package secretsstore

import (
	"errors"
	"fmt"
	"slices"
	"strings"

	bolt "go.etcd.io/bbolt"
)

var boltStoreBucketName []byte = []byte("secrets-store")

// bboltStore implements the SecretsStore interface on top of a bbolt bucket.
type bboltStore struct {
	db *bolt.DB
}

// newBboltStore opens a bolt db at path, creates a default bucket, and uses it
// as the backing storage for a SecretsStore. Fails if dbpath does not have a
// `.db` suffix.
func newBboltStore(dbpath string) (*bboltStore, error) {
	if !strings.HasSuffix(dbpath, ".db") {
		return nil, errors.New("store path must end in `.db`")
	}
	db, err := bolt.Open(dbpath, 0600, nil)
	if err != nil {
		return nil, fmt.Errorf("opening db: %w", err)
	}
	// Ensure the default bucket.
	err = db.Update(func(tx *bolt.Tx) error {
		if _, err := tx.CreateBucketIfNotExists(boltStoreBucketName); err != nil {
			return err
		}
		return nil
	})
	return &bboltStore{db: db}, nil
}

func (s *bboltStore) Get(key Key) ([]byte, error) {
	var res []byte
	err := s.db.View(func(tx *bolt.Tx) error {
		b := tx.Bucket(boltStoreBucketName)
		if b == nil {
			return ErrInvalidStore
		}
		val := b.Get([]byte(key))
		if val == nil {
			return ErrKeyDoesNotExist
		}

		// Must allocate and copy, memory is owned by bolt, and we should not
		// assume that its lifetime extends beyond the duration of this tx.
		res = slices.Clone(val)
		return nil
	})
	if err != nil {
		return nil, err
	}
	return res, nil
}

func (s *bboltStore) Put(key Key, val []byte) error {
	return s.db.Update(func(tx *bolt.Tx) error {
		b := tx.Bucket(boltStoreBucketName)
		if b == nil {
			return ErrInvalidStore
		}
		err := b.Put([]byte(key), val)
		if err != nil {
			return errors.Join(ErrCouldNotStoreKey, err)
		}
		return nil
	})
}

func (s *bboltStore) Delete(key Key) error {
	return s.db.Update(func(tx *bolt.Tx) error {
		b := tx.Bucket(boltStoreBucketName)
		if b == nil {
			return ErrInvalidStore
		}
		err := b.Delete([]byte(key))
		if err != nil {
			return errors.Join(ErrCouldNotDeleteKey, err)
		}
		return nil
	})
}