package checker

import (
	"context"
	"fmt"

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

// Defaults are centralised so Definition's docs and runtime reads cannot drift.
const (
	defaultMaxChainLength          = 8
	defaultMinTargetTTL            = 60
	defaultRequireResolvableTarget = true
	defaultAllowApexCNAME          = false
	defaultRecognizeApexFlattening = true

	// hintKey is the CheckState.Meta key the HTML report reads to render the
	// "How to fix" block: keep them in sync.
	hintKey = "hint"
)

func loadAlias(ctx context.Context, obs sdk.ObservationGetter) (*AliasData, []sdk.CheckState) {
	var data AliasData
	if err := obs.Get(ctx, ObservationKeyAlias, &data); err != nil {
		return nil, []sdk.CheckState{{
			Status:  sdk.StatusError,
			Message: fmt.Sprintf("failed to read alias observation: %v", err),
		}}
	}
	return &data, nil
}

// skipped is the "nothing to judge right now" return: rules must produce at
// least one state, otherwise the SDK substitutes StatusUnknown.
func skipped(reason string) []sdk.CheckState {
	return []sdk.CheckState{{
		Status:  sdk.StatusUnknown,
		Message: "skipped: " + reason,
	}}
}

func okState(subject, message string) []sdk.CheckState {
	return []sdk.CheckState{{
		Status:  sdk.StatusOK,
		Subject: subject,
		Message: message,
	}}
}

// withHint is a no-op when hint is empty so callers can pass through unchecked.
func withHint(s sdk.CheckState, hint string) sdk.CheckState {
	if hint == "" {
		return s
	}
	if s.Meta == nil {
		s.Meta = map[string]any{}
	}
	s.Meta[hintKey] = hint
	return s
}

// apexKnown gates chain-oriented rules with a uniform "apex lookup failed"
// skip line so the UI stays consistent across rules.
func apexKnown(data *AliasData) bool {
	return data.ApexLookupError == "" && data.Apex != ""
}

func allowApexCNAME(opts sdk.CheckerOptions) bool {
	return sdk.GetBoolOption(opts, "allowApexCNAME", defaultAllowApexCNAME)
}

func recognizeApexFlattening(opts sdk.CheckerOptions) bool {
	return sdk.GetBoolOption(opts, "recognizeApexFlattening", defaultRecognizeApexFlattening)
}