Added support for Badger as an alternative storage backend

internal/datastore/badger_datastore/db_abstractions.go

@@ -0,0 +1,207 @@
+package badgerdatastore
+
+import (
+	"bytes"
+	"encoding/gob"
+
+	"github.com/dgraph-io/badger/v4"
+	"github.com/pikami/cosmium/internal/datastore"
+	"github.com/pikami/cosmium/internal/logger"
+	"github.com/pikami/cosmium/internal/resourceid"
+)
+
+const (
+	DatabaseKeyPrefix            = "DB:"
+	CollectionKeyPrefix          = "COL:"
+	DocumentKeyPrefix            = "DOC:"
+	TriggerKeyPrefix             = "TRG:"
+	StoredProcedureKeyPrefix     = "SP:"
+	UserDefinedFunctionKeyPrefix = "UDF:"
+)
+
+func generateKey(
+	resourceType resourceid.ResourceType,
+	databaseId string,
+	collectionId string,
+	resourceId string,
+) string {
+	result := ""
+
+	switch resourceType {
+	case resourceid.ResourceTypeDatabase:
+		result += DatabaseKeyPrefix
+	case resourceid.ResourceTypeCollection:
+		result += CollectionKeyPrefix
+	case resourceid.ResourceTypeDocument:
+		result += DocumentKeyPrefix
+	case resourceid.ResourceTypeTrigger:
+		result += TriggerKeyPrefix
+	case resourceid.ResourceTypeStoredProcedure:
+		result += StoredProcedureKeyPrefix
+	case resourceid.ResourceTypeUserDefinedFunction:
+		result += UserDefinedFunctionKeyPrefix
+	}
+
+	if databaseId != "" {
+		result += databaseId
+	}
+
+	if collectionId != "" {
+		result += "/colls/" + collectionId
+	}
+
+	if resourceId != "" {
+		result += "/" + resourceId
+	}
+
+	return result
+}
+
+func generateDatabaseKey(databaseId string) string {
+	return generateKey(resourceid.ResourceTypeDatabase, databaseId, "", "")
+}
+
+func generateCollectionKey(databaseId string, collectionId string) string {
+	return generateKey(resourceid.ResourceTypeCollection, databaseId, collectionId, "")
+}
+
+func generateDocumentKey(databaseId string, collectionId string, documentId string) string {
+	return generateKey(resourceid.ResourceTypeDocument, databaseId, collectionId, documentId)
+}
+
+func generateTriggerKey(databaseId string, collectionId string, triggerId string) string {
+	return generateKey(resourceid.ResourceTypeTrigger, databaseId, collectionId, triggerId)
+}
+
+func generateStoredProcedureKey(databaseId string, collectionId string, storedProcedureId string) string {
+	return generateKey(resourceid.ResourceTypeStoredProcedure, databaseId, collectionId, storedProcedureId)
+}
+
+func generateUserDefinedFunctionKey(databaseId string, collectionId string, udfId string) string {
+	return generateKey(resourceid.ResourceTypeUserDefinedFunction, databaseId, collectionId, udfId)
+}
+
+func insertKey(txn *badger.Txn, key string, value interface{}) datastore.DataStoreStatus {
+	_, err := txn.Get([]byte(key))
+	if err == nil {
+		return datastore.Conflict
+	}
+
+	if err != badger.ErrKeyNotFound {
+		logger.ErrorLn("Error while checking if key exists:", err)
+		return datastore.Unknown
+	}
+
+	var buf bytes.Buffer
+	err = gob.NewEncoder(&buf).Encode(value)
+	if err != nil {
+		logger.ErrorLn("Error while encoding value:", err)
+		return datastore.Unknown
+	}
+
+	err = txn.Set([]byte(key), buf.Bytes())
+	if err != nil {
+		logger.ErrorLn("Error while setting key:", err)
+		return datastore.Unknown
+	}
+
+	err = txn.Commit()
+	if err != nil {
+		logger.ErrorLn("Error while committing transaction:", err)
+		return datastore.Unknown
+	}
+
+	return datastore.StatusOk
+}
+
+func getKey(txn *badger.Txn, key string, value interface{}) datastore.DataStoreStatus {
+	item, err := txn.Get([]byte(key))
+	if err != nil {
+		if err == badger.ErrKeyNotFound {
+			return datastore.StatusNotFound
+		}
+		logger.ErrorLn("Error while getting key:", err)
+		return datastore.Unknown
+	}
+
+	val, err := item.ValueCopy(nil)
+	if err != nil {
+		logger.ErrorLn("Error while copying value:", err)
+		return datastore.Unknown
+	}
+
+	if value == nil {
+		logger.ErrorLn("getKey called with nil value")
+		return datastore.Unknown
+	}
+
+	err = gob.NewDecoder(bytes.NewReader(val)).Decode(value)
+	if err != nil {
+		logger.ErrorLn("Error while decoding value:", err)
+		return datastore.Unknown
+	}
+
+	return datastore.StatusOk
+}
+
+func keyExists(txn *badger.Txn, key string) (bool, error) {
+	_, err := txn.Get([]byte(key))
+	if err == nil {
+		return true, nil
+	}
+
+	if err == badger.ErrKeyNotFound {
+		return false, nil
+	}
+
+	return false, err
+}
+
+func listByPrefix[T any](db *badger.DB, prefix string) ([]T, datastore.DataStoreStatus) {
+	var results []T
+
+	err := db.View(func(txn *badger.Txn) error {
+		opts := badger.DefaultIteratorOptions
+		opts.Prefix = []byte(prefix)
+		it := txn.NewIterator(opts)
+		defer it.Close()
+
+		for it.Rewind(); it.Valid(); it.Next() {
+			item := it.Item()
+			var entry T
+
+			status := getKey(txn, string(item.Key()), &entry)
+			if status != datastore.StatusOk {
+				logger.ErrorLn("Failed to retrieve entry:", string(item.Key()))
+				continue
+			}
+
+			results = append(results, entry)
+		}
+		return nil
+	})
+
+	if err != nil {
+		logger.ErrorLn("Error while listing entries:", err)
+		return nil, datastore.Unknown
+	}
+
+	return results, datastore.StatusOk
+}
+
+func deleteKeysByPrefix(txn *badger.Txn, prefix string) error {
+	opts := badger.DefaultIteratorOptions
+	opts.Prefix = []byte(prefix)
+	it := txn.NewIterator(opts)
+	defer it.Close()
+
+	for it.Rewind(); it.Valid(); it.Next() {
+		key := it.Item().KeyCopy(nil)
+		if err := txn.Delete(key); err != nil {
+			logger.ErrorLn("Failed to delete key:", string(key), "Error:", err)
+			return err
+		}
+	}
+
+	return nil
+}