import { RLP } from '@nomicfoundation/ethereumjs-rlp'
import {
  BIGINT_2,
  BIGINT_8,
  MAX_INTEGER,
  bigIntToHex,
  bigIntToUnpaddedBytes,
  bytesToBigInt,
  toBytes,
  unpadBytes,
  validateNoLeadingZeroes,
} from '@nomicfoundation/ethereumjs-util'
import { keccak256 as bufferKeccak256 } from 'ethereum-cryptography/keccak.js'

import { BaseTransaction } from './baseTransaction.js'
import * as Legacy from './capabilities/legacy.js'
import { Capability, TransactionType } from './types.js'

import type {
  TxData as AllTypesTxData,
  TxValuesArray as AllTypesTxValuesArray,
  JsonTx,
  TxOptions,
} from './types.js'
import type { Common } from '@nomicfoundation/ethereumjs-common'

function keccak256(msg: Uint8Array): Uint8Array {
  return new Uint8Array(bufferKeccak256(Buffer.from(msg)))
}

type TxData = AllTypesTxData[TransactionType.Legacy]
type TxValuesArray = AllTypesTxValuesArray[TransactionType.Legacy]

function meetsEIP155(_v: bigint, chainId: bigint) {
  const v = Number(_v)
  const chainIdDoubled = Number(chainId) * 2
  return v === chainIdDoubled + 35 || v === chainIdDoubled + 36
}

/**
 * An Ethereum non-typed (legacy) transaction
 */
export class LegacyTransaction extends BaseTransaction<TransactionType.Legacy> {
  public readonly gasPrice: bigint

  public readonly common: Common
  private keccakFunction: (msg: Uint8Array) => Uint8Array

  /**
   * Instantiate a transaction from a data dictionary.
   *
   * Format: { nonce, gasPrice, gasLimit, to, value, data, v, r, s }
   *
   * Notes:
   * - All parameters are optional and have some basic default values
   */
  public static fromTxData(txData: TxData, opts: TxOptions = {}) {
    return new LegacyTransaction(txData, opts)
  }

  /**
   * Instantiate a transaction from the serialized tx.
   *
   * Format: `rlp([nonce, gasPrice, gasLimit, to, value, data, v, r, s])`
   */
  public static fromSerializedTx(serialized: Uint8Array, opts: TxOptions = {}) {
    const values = RLP.decode(serialized)

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

    return this.fromValuesArray(values as TxValuesArray, opts)
  }

  /**
   * Create a transaction from a values array.
   *
   * Format: `[nonce, gasPrice, gasLimit, to, value, data, v, r, s]`
   */
  public static fromValuesArray(values: TxValuesArray, opts: TxOptions = {}) {
    // If length is not 6, it has length 9. If v/r/s are empty Uint8Arrays, it is still an unsigned transaction
    // This happens if you get the RLP data from `raw()`
    if (values.length !== 6 && values.length !== 9) {
      throw new Error(
        'Invalid transaction. Only expecting 6 values (for unsigned tx) or 9 values (for signed tx).'
      )
    }

    const [nonce, gasPrice, gasLimit, to, value, data, v, r, s] = values

    validateNoLeadingZeroes({ nonce, gasPrice, gasLimit, value, v, r, s })

    return new LegacyTransaction(
      {
        nonce,
        gasPrice,
        gasLimit,
        to,
        value,
        data,
        v,
        r,
        s,
      },
      opts
    )
  }

  /**
   * This constructor takes the values, validates them, assigns them and freezes the object.
   *
   * It is not recommended to use this constructor directly. Instead use
   * the static factory methods to assist in creating a Transaction object from
   * varying data types.
   */
  public constructor(txData: TxData, opts: TxOptions = {}) {
    super({ ...txData, type: TransactionType.Legacy }, opts)

    this.common = this._validateTxV(this.v, opts.common)
    this.keccakFunction = this.common.customCrypto.keccak256 ?? keccak256
    this.gasPrice = bytesToBigInt(toBytes(txData.gasPrice === '' ? '0x' : txData.gasPrice))

    if (this.gasPrice * this.gasLimit > MAX_INTEGER) {
      const msg = this._errorMsg('gas limit * gasPrice cannot exceed MAX_INTEGER (2^256-1)')
      throw new Error(msg)
    }

    this._validateCannotExceedMaxInteger({ gasPrice: this.gasPrice })
    BaseTransaction._validateNotArray(txData)

    if (this.common.gteHardfork('spuriousDragon')) {
      if (!this.isSigned()) {
        this.activeCapabilities.push(Capability.EIP155ReplayProtection)
      } else {
        // EIP155 spec:
        // If block.number >= 2,675,000 and v = CHAIN_ID * 2 + 35 or v = CHAIN_ID * 2 + 36
        // then when computing the hash of a transaction for purposes of signing or recovering
        // instead of hashing only the first six elements (i.e. nonce, gasprice, startgas, to, value, data)
        // hash nine elements, with v replaced by CHAIN_ID, r = 0 and s = 0.
        // v and chain ID meet EIP-155 conditions
        if (meetsEIP155(this.v!, this.common.chainId())) {
          this.activeCapabilities.push(Capability.EIP155ReplayProtection)
        }
      }
    }

    const freeze = opts?.freeze ?? true
    if (freeze) {
      Object.freeze(this)
    }
  }

  /**
   * Returns a Uint8Array Array of the raw Bytes of the legacy transaction, in order.
   *
   * Format: `[nonce, gasPrice, gasLimit, to, value, data, v, r, s]`
   *
   * For legacy txs this is also the correct format to add transactions
   * to a block with {@link Block.fromValuesArray} (use the `serialize()` method
   * for typed txs).
   *
   * For an unsigned tx this method returns the empty Bytes values
   * for the signature parameters `v`, `r` and `s`. For an EIP-155 compliant
   * representation have a look at {@link Transaction.getMessageToSign}.
   */
  raw(): TxValuesArray {
    return [
      bigIntToUnpaddedBytes(this.nonce),
      bigIntToUnpaddedBytes(this.gasPrice),
      bigIntToUnpaddedBytes(this.gasLimit),
      this.to !== undefined ? this.to.bytes : new Uint8Array(0),
      bigIntToUnpaddedBytes(this.value),
      this.data,
      this.v !== undefined ? bigIntToUnpaddedBytes(this.v) : new Uint8Array(0),
      this.r !== undefined ? bigIntToUnpaddedBytes(this.r) : new Uint8Array(0),
      this.s !== undefined ? bigIntToUnpaddedBytes(this.s) : new Uint8Array(0),
    ]
  }

  /**
   * Returns the serialized encoding of the legacy transaction.
   *
   * Format: `rlp([nonce, gasPrice, gasLimit, to, value, data, v, r, s])`
   *
   * For an unsigned tx this method uses the empty Uint8Array values for the
   * signature parameters `v`, `r` and `s` for encoding. For an EIP-155 compliant
   * representation for external signing use {@link Transaction.getMessageToSign}.
   */
  serialize(): Uint8Array {
    return RLP.encode(this.raw())
  }

  /**
   * Returns the raw unsigned tx, which can be used
   * to sign the transaction (e.g. for sending to a hardware wallet).
   *
   * Note: the raw message message format for the legacy tx is not RLP encoded
   * and you might need to do yourself with:
   *
   * ```javascript
   * import { RLP } from '@nomicfoundation/ethereumjs-rlp'
   * const message = tx.getMessageToSign()
   * const serializedMessage = RLP.encode(message)) // use this for the HW wallet input
   * ```
   */
  getMessageToSign(): Uint8Array[] {
    const message = [
      bigIntToUnpaddedBytes(this.nonce),
      bigIntToUnpaddedBytes(this.gasPrice),
      bigIntToUnpaddedBytes(this.gasLimit),
      this.to !== undefined ? this.to.bytes : new Uint8Array(0),
      bigIntToUnpaddedBytes(this.value),
      this.data,
    ]

    if (this.supports(Capability.EIP155ReplayProtection)) {
      message.push(bigIntToUnpaddedBytes(this.common.chainId()))
      message.push(unpadBytes(toBytes(0)))
      message.push(unpadBytes(toBytes(0)))
    }

    return message
  }

  /**
   * Returns the hashed serialized unsigned tx, which can be used
   * to sign the transaction (e.g. for sending to a hardware wallet).
   */
  getHashedMessageToSign() {
    const message = this.getMessageToSign()
    return this.keccakFunction(RLP.encode(message))
  }

  /**
   * The amount of gas paid for the data in this tx
   */
  getDataFee(): bigint {
    return Legacy.getDataFee(this)
  }

  /**
   * The up front amount that an account must have for this transaction to be valid
   */
  getUpfrontCost(): bigint {
    return this.gasLimit * this.gasPrice + this.value
  }

  /**
   * Computes a sha3-256 hash of the serialized tx.
   *
   * This method can only be used for signed txs (it throws otherwise).
   * Use {@link Transaction.getMessageToSign} to get a tx hash for the purpose of signing.
   */
  hash(): Uint8Array {
    return Legacy.hash(this)
  }

  /**
   * Computes a sha3-256 hash which can be used to verify the signature
   */
  getMessageToVerifySignature() {
    if (!this.isSigned()) {
      const msg = this._errorMsg('This transaction is not signed')
      throw new Error(msg)
    }
    return this.getHashedMessageToSign()
  }

  /**
   * Returns the public key of the sender
   */
  _getSenderPublicKey(): Uint8Array {
    return Legacy.getSenderPublicKey(this)
  }

  /**
   * Process the v, r, s values from the `sign` method of the base transaction.
   */
  protected _processSignature(v: bigint, r: Uint8Array, s: Uint8Array) {
    if (this.supports(Capability.EIP155ReplayProtection)) {
      v += this.common.chainId() * BIGINT_2 + BIGINT_8
    }

    const opts = { ...this.txOptions, common: this.common }

    return LegacyTransaction.fromTxData(
      {
        nonce: this.nonce,
        gasPrice: this.gasPrice,
        gasLimit: this.gasLimit,
        to: this.to,
        value: this.value,
        data: this.data,
        v,
        r: bytesToBigInt(r),
        s: bytesToBigInt(s),
      },
      opts
    )
  }

  /**
   * Returns an object with the JSON representation of the transaction.
   */
  toJSON(): JsonTx {
    const baseJson = super.toJSON()
    return {
      ...baseJson,
      gasPrice: bigIntToHex(this.gasPrice),
    }
  }

  /**
   * Validates tx's `v` value
   */
  protected _validateTxV(_v?: bigint, common?: Common): Common {
    let chainIdBigInt
    const v = _v !== undefined ? Number(_v) : undefined
    // Check for valid v values in the scope of a signed legacy tx
    if (v !== undefined) {
      // v is 1. not matching the EIP-155 chainId included case and...
      // v is 2. not matching the classic v=27 or v=28 case
      if (v < 37 && v !== 27 && v !== 28) {
        throw new Error(
          `Legacy txs need either v = 27/28 or v >= 37 (EIP-155 replay protection), got v = ${v}`
        )
      }
    }

    // No unsigned tx and EIP-155 activated and chain ID included
    if (
      v !== undefined &&
      v !== 0 &&
      (!common || common.gteHardfork('spuriousDragon')) &&
      v !== 27 &&
      v !== 28
    ) {
      if (common) {
        if (!meetsEIP155(BigInt(v), common.chainId())) {
          throw new Error(
            `Incompatible EIP155-based V ${v} and chain id ${common.chainId()}. See the Common parameter of the Transaction constructor to set the chain id.`
          )
        }
      } else {
        // Derive the original chain ID
        let numSub
        if ((v - 35) % 2 === 0) {
          numSub = 35
        } else {
          numSub = 36
        }
        // Use derived chain ID to create a proper Common
        chainIdBigInt = BigInt(v - numSub) / BIGINT_2
      }
    }
    return this._getCommon(common, chainIdBigInt)
  }

  /**
   * Return a compact error string representation of the object
   */
  public errorStr() {
    let errorStr = this._getSharedErrorPostfix()
    errorStr += ` gasPrice=${this.gasPrice}`
    return errorStr
  }

  /**
   * Internal helper function to create an annotated error message
   *
   * @param msg Base error message
   * @hidden
   */
  protected _errorMsg(msg: string) {
    return Legacy.errorMsg(this, msg)
  }
}