// 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"

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

type ruleRedundancy struct{}

func RuleRedundancy() sdk.CheckRule { return &ruleRedundancy{} }
func (ruleRedundancy) Name() string { return "srv_redundancy" }
func (ruleRedundancy) Description() string {
	return "At least two distinct SRV targets exist (avoids single point of failure)."
}
func (ruleRedundancy) Evaluate(ctx context.Context, obs sdk.ObservationGetter, _ sdk.CheckerOptions) []sdk.CheckState {
	d, cs := getData(ctx, obs)
	if cs != nil {
		return []sdk.CheckState{*cs}
	}
	targets := map[string]bool{}
	for _, r := range d.Records {
		if r.IsNullTarget {
			continue
		}
		targets[r.Target] = true
	}
	if len(targets) >= 2 {
		return []sdk.CheckState{{Status: sdk.StatusOK, Code: "srv_redundant",
			Message: fmt.Sprintf("%d distinct targets.", len(targets))}}
	}
	if len(targets) == 1 {
		return []sdk.CheckState{{Status: sdk.StatusInfo, Code: "srv_single_target",
			Message: "Single SRV target: no redundancy at DNS level."}}
	}
	return []sdk.CheckState{{Status: sdk.StatusUnknown, Code: "srv_no_targets_redundancy",
		Message: "No usable SRV targets."}}
}