package ratelimit

import (
	"io"
	"net/http"
	"net/http/httptest"
	"strconv"
	"sync"
	"sync/atomic"
	"testing"
	"time"

	"github.com/stretchr/testify/assert"
	"github.com/stretchr/testify/require"
)

func TestRateLimitSequential(t *testing.T) {
	rateLimit := Middleware(
		SetLimit(5),
	)

	handler := http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		_, err := w.Write([]byte("resp"))
		require.NoError(t, err)
	})

	server := httptest.NewServer(rateLimit(handler))
	defer server.Close()

	for i := 0; i < 10; i++ {
		res, err := http.Get(server.URL)
		assert.NoError(t, err)
		defer res.Body.Close()

		if i < 5 {
			assert.Equal(t, http.StatusOK, res.StatusCode)
		} else {
			assert.Equal(t, http.StatusTooManyRequests, res.StatusCode)
		}
	}
}

func TestRateLimitConcurrent(t *testing.T) {
	rateLimit := Middleware(
		SetLimit(5),
	)

	handler := http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		_, err := w.Write([]byte("resp"))
		require.NoError(t, err)
	})

	server := httptest.NewServer(rateLimit(handler))
	defer server.Close()

	counter := int64(0)
	var wg sync.WaitGroup

	for i := 0; i < 10; i++ {
		wg.Add(1)
		go func() {
			defer wg.Done()

			res, err := http.Get(server.URL)
			assert.NoError(t, err)
			defer res.Body.Close()

			if res.StatusCode == http.StatusOK {
				atomic.AddInt64(&counter, 1)
			}
		}()
	}

	wg.Wait()
	assert.Equal(t, int64(5), atomic.LoadInt64(&counter))
}

func TestRateLimitHeaders(t *testing.T) {
	rateLimit := Middleware(
		SetLimit(1),
	)

	handler := http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		_, err := w.Write([]byte("resp"))
		require.NoError(t, err)
	})

	server := httptest.NewServer(rateLimit(handler))
	defer server.Close()

	now := time.Now()

	res, err := http.Get(server.URL)
	assert.NoError(t, err)
	defer res.Body.Close()
	assert.Equal(t, http.StatusOK, res.StatusCode)
	assert.Equal(t, "1", res.Header.Get("X-RateLimit-Limit"))
	assert.Equal(t, "0", res.Header.Get("X-RateLimit-Remaining"))

	resetTS, err := strconv.Atoi(res.Header.Get("X-RateLimit-Reset"))
	assert.NoError(t, err)
	assert.InDelta(t, now.Add(time.Minute*1).Unix(), resetTS, 1)

	b, err := io.ReadAll(res.Body)
	assert.NoError(t, err)
	assert.Equal(t, "resp", string(b))

	res, err = http.Get(server.URL)
	assert.NoError(t, err)
	defer res.Body.Close()
	assert.Equal(t, http.StatusTooManyRequests, res.StatusCode)
	assert.Equal(t, "1", res.Header.Get("X-RateLimit-Limit"))
	assert.Equal(t, "0", res.Header.Get("X-RateLimit-Remaining"))

	resetTS, err = strconv.Atoi(res.Header.Get("X-RateLimit-Reset"))
	assert.NoError(t, err)
	assert.InDelta(t, now.Add(time.Minute*1).Unix(), resetTS, 1)

	b, err = io.ReadAll(res.Body)
	assert.NoError(t, err)
	assert.Equal(t, "Too Many Requests\n", string(b))
}

func TestRateLimitExpiration(t *testing.T) {
	rateLimit := Middleware(
		SetLimit(5),
		SetPeriod(time.Millisecond*500),
	)

	handler := http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		_, err := w.Write([]byte("resp"))
		require.NoError(t, err)
	})

	server := httptest.NewServer(rateLimit(handler))
	defer server.Close()

	for i := 0; i < 10; i++ {
		res, err := http.Get(server.URL)
		assert.NoError(t, err)
		defer res.Body.Close()

		if i < 5 {
			assert.Equal(t, http.StatusOK, res.StatusCode)
		} else {
			assert.Equal(t, http.StatusTooManyRequests, res.StatusCode)
		}
	}

	time.Sleep(time.Millisecond * 500)

	for i := 0; i < 10; i++ {
		res, err := http.Get(server.URL)
		assert.NoError(t, err)
		defer res.Body.Close()

		if i < 5 {
			assert.Equal(t, http.StatusOK, res.StatusCode)
		} else {
			assert.Equal(t, http.StatusTooManyRequests, res.StatusCode)
		}
	}
}