package matrixbotlib

import (
	"bytes"
	"encoding/gob"

	"os"

	"maunium.net/go/mautrix"
	"maunium.net/go/mautrix/id"
)

//LazyMemStore is a very simple persistent Mautrix.Storer by saving to a statefile
//It should only be used if for some reason the InMemoryStore or AccountDataStore aren't acceptable
type LazyMemStore struct {
	mem       *mautrix.InMemoryStore
	NextBatch map[id.UserID]string
	saveFile  string
}

func NewLazyMemStore(fileloc string) *LazyMemStore {
	return &LazyMemStore{
		mem:       mautrix.NewInMemoryStore(),
		NextBatch: make(map[id.UserID]string),
		saveFile:  fileloc,
	}
}

func (l *LazyMemStore) SaveFilterID(userID id.UserID, filterID string) {
	l.mem.SaveFilterID(userID, filterID)
}

func (l *LazyMemStore) LoadFilterID(userID id.UserID) string {
	return l.mem.LoadFilterID(userID)
}

func (l *LazyMemStore) SaveNextBatch(userID id.UserID, nextBatchToken string) {
	b := new(bytes.Buffer)
	l.NextBatch[userID] = nextBatchToken
	e := gob.NewEncoder(b)
	err := e.Encode(l.NextBatch)
	if err != nil {
		panic(err)
	}
	if err := os.WriteFile(l.saveFile, b.Bytes(), 0666); err != nil {
		panic(err)
	}

}

func (l *LazyMemStore) LoadNextBatch(userID id.UserID) string {

	dat, err := os.ReadFile(l.saveFile)
	if err != nil {
		if os.IsNotExist(err) {
			b := new(bytes.Buffer)
			e := gob.NewEncoder(b)
			err := e.Encode(l.NextBatch)
			if err != nil {
				panic(err)
			}
			if err := os.WriteFile(l.saveFile, b.Bytes(), 0666); err != nil {
				panic(err)
			}
			dat, err = os.ReadFile(l.saveFile)
			if err != nil {
				panic(err)
			}
		} else {
			panic(err)
		}
	}
	d := gob.NewDecoder(bytes.NewBuffer(dat))
	err = d.Decode(&l.NextBatch)
	if err != nil {
		panic(err)
	}
	return l.NextBatch[userID]
}

func (l *LazyMemStore) SaveRoom(room *mautrix.Room) {
	l.mem.SaveRoom(room)
}

func (l *LazyMemStore) LoadRoom(roomID id.RoomID) *mautrix.Room {
	return l.mem.LoadRoom(roomID)
}