From 38ca643d05e46c695cab964761ffeb1e7f4f687f Mon Sep 17 00:00:00 2001
From: Sahil <issahil404@gmail.com>
Date: Tue, 25 Jun 2024 18:23:54 +0530
Subject: [PATCH] feat: added RENAME command

---
 echovault/api_generic.go              | 22 ++++++++++++
 internal/modules/generic/commands.go  | 48 ++++++++++++++++++++++++---
 internal/modules/generic/key_funcs.go |  9 +++++
 3 files changed, 74 insertions(+), 5 deletions(-)

diff --git a/echovault/api_generic.go b/echovault/api_generic.go
index 2116d1b6..dac2754b 100644
--- a/echovault/api_generic.go
+++ b/echovault/api_generic.go
@@ -507,3 +507,25 @@ func (server *EchoVault) DecrBy(key string, value string) (int, error) {
 	// Parse the integer response
 	return internal.ParseIntegerResponse(b)
 }
+
+// Rename renames the key from oldKey to newKey.
+// If the oldKey does not exist, an error is returned.
+//
+// Parameters:
+//
+// `oldKey` - string - The key to be renamed.
+//
+// `newKey` - string - The new name for the key.
+//
+// Returns: A string indicating the success of the operation.
+func (server *EchoVault) Rename(oldKey string, newKey string) (string, error) {
+	// Construct the command
+	cmd := []string{"RENAME", oldKey, newKey}
+	// Execute the command
+	b, err := server.handleCommand(server.context, internal.EncodeCommand(cmd), nil, false, true)
+	if err != nil {
+		return "", err
+	}
+	// Parse the simple string response
+	return internal.ParseStringResponse(b)
+}
diff --git a/internal/modules/generic/commands.go b/internal/modules/generic/commands.go
index 5bb5bd17..e8e3c368 100644
--- a/internal/modules/generic/commands.go
+++ b/internal/modules/generic/commands.go
@@ -581,6 +581,35 @@ func handleDecrBy(params internal.HandlerFuncParams) ([]byte, error) {
 	return []byte(fmt.Sprintf(":%d\r\n", newValue)), nil
 }
 
+func handleRename(params internal.HandlerFuncParams) ([]byte, error) {
+	if len(params.Command) != 3 {
+		return nil, errors.New("wrong number of arguments for RENAME")
+	}
+
+	oldKey := params.Command[1]
+	newKey := params.Command[2]
+
+	// Get the current value for the old key
+	values := params.GetValues(params.Context, []string{oldKey})
+	oldValue, ok := values[oldKey]
+
+	if !ok || oldValue == nil {
+		return nil, errors.New("no such key")
+	}
+
+	// Set the new key with the old value
+	if err := params.SetValues(params.Context, map[string]interface{}{newKey: oldValue}); err != nil {
+		return nil, err
+	}
+
+	// Delete the old key
+	if err := params.DeleteKey(oldKey); err != nil {
+		return nil, err
+	}
+
+	return []byte("+OK\r\n"), nil
+}
+
 func Commands() []internal.Command {
 	return []internal.Command{
 		{
@@ -778,8 +807,8 @@ This operation is limited to 64 bit signed integers.`,
 			Command:    "incrby",
 			Module:     constants.GenericModule,
 			Categories: []string{constants.KeyspaceCategory, constants.WriteCategory, constants.FastCategory},
-			Description: `(INCRBY key increment) 
-Increments the number stored at key by increment. If the key does not exist, it is set to 0 before performing the operation. 
+			Description: `(INCRBY key increment)
+Increments the number stored at key by increment. If the key does not exist, it is set to 0 before performing the operation.
 An error is returned if the key contains a value of the wrong type or contains a string that can not be represented as integer.`,
 			Sync:              true,
 			KeyExtractionFunc: incrByKeyFunc,
@@ -789,13 +818,22 @@ An error is returned if the key contains a value of the wrong type or contains a
 			Command:    "decrby",
 			Module:     constants.GenericModule,
 			Categories: []string{constants.KeyspaceCategory, constants.WriteCategory, constants.FastCategory},
-			Description: `(DECRBY key decrement) 
-The DECRBY command reduces the value stored at the specified key by the specified decrement. 
-If the key does not exist, it is initialized with a value of 0 before performing the operation. 
+			Description: `(DECRBY key decrement)
+The DECRBY command reduces the value stored at the specified key by the specified decrement.
+If the key does not exist, it is initialized with a value of 0 before performing the operation.
 If the key's value is not of the correct type or cannot be represented as an integer, an error is returned.`,
 			Sync:              true,
 			KeyExtractionFunc: decrByKeyFunc,
 			HandlerFunc:       handleDecrBy,
 		},
+		{
+			Command:           "rename",
+			Module:            constants.GenericModule,
+			Categories:        []string{constants.KeyspaceCategory, constants.WriteCategory, constants.FastCategory},
+			Description:       `(RENAME key newkey) Renames key to newkey. If newkey already exists, it is overwritten. If key does not exist, an error is returned.`,
+			Sync:              true,
+			KeyExtractionFunc: renameKeyFunc,
+			HandlerFunc:       handleRename,
+		},
 	}
 }
diff --git a/internal/modules/generic/key_funcs.go b/internal/modules/generic/key_funcs.go
index 9c5de68f..150d0ea6 100644
--- a/internal/modules/generic/key_funcs.go
+++ b/internal/modules/generic/key_funcs.go
@@ -172,3 +172,12 @@ func decrByKeyFunc(cmd []string) (internal.KeyExtractionFuncResult, error) {
 		WriteKeys: []string{cmd[1]},
 	}, nil
 }
+
+func renameKeyFunc(cmd []string) (internal.KeyExtractionFuncResult, error) {
+	if len(cmd) != 3 {
+		return internal.KeyExtractionFuncResult{}, errors.New(constants.WrongArgsResponse)
+	}
+	return internal.KeyExtractionFuncResult{
+		WriteKeys: cmd[1:3],
+	}, nil
+}