/
cursors.go
53 lines (40 loc) · 1.09 KB
/
cursors.go
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package datastore
import (
"encoding/base64"
"errors"
"os"
"github.com/huysamen/gcpkit/utils/encryption"
"cloud.google.com/go/datastore"
)
func NewCursorCodecs() (encoder func(*datastore.Cursor) (string, error), decoder func(string) (*datastore.Cursor, error)) {
key := encryption.NewEncryptionKey(os.Getenv("GCPKIT_DATASTORE_CURSOR_SECRET"))
enc := func(cursor *datastore.Cursor) (string, error) {
if cursor == nil {
return "", errors.New("nil cursor")
}
encrypted, err := encryption.Encrypt([]byte(cursor.String()), key)
if err != nil {
return "", err
}
return base64.URLEncoding.EncodeToString(encrypted), nil
}
dec := func(encoded string) (*datastore.Cursor, error) {
if encoded == "" {
return nil, errors.New("cursor not valid")
}
decoded, err := base64.URLEncoding.DecodeString(encoded)
if err != nil {
return nil, err
}
decrypted, err := encryption.Decrypt(decoded, key)
if err != nil {
return nil, err
}
cursor, err := datastore.DecodeCursor(string(decrypted))
if err != nil {
return nil, err
}
return &cursor, nil
}
return enc, dec
}