From 6302b60d273baf762d11e2073dd736b46901cde6 Mon Sep 17 00:00:00 2001
From: rishavvajpayee <reshavvajpayee@gmail.com>
Date: Mon, 28 Oct 2024 19:33:37 +0530
Subject: [PATCH 1/2] WIP: add cleanup and commands left in /health headers

---
 internal/middleware/ratelimiter.go |  3 +-
 internal/server/http.go            | 49 ++++++++++++++++++++++++++++++
 2 files changed, 50 insertions(+), 2 deletions(-)

diff --git a/internal/middleware/ratelimiter.go b/internal/middleware/ratelimiter.go
index f8d3c52..1f9ad61 100644
--- a/internal/middleware/ratelimiter.go
+++ b/internal/middleware/ratelimiter.go
@@ -111,8 +111,7 @@ func calculateNextCleanupTime(ctx context.Context, client *db.DiceDB, cronFreque
 
 	lastCleanupTime := time.UnixMilli(lastCronCleanupTime)
 	nextCleanupTime := lastCleanupTime.Add(cronFrequencyInterval)
-	timeDifference := nextCleanupTime.Sub(time.Now())
-	return int64(timeDifference.Seconds()), nil
+	return int64(time.Until(nextCleanupTime).Seconds()), nil
 }
 
 func MockRateLimiter(client *mock.DiceDBMock, next http.Handler, limit int64, window float64) http.Handler {
diff --git a/internal/server/http.go b/internal/server/http.go
index b5209c2..b450bb3 100644
--- a/internal/server/http.go
+++ b/internal/server/http.go
@@ -6,12 +6,16 @@ import (
 	"errors"
 	"log/slog"
 	"net/http"
+	"strconv"
 	"strings"
 	"time"
 
 	"server/internal/db"
 	"server/internal/middleware"
+	"server/internal/server/utils"
 	util "server/util"
+
+	"github.com/dicedb/dicedb-go"
 )
 
 type HTTPServer struct {
@@ -100,6 +104,22 @@ func (s *HTTPServer) Shutdown() error {
 }
 
 func (s *HTTPServer) HealthCheck(w http.ResponseWriter, request *http.Request) {
+	nextCleanup, err := s.getNextCleanupTime()
+	if err != nil {
+		slog.Error("Failed to get the cleanupTime", slog.Any("err", err))
+		http.Error(w, errorResponse("internal server error"), http.StatusInternalServerError)
+		return
+	}
+
+	commandsLeft, err := s.getCommandsLeft()
+	if err != nil {
+		slog.Error("Failed to get the commands Left", slog.Any("err", err))
+		http.Error(w, errorResponse("internal server error"), http.StatusInternalServerError)
+		return
+	}
+
+	w.Header().Set("x-next-cleanup-time", strconv.FormatInt(nextCleanup, 10))
+	w.Header().Set("x-commands-left", strconv.FormatInt(commandsLeft, 10))
 	util.JSONResponse(w, http.StatusOK, map[string]string{"message": "server is running"})
 }
 
@@ -142,3 +162,32 @@ func (s *HTTPServer) CliHandler(w http.ResponseWriter, r *http.Request) {
 func (s *HTTPServer) SearchHandler(w http.ResponseWriter, request *http.Request) {
 	util.JSONResponse(w, http.StatusOK, map[string]string{"message": "search results"})
 }
+
+func (s *HTTPServer) getNextCleanupTime() (int64, error) {
+	resp := s.DiceClient.Client.Get(context.Background(), utils.LastCronCleanupTimeUnixMs)
+	if resp.Err() != nil {
+		if errors.Is(resp.Err(), dicedb.Nil) {
+			return time.Now().UnixMilli(), nil
+		}
+		return 0, resp.Err()
+	}
+
+	lastCleanupStr := resp.Val()
+	if lastCleanupStr == "" {
+		return 0, resp.Err()
+	}
+
+	lastCleanup, err := strconv.ParseInt(lastCleanupStr, 10, 64)
+	if err != nil {
+		return 0, err
+	}
+	lastCleanupTime := time.UnixMilli(lastCleanup)
+	nextCleanupTime := lastCleanupTime.Add(15 * time.Minute).UnixMilli()
+
+	return nextCleanupTime, nil
+}
+
+func (s *HTTPServer) getCommandsLeft() (int64, error) {
+	// clarification required
+	return 1, nil
+}

From 5febcceecb34a69bac14e58c3db4a8695b91f21e Mon Sep 17 00:00:00 2001
From: rishavvajpayee <reshavvajpayee@gmail.com>
Date: Tue, 29 Oct 2024 13:50:59 +0530
Subject: [PATCH 2/2] added commands left to headers

---
 internal/server/http.go | 26 ++++++++++++++++++++++++--
 1 file changed, 24 insertions(+), 2 deletions(-)

diff --git a/internal/server/http.go b/internal/server/http.go
index b450bb3..cd4f631 100644
--- a/internal/server/http.go
+++ b/internal/server/http.go
@@ -4,12 +4,14 @@ import (
 	"context"
 	"encoding/json"
 	"errors"
+	"fmt"
 	"log/slog"
 	"net/http"
 	"strconv"
 	"strings"
 	"time"
 
+	"server/config"
 	"server/internal/db"
 	"server/internal/middleware"
 	"server/internal/server/utils"
@@ -188,6 +190,26 @@ func (s *HTTPServer) getNextCleanupTime() (int64, error) {
 }
 
 func (s *HTTPServer) getCommandsLeft() (int64, error) {
-	// clarification required
-	return 1, nil
+	configValue := config.LoadConfig()
+	currentWindow := time.Now().Unix() / int64(configValue.Server.RequestWindowSec)
+	key := fmt.Sprintf("request_count:%d", currentWindow)
+
+	val, err := s.DiceClient.Client.Get(context.Background(), key).Result()
+	if err != nil {
+		if errors.Is(err, dicedb.Nil) {
+			return 1000, nil
+		}
+		return 0, err
+	}
+
+	requestCount, err := strconv.ParseInt(val, 10, 64)
+	if err != nil {
+		return 0, err
+	}
+
+	remaining := int64(1000) - requestCount
+	if remaining < 0 {
+		remaining = 0
+	}
+	return remaining, nil
 }