From 65ddeb8506ff654b5d68b3b046dc592c22e6fd92 Mon Sep 17 00:00:00 2001
From: karthick <rkarthi511@gmail.com>
Date: Sun, 11 Aug 2024 21:37:34 +0530
Subject: [PATCH] added support for RANDOMKEY

---
 core/commands.go       |  7 +++++
 core/eval.go           | 11 ++++++++
 core/store.go          | 16 +++++++++++
 tests/commands_test.go | 60 ++++++++++++++++++++++++++++++++++++++++++
 4 files changed, 94 insertions(+)
 create mode 100644 tests/commands_test.go

diff --git a/core/commands.go b/core/commands.go
index 4c90734a06..ec1afaf4f7 100644
--- a/core/commands.go
+++ b/core/commands.go
@@ -510,6 +510,12 @@ var (
 		Arity:    3,
 		KeySpecs: KeySpecs{BeginIndex: 1},
 	}
+	randomKeyCmdMeta = DiceCmdMeta{
+		Name:  "RANDOMKEY",
+		Info:  "Return a random key",
+		Eval:  evalRandomKey,
+		Arity: 1,
+	}
 )
 
 func init() {
@@ -570,4 +576,5 @@ func init() {
 	diceCmds["GETDEL"] = getDelCmdMeta
 	diceCmds["DECRBY"] = decrByCmdMeta
 	diceCmds["RENAME"] = renameCmdMeta
+	diceCmds["RANDOMKEY"] = randomKeyCmdMeta
 }
diff --git a/core/eval.go b/core/eval.go
index bfa177b09a..6d7e567be8 100644
--- a/core/eval.go
+++ b/core/eval.go
@@ -1688,6 +1688,17 @@ func evalEXISTS(args []string) []byte {
 
 	return Encode(count, false)
 }
+func evalRandomKey(args []string) []byte {
+	if len(args) != 0 {
+		return Encode(errors.New("ERR wrong number of arguments for RANDOMKEY command"), false)
+	}
+
+	key := RandomKey()
+	if key == "" {
+		return RESP_NIL
+	}
+	return Encode(key, false)
+}
 
 func executeCommand(cmd *RedisCmd, c *Client) []byte {
 	diceCmd, ok := diceCmds[cmd.Cmd]
diff --git a/core/store.go b/core/store.go
index bfbe4f1ae0..6efa62637f 100644
--- a/core/store.go
+++ b/core/store.go
@@ -1,6 +1,7 @@
 package core
 
 import (
+	"math/rand"
 	"path"
 	"sync"
 	"time"
@@ -328,3 +329,18 @@ func delByPtr(ptr unsafe.Pointer) bool {
 	}
 	return false
 }
+
+func RandomKey() string {
+	if len(keypool) == 0 {
+		return ""
+	}
+	index := rand.Intn(len(keypool))
+	currentIndex := 0
+	for key := range keypool {
+		if currentIndex == index {
+			return key
+		}
+		currentIndex++
+	}
+	return ""
+}
diff --git a/tests/commands_test.go b/tests/commands_test.go
new file mode 100644
index 0000000000..d7c3d64c7f
--- /dev/null
+++ b/tests/commands_test.go
@@ -0,0 +1,60 @@
+package tests
+
+import (
+	"testing"
+
+	"gotest.tools/v3/assert"
+)
+
+func TestCommandRandomKey(t *testing.T) {
+	var randomKeyTestCases = []struct {
+		name     string
+		inCmd    []string
+		expected []interface{}
+	}{
+		{
+			name:     "Try to get RandomKey with 0 keys in map",
+			inCmd:    []string{"RANDOMKEY"},
+			expected: []interface{}{"(nil)"},
+		},
+		{
+			name:     "Set a key and get a RandomKey",
+			inCmd:    []string{"set Key hello", "RANDOMKEY"},
+			expected: []interface{}{"OK", "Key"},
+		},
+		{
+			name:     "Set another two keys and check the RandomKey",
+			inCmd:    []string{"set Key2 hello2", "set Key3 hello3", "RANDOMKEY"},
+			expected: []interface{}{"OK", "OK"},
+		},
+	}
+
+	conn := getLocalConnection()
+	defer conn.Close()
+
+	for _, tc := range randomKeyTestCases {
+		t.Run(tc.name, func(t *testing.T) {
+			var actual []interface{}
+			for _, cmd := range tc.inCmd {
+				result := fireCommand(conn, cmd)
+				actual = append(actual, result)
+			}
+
+			if tc.name == "Set another two keys and check the RandomKey" {
+				// Manually check if the last result is one of the expected keys
+				lastResult := actual[len(actual)-1]
+				expectedKeys := []string{"Key", "Key2", "Key3"}
+				found := false
+				for _, key := range expectedKeys {
+					if lastResult == key {
+						found = true
+						break
+					}
+				}
+				assert.Assert(t, found, "Expected one of %v, but got %v", expectedKeys, lastResult)
+			} else {
+				assert.DeepEqual(t, tc.expected, actual)
+			}
+		})
+	}
+}