import { MerklePatriciaTrie } from '@ethereumjs/mpt'
import { RLP } from '@ethereumjs/rlp'
import { Blob4844Tx } from '@ethereumjs/tx'
import {
  BIGINT_0,
  BIGINT_1,
  EthereumJSErrorWithoutCode,
  TypeOutput,
  concatBytes,
  isHexString,
  toType,
} from '@ethereumjs/util'

import { type Common } from '@ethereumjs/common'
import type { TypedTransaction } from '@ethereumjs/tx'
import type { CLRequest, CLRequestType, PrefixedHexString, Withdrawal } from '@ethereumjs/util'
import type { BlockHeaderBytes, HeaderData } from './types.ts'
/**
 * Returns a 0x-prefixed hex number string from a hex string or string integer.
 * @param {string} input string to check, convert, and return
 */
export const numberToHex = function (input?: string): PrefixedHexString | undefined {
  if (input === undefined) return undefined
  if (!isHexString(input)) {
    const regex = new RegExp(/^\d+$/) // test to make sure input contains only digits
    if (!regex.test(input)) {
      const msg = `Cannot convert string to hex string. numberToHex only supports 0x-prefixed hex or integer strings but the given string was: ${input}`
      throw EthereumJSErrorWithoutCode(msg)
    }
    return `0x${parseInt(input, 10).toString(16)}`
  }
  return input
}

/**
 * Converts the canonical byte-array representation of a header into structured {@link HeaderData}.
 * @param values Header field values in canonical order
 * @returns Parsed header data
 */
export function valuesArrayToHeaderData(values: BlockHeaderBytes): HeaderData {
  const [
    parentHash,
    uncleHash,
    coinbase,
    stateRoot,
    transactionsTrie,
    receiptTrie,
    logsBloom,
    difficulty,
    number,
    gasLimit,
    gasUsed,
    timestamp,
    extraData,
    mixHash,
    nonce,
    baseFeePerGas,
    withdrawalsRoot,
    blobGasUsed,
    excessBlobGas,
    parentBeaconBlockRoot,
    requestsHash,
    blockAccessListHash,
    slotNumber,
  ] = values

  if (values.length > 23) {
    throw EthereumJSErrorWithoutCode(
      `invalid header. More values than expected were received. Max: 23, got: ${values.length}`,
    )
  }
  if (values.length < 15) {
    throw EthereumJSErrorWithoutCode(
      `invalid header. Less values than expected were received. Min: 15, got: ${values.length}`,
    )
  }

  return {
    parentHash,
    uncleHash,
    coinbase,
    stateRoot,
    transactionsTrie,
    receiptTrie,
    logsBloom,
    difficulty,
    number,
    gasLimit,
    gasUsed,
    timestamp,
    extraData,
    mixHash,
    nonce,
    baseFeePerGas,
    withdrawalsRoot,
    blobGasUsed,
    excessBlobGas,
    parentBeaconBlockRoot,
    requestsHash,
    blockAccessListHash,
    slotNumber,
  }
}

/**
 * Retrieves the header difficulty as a bigint if the field is provided.
 * @param headerData Header data potentially containing a difficulty value
 * @returns Difficulty as bigint, or `null` when unset
 */
export function getDifficulty(headerData: HeaderData): bigint | null {
  const { difficulty } = headerData
  if (difficulty !== undefined) {
    return toType(difficulty, TypeOutput.BigInt)
  }
  return null
}

/**
 * Counts the total number of blob commitments contained in the provided transactions.
 * @param transactions Transactions to inspect for blob data
 * @returns Number of blob versioned hashes referenced
 */
export const getNumBlobs = (transactions: TypedTransaction[]) => {
  let numBlobs = 0
  for (const tx of transactions) {
    if (tx instanceof Blob4844Tx) {
      numBlobs += tx.blobVersionedHashes.length
    }
  }
  return numBlobs
}

/**
 * Approximates `factor * e ** (numerator / denominator)` using Taylor expansion
 */
export const fakeExponential = (factor: bigint, numerator: bigint, denominator: bigint) => {
  let i = BIGINT_1
  let output = BIGINT_0
  let numerator_accumulator = factor * denominator
  while (numerator_accumulator > BIGINT_0) {
    output += numerator_accumulator
    numerator_accumulator = (numerator_accumulator * numerator) / (denominator * i)
    i++
  }

  return output / denominator
}

/**
 * Returns the blob gas price depending upon the `excessBlobGas` value
 * @param excessBlobGas
 * @param common
 */
export const computeBlobGasPrice = (excessBlobGas: bigint, common: Common) => {
  return fakeExponential(
    common.param('minBlobGas'),
    excessBlobGas,
    common.param('blobGasPriceUpdateFraction'),
  )
}

/**
 * Returns the withdrawals trie root for array of Withdrawal.
 * @param wts array of Withdrawal to compute the root of
 * @param emptyTrie Optional trie used to generate the root
 */
export async function genWithdrawalsTrieRoot(wts: Withdrawal[], emptyTrie?: MerklePatriciaTrie) {
  const trie = emptyTrie ?? new MerklePatriciaTrie()
  for (const [i, wt] of wts.entries()) {
    await trie.put(RLP.encode(i), RLP.encode(wt.raw()))
  }
  return trie.root()
}

/**
 * Returns the txs trie root for array of TypedTransaction
 * @param txs array of TypedTransaction to compute the root of
 * @param emptyTrie Optional trie used to generate the root
 */
export async function genTransactionsTrieRoot(
  txs: TypedTransaction[],
  emptyTrie?: MerklePatriciaTrie,
) {
  const trie = emptyTrie ?? new MerklePatriciaTrie()
  for (const [i, tx] of txs.entries()) {
    await trie.put(RLP.encode(i), tx.serialize())
  }
  return trie.root()
}

/**
 * Returns the requests trie root for an array of CLRequests
 * @param requests - an array of CLRequests
 * @param sha256Function Hash function used to derive the requests root
 * @param emptyTrie optional empty trie used to generate the root
 * @returns a 32 byte Uint8Array representing the requests trie root
 */
export function genRequestsRoot(
  requests: CLRequest<CLRequestType>[],
  sha256Function: (msg: Uint8Array) => Uint8Array,
) {
  // Requests should be sorted in monotonically ascending order based on type
  // and whatever internal sorting logic is defined by each request type
  if (requests.length > 1) {
    for (let x = 1; x < requests.length; x++) {
      if (requests[x].type < requests[x - 1].type)
        throw EthereumJSErrorWithoutCode('requests are not sorted in ascending order')
    }
  }

  // def compute_requests_hash(list):
  //    return keccak_256(rlp.encode([rlp.encode(req) for req in list]))

  let flatRequests = new Uint8Array()
  for (const req of requests) {
    if (req.bytes.length > 1) {
      // Only append requests if they have content
      flatRequests = concatBytes(flatRequests, sha256Function(req.bytes))
    }
  }

  return sha256Function(flatRequests)
}