webboot / crypto / 40

  try {

    const options = Object.assign({}, defaultArgs, params)

    let { min, max } = options

    const distance = max - min

    if (min > max) {

      const m = min

      min = max

      max = m

    }

    if (max > Number.MAX_SAFE_INTEGER) {

      throw new Error(

        `${libName}: Max number should be Number.MAX_SAFE_INTEGER too high by: ${

          max - Number.MAX_SAFE_INTEGER

        }`,

      )

    }

    if (distance > 281474976710655) {

      throw new Error(`${libName}: Distance is greater than 256^6-1 ${distance}`)

    }

    let subOnEnd = 0

    if (min < 0) {

      subOnEnd = min

      max += Math.abs(min)

      min = 0

    }

    let maxBytes = 6

    let maxDec = 281474976710656

    // Adjust maxBytes for small ranges

    if (distance < 256) {

      maxBytes = 1

      maxDec = 256

    } else if (distance < 65536) {

      maxBytes = 2

      maxDec = 65536

    } else if (distance < 16777216) {

      maxBytes = 3

      maxDec = 16777216

    } else if (distance < 4294967296) {

      maxBytes = 4

      maxDec = 4294967296

    } else if (distance < 1099511627776) {

      maxBytes = 4

      maxDec = 1099511627776

    }

    const byteString = await crypto.randomBytes(maxBytes).toString('hex')

    const randbytes = parseInt(byteString, 16)

    return Math.min(max, Math.floor((randbytes / maxDec) * (max - min + 1) + min + subOnEnd))

  } catch (e) {

    e.message = `${libName} ${e.message}`

    throw e

  }

}