UUIDV7.scala

import java.util.UUID
import java.security.SecureRandom
import java.time.Instant

object UUIDV7 {
  lazy val defaultRandom = new SecureRandom()
  
  def create: UUID = create(defaultRandom)
  
  def create(rnd: SecureRandom): UUID = create(rnd, System.currentTimeMillis)
  
  def createFromInstant(instant: Instant): UUID = createFromInstant(defaultRandom, instant)
  
  def createFromInstant(rnd: SecureRandom, instant: Instant): UUID = create(rnd, instant.toEpochMilli)
  
  private def create(rnd: SecureRandom, now: Long): UUID = {    
    val msb = (now << 16) | (rnd.nextLong & 0x0fffL) | 0x7000L
    val lsb = (rnd.nextLong & 0x3fffffffffffffffL) | 0x8000000000000000L
    new UUID(msb, lsb)
  }
  
  def min(instant: Instant): UUID = {
    val time = instant.toEpochMilli
    new UUID((time << 16) | 0x7000L, 0x8000000000000000L)
  }
  
  def max(instant: Instant): UUID = {
    val time = instant.toEpochMilli
    new UUID((time << 16) | 0x7fffL, 0xbfffffffffffffffL) 
  }
}