// retoor <retoor@molodetz.nl>

import "crypto" for Crypto
import "strutil" for Str
import "bytes" for Bytes

class Uuid {
  static toHex_(bytes) { Str.hexEncode(Bytes.fromList(bytes)) }

  static v4() {
    var bytes = Crypto.randomBytes(16)
    bytes[6] = (bytes[6] & 0x0F) | 0x40
    bytes[8] = (bytes[8] & 0x3F) | 0x80
    var hex = toHex_(bytes)
    return hex[0..7] + "-" + hex[8..11] + "-" + hex[12..15] + "-" + hex[16..19] + "-" + hex[20..31]
  }

  static isValid(string) {
    if (!(string is String)) return false
    if (string.count != 36) return false
    if (string[8] != "-" || string[13] != "-" || string[18] != "-" || string[23] != "-") return false
    var hexChars = "0123456789abcdefABCDEF"
    var positions = [0, 1, 2, 3, 4, 5, 6, 7, 9, 10, 11, 12, 14, 15, 16, 17, 19, 20, 21, 22, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35]
    for (pos in positions) {
      if (!hexChars.contains(string[pos])) return false
    }
    return true
  }

  static isV4(string) {
    if (!isValid(string)) return false
    var version = string[14]
    if (version != "4") return false
    var variant = string[19]
    if (variant != "8" && variant != "9" && variant != "a" && variant != "b" && variant != "A" && variant != "B") return false
    return true
  }
}