package dns

// Everything is assumed in the ClassINET class. If
// you need other classes you are on your own.

// Create a reply packet from a request message.
func (dns *Msg) SetReply(request *Msg) {
	dns.MsgHdr.Id = request.MsgHdr.Id
	dns.MsgHdr.Authoritative = true
	dns.MsgHdr.Response = true
	dns.MsgHdr.Opcode = OpcodeQuery
	dns.MsgHdr.Rcode = RcodeSuccess
	dns.Question = make([]Question, 1)
	dns.Question[0] = request.Question[0]
}

// Create a question packet.
func (dns *Msg) SetQuestion(z string, t uint16) {
	dns.MsgHdr.Id = Id()
	dns.MsgHdr.RecursionDesired = true
	dns.Question = make([]Question, 1)
	dns.Question[0] = Question{z, t, ClassINET}
}

// Create a notify packet.
func (dns *Msg) SetNotify(z string) {
	dns.MsgHdr.Opcode = OpcodeNotify
	dns.MsgHdr.Authoritative = true
	dns.MsgHdr.Id = Id()
	dns.Question = make([]Question, 1)
	dns.Question[0] = Question{z, TypeSOA, ClassINET}
}

// Is the message a dynamic update packet?
func (dns *Msg) IsUpdate() (ok bool) {
	if len(dns.Question) == 0 {
		return false
	}
	ok = dns.MsgHdr.Opcode == OpcodeUpdate
	ok = ok && dns.Question[0].Qtype == TypeSOA
	return
}

// Is the message a valid notify packet?
func (dns *Msg) IsNotify() (ok bool) {
	if len(dns.Question) == 0 {
		return false
	}
	ok = dns.MsgHdr.Opcode == OpcodeNotify
	ok = ok && dns.Question[0].Qclass == ClassINET
	ok = ok && dns.Question[0].Qtype == TypeSOA
	return
}

// Create a dns msg suitable for requesting an ixfr.
func (dns *Msg) SetIxfr(z string, serial uint32) {
	dns.MsgHdr.Id = Id()
	dns.Question = make([]Question, 1)
	dns.Ns = make([]RR, 1)
	s := new(RR_SOA)
	s.Hdr = RR_Header{z, TypeSOA, ClassINET, DefaultTTL, 0}
	s.Serial = serial

	dns.Question[0] = Question{z, TypeIXFR, ClassINET}
	dns.Ns[0] = s
}

// Create a dns msg suitable for requesting an axfr.
func (dns *Msg) SetAxfr(z string) {
	dns.MsgHdr.Id = Id()
	dns.Question = make([]Question, 1)
	dns.Question[0] = Question{z, TypeAXFR, ClassINET}
}

// Is the message a valid axfr request packet?
func (dns *Msg) IsAxfr() (ok bool) {
	if len(dns.Question) == 0 {
		return false
	}
	ok = dns.MsgHdr.Opcode == OpcodeQuery
	ok = ok && dns.Question[0].Qclass == ClassINET
	ok = ok && dns.Question[0].Qtype == TypeAXFR
	return
}

// Is the message a valid ixfr request packet?
func (dns *Msg) IsIxfr() (ok bool) {
	if len(dns.Question) == 0 {
		return false
	}
	ok = dns.MsgHdr.Opcode == OpcodeQuery
	ok = ok && dns.Question[0].Qclass == ClassINET
	ok = ok && dns.Question[0].Qtype == TypeIXFR
	return
}

// Has the message a TSIG record as the last record?
func (dns *Msg) IsTsig() (ok bool) {
	if len(dns.Extra) > 0 {
		return dns.Extra[0].Header().Rrtype == TypeTSIG
	}
	return
}

// SetTsig Calculates and appends a TSIG RR on the message.
func (dns *Msg) SetTsig(z, algo string, fudge uint16, timesigned uint64) {
	t := new(RR_TSIG)
	t.Hdr = RR_Header{z, TypeTSIG, ClassANY, 0, 0}
	t.Algorithm = algo
	t.Fudge = fudge
	t.TimeSigned = timesigned
	dns.Extra = append(dns.Extra, t)
}