package scheduling

import (
	"context"
	"fmt"
	"math"
	"math/rand/v2"
	"strconv"
	"testing"
	"time"

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

type noopMClockScheduler struct{}

var (
	releaseStub      ReleaseFunc = func() {}
	defaultLimit     float64     = 100_000
	shortReservation float64     = 1
	medReservation   float64     = 100
	largeReservation float64     = 10_000
)

func (s *noopMClockScheduler) RequestArrival(context.Context, string) ReleaseFunc {
	return releaseStub
}

func BenchmarkMClock(b *testing.B) {
	tagsCount := []int{1, 2, 4, 8, 16}
	ioDuration := time.Millisecond
	parallelismValues := []int{1, 8, 32, 64}
	limits := []*float64{nil, &defaultLimit}
	reservations := []*float64{nil, &shortReservation, &medReservation, &largeReservation}
	for _, parallelism := range parallelismValues {
		b.SetParallelism(parallelism)

		noopMClock := &noopMClockScheduler{}
		b.Run(fmt.Sprintf("impl=noop/parallelism=%d", parallelism), func(b *testing.B) {
			b.ResetTimer()
			b.ReportAllocs()
			b.RunParallel(func(pb *testing.PB) {
				for pb.Next() {
					release := noopMClock.RequestArrival(context.Background(), "tag")
					time.Sleep(ioDuration)
					release()
				}
			})
		})

		for _, limit := range limits {
			for _, reservation := range reservations {
				for _, tags := range tagsCount {
					tagInfos := make(map[string]TagInfo)
					for tag := 0; tag < tags; tag++ {
						tagInfos["tag"+strconv.FormatInt(int64(tag), 10)] = TagInfo{Share: 50, LimitIOPS: limit, ReservedIOPS: reservation}
					}

					mClockQ, _ := NewMClock(math.MaxUint64, math.MaxUint64, tagInfos, time.Hour)

					resStr := "no"
					if reservation != nil {
						resStr = strconv.FormatFloat(*reservation, 'f', 1, 64)
					}
					limitStr := "no"
					if limit != nil {
						limitStr = strconv.FormatFloat(*limit, 'f', 1, 64)
					}
					b.Run(fmt.Sprintf("impl=mclock/limit=%s/reservation=%s/parallelism=%d/tags=%d", limitStr, resStr, parallelism, tags), func(b *testing.B) {
						b.ResetTimer()
						b.ReportAllocs()
						b.RunParallel(func(pb *testing.PB) {
							for pb.Next() {
								tag := rand.Int64N(int64(tags))
								release, err := mClockQ.RequestArrival(context.Background(), "tag"+strconv.FormatInt(int64(tag), 10))
								require.NoError(b, err)
								time.Sleep(ioDuration)
								release()
							}
						})
					})
				}
			}
		}

	}
}