package benchmarks

import (
	"bufio"
	"context"
	"encoding/json"
	"fmt"
	"github.com/gofiber/fiber/v2"
	"github.com/stretchr/testify/require"
	"go.mongodb.org/mongo-driver/bson"
	"go.mongodb.org/mongo-driver/mongo"
	"go.mongodb.org/mongo-driver/mongo/options"
	"go.uber.org/zap"
	"log"
	"net/http"
	"penahub.gitlab.yandexcloud.net/pena-services/customer/internal/workers"
	"sync"
	"testing"
	"time"
)

func initDB(ctx context.Context) (*mongo.Client, *mongo.Collection) {
	clientOptions := options.Client().ApplyURI("mongodb://localhost:27017,localhost:27018,localhost:27019/?replicaSet=rs0&readPreference=primary&ssl=false")
	client, err := mongo.Connect(context.Background(), clientOptions)
	if err != nil {
		panic(err)
	}

	collection := client.Database("testdb").Collection("testcollection")
	collection.Drop(ctx)
	for i := 0; i < 1000; i++ {
		_, err := collection.InsertOne(ctx, bson.M{"userId": fmt.Sprintf("user%d", i), "field": "value"})
		if err != nil {
			panic(err)
		}
	}

	return client, collection
}

func initSrv(repo *AccountRepository, logger *zap.Logger, watchWorker *workers.WatchWorker) *fiber.App {
	app := fiber.New()
	controller := &AccountController{
		accountRepo: repo,
		logger:      logger,
		watchWorker: watchWorker,
	}
	app.Get("/account-pipe/:userID", controller.AccountPipe)
	app.Use("/account-pipe-wc/:userID", controller.AccountPipeWC)
	return app
}

type AccountController struct {
	accountRepo *AccountRepository
	logger      *zap.Logger
	watchWorker *workers.WatchWorker
}

func (receiver *AccountController) AccountPipe(ctx *fiber.Ctx) error {
	userID := ctx.Params("userID")

	ctx.Set(fiber.HeaderContentType, "text/event-stream")
	ctx.Set("Cache-Control", "no-cache")
	ctx.Set("Connection", "keep-alive")
	ctx.Set("Transfer-Encoding", "chunked")

	accountCh := make(chan map[string]interface{})
	cancelCtx, cancel := context.WithCancel(ctx.Context())

	go func(ctx context.Context) {
		defer close(accountCh)
		if err := receiver.accountRepo.AccountPipe(ctx, userID, accountCh); err != nil {
			//receiver.logger.Error("error in account pipe repo method", zap.Error(err))
		}
	}(cancelCtx)

	ctx.Status(fiber.StatusOK).Context().SetBodyStreamWriter(func(w *bufio.Writer) {
		pingTicker := time.NewTicker(5 * time.Second)
		defer pingTicker.Stop()
		for {
			select {
			case accountData, ok := <-accountCh:
				if !ok {
					return
				}
				accountJSON, err := json.Marshal(accountData)
				if err != nil {
					//receiver.logger.Error("error marshal account JSON", zap.Error(err))
					continue
				}
				fmt.Fprintf(w, "data: %s\n\n", accountJSON)
				if err := w.Flush(); err != nil {
					//receiver.logger.Error("error flushing", zap.Error(err))
					cancel()
					//receiver.logger.Info("Close connection Account Pipe sse")
					return
				}
			case <-pingTicker.C:
				fmt.Fprintf(w, "data: %s\n\n", `{"event": "ping"}`)
				if err := w.Flush(); err != nil {
					//receiver.logger.Error("error sending ping Account Pipe sse, close connection", zap.Error(err))
					cancel()
					return
				}
			}
		}
	})

	return nil
}

func (receiver *AccountController) AccountPipeWC(ctx *fiber.Ctx) error {
	userID := ctx.Params("userID")

	ctx.Set(fiber.HeaderContentType, "text/event-stream")
	ctx.Set("Cache-Control", "no-cache")
	ctx.Set("Connection", "keep-alive")
	ctx.Set("Transfer-Encoding", "chunked")

	accountCh := make(chan map[string]interface{})
	//cancelCtx, cancel := context.WithCancel(ctx.Context())

	receiver.watchWorker.AddChannel(userID, accountCh)

	ctx.Status(fiber.StatusOK).Context().SetBodyStreamWriter(func(w *bufio.Writer) {
		pingTicker := time.NewTicker(5 * time.Second)
		defer pingTicker.Stop()
		for {
			select {
			case accountData, ok := <-accountCh:
				if !ok {
					return
				}
				accountJSON, err := json.Marshal(accountData)
				if err != nil {
					receiver.logger.Error("error marshal account JSON", zap.Error(err))
					continue
				}
				fmt.Fprintf(w, "data: %s\n\n", accountJSON)
				if err := w.Flush(); err != nil {
					//receiver.logger.Error("error flushing", zap.Error(err))
					//cancel()
					//receiver.logger.Info("Close connection Account Pipe sse")
					//receiver.watchWorker.DropChannel(userID)
					return
				}
			case <-pingTicker.C:
				fmt.Fprintf(w, "data: %s\n\n", `{"event": "ping"}`)
				if err := w.Flush(); err != nil {
					//receiver.logger.Error("error sending ping Account Pipe sse, close connection", zap.Error(err))
					//receiver.watchWorker.DropChannel(userID)
					//cancel()
					return
				}
			}
		}
	})

	return nil
}

type AccountRepository struct {
	mongoDB *mongo.Collection
	logger  *zap.Logger
}

func (receiver *AccountRepository) AccountPipe(ctx context.Context, userID string, accountCh chan<- map[string]interface{}) error {
	pipeline := mongo.Pipeline{
		{{"$match", bson.M{"operationType": "update", "fullDocument.userId": userID}}},
	}

	opts := options.ChangeStream()
	opts.SetFullDocument(options.UpdateLookup)
	changeStream, err := receiver.mongoDB.Watch(ctx, pipeline, opts)
	if err != nil {
		return err
	}
	defer changeStream.Close(ctx)

	for {
		select {
		case <-ctx.Done():
			//receiver.logger.Info("Context canceled, thread is closed now")
			return nil
		default:
			if changeStream.Next(ctx) {
				var changeEvent struct {
					UpdateDescription struct {
						UpdatedFields map[string]interface{} `bson:"updatedFields"`
					} `bson:"updateDescription"`
				}
				if err := changeStream.Decode(&changeEvent); err != nil {
					//receiver.logger.Error("error decoding change event", zap.Error(err))
					continue
				}
				select {
				case accountCh <- changeEvent.UpdateDescription.UpdatedFields:
				case <-ctx.Done():
					return nil
				}
			}
		}
	}
}

//goos: windows
//goarch: amd64
//pkg: penahub.gitlab.yandexcloud.net/pena-services/customer/tests/benchmarks
//cpu: AMD Ryzen 5 5600H with Radeon Graphics
//BenchmarkAccountPipe/COUNT_10-12                       1        18041336300 ns/op       13851296 B/op     161900 allocs/op
//BenchmarkAccountPipe/COUNT_20-12                       1        18034383800 ns/op       14816216 B/op     173328 allocs/op
//BenchmarkAccountPipe/COUNT_30-12                       1        21409782300 ns/op       17761944 B/op     211032 allocs/op
//BenchmarkAccountPipe/COUNT_40-12                       1        18021639700 ns/op       19411096 B/op     231789 allocs/op
//BenchmarkAccountPipe/COUNT_50-12                       1        19064359600 ns/op       20592840 B/op     245590 allocs/op
//PASS
//ok      penahub.gitlab.yandexcloud.net/pena-services/customer/tests/benchmarks  130.316s

func BenchmarkAccountPipe(b *testing.B) {
	ctx, cancel := context.WithCancel(context.Background())
	defer cancel()
	logger, err := zap.NewProduction(zap.AddStacktrace(zap.DPanicLevel))
	if err != nil {
		log.Fatalf("failed to init zap logger: %v", err)
	}
	client, collection := initDB(ctx)
	defer client.Disconnect(ctx)

	go func() {
		for {
			select {
			case <-ctx.Done():
				fmt.Println("DROPED")
				return
			default:
				for i := 0; i < 100; i++ {
					_, err := collection.UpdateOne(ctx, bson.M{"userId": fmt.Sprintf("user%d", i)},
						bson.M{"$set": bson.M{"field": fmt.Sprintf("value-%d", time.Now().UnixNano())}})
					if err != nil {
						logger.Error("failed update", zap.Error(err))
					}
				}
				time.Sleep(1 * time.Second)
			}
		}
	}()

	watchWorker := workers.NewWatchWorker(collection, logger)
	repo := &AccountRepository{mongoDB: collection, logger: logger}
	app := initSrv(repo, logger, watchWorker)

	go func() {
		if err := app.Listen(":3000"); err != nil {
			b.Fatal(err)
		}
	}()
	time.Sleep(5 * time.Second)

	for _, n := range []int{10, 20, 30, 40, 50} {
		b.Run(fmt.Sprintf("COUNT_%d", n), func(b *testing.B) {
			var wg sync.WaitGroup
			for i := 0; i < b.N; i++ {
				wg.Add(n)
				for j := 0; j < n; j++ {
					go func(j int) {
						defer wg.Done()
						userID := fmt.Sprintf("user%d", j)
						//fmt.Println(userID)
						resp, err := http.Get(fmt.Sprintf("http://localhost:3000/account-pipe/%s", userID))
						require.NoError(b, err)
						defer resp.Body.Close()
						scanner := bufio.NewScanner(resp.Body)
						count := 0
						for scanner.Scan() {
							if count == 25 {
								break
							}
							count++
							//line := scanner.Text()
							//fmt.Println("Received:", line)
						}
						time.Sleep(2 * time.Second)
					}(j)
				}
				wg.Wait()
				time.Sleep(1 * time.Second)
			}
		})
	}

	if err := app.Shutdown(); err != nil {
		b.Fatalf("error return srv: %s", err.Error())
	}
}

//goos: windows
//goarch: amd64
//pkg: penahub.gitlab.yandexcloud.net/pena-services/customer/tests/benchmarks
//cpu: AMD Ryzen 5 5600H with Radeon Graphics
//BenchmarkAccountPipeWithWorker/COUNT_10-12                     1        68031591200 ns/op       45935456 B/op     545790 allocs/op
//BenchmarkAccountPipeWithWorker/COUNT_20-12                     1        68020876100 ns/op       46873480 B/op     557504 allocs/op
//BenchmarkAccountPipeWithWorker/COUNT_30-12                     1        68048437700 ns/op       47456704 B/op     562015 allocs/op
//BenchmarkAccountPipeWithWorker/COUNT_40-12                     1        68025191100 ns/op       47200848 B/op     556732 allocs/op
//BenchmarkAccountPipeWithWorker/COUNT_50-12                     1        68030922700 ns/op       48254768 B/op     567123 allocs/op
//PASS

//func BenchmarkAccountPipeWithWorker(b *testing.B) {
//	ctx, cancel := context.WithCancel(context.Background())
//	defer cancel()
//	logger, err := zap.NewProduction(zap.AddStacktrace(zap.DPanicLevel))
//	if err != nil {
//		log.Fatalf("failed to init zap logger: %v", err)
//	}
//	client, collection := initDB(ctx)
//	defer client.Disconnect(ctx)
//
//	go func() {
//		for {
//			select {
//			case <-ctx.Done():
//				fmt.Println("DROPED")
//				return
//			default:
//				for i := 0; i < 100; i++ {
//					_, err := collection.UpdateOne(ctx, bson.M{"userId": fmt.Sprintf("user%d", i)},
//						bson.M{"$set": bson.M{"field": fmt.Sprintf("value-%d", time.Now().UnixNano())}})
//					if err != nil {
//						logger.Error("failed update", zap.Error(err))
//					}
//				}
//				time.Sleep(1 * time.Second)
//			}
//		}
//	}()
//
//	watchWorker := workers.NewWatchWorker(collection, logger)
//	repo := &AccountRepository{mongoDB: collection, logger: logger}
//	app := initSrv(repo, logger, watchWorker)
//
//	go func() {
//		if err := app.Listen(":3000"); err != nil {
//			b.Fatal(err)
//		}
//	}()
//	time.Sleep(5 * time.Second)
//
//	for _, n := range []int{10, 20, 30, 40, 50} {
//		b.Run(fmt.Sprintf("COUNT_%d", n), func(b *testing.B) {
//			var wg sync.WaitGroup
//			for i := 0; i < b.N; i++ {
//				wg.Add(n)
//				for j := 0; j < n; j++ {
//					go func(j int) {
//						defer wg.Done()
//						userID := fmt.Sprintf("user%d", j)
//						//fmt.Println(userID)
//						resp, err := http.Get(fmt.Sprintf("http://localhost:3000/account-pipe-wc/%s", userID))
//						require.NoError(b, err)
//						defer resp.Body.Close()
//						scanner := bufio.NewScanner(resp.Body)
//						count := 0
//						for scanner.Scan() {
//							if count == 25 {
//								break
//							}
//							count++
//							//line := scanner.Text()
//							//fmt.Println("Received:", line)
//						}
//						time.Sleep(2 * time.Second)
//					}(j)
//				}
//				wg.Wait()
//				time.Sleep(1 * time.Second)
//			}
//		})
//	}
//
//	if err := app.Shutdown(); err != nil {
//		b.Fatalf("error return srv: %s", err.Error())
//	}
//}