update code solution

Dockerfile

@@ -0,0 +1,15 @@
+# Sử dụng ảnh golang:1.16.0-alpine làm base image
+FROM golang:latest
+
+# Sao chép mã nguồn vào thư mục /app trong container
+COPY Dockerfile docker-compose.yaml go.mod main.go /app/
+
+# Đặt thư mục làm việc mặc định trong container
+WORKDIR /app
+
+RUN go get github.com/EngineerProOrg/BE-K01
+# Cài đặt dependencies và biên dịch ứng dụng
+RUN go mod download && go build -o main .
+
+# Chạy ứng dụng
+CMD ["./main"]

docker-compose.yaml

@@ -0,0 +1,12 @@
+version: '3'
+services:
+  redis:
+    image: redis:latest
+    ports:
+      - 6379:6379
+  app:
+    build: .
+    ports:
+      - 8080:8080
+    depends_on:
+      - redis

main.go

@@ -0,0 +1,145 @@
+package main
+
+import (
+	"log"
+	"time"
+	"net/http"
+	"fmt"
+
+	"github.com/gin-gonic/gin"
+	"github.com/go-redis/redis/v8"
+	"github.com/google/uuid"
+)
+
+var client *redis.Client
+var hllKey = "ping_callers"
+
+
+func init() {
+	// Initialize Redis client
+	client = redis.NewClient(&redis.Options{
+		Addr:     "redis:6379",
+	})
+}
+
+func main() {
+
+	// Check to connect Redis
+	_, err := client.Ping(client.Context()).Result()
+	if err != nil {
+		log.Fatal(err)
+	}
+
+	router := gin.Default()
+
+	router.POST("/login", loginHandler)
+	router.GET("/ping", pingHandler)
+	router.GET("/top", topHandler)
+	router.GET("/count", countHandler)
+
+	router.Run(":8080")
+}
+
+func loginHandler(c *gin.Context) {
+	sessionID := c.GetHeader("session_id")
+	if sessionID != "" {
+		// Session ID already exists, no need to create a new session
+		c.JSON(http.StatusOK, gin.H{"message": "Already logged in"})
+		return
+	}
+
+	username := c.PostForm("username")
+	sessionID = generateSessionID()
+
+	// Store the session ID and user name in Redis
+	err := client.Set(c, sessionID, username, 0).Err()
+	if err != nil {
+		log.Println(err)
+		c.JSON(http.StatusInternalServerError, gin.H{"error": "Internal Server Error"})
+		return
+	}
+
+	// Set sessionID cookie
+	c.SetCookie("session_id", sessionID, 300, "/", "localhost", false, true)
+
+	c.JSON(http.StatusOK, gin.H{"session_id": sessionID, "username": username, "message": "Session created successfully"})
+}
+
+func pingHandler(c *gin.Context) {
+	sessionID, err := c.Cookie("session_id")
+	if err != nil {
+		c.JSON(http.StatusUnauthorized, gin.H{"error": "session ID not found"})
+		return
+	}
+
+	// Check if the session ID is valid
+	userName, err := client.Get(c, sessionID).Result()
+	if err == nil {
+		c.JSON(http.StatusUnauthorized, gin.H{"error": "invalid session ID"})
+		return
+	} else if err != nil {
+		c.JSON(http.StatusInternalServerError, gin.H{"error": "failed to retrieve session"})
+		return
+	}
+
+	// Acquire distributed lock to ensure only one person can call /ping at a time
+	lockKey := fmt.Sprintf("lock:%s", userName)
+	ok, err := client.SetNX(c, lockKey, "locked", 5*time.Second).Result()
+	if err != nil {
+		c.JSON(http.StatusInternalServerError, gin.H{"error": "failed to obtain lock"})
+		return
+	}
+	if !ok {
+		c.JSON(http.StatusTooManyRequests, gin.H{"error": "failed to obtain lock"})
+		return
+	}
+
+	// Implement Redis-based rate limiting
+	rateLimitKey := fmt.Sprintf("ratelimit:%s", userName)
+	remaining, err := client.Incr(c, rateLimitKey).Result()
+	if err != nil {
+		c.JSON(http.StatusInternalServerError, gin.H{"error": "failed to increment rate limit"})
+		return
+	}
+
+	if remaining > 2 {
+		c.JSON(http.StatusTooManyRequests, gin.H{"error": "rate limit exceeded"})
+		return
+	}
+
+	// Sleep for 5 seconds to simulate processing time
+	time.Sleep(5 * time.Second)
+
+	c.JSON(http.StatusOK, gin.H{"message": "pong"})
+}
+
+func topHandler(c *gin.Context) {
+	// Retrieve the top 10 most-called /ping APIs
+	result, err := client.ZRevRangeWithScores(c, hllKey, 0, 9).Result()
+	if err != nil {
+		c.JSON(http.StatusInternalServerError, gin.H{"error": "failed to retrieve top APIs"})
+		return
+	}
+
+	var topAPIs []string
+	for _, z := range result {
+		topAPIs = append(topAPIs, z.Member.(string))
+	}
+
+	c.JSON(http.StatusOK, gin.H{"top_apis": topAPIs})
+}
+
+func countHandler(c *gin.Context) {
+	// Retrieve the approximate number of callers to /ping API using HyperLogLog
+	count, err := client.PFCount(c, hllKey).Result()
+	if err != nil {
+		c.JSON(http.StatusInternalServerError, gin.H{"error": "failed to retrieve count"})
+		return
+	}
+
+	c.JSON(http.StatusOK, gin.H{"count": count})
+}
+
+func generateSessionID() string {
+	return uuid.New().String()
+}