/*
Copyright 2020 The Kubernetes Authors.

Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at

    http://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.
*/

/*
Copyright 2020 The Kubernetes Authors.

Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at

    http://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.
*/

/*
Copyright 2020 The Kubernetes Authors.

Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at

    http://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.
*/

// Copyright (C) 2013-2018 by Maxim Bublis <b@codemonkey.ru>
//
// Permission is hereby granted, free of charge, to any person obtaining
// a copy of this software and associated documentation files (the
// "Software"), to deal in the Software without restriction, including
// without limitation the rights to use, copy, modify, merge, publish,
// distribute, sublicense, and/or sell copies of the Software, and to
// permit persons to whom the Software is furnished to do so, subject to
// the following conditions:
//
// The above copyright notice and this permission notice shall be
// included in all copies or substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
// EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
// MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
// NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
// LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
// OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
// WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.

package uuid

import (
	"bytes"
	"encoding/hex"
	"fmt"
)

// FromBytes returns a UUID generated from the raw byte slice input.
// It will return an error if the slice isn't 16 bytes long.
func FromBytes(input []byte) (UUID, error) {
	u := UUID{}
	err := u.UnmarshalBinary(input)
	return u, err
}

// FromBytesOrNil returns a UUID generated from the raw byte slice input.
// Same behavior as FromBytes(), but returns uuid.Nil instead of an error.
func FromBytesOrNil(input []byte) UUID {
	uuid, err := FromBytes(input)
	if err != nil {
		return Nil
	}
	return uuid
}

// FromString returns a UUID parsed from the input string.
// Input is expected in a form accepted by UnmarshalText.
func FromString(input string) (UUID, error) {
	u := UUID{}
	err := u.UnmarshalText([]byte(input))
	return u, err
}

// FromStringOrNil returns a UUID parsed from the input string.
// Same behavior as FromString(), but returns uuid.Nil instead of an error.
func FromStringOrNil(input string) UUID {
	uuid, err := FromString(input)
	if err != nil {
		return Nil
	}
	return uuid
}

// MarshalText implements the encoding.TextMarshaler interface.
// The encoding is the same as returned by the String() method.
func (u UUID) MarshalText() ([]byte, error) {
	return []byte(u.String()), nil
}

// UnmarshalText implements the encoding.TextUnmarshaler interface.
// Following formats are supported:
//
//   "6ba7b810-9dad-11d1-80b4-00c04fd430c8",
//   "{6ba7b810-9dad-11d1-80b4-00c04fd430c8}",
//   "urn:uuid:6ba7b810-9dad-11d1-80b4-00c04fd430c8"
//   "6ba7b8109dad11d180b400c04fd430c8"
//   "{6ba7b8109dad11d180b400c04fd430c8}",
//   "urn:uuid:6ba7b8109dad11d180b400c04fd430c8"
//
// ABNF for supported UUID text representation follows:
//
//   URN := 'urn'
//   UUID-NID := 'uuid'
//
//   hexdig := '0' | '1' | '2' | '3' | '4' | '5' | '6' | '7' | '8' | '9' |
//             'a' | 'b' | 'c' | 'd' | 'e' | 'f' |
//             'A' | 'B' | 'C' | 'D' | 'E' | 'F'
//
//   hexoct := hexdig hexdig
//   2hexoct := hexoct hexoct
//   4hexoct := 2hexoct 2hexoct
//   6hexoct := 4hexoct 2hexoct
//   12hexoct := 6hexoct 6hexoct
//
//   hashlike := 12hexoct
//   canonical := 4hexoct '-' 2hexoct '-' 2hexoct '-' 6hexoct
//
//   plain := canonical | hashlike
//   uuid := canonical | hashlike | braced | urn
//
//   braced := '{' plain '}' | '{' hashlike  '}'
//   urn := URN ':' UUID-NID ':' plain
//
func (u *UUID) UnmarshalText(text []byte) error {
	switch len(text) {
	case 32:
		return u.decodeHashLike(text)
	case 34, 38:
		return u.decodeBraced(text)
	case 36:
		return u.decodeCanonical(text)
	case 41, 45:
		return u.decodeURN(text)
	default:
		return fmt.Errorf("uuid: incorrect UUID length: %s", text)
	}
}

// decodeCanonical decodes UUID strings that are formatted as defined in RFC-4122 (section 3):
// "6ba7b810-9dad-11d1-80b4-00c04fd430c8".
func (u *UUID) decodeCanonical(t []byte) error {
	if t[8] != '-' || t[13] != '-' || t[18] != '-' || t[23] != '-' {
		return fmt.Errorf("uuid: incorrect UUID format %s", t)
	}

	src := t
	dst := u[:]

	for i, byteGroup := range byteGroups {
		if i > 0 {
			src = src[1:] // skip dash
		}
		_, err := hex.Decode(dst[:byteGroup/2], src[:byteGroup])
		if err != nil {
			return err
		}
		src = src[byteGroup:]
		dst = dst[byteGroup/2:]
	}

	return nil
}

// decodeHashLike decodes UUID strings that are using the following format:
//  "6ba7b8109dad11d180b400c04fd430c8".
func (u *UUID) decodeHashLike(t []byte) error {
	src := t[:]
	dst := u[:]

	_, err := hex.Decode(dst, src)
	return err
}

// decodeBraced decodes UUID strings that are using the following formats:
//  "{6ba7b810-9dad-11d1-80b4-00c04fd430c8}"
//  "{6ba7b8109dad11d180b400c04fd430c8}".
func (u *UUID) decodeBraced(t []byte) error {
	l := len(t)

	if t[0] != '{' || t[l-1] != '}' {
		return fmt.Errorf("uuid: incorrect UUID format %s", t)
	}

	return u.decodePlain(t[1 : l-1])
}

// decodeURN decodes UUID strings that are using the following formats:
//  "urn:uuid:6ba7b810-9dad-11d1-80b4-00c04fd430c8"
//  "urn:uuid:6ba7b8109dad11d180b400c04fd430c8".
func (u *UUID) decodeURN(t []byte) error {
	total := len(t)

	urnUUIDPrefix := t[:9]

	if !bytes.Equal(urnUUIDPrefix, urnPrefix) {
		return fmt.Errorf("uuid: incorrect UUID format: %s", t)
	}

	return u.decodePlain(t[9:total])
}

// decodePlain decodes UUID strings that are using the following formats:
//  "6ba7b810-9dad-11d1-80b4-00c04fd430c8" or in hash-like format
//  "6ba7b8109dad11d180b400c04fd430c8".
func (u *UUID) decodePlain(t []byte) error {
	switch len(t) {
	case 32:
		return u.decodeHashLike(t)
	case 36:
		return u.decodeCanonical(t)
	default:
		return fmt.Errorf("uuid: incorrect UUID length: %s", t)
	}
}

// MarshalBinary implements the encoding.BinaryMarshaler interface.
func (u UUID) MarshalBinary() ([]byte, error) {
	return u.Bytes(), nil
}

// UnmarshalBinary implements the encoding.BinaryUnmarshaler interface.
// It will return an error if the slice isn't 16 bytes long.
func (u *UUID) UnmarshalBinary(data []byte) error {
	if len(data) != Size {
		return fmt.Errorf("uuid: UUID must be exactly 16 bytes long, got %d bytes", len(data))
	}
	copy(u[:], data)

	return nil
}
