// 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 (
	"context"
	"fmt"
	"strings"

	sdk "git.happydns.org/checker-sdk-go/checker"
)

type ruleNullTarget struct{}

func RuleNullTarget() sdk.CheckRule { return &ruleNullTarget{} }
func (ruleNullTarget) Name() string { return "srv_null_target" }
func (ruleNullTarget) Description() string {
	return "Detects SRV records with target \".\", which signals the service is intentionally not available."
}
func (ruleNullTarget) Evaluate(ctx context.Context, obs sdk.ObservationGetter, _ sdk.CheckerOptions) []sdk.CheckState {
	d, cs := getData(ctx, obs)
	if cs != nil {
		return []sdk.CheckState{*cs}
	}
	var nulls []string
	for _, r := range d.Records {
		if r.IsNullTarget {
			nulls = append(nulls, r.Owner)
		}
	}
	if len(nulls) == 0 {
		return []sdk.CheckState{{Status: sdk.StatusOK, Code: "srv_no_null",
			Message: "No null-target SRV records."}}
	}
	if len(nulls) == len(d.Records) {
		return []sdk.CheckState{{Status: sdk.StatusWarn, Code: "srv_all_null",
			Message: fmt.Sprintf("All %d SRV records use null target (\".\"): service explicitly disabled.", len(nulls))}}
	}
	return []sdk.CheckState{{Status: sdk.StatusInfo, Code: "srv_some_null",
		Message: fmt.Sprintf("%d record(s) have null target: %s", len(nulls), strings.Join(nulls, ", "))}}
}