import {
  EnsInvalidChainIdError,
  type EnsInvalidChainIdErrorType,
} from '../../errors/ens.js'
import type { ErrorType } from '../../errors/utils.js'

export type ToCoinTypeError = EnsInvalidChainIdErrorType | ErrorType

const SLIP44_MSB = 0x80000000

/**
 * @description Converts a chainId to a ENSIP-9 compliant coinType
 *
 * @example
 * toCoinType(10)
 * 2147483658n
 */
export function toCoinType(chainId: number): bigint {
  if (chainId === 1) return 60n
  if (chainId >= SLIP44_MSB || chainId < 0)
    throw new EnsInvalidChainIdError({ chainId })
  return BigInt((0x80000000 | chainId) >>> 0)
}