class Fields

final class Fields implements FieldsInterface {
    use MaxTrait;
    use NilTrait;
    use SerializableFieldsTrait;
    use VariantTrait;
    use VersionTrait;
    
    /**
     * @param string $bytes A 16-byte binary string representation of a UUID
     *
     * @throws InvalidArgumentException if the byte string is not exactly 16 bytes
     * @throws InvalidArgumentException if the byte string does not represent an RFC 4122 UUID
     * @throws InvalidArgumentException if the byte string does not contain a valid version
     */
    public function __construct(string $bytes) {
        if (strlen($this->bytes) !== 16) {
            throw new InvalidArgumentException('The byte string must be 16 bytes long; ' . 'received ' . strlen($this->bytes) . ' bytes');
        }
        if (!$this->isCorrectVariant()) {
            throw new InvalidArgumentException('The byte string received does not conform to the RFC 4122 variant');
        }
        if (!$this->isCorrectVersion()) {
            throw new InvalidArgumentException('The byte string received does not contain a valid RFC 4122 version');
        }
    }
    public function getBytes() : string {
        return $this->bytes;
    }
    public function getClockSeq() : Hexadecimal {
        if ($this->isMax()) {
            $clockSeq = 0xffff;
        }
        elseif ($this->isNil()) {
            $clockSeq = 0x0;
        }
        else {
            $clockSeq = hexdec(bin2hex(substr($this->bytes, 8, 2))) & 0x3fff;
        }
        return new Hexadecimal(str_pad(dechex($clockSeq), 4, '0', STR_PAD_LEFT));
    }
    public function getClockSeqHiAndReserved() : Hexadecimal {
        return new Hexadecimal(bin2hex(substr($this->bytes, 8, 1)));
    }
    public function getClockSeqLow() : Hexadecimal {
        return new Hexadecimal(bin2hex(substr($this->bytes, 9, 1)));
    }
    public function getNode() : Hexadecimal {
        return new Hexadecimal(bin2hex(substr($this->bytes, 10)));
    }
    public function getTimeHiAndVersion() : Hexadecimal {
        return new Hexadecimal(bin2hex(substr($this->bytes, 6, 2)));
    }
    public function getTimeLow() : Hexadecimal {
        return new Hexadecimal(bin2hex(substr($this->bytes, 0, 4)));
    }
    public function getTimeMid() : Hexadecimal {
        return new Hexadecimal(bin2hex(substr($this->bytes, 4, 2)));
    }
    
    /**
     * Returns the full 60-bit timestamp, without the version
     *
     * For version 2 UUIDs, the time_low field is the local identifier and
     * should not be returned as part of the time. For this reason, we set the
     * bottom 32 bits of the timestamp to 0's. As a result, there is some loss
     * of fidelity of the timestamp, for version 2 UUIDs. The timestamp can be
     * off by a range of 0 to 429.4967295 seconds (or 7 minutes, 9 seconds, and
     * 496730 microseconds).
     *
     * For version 6 UUIDs, the timestamp order is reversed from the typical RFC
     * 4122 order (the time bits are in the correct bit order, so that it is
     * monotonically increasing). In returning the timestamp value, we put the
     * bits in the order: time_low + time_mid + time_hi.
     */
    public function getTimestamp() : Hexadecimal {
        $timestamp = match ($this->getVersion()) {    Uuid::UUID_TYPE_DCE_SECURITY => sprintf('%03x%04s%08s', hexdec($this->getTimeHiAndVersion()
                ->toString()) & 0xfff, $this->getTimeMid()
                ->toString(), ''),
            Uuid::UUID_TYPE_REORDERED_TIME => sprintf('%08s%04s%03x', $this->getTimeLow()
                ->toString(), $this->getTimeMid()
                ->toString(), hexdec($this->getTimeHiAndVersion()
                ->toString()) & 0xfff),
            Uuid::UUID_TYPE_UNIX_TIME => sprintf('%011s%04s', $this->getTimeLow()
                ->toString(), $this->getTimeMid()
                ->toString()),
            default => sprintf('%03x%04s%08s', hexdec($this->getTimeHiAndVersion()
                ->toString()) & 0xfff, $this->getTimeMid()
                ->toString(), $this->getTimeLow()
                ->toString()),
        
        };
        return new Hexadecimal($timestamp);
    }
    public function getVersion() : ?int {
        if ($this->isNil() || $this->isMax()) {
            return null;
        }
        
        /** @var int[] $parts */
        $parts = unpack('n*', $this->bytes);
        return $parts[4] >> 12;
    }
    private function isCorrectVariant() : bool {
        if ($this->isNil() || $this->isMax()) {
            return true;
        }
        return $this->getVariant() === Uuid::RFC_4122;
    }

}