export interface BigIntToNumberOptions {
  /**
   * The number of digits starting from the right of `value` to consider as decimal places.
   *
   * @default 18n
   */
  precision?: bigint | undefined
}

/**
 * Converts a bigint to a number.
 *
 * @param value - The bigint to convert to a number.
 * @param options - Conversion options.
 * @returns The number representation of `value`
 */
export function bigIntToNumber(value: bigint, options?: BigIntToNumberOptions): number {
  const { precision = 18n } = options ?? {}
  if (precision < 0n) {
    throw new Error(`[bigIntToNumber] \`precision\` must be positive, got ${precision}`)
  }
  if (precision === 0n) {
    return Number(value)
  } else {
    const valueString = String(value)
    const decimalPointIndex = valueString.length - Number(precision)
    if (decimalPointIndex <= 0) {
      return Number(`0.${'0'.repeat(Math.abs(decimalPointIndex))}${valueString}`)
    }
    return Number(
      `${valueString.slice(0, decimalPointIndex)}.${valueString.slice(decimalPointIndex)}`,
    )
  }
}