package app

import (
	"encoding/json"
	"os"
	"path/filepath"
	"time"
)

func normalizeSmartDNSRuntimeState(st smartDNSRuntimeState) smartDNSRuntimeState {
	if st.Version <= 0 {
		st.Version = smartdnsRuntimeStateVersion
	}
	return st
}

func inferSmartDNSRuntimeEnabled() bool {
	enabled, err := smartDNSRuntimeEnabledFromConfig()
	if err != nil {
		// Keep historical behavior on first run when config is unavailable.
		return true
	}
	return enabled
}

func loadSmartDNSRuntimeState(logf func(string, ...any)) smartDNSRuntimeState {
	if data, err := os.ReadFile(smartdnsRTPath); err == nil {
		var st smartDNSRuntimeState
		if json.Unmarshal(data, &st) == nil {
			return normalizeSmartDNSRuntimeState(st)
		}
		if logf != nil {
			logf("smartdns runtime: invalid state json at %s, rebuilding", smartdnsRTPath)
		}
	}

	st := smartDNSRuntimeState{
		Version:   smartdnsRuntimeStateVersion,
		Enabled:   inferSmartDNSRuntimeEnabled(),
		UpdatedAt: time.Now().UTC().Format(time.RFC3339),
	}
	_ = saveSmartDNSRuntimeState(st)
	return st
}

func saveSmartDNSRuntimeState(st smartDNSRuntimeState) error {
	st = normalizeSmartDNSRuntimeState(st)
	st.UpdatedAt = time.Now().UTC().Format(time.RFC3339)
	data, err := json.MarshalIndent(st, "", "  ")
	if err != nil {
		return err
	}
	if err := os.MkdirAll(filepath.Dir(smartdnsRTPath), 0o755); err != nil {
		return err
	}
	tmp := smartdnsRTPath + ".tmp"
	if err := os.WriteFile(tmp, data, 0o644); err != nil {
		return err
	}
	return os.Rename(tmp, smartdnsRTPath)
}

func smartDNSRuntimeEnabled() bool {
	return loadSmartDNSRuntimeState(nil).Enabled
}