/**********************************************************\
|                                                          |
|                          hprose                          |
|                                                          |
| Official WebSite: http://www.hprose.com/                 |
|                   http://www.hprose.org/                 |
|                                                          |
\**********************************************************/
/**********************************************************\
 *                                                        *
 * hprose/uuid.go                                         *
 *                                                        *
 * hprose uuid for Go.                                    *
 *                                                        *
 * LastModified: Feb 14, 2014                             *
 * Author: Ma Bingyao <andot@hprose.com>                  *
 *                                                        *
\**********************************************************/

package hprose

import (
	"fmt"
	"strings"
)

// UUID type is only a UUID wrapper for hprose serialize/unserialize,
// If you want to generate UUIDs, you should use other UUID package.
type UUID []byte

// xvalues returns the value of a byte as a hexadecimal digit or 255.
var xvalues = []byte{
	255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255,
	255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255,
	255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255,
	0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 255, 255, 255, 255, 255, 255,
	255, 10, 11, 12, 13, 14, 15, 255, 255, 255, 255, 255, 255, 255, 255, 255,
	255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255,
	255, 10, 11, 12, 13, 14, 15, 255, 255, 255, 255, 255, 255, 255, 255, 255,
	255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255,
	255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255,
	255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255,
	255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255,
	255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255,
	255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255,
	255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255,
	255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255,
	255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255,
}

// xtob converts the the first two hex bytes of x into a byte.
func xtob(x string) (byte, bool) {
	b1 := xvalues[x[0]]
	b2 := xvalues[x[1]]
	return (b1 << 4) | b2, b1 != 255 && b2 != 255
}

// ToUUID decodes s into a UUID or returns nil.  Both the UUID form of
// xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx and
// urn:uuid:xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx are decoded.
func ToUUID(s string) UUID {
	if len(s) == 36+9 {
		if strings.ToLower(s[:9]) != "urn:uuid:" {
			return nil
		}
		s = s[9:]
	} else if len(s) != 36 {
		return nil
	}
	if s[8] != '-' || s[13] != '-' || s[18] != '-' || s[23] != '-' {
		return nil
	}
	uuid := make([]byte, 16)
	for i, x := range []int{
		0, 2, 4, 6,
		9, 11,
		14, 16,
		19, 21,
		24, 26, 28, 30, 32, 34} {
		v, ok := xtob(s[x:])
		if !ok {
			return nil
		}
		uuid[i] = v
	}
	return uuid
}

// String returns the string form of uuid, xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx
// , or "" if uuid is invalid.
func (uuid UUID) String() string {
	if uuid == nil || len(uuid) != 16 {
		return ""
	}
	b := []byte(uuid)
	return fmt.Sprintf("%08x-%04x-%04x-%04x-%012x",
		b[:4], b[4:6], b[6:8], b[8:10], b[10:])
}