package tests

import (
	"context"
	"sync"
	"testing"
	"time"

	"github.com/stretchr/testify/require"
	"github.com/tidbcloud/metrics-server/pkg/grpc/middleware/ratelimit"
)

// TestStoreSequentialAccess verify that store works as expected with a sequential access.
func TestStoreSequentialAccess(t *testing.T, store ratelimit.Store) {
	is := require.New(t)
	ctx := context.Background()

	limiter := ratelimit.New(store, ratelimit.Rate{
		Limit:  3,
		Period: time.Minute,
	}, "Global", []ratelimit.Method{{Name: "*"}})

	// Check counter increment.
	{
		for i := 1; i <= 6; i++ {

			if i <= 3 {

				lctx, err := limiter.Peek(ctx, "foo")
				is.NoError(err)
				is.NotZero(lctx)
				is.Equal(int64(3-(i-1)), lctx.Remaining)
				is.False(lctx.Reached)

			}

			lctx, err := limiter.Get(ctx, "foo")
			is.NoError(err)
			is.NotZero(lctx)

			if i <= 3 {

				is.Equal(int64(3), lctx.Limit)
				is.Equal(int64(3-i), lctx.Remaining)
				is.True((lctx.Reset - time.Now().Unix()) <= 60)
				is.False(lctx.Reached)

				lctx, err = limiter.Peek(ctx, "foo")
				is.NoError(err)
				is.Equal(int64(3-i), lctx.Remaining)
				is.False(lctx.Reached)

			} else {

				is.Equal(int64(3), lctx.Limit)
				is.Equal(int64(0), lctx.Remaining)
				is.True((lctx.Reset - time.Now().Unix()) <= 60)
				is.True(lctx.Reached)

			}
		}
	}

	// Check counter reset.
	{
		lctx, err := limiter.Peek(ctx, "foo")
		is.NoError(err)
		is.NotZero(lctx)

		is.Equal(int64(3), lctx.Limit)
		is.Equal(int64(0), lctx.Remaining)
		is.True((lctx.Reset - time.Now().Unix()) <= 60)
		is.True(lctx.Reached)

		lctx, err = limiter.Reset(ctx, "foo")
		is.NoError(err)
		is.NotZero(lctx)

		is.Equal(int64(3), lctx.Limit)
		is.Equal(int64(3), lctx.Remaining)
		is.True((lctx.Reset - time.Now().Unix()) <= 60)
		is.False(lctx.Reached)

		lctx, err = limiter.Peek(ctx, "foo")
		is.NoError(err)
		is.NotZero(lctx)

		is.Equal(int64(3), lctx.Limit)
		is.Equal(int64(3), lctx.Remaining)
		is.True((lctx.Reset - time.Now().Unix()) <= 60)
		is.False(lctx.Reached)

		lctx, err = limiter.Get(ctx, "foo")
		is.NoError(err)
		is.NotZero(lctx)

		lctx, err = limiter.Reset(ctx, "foo")
		is.NoError(err)
		is.NotZero(lctx)

		is.Equal(int64(3), lctx.Limit)
		is.Equal(int64(3), lctx.Remaining)
		is.True((lctx.Reset - time.Now().Unix()) <= 60)
		is.False(lctx.Reached)

		lctx, err = limiter.Reset(ctx, "foo")
		is.NoError(err)
		is.NotZero(lctx)

		is.Equal(int64(3), lctx.Limit)
		is.Equal(int64(3), lctx.Remaining)
		is.True((lctx.Reset - time.Now().Unix()) <= 60)
		is.False(lctx.Reached)
	}
}

// TestStoreConcurrentAccess verify that store works as expected with a concurrent access.
func TestStoreConcurrentAccess(t *testing.T, store ratelimit.Store) {
	is := require.New(t)
	ctx := context.Background()

	limiter := ratelimit.New(store, ratelimit.Rate{
		Limit:  100000,
		Period: 10 * time.Second,
	}, "Global", []ratelimit.Method{{Name: "*"}})

	goroutines := 500
	ops := 500

	wg := &sync.WaitGroup{}
	wg.Add(goroutines)
	for i := 0; i < goroutines; i++ {
		go func(i int) {
			for j := 0; j < ops; j++ {
				lctx, err := limiter.Get(ctx, "foo")
				is.NoError(err)
				is.NotZero(lctx)
			}
			wg.Done()
		}(i)
	}
	wg.Wait()
}