package main

import (
    "encoding/json"
    "net/http"
    "strings"
    "time"

    "github.com/go-chi/chi"
    "golang.org/x/time/rate"
)

func main() {
    r := chi.NewRouter()

    // Applies the RateLimiter globally, limiting 5 requests per second and a burst of 10 requests
    r.Use(RateLimiter(rate.Limit(5), 10, 1*time.Second))

    // Define a route for testing
    r.Get("/", func(w http.ResponseWriter, r *http.Request) {
        w.Write([]byte("Requisição bem-sucedida"))
    })

    http.ListenAndServe(":3000", r)
}

// RateLimiter middleware to limit a client's requests
func RateLimiter(limit rate.Limit, burst int, waitTime time.Duration) func(next http.Handler) http.Handler {
    limiterMap := make(map[string]*rate.Limiter)
    lastRequestMap := make(map[string]time.Time)

    return func(next http.Handler) http.Handler {
        return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
            // Capture the client IP
      ip := strings.Split(r.RemoteAddr, ":")[0]

            // Checks if the IP already has a Limiter configured
            limiter, exists := limiterMap[ip]
            if !exists {
                limiter = rate.NewLimiter(limit, burst)
                limiterMap[ip] = limiter
            }

            // Check if the client made a recent request and wait for the timeout if necessary
            lastRequestTime, lastRequestExists := lastRequestMap[ip]
            if lastRequestExists && time.Since(lastRequestTime) < waitTime {
                w.Header().Set("Content-Type", "application/json")
                w.WriteHeader(http.StatusTooManyRequests)
                json.NewEncoder(w).Encode(map[string]string{"error": "Too many requests"})
                return
            }

            // Check if the limit has been reached
            if !limiter.Allow() {
                lastRequestMap[ip] = time.Now()
                w.Header().Set("Content-Type", "application/json")
                w.WriteHeader(http.StatusTooManyRequests)
                json.NewEncoder(w).Encode(map[string]string{"error": "Too many requests"})
            }

            // If everything is ok, move on to the next handler
            next.ServeHTTP(w, r)
        })
    }
}