package main

import (
	"encoding/gob"
	"fmt"
	"os"
	"time"
)

func init() {

	gob.Register(map[uint64]int64{})
}

type DiskStorage struct {
	stateFile string
	lastSave  int64
	LastSaves map[uint64]int64
}

func NewDiskStorage(stateFile string) (*DiskStorage, error) {
	ret := &DiskStorage{
		stateFile: stateFile,
		LastSaves: make(map[uint64]int64),
	}
	err := ret.loadState()
	return ret, err
}

func saveMessages(_ interface{}, _ CartId) error {
	// No-op: legacy event log persistence removed in oneof refactor.
	return nil
}

func getCartPath(id string) string {
	return fmt.Sprintf("data/%s.prot", id)
}

func loadMessages(_ Grain, _ CartId) error {
	// No-op: legacy replay removed in oneof refactor.
	return nil
}

func (s *DiskStorage) saveState() error {
	tmpFile := s.stateFile + "_tmp"
	file, err := os.Create(tmpFile)
	if err != nil {
		return err
	}
	defer file.Close()
	err = gob.NewEncoder(file).Encode(s.LastSaves)
	if err != nil {
		return err
	}
	os.Remove(s.stateFile + ".bak")
	os.Rename(s.stateFile, s.stateFile+".bak")
	return os.Rename(tmpFile, s.stateFile)
}

func (s *DiskStorage) loadState() error {
	file, err := os.Open(s.stateFile)
	if err != nil {
		return err
	}
	defer file.Close()
	return gob.NewDecoder(file).Decode(&s.LastSaves)
}

func (s *DiskStorage) Store(id CartId, _ *CartGrain) error {
	// With the removal of the legacy message log, we only update the timestamp.
	ts := time.Now().Unix()
	s.LastSaves[uint64(id)] = ts
	s.lastSave = ts
	return nil
}