// This file is part of the happyDomain (R) project.
// Copyright (c) 2020-2026 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 checker

import (
	"fmt"

	sdk "git.happydns.org/checker-sdk-go/checker"
	tlsct "git.happydns.org/checker-tls/contract"
)

// Matching on the service name is more authoritative than matching on the
// port: port 636 could carry anything, but _ldaps._tcp unambiguously
// designates LDAP over TLS, even on a non-standard port.
var directTLSServices = map[string]bool{
	"https":        true,
	"ftps":         true, // FTPS implicit
	"smtps":        true, // SMTP over TLS (legacy port 465 semantics)
	"submissions":  true, // RFC 8314: SMTP submission over TLS
	"imaps":        true,
	"pop3s":        true,
	"nntps":        true,
	"ircs":         true,
	"telnets":      true,
	"ldaps":        true,
	"sips":         true,
	"ipps":         true, // IPP over TLS (printing)
	"xmpps-client": true, // XMPP client over direct TLS
	"xmpps-server": true, // XMPP server-to-server over direct TLS
	"mqtts":        true,
	"coaps":        true,
	"stuns":        true,
	"turns":        true,
}

type starttlsSpec struct {
	// When two SRV services share the same wire upgrade (submission/smtp both do
	// ESMTP STARTTLS), Proto is the canonical one agreed with checker-tls/contract.
	Proto string

	// Required is false for opportunistic STARTTLS (e.g. SMTP on port 25, s2s XMPP).
	// The consumer uses this to pick severity when the server does not advertise STARTTLS.
	Required bool
}

// Proto values follow the tls.endpoint.v1 contract's vocabulary; the SDK
// itself has no opinion on these values, they belong to checker-tls.
var starttlsServices = map[string]starttlsSpec{
	"submission":  {"smtp", true},  // RFC 8314: STARTTLS required
	"smtp":        {"smtp", false}, // port 25: opportunistic
	"imap":        {"imap", true},
	"pop3":        {"pop3", true},
	"xmpp-client": {"xmpp-client", true},  // RFC 7590
	"xmpp-server": {"xmpp-server", false}, // s2s: opportunistic
	"ldap":        {"ldap", false},
	"nntp":        {"nntp", false},
	"ftp":         {"ftp", false},
	"sieve":       {"sieve", true},
	"postgresql":  {"postgres", false},
}

// DiscoverEntries publishes tls.endpoint.v1 entries for known TLS/STARTTLS services.
// Unknown service names produce no entries: we lean on the SRV naming
// convention rather than guessing from the port, since a port alone
// conveys no protocol semantics.
func (p *srvProvider) DiscoverEntries(data any) ([]sdk.DiscoveryEntry, error) {
	d, ok := data.(*SRVData)
	if !ok {
		return nil, fmt.Errorf("unexpected data type %T", data)
	}
	var out []sdk.DiscoveryEntry
	for _, r := range d.Records {
		if r.IsNullTarget || r.Target == "" {
			continue
		}

		if directTLSServices[r.Service] {
			e, err := tlsct.NewEntry(tlsct.TLSEndpoint{
				Host: r.Target,
				Port: r.Port,
				SNI:  r.Target,
			})
			if err != nil {
				return nil, fmt.Errorf("build tls entry for %s:%d: %w", r.Target, r.Port, err)
			}
			out = append(out, e)
			continue
		}

		if spec, ok := starttlsServices[r.Service]; ok {
			e, err := tlsct.NewEntry(tlsct.TLSEndpoint{
				Host:            r.Target,
				Port:            r.Port,
				SNI:             r.Target,
				STARTTLS:        spec.Proto,
				RequireSTARTTLS: spec.Required,
			})
			if err != nil {
				return nil, fmt.Errorf("build starttls entry for %s:%d: %w", r.Target, r.Port, err)
			}
			out = append(out, e)
		}
	}
	return out, nil
}