import { RLP } from '@nomicfoundation/ethereumjs-rlp'
import { keccak256 } from 'ethereum-cryptography/keccak.js'
import {
  privateKeyVerify,
  publicKeyConvert,
  publicKeyCreate,
  publicKeyVerify,
} from 'ethereum-cryptography/secp256k1'

import {
  bigIntToUnpaddedBytes,
  bytesToBigInt,
  bytesToHex,
  concatBytes,
  equalsBytes,
  hexToBytes,
  toBytes,
  utf8ToBytes,
  zeros,
} from './bytes.js'
import { BIGINT_0, KECCAK256_NULL, KECCAK256_RLP } from './constants.js'
import { assertIsBytes, assertIsHexString, assertIsString } from './helpers.js'
import { stripHexPrefix } from './internal.js'

import type { BigIntLike, BytesLike } from './types.js'

export interface AccountData {
  nonce?: BigIntLike
  balance?: BigIntLike
  storageRoot?: BytesLike
  codeHash?: BytesLike
}

export type AccountBodyBytes = [Uint8Array, Uint8Array, Uint8Array, Uint8Array]

export class Account {
  nonce: bigint
  balance: bigint
  storageRoot: Uint8Array
  codeHash: Uint8Array

  static fromAccountData(accountData: AccountData) {
    const { nonce, balance, storageRoot, codeHash } = accountData

    return new Account(
      nonce !== undefined ? bytesToBigInt(toBytes(nonce)) : undefined,
      balance !== undefined ? bytesToBigInt(toBytes(balance)) : undefined,
      storageRoot !== undefined ? toBytes(storageRoot) : undefined,
      codeHash !== undefined ? toBytes(codeHash) : undefined
    )
  }

  public static fromRlpSerializedAccount(serialized: Uint8Array) {
    const values = RLP.decode(serialized) as Uint8Array[]

    if (!Array.isArray(values)) {
      throw new Error('Invalid serialized account input. Must be array')
    }

    return this.fromValuesArray(values)
  }

  public static fromValuesArray(values: Uint8Array[]) {
    const [nonce, balance, storageRoot, codeHash] = values

    return new Account(bytesToBigInt(nonce), bytesToBigInt(balance), storageRoot, codeHash)
  }

  /**
   * This constructor assigns and validates the values.
   * Use the static factory methods to assist in creating an Account from varying data types.
   */
  constructor(
    nonce = BIGINT_0,
    balance = BIGINT_0,
    storageRoot = KECCAK256_RLP,
    codeHash = KECCAK256_NULL
  ) {
    this.nonce = nonce
    this.balance = balance
    this.storageRoot = storageRoot
    this.codeHash = codeHash

    this._validate()
  }

  private _validate() {
    if (this.nonce < BIGINT_0) {
      throw new Error('nonce must be greater than zero')
    }
    if (this.balance < BIGINT_0) {
      throw new Error('balance must be greater than zero')
    }
    if (this.storageRoot.length !== 32) {
      throw new Error('storageRoot must have a length of 32')
    }
    if (this.codeHash.length !== 32) {
      throw new Error('codeHash must have a length of 32')
    }
  }

  /**
   * Returns an array of Uint8Arrays of the raw bytes for the account, in order.
   */
  raw(): Uint8Array[] {
    return [
      bigIntToUnpaddedBytes(this.nonce),
      bigIntToUnpaddedBytes(this.balance),
      this.storageRoot,
      this.codeHash,
    ]
  }

  /**
   * Returns the RLP serialization of the account as a `Uint8Array`.
   */
  serialize(): Uint8Array {
    return RLP.encode(this.raw())
  }

  /**
   * Returns a `Boolean` determining if the account is a contract.
   */
  isContract(): boolean {
    return !equalsBytes(this.codeHash, KECCAK256_NULL)
  }

  /**
   * Returns a `Boolean` determining if the account is empty complying to the definition of
   * account emptiness in [EIP-161](https://eips.ethereum.org/EIPS/eip-161):
   * "An account is considered empty when it has no code and zero nonce and zero balance."
   */
  isEmpty(): boolean {
    return (
      this.balance === BIGINT_0 &&
      this.nonce === BIGINT_0 &&
      equalsBytes(this.codeHash, KECCAK256_NULL)
    )
  }
}

/**
 * Checks if the address is a valid. Accepts checksummed addresses too.
 */
export const isValidAddress = function (hexAddress: string): boolean {
  try {
    assertIsString(hexAddress)
  } catch (e: any) {
    return false
  }

  return /^0x[0-9a-fA-F]{40}$/.test(hexAddress)
}

/**
 * Returns a checksummed address.
 *
 * If an eip1191ChainId is provided, the chainId will be included in the checksum calculation. This
 * has the effect of checksummed addresses for one chain having invalid checksums for others.
 * For more details see [EIP-1191](https://eips.ethereum.org/EIPS/eip-1191).
 *
 * WARNING: Checksums with and without the chainId will differ and the EIP-1191 checksum is not
 * backwards compatible to the original widely adopted checksum format standard introduced in
 * [EIP-55](https://eips.ethereum.org/EIPS/eip-55), so this will break in existing applications.
 * Usage of this EIP is therefore discouraged unless you have a very targeted use case.
 */
export const toChecksumAddress = function (
  hexAddress: string,
  eip1191ChainId?: BigIntLike
): string {
  assertIsHexString(hexAddress)
  const address = stripHexPrefix(hexAddress).toLowerCase()

  let prefix = ''
  if (eip1191ChainId !== undefined) {
    const chainId = bytesToBigInt(toBytes(eip1191ChainId))
    prefix = chainId.toString() + '0x'
  }

  const bytes = utf8ToBytes(prefix + address)
  const hash = bytesToHex(keccak256(Buffer.from(bytes))).slice(2)
  let ret = '0x'

  for (let i = 0; i < address.length; i++) {
    if (parseInt(hash[i], 16) >= 8) {
      ret += address[i].toUpperCase()
    } else {
      ret += address[i]
    }
  }

  return ret
}

/**
 * Checks if the address is a valid checksummed address.
 *
 * See toChecksumAddress' documentation for details about the eip1191ChainId parameter.
 */
export const isValidChecksumAddress = function (
  hexAddress: string,
  eip1191ChainId?: BigIntLike
): boolean {
  return isValidAddress(hexAddress) && toChecksumAddress(hexAddress, eip1191ChainId) === hexAddress
}

/**
 * Generates an address of a newly created contract.
 * @param from The address which is creating this new address
 * @param nonce The nonce of the from account
 */
export const generateAddress = function (from: Uint8Array, nonce: Uint8Array): Uint8Array {
  assertIsBytes(from)
  assertIsBytes(nonce)

  if (bytesToBigInt(nonce) === BIGINT_0) {
    // in RLP we want to encode null in the case of zero nonce
    // read the RLP documentation for an answer if you dare
    return keccak256(Buffer.from(RLP.encode([from, Uint8Array.from([])]))).subarray(-20)
  }

  // Only take the lower 160bits of the hash
  return keccak256(Buffer.from(RLP.encode([from, nonce]))).subarray(-20)
}

/**
 * Generates an address for a contract created using CREATE2.
 * @param from The address which is creating this new address
 * @param salt A salt
 * @param initCode The init code of the contract being created
 */
export const generateAddress2 = function (
  from: Uint8Array,
  salt: Uint8Array,
  initCode: Uint8Array
): Uint8Array {
  assertIsBytes(from)
  assertIsBytes(salt)
  assertIsBytes(initCode)

  if (from.length !== 20) {
    throw new Error('Expected from to be of length 20')
  }
  if (salt.length !== 32) {
    throw new Error('Expected salt to be of length 32')
  }

  const address = keccak256(
    Buffer.from(concatBytes(hexToBytes('0xff'), from, salt, keccak256(Buffer.from(initCode))))
  )

  return address.subarray(-20)
}

/**
 * Checks if the private key satisfies the rules of the curve secp256k1.
 */
export const isValidPrivate = function (privateKey: Uint8Array): boolean {
  try {
    return privateKeyVerify(privateKey)
  } catch {
    return false
  }
}

/**
 * Checks if the public key satisfies the rules of the curve secp256k1
 * and the requirements of Ethereum.
 * @param publicKey The two points of an uncompressed key, unless sanitize is enabled
 * @param sanitize Accept public keys in other formats
 */
export const isValidPublic = function (publicKey: Uint8Array, sanitize: boolean = false): boolean {
  assertIsBytes(publicKey)
  if (publicKey.length === 64) {
    // Convert to SEC1 for secp256k1
    return publicKeyVerify(Buffer.concat([Buffer.from([4]), publicKey]))
  }

  if (!sanitize) {
    return false
  }

  return publicKeyVerify(publicKey)
}

/**
 * Returns the ethereum address of a given public key.
 * Accepts "Ethereum public keys" and SEC1 encoded keys.
 * @param pubKey The two points of an uncompressed key, unless sanitize is enabled
 * @param sanitize Accept public keys in other formats
 */
export const pubToAddress = function (pubKey: Uint8Array, sanitize: boolean = false): Uint8Array {
  assertIsBytes(pubKey)
  if (sanitize && pubKey.length !== 64) {
    pubKey = Buffer.from(publicKeyConvert(pubKey, false).slice(1))
  }
  if (pubKey.length !== 64) {
    throw new Error('Expected pubKey to be of length 64')
  }
  // Only take the lower 160bits of the hash
  return Buffer.from(keccak256(Buffer.from(pubKey))).slice(-20)
}
export const publicToAddress = pubToAddress

/**
 * Returns the ethereum public key of a given private key.
 * @param privateKey A private key must be 256 bits wide
 */
export const privateToPublic = function (privateKey: Uint8Array): Uint8Array {
  assertIsBytes(privateKey)
  // skip the type flag and use the X, Y points
  return Buffer.from(publicKeyCreate(privateKey, false)).slice(1)
}

/**
 * Returns the ethereum address of a given private key.
 * @param privateKey A private key must be 256 bits wide
 */
export const privateToAddress = function (privateKey: Uint8Array): Uint8Array {
  return publicToAddress(privateToPublic(privateKey))
}

/**
 * Converts a public key to the Ethereum format.
 */
export const importPublic = function (publicKey: Uint8Array): Uint8Array {
  assertIsBytes(publicKey)
  if (publicKey.length !== 64) {
    publicKey = Buffer.from(publicKeyConvert(publicKey, false).slice(1))
  }
  return publicKey
}

/**
 * Returns the zero address.
 */
export const zeroAddress = function (): string {
  const addressLength = 20
  const addr = zeros(addressLength)
  return bytesToHex(addr)
}

/**
 * Checks if a given address is the zero address.
 */
export const isZeroAddress = function (hexAddress: string): boolean {
  try {
    assertIsString(hexAddress)
  } catch (e: any) {
    return false
  }

  const zeroAddr = zeroAddress()
  return zeroAddr === hexAddress
}

export function accountBodyFromSlim(body: AccountBodyBytes) {
  const [nonce, balance, storageRoot, codeHash] = body
  return [
    nonce,
    balance,
    storageRoot.length === 0 ? KECCAK256_RLP : storageRoot,
    codeHash.length === 0 ? KECCAK256_NULL : codeHash,
  ]
}

const emptyUint8Arr = new Uint8Array(0)
export function accountBodyToSlim(body: AccountBodyBytes) {
  const [nonce, balance, storageRoot, codeHash] = body
  return [
    nonce,
    balance,
    equalsBytes(storageRoot, KECCAK256_RLP) ? emptyUint8Arr : storageRoot,
    equalsBytes(codeHash, KECCAK256_NULL) ? emptyUint8Arr : codeHash,
  ]
}

/**
 * Converts a slim account (per snap protocol spec) to the RLP encoded version of the account
 * @param body Array of 4 Uint8Array-like items to represent the account
 * @returns RLP encoded version of the account
 */
export function accountBodyToRLP(body: AccountBodyBytes, couldBeSlim = true) {
  const accountBody = couldBeSlim ? accountBodyFromSlim(body) : body
  return RLP.encode(accountBody)
}