package checker

import (
	"context"
	"fmt"

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

// Rule returns the alias check rule.
func Rule() sdk.CheckRule {
	return &aliasRule{}
}

type aliasRule struct{}

func (r *aliasRule) Name() string { return "alias_check" }

func (r *aliasRule) Description() string {
	return "Verifies a CNAME / DNAME / ALIAS chain: coexistence, loops, length, target resolvability, DNSSEC coverage."
}

func (r *aliasRule) ValidateOptions(opts sdk.CheckerOptions) error {
	if v, ok := opts["maxChainLength"]; ok {
		f, ok := v.(float64)
		if !ok {
			return fmt.Errorf("maxChainLength must be a number")
		}
		if f < 1 {
			return fmt.Errorf("maxChainLength must be >= 1")
		}
	}
	return nil
}

func (r *aliasRule) Evaluate(ctx context.Context, obs sdk.ObservationGetter, opts sdk.CheckerOptions) []sdk.CheckState {
	var data AliasData
	if err := obs.Get(ctx, ObservationKeyAlias, &data); err != nil {
		return []sdk.CheckState{{
			Status:  sdk.StatusError,
			Message: fmt.Sprintf("failed to get alias data: %v", err),
			Code:    "alias_error",
		}}
	}
	return Evaluate(&data)
}