first commit

internal/middleware/ratelimit.go

@@ -0,0 +1,94 @@
+package middleware
+
+import (
+	"net/http"
+	"sync"
+	"time"
+
+	"github.com/gin-gonic/gin"
+)
+
+type RateLimitConfig struct {
+	Enabled  bool
+	Requests int
+	Window   int
+}
+
+type rateLimitEntry struct {
+	count     int
+	expiresAt time.Time
+}
+
+type rateLimiter struct {
+	entries map[string]*rateLimitEntry
+	mu      sync.Mutex
+	config  RateLimitConfig
+}
+
+func newRateLimiter(config RateLimitConfig) *rateLimiter {
+	rl := &rateLimiter{
+		entries: make(map[string]*rateLimitEntry),
+		config:  config,
+	}
+
+	go rl.cleanup()
+
+	return rl
+}
+
+func (rl *rateLimiter) cleanup() {
+	ticker := time.NewTicker(time.Minute)
+	for range ticker.C {
+		rl.mu.Lock()
+		now := time.Now()
+		for key, entry := range rl.entries {
+			if now.After(entry.expiresAt) {
+				delete(rl.entries, key)
+			}
+		}
+		rl.mu.Unlock()
+	}
+}
+
+func (rl *rateLimiter) allow(key string) bool {
+	rl.mu.Lock()
+	defer rl.mu.Unlock()
+
+	now := time.Now()
+	entry, exists := rl.entries[key]
+
+	if !exists || now.After(entry.expiresAt) {
+		rl.entries[key] = &rateLimitEntry{
+			count:     1,
+			expiresAt: now.Add(time.Duration(rl.config.Window) * time.Second),
+		}
+		return true
+	}
+
+	entry.count++
+	return entry.count <= rl.config.Requests
+}
+
+func RateLimit(config RateLimitConfig) gin.HandlerFunc {
+	if !config.Enabled {
+		return func(c *gin.Context) {
+			c.Next()
+		}
+	}
+
+	limiter := newRateLimiter(config)
+
+	return func(c *gin.Context) {
+		clientIP := c.ClientIP()
+
+		if !limiter.allow(clientIP) {
+			c.JSON(http.StatusTooManyRequests, gin.H{
+				"error": "リクエスト数が制限を超えました。しばらくしてからお試しください。",
+			})
+			c.Abort()
+			return
+		}
+
+		c.Next()
+	}
+}