package main

import "log"
import "io/ioutil"
import "github.com/dgraph-io/badger"

type KeyValueStore struct {
	db *badger.DB
}

func NewKeyValueStore() *KeyValueStore {
	kv := new(KeyValueStore)
	kv.init()
	return kv
}

func (kv *KeyValueStore) init() {
	dir, err := ioutil.TempDir("", "badger")
	if err != nil {
		log.Fatal(err)
	}

	opts := badger.DefaultOptions
	opts.Dir = dir
	opts.ValueDir = dir
	kv.db, err = badger.Open(opts)
	if err != nil {
		log.Fatal(err)
	}
}

func (kv *KeyValueStore) Close() {
	kv.db.Close()
}

func (kv *KeyValueStore) Put(key *string, value *string) error {
	txn := kv.db.NewTransaction(true) // Read-write txn
	err := txn.Set([]byte(*key), []byte(*value))
	if err != nil {
		log.Fatal(err)
	}
	err = txn.Commit(nil)
	if err != nil {
		log.Fatal(err)
	}
	return nil
}

func (kv *KeyValueStore) Get(key *string) (*string, error) {
	txn := kv.db.NewTransaction(true) // Read-write txn
	item, err := txn.Get([]byte(*key))
	if err != nil {
		return nil, err
	}

	val, err := item.ValueCopy(nil)
	if err != nil {
		return nil, err
	}
	s := string(val)
	return &s, nil
}