import {
  InvalidSerializedTransactionTypeError,
  type InvalidSerializedTransactionTypeErrorType,
} from '../../errors/transaction.js'
import type { ErrorType } from '../../errors/utils.js'
import type {
  TransactionSerialized,
  TransactionSerializedEIP1559,
  TransactionSerializedEIP2930,
} from '../../types/transaction.js'
import { type SliceHexErrorType, sliceHex } from '../data/slice.js'
import { type HexToNumberErrorType, hexToNumber } from '../encoding/fromHex.js'

export type GetSerializedTransactionType<
  TTransactionSerialized extends TransactionSerialized = TransactionSerialized,
> = TTransactionSerialized extends TransactionSerializedEIP1559
  ? 'eip1559'
  : TTransactionSerialized extends TransactionSerializedEIP2930
    ? 'eip2930'
    : 'legacy'

export type GetSerializedTransactionTypeErrorType =
  | HexToNumberErrorType
  | InvalidSerializedTransactionTypeErrorType
  | SliceHexErrorType
  | ErrorType

export function getSerializedTransactionType<
  TSerialized extends TransactionSerialized,
>(
  serializedTransaction: TSerialized,
): GetSerializedTransactionType<TSerialized> {
  const serializedType = sliceHex(serializedTransaction, 0, 1)

  if (serializedType === '0x02')
    return 'eip1559' as GetSerializedTransactionType<TSerialized>

  if (serializedType === '0x01')
    return 'eip2930' as GetSerializedTransactionType<TSerialized>

  if (serializedType !== '0x' && hexToNumber(serializedType) >= 0xc0)
    return 'legacy' as GetSerializedTransactionType<TSerialized>

  throw new InvalidSerializedTransactionTypeError({ serializedType })
}