// This file is part of the happyDomain (R) project.
// Copyright (c) 2020-2024 happyDomain
// Authors: Pierre-Olivier Mercier, et al.
//
// This program is offered under a commercial and under the AGPL license.
// For commercial licensing, contact us at <contact@happydomain.org>.
//
// For AGPL licensing:
// This program is free software: you can redistribute it and/or modify
// it under the terms of the GNU Affero General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
//
// This program is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
// GNU Affero General Public License for more details.
//
// You should have received a copy of the GNU Affero General Public License
// along with this program.  If not, see <https://www.gnu.org/licenses/>.

package svcs

import (
	"fmt"
	"strconv"
	"strings"

	"github.com/miekg/dns"

	"git.happydns.org/happyDomain/internal/helpers"
	svc "git.happydns.org/happyDomain/internal/serviceanalyzer"
	"git.happydns.org/happyDomain/model"
)

type TLS_RPT struct {
	Record *happydns.TXT `json:"txt"`
}

func (s *TLS_RPT) GetNbResources() int {
	return 1
}

func (s *TLS_RPT) GenComment() string {
	t := TLS_RPTField{}
	t.Analyze(s.Record.Txt)

	return strings.Join(t.Rua, ", ")
}

func (s *TLS_RPT) GetRecords(domain string, ttl uint32, origin string) ([]happydns.Record, error) {
	return []happydns.Record{s.Record}, nil
}

type TLS_RPTField struct {
	Version uint     `json:"version" happydomain:"label=Version,placeholder=1,required,description=The version of TLSRPT to use.,default=1,hidden"`
	Rua     []string `json:"rua" happydomain:"label=Aggregate Report URI,placeholder=https://example.com/path|mailto:name@example.com"`
}

func (t *TLS_RPTField) Analyze(txt string) error {
	fields := strings.Split(txt, ";")

	if len(fields) < 2 {
		return fmt.Errorf("not a valid TLS-RPT record: should have a version AND a rua, only one field found")
	}
	if len(fields) > 3 || (len(fields) == 3 && fields[2] != "") {
		return fmt.Errorf("not a valid TLS-RPT record: should have exactly 2 fields: seen %d", len(fields))
	}

	for i := range fields {
		fields[i] = strings.TrimSpace(fields[i])
	}

	if !strings.HasPrefix(fields[0], "v=TLSRPTv") {
		return fmt.Errorf("not a valid TLS-RPT record: should begin with v=TLSRPTv1, seen %q", fields[0])
	}

	version, err := strconv.ParseUint(fields[0][9:], 10, 32)
	if err != nil {
		return fmt.Errorf("not a valid TLS-RPT record: bad version number: %w", err)
	}
	t.Version = uint(version)

	if !strings.HasPrefix(fields[1], "rua=") {
		return fmt.Errorf("not a valid TLS-RPT record: expected rua=, found %q", fields[1])
	}

	t.Rua = strings.Split(strings.TrimPrefix(fields[1], "rua="), ",")

	for i := range t.Rua {
		t.Rua[i] = strings.TrimSpace(t.Rua[i])
	}

	return nil
}

func (t *TLS_RPTField) String() string {
	return fmt.Sprintf("v=TLSRPTv%d; rua=%s", t.Version, strings.Join(t.Rua, ","))
}

func tlsrpt_analyze(a *svc.Analyzer) (err error) {
	for _, record := range a.SearchRR(svc.AnalyzerRecordFilter{Type: dns.TypeTXT, Prefix: "_smtp._tls."}) {
		txt, ok := record.(*happydns.TXT)

		// rfc8460: 3. records that do not begin with "v=TLSRPTv1;" are discarded
		if !ok || !strings.HasPrefix(txt.Txt, "v=TLSRPT") {
			continue
		}

		domain := strings.TrimPrefix(record.Header().Name, "_smtp._tls.")

		err = a.UseRR(record, domain, &TLS_RPT{
			Record: helpers.RRRelativeSubdomain(record, a.GetOrigin(), domain).(*happydns.TXT),
		})
		if err != nil {
			return
		}
	}

	return
}

func init() {
	svc.RegisterService(
		func() happydns.ServiceBody {
			return &TLS_RPT{}
		},
		tlsrpt_analyze,
		happydns.ServiceInfos{
			Name:        "TLS-RPT",
			Description: "SMTP TLS Reporting.",
			Categories: []string{
				"email",
			},
			RecordTypes: []uint16{
				dns.TypeTXT,
			},
			Restrictions: happydns.ServiceRestrictions{
				NearAlone: true,
				NeedTypes: []uint16{
					dns.TypeTXT,
				},
			},
		},
		1,
	)
}
