/*
Copyright 2014 Google Inc. All rights reserved.

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.
*/

package util

import (
	"net"
	"regexp"
)

const qnameCharFmt string = "[A-Za-z0-9]"
const qnameExtCharFmt string = "[-A-Za-z0-9_.]"
const qnameTokenFmt string = "(" + qnameCharFmt + qnameExtCharFmt + "*)?" + qnameCharFmt

const LabelValueFmt string = "(" + qnameTokenFmt + ")?"
const LabelValueMaxLength int = 63

var labelValueRegexp = regexp.MustCompile("^" + LabelValueFmt + "$")

func IsValidLabelValue(value string) bool {
	return (len(value) <= LabelValueMaxLength && labelValueRegexp.MatchString(value))
}

const QualifiedNameFmt string = "(" + qnameTokenFmt + "/)?" + qnameTokenFmt
const QualifiedNameMaxLength int = 253

var qualifiedNameRegexp = regexp.MustCompile("^" + QualifiedNameFmt + "$")

func IsQualifiedName(value string) bool {
	return (len(value) <= QualifiedNameMaxLength && qualifiedNameRegexp.MatchString(value))
}

const DNS1123LabelFmt string = "[a-z0-9]([-a-z0-9]*[a-z0-9])?"
const DNS1123LabelMaxLength int = 63

var dns1123LabelRegexp = regexp.MustCompile("^" + DNS1123LabelFmt + "$")

// IsDNS1123Label tests for a string that conforms to the definition of a label in
// DNS (RFC 1123).
func IsDNS1123Label(value string) bool {
	return len(value) <= DNS1123LabelMaxLength && dns1123LabelRegexp.MatchString(value)
}

const DNS1123SubdomainFmt string = DNS1123LabelFmt + "(\\." + DNS1123LabelFmt + ")*"
const DNS1123SubdomainMaxLength int = 253

var dns1123SubdomainRegexp = regexp.MustCompile("^" + DNS1123SubdomainFmt + "$")

// IsDNS1123Subdomain tests for a string that conforms to the definition of a
// subdomain in DNS (RFC 1123).
func IsDNS1123Subdomain(value string) bool {
	return len(value) <= DNS1123SubdomainMaxLength && dns1123SubdomainRegexp.MatchString(value)
}

const DNS952LabelFmt string = "[a-z]([-a-z0-9]*[a-z0-9])?"
const DNS952LabelMaxLength int = 24

var dns952LabelRegexp = regexp.MustCompile("^" + DNS952LabelFmt + "$")

// IsDNS952Label tests for a string that conforms to the definition of a label in
// DNS (RFC 952).
func IsDNS952Label(value string) bool {
	return len(value) <= DNS952LabelMaxLength && dns952LabelRegexp.MatchString(value)
}

const CIdentifierFmt string = "[A-Za-z_][A-Za-z0-9_]*"

var cIdentifierRegexp = regexp.MustCompile("^" + CIdentifierFmt + "$")

// IsCIdentifier tests for a string that conforms the definition of an identifier
// in C. This checks the format, but not the length.
func IsCIdentifier(value string) bool {
	return cIdentifierRegexp.MatchString(value)
}

// IsValidPortNum tests that the argument is a valid, non-zero port number.
func IsValidPortNum(port int) bool {
	return 0 < port && port < 65536
}

// IsValidIPv4 tests that the argument is a valid IPv4 address.
func IsValidIPv4(value string) bool {
	return net.ParseIP(value) != nil && net.ParseIP(value).To4() != nil
}