package middleware

import (
	"net/http"
	"net/http/httptest"
	"sync/atomic"
	"testing"
	"time"
)

func TestGlobalRateLimit_AllowsUnderLimit(t *testing.T) {
	h := GlobalRateLimit(GlobalRateLimitConfig{
		Requests: 100,
		Window:   10 * time.Second,
	}, nil)(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		w.WriteHeader(http.StatusOK)
	}))

	for i := 0; i < 100; i++ {
		req := httptest.NewRequest("GET", "/search", nil)
		rec := httptest.NewRecorder()
		h.ServeHTTP(rec, req)
		if rec.Code != http.StatusOK {
			t.Fatalf("request %d: expected 200, got %d", i+1, rec.Code)
		}
	}
}

func TestGlobalRateLimit_BlocksOverLimit(t *testing.T) {
	h := GlobalRateLimit(GlobalRateLimitConfig{
		Requests: 5,
		Window:   10 * time.Second,
	}, nil)(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		w.WriteHeader(http.StatusOK)
	}))

	for i := 0; i < 5; i++ {
		req := httptest.NewRequest("GET", "/search", nil)
		rec := httptest.NewRecorder()
		h.ServeHTTP(rec, req)
		if rec.Code != http.StatusOK {
			t.Fatalf("request %d: expected 200, got %d", i+1, rec.Code)
		}
	}

	req := httptest.NewRequest("GET", "/search", nil)
	rec := httptest.NewRecorder()
	h.ServeHTTP(rec, req)
	if rec.Code != http.StatusServiceUnavailable {
		t.Errorf("expected 503, got %d", rec.Code)
	}
}

func TestGlobalRateLimit_WindowResets(t *testing.T) {
	limiter := &globalLimiter{
		requests: 3,
		window:   50 * time.Millisecond,
	}

	if !limiter.allow() {
		t.Error("first request should be allowed")
	}
	if !limiter.allow() {
		t.Error("second request should be allowed")
	}
	if !limiter.allow() {
		t.Error("third request should be allowed")
	}
	if limiter.allow() {
		t.Error("fourth request should be blocked")
	}

	// Simulate window reset.
	old := limiter.count.Swap(0)
	if old != 3 {
		t.Errorf("expected count 3, got %d", old)
	}

	if !limiter.allow() {
		t.Error("after reset, request should be allowed")
	}
}

func TestGlobalRateLimit_Disabled(t *testing.T) {
	h := GlobalRateLimit(GlobalRateLimitConfig{Requests: 0}, nil)(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		w.WriteHeader(http.StatusOK)
	}))

	// Should allow unlimited requests.
	for i := 0; i < 200; i++ {
		req := httptest.NewRequest("GET", "/search", nil)
		rec := httptest.NewRecorder()
		h.ServeHTTP(rec, req)
		if rec.Code != http.StatusOK {
			t.Fatalf("request %d: expected 200 with disabled limiter, got %d", i+1, rec.Code)
		}
	}
}

func TestGlobalRateLimit_LockFree(t *testing.T) {
	// Verify the atomic counter doesn't panic under concurrent access.
	h := GlobalRateLimit(GlobalRateLimitConfig{
		Requests: 10000,
		Window:   10 * time.Second,
	}, nil)(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		w.WriteHeader(http.StatusOK)
	}))

	var allowed, blocked atomic.Int64
	done := make(chan struct{})

	for i := 0; i < 100; i++ {
		go func() {
			for j := 0; j < 200; j++ {
				req := httptest.NewRequest("GET", "/", nil)
				rec := httptest.NewRecorder()
				h.ServeHTTP(rec, req)
				if rec.Code == http.StatusOK {
					allowed.Add(1)
				} else {
					blocked.Add(1)
				}
			}
			done <- struct{}{}
		}()
	}

	for i := 0; i < 100; i++ {
		<-done
	}

	total := allowed.Load() + blocked.Load()
	if total != 20000 {
		t.Errorf("expected 20000 total requests, got %d", total)
	}
	if allowed.Load() != 10000 {
		t.Errorf("expected exactly 10000 allowed, got %d", allowed.Load())
	}
	t.Logf("concurrent test: %d allowed, %d blocked", allowed.Load(), blocked.Load())
}