package badger

import (
	"encoding/binary"
	"fmt"

	"github.com/dgraph-io/badger/v4"
	"github.com/fiatjaf/eventstore"
)

const (
	dbVersionKey          byte = 255
	rawEventStorePrefix   byte = 0
	indexCreatedAtPrefix  byte = 1
	indexIdPrefix         byte = 2
	indexKindPrefix       byte = 3
	indexPubkeyPrefix     byte = 4
	indexPubkeyKindPrefix byte = 5
	indexTagPrefix        byte = 6
	indexTag32Prefix      byte = 7
	indexTagAddrPrefix    byte = 8
)

var _ eventstore.Store = (*BadgerBackend)(nil)

type BadgerBackend struct {
	Path     string
	MaxLimit int

	*badger.DB
	seq *badger.Sequence
}

func (b *BadgerBackend) Init() error {
	db, err := badger.Open(badger.DefaultOptions(b.Path))
	if err != nil {
		return err
	}
	b.DB = db
	b.seq, err = db.GetSequence([]byte("events"), 1000)
	if err != nil {
		return err
	}

	if err := b.runMigrations(); err != nil {
		return fmt.Errorf("error running migrations: %w", err)
	}

	if b.MaxLimit == 0 {
		b.MaxLimit = 500
	}

	return nil
}

func (b BadgerBackend) Close() {
	b.DB.Close()
	b.seq.Release()
}

func (b BadgerBackend) Serial() []byte {
	v, _ := b.seq.Next()
	vb := make([]byte, 5)
	vb[0] = rawEventStorePrefix
	binary.BigEndian.PutUint32(vb[1:], uint32(v))
	return vb
}