salt (e.g. USDC.e on Polygon)
 * @link https://eips.ethereum.org/EIPS/eip-712#specification
 *
 * keccak256(toBytes(
 *   'EIP712Domain(string name,string version,address verifyingContract,bytes32 salt)'
 * ))
 */
const EIP712_DOMAIN_TYPEHASH_WITH_SALT =
  '0x36c25de3e541d5d970f66e4210d728721220fff5c077cc6cd008b3a0c62adab7' as Hex

function makeDomainSeparator({
  name,
  version,
  chainId,
  verifyingContract,
  withSalt = false,
}: {
  name: string
  version: string
  chainId: number
  verifyingContract: Address
  withSalt?: boolean
}): Hex {
  const nameHash = keccak256(toBytes(name))
  const versionHash = keccak256(toBytes(version))

  const encoded = withSalt
    ? encodeAbiParameters(
        parseAbiParameters('bytes32, bytes32, bytes32, address, bytes32'),
        [
          EIP712_DOMAIN_TYPEHASH_WITH_SALT,
          nameHash,
          versionHash,
          verifyingContract,
          pad(toHex(chainId), { size: 32 }),
        ]
      )
    : encodeAbiParameters(
        parseAbiParameters('bytes32, bytes32, bytes32, uint256, address'),
        [
          EIP712_DOMAIN_TYPEHASH,
          nameHash,
          versionHash,
          BigInt(chainId),
          verifyingContract,
        ]
      )

  return keccak256(encoded)
}

// TODO: Add support for EIP-5267 when adoption increases
// This EIP provides a standard way to query domain separator and permit type hash
// via eip712Domain() function, which would simplify permit validation
// https://eips.ethereum.org/EIPS/eip-5267
function validateDomainSeparator({
  name,
  version,
  chainId,
  verifyingContract,
  domainSeparator,
}: {
  name: string
  version: string
  chainId: number
  verifyingContract: Address
  domainSeparator: Hex
}): { isValid: boolean; domain: TypedDataDomain } {
  if (!name || !domainSeparator) {
    return {
      isValid: false,
      domain: {},
    }
  }

  for (const withSalt of [false, true]) {
    const computedDS = makeDomainSeparator({
      name,
      version,
      chainId,
      verifyingContract,
      withSalt,
    })
    if (domainSeparator.toLowerCase() === computedDS.toLowerCase()) {
      return {
        isValid: true,
        domain: withSalt
          ? {
              name,
              version,
              verifyingContract,
              salt: pad(toHex(chainId), { size: 32 }),
            }
          : {
              name,
              version,
              chainId,
              verifyingContract,
            },
      }
    }
  }

  return {
    isValid: false,
    domain: {},
  }
}

/**
 * Retrieves native permit data (EIP-2612) for a token on a specific chain
 * @link https://eips.ethereum.org/EIPS/eip-2612
 * @param client - The Viem client instance
 * @param chain - The extended chain object containing chain details
 * @param tokenAddress - The address of the token to check for permit support
 * @returns {Promise<NativePermitData>} Object containing permit data including name, version, nonce and support status
 */
export const getNativePermit = async (
  client: Client,
  chainId: number,
  tokenAddress: Address,
  spenderAddress: Address,
  amount: bigint
): Promise<NativePermitData | undefined> => {
  try {
    const multicallAddress = await getMulticallAddress(chainId)

    const contractCalls = [
      {
        address: tokenAddress,
        abi: eip2612Abi,
        functionName: 'name',
      },
      {
        address: tokenAddress,
        abi: eip2612Abi,
        functionName: 'DOMAIN_SEPARATOR',
      },
      {
        address: tokenAddress,
        abi: eip2612Abi,
        functionName: 'nonces',
        args: [client.account!.address],
      },
      {
        address: tokenAddress,
        abi: eip2612Abi,
        functionName: 'version',
      },
    ] as const

    if (multicallAddress) {
      const [nameResult, domainSeparatorResult, noncesResult, versionResult] =
        await multicall(client, {
          contracts: contractCalls,
          multicallAddress,
        })

      if (
        nameResult.status !== 'success' ||
        domainSeparatorResult.status !== 'success' ||
        noncesResult.status !== 'success' ||
        !nameResult.result ||
        !domainSeparatorResult.result ||
        noncesResult.result === undefined
      ) {
        return undefined
      }

      const { isValid, domain } = validateDomainSeparator({
        name: nameResult.result,
        version: versionResult.result ?? '1',
        chainId,
        verifyingContract: tokenAddress,
        domainSeparator: domainSeparatorResult.result,
      })

      if (!isValid) {
        return undefined
      }

      const message = {
        owner: client.account!.address,
        spender: spenderAddress,
        value: amount.toString(),
        nonce: noncesResult.result.toString(),
        deadline: BigInt(Math.floor(Date.now() / 1000) + 30 * 60).toString(), // 30 minutes
      }

      return {
        primaryType: 'Permit',
        domain,
        types: eip2612Types,
        message,
      }
    }

    const [nameResult, domainSeparatorResult, noncesResult, versionResult] =
      (await Promise.allSettled(
        contractCalls.map((call) => readContract(client, call))
      )) as [
        PromiseSettledResult<string>,
        PromiseSettledResult<Hex>,
        PromiseSettledResult<bigint>,
        PromiseSettledResult<string>,
      ]

    if (
      nameResult.status !== 'fulfilled' ||
      domainSeparatorResult.status !== 'fulfilled' ||
      noncesResult.status !== 'fulfilled'
    ) {
      return undefined
    }

    const name = nameResult.value
    const version =
      versionResult.status === 'fulfilled' ? versionResult.value : '1'
    const { isValid, domain } = validateDomainSeparator({
      name,
      version,
      chainId,
      verifyingContract: tokenAddress,
      domainSeparator: domainSeparatorResult.value,
    })

    if (!isValid) {
      return undefined
    }

    const message = {
      owner: client.account!.address,
      spender: spenderAddress,
      value: amount.toString(),
      nonce: noncesResult.value.toString(),
      deadline: BigInt(Math.floor(Date.now() / 1000) + 30 * 60).toString(), // 30 minutes
    }

    return {
      primaryType: 'Permit',
      domain,
      types: eip2612Types,
      message,
    }
  } catch {
    return undefined
  }
}