// Copyright 2015 CoreOS, Inc.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//     http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

package cmd

import (
	"encoding/binary"
	"fmt"
	"math/rand"
	"os"
	"sync/atomic"
	"time"

	v3 "github.com/coreos/etcd/clientv3"

	"github.com/spf13/cobra"
	"golang.org/x/net/context"
	"gopkg.in/cheggaaa/pb.v1"
)

// watchCmd represents the watch command
var watchCmd = &cobra.Command{
	Use:   "watch",
	Short: "Benchmark watch",
	Long: `Benchmark watch tests the performance of processing watch requests and 
sending events to watchers. It tests the sending performance by 
changing the value of the watched keys with concurrent put 
requests.

During the test, each watcher watches (--total/--watchers) keys 
(a watcher might watch on the same key multiple times if 
--watched-key-total is small).

Each key is watched by (--total/--watched-key-total) watchers.
`,
	Run: watchFunc,
}

var (
	watchTotalStreams int
	watchTotal        int
	watchedKeyTotal   int

	watchPutRate  int
	watchPutTotal int

	watchKeySize      int
	watchKeySpaceSize int
	watchSeqKeys      bool

	eventsTotal int

	nrWatchCompleted       int32
	nrRecvCompleted        int32
	watchCompletedNotifier chan struct{}
	putStartNotifier       chan struct{}
	recvCompletedNotifier  chan struct{}
)

func init() {
	RootCmd.AddCommand(watchCmd)
	watchCmd.Flags().IntVar(&watchTotalStreams, "watchers", 10000, "Total number of watchers")
	watchCmd.Flags().IntVar(&watchTotal, "total", 100000, "Total number of watch requests")
	watchCmd.Flags().IntVar(&watchedKeyTotal, "watched-key-total", 10000, "Total number of keys to be watched")

	watchCmd.Flags().IntVar(&watchPutRate, "put-rate", 100, "Number of keys to put per second")
	watchCmd.Flags().IntVar(&watchPutTotal, "put-total", 10000, "Number of put requests")

	watchCmd.Flags().IntVar(&watchKeySize, "key-size", 32, "Key size of watch request")
	watchCmd.Flags().IntVar(&watchKeySpaceSize, "key-space-size", 1, "Maximum possible keys")
	watchCmd.Flags().BoolVar(&watchSeqKeys, "sequential-keys", false, "Use sequential keys")
}

func watchFunc(cmd *cobra.Command, args []string) {
	if watchKeySpaceSize <= 0 {
		fmt.Fprintf(os.Stderr, "expected positive --key-space-size, got (%v)", watchKeySpaceSize)
		os.Exit(1)
	}

	watched := make([]string, watchedKeyTotal)
	for i := range watched {
		k := make([]byte, watchKeySize)
		if watchSeqKeys {
			binary.PutVarint(k, int64(i%watchKeySpaceSize))
		} else {
			binary.PutVarint(k, int64(rand.Intn(watchKeySpaceSize)))
		}
		watched[i] = string(k)
	}

	requests := make(chan string, totalClients)

	clients := mustCreateClients(totalClients, totalConns)

	streams := make([]v3.Watcher, watchTotalStreams)
	for i := range streams {
		streams[i] = v3.NewWatcher(clients[i%len(clients)])
	}

	putStartNotifier = make(chan struct{})

	// watching phase
	results = make(chan result)
	bar = pb.New(watchTotal)

	bar.Format("Bom !")
	bar.Start()

	pdoneC := printRate(results)

	atomic.StoreInt32(&nrWatchCompleted, int32(0))
	watchCompletedNotifier = make(chan struct{})
	for i := range streams {
		go doWatch(streams[i], requests)
	}

	go func() {
		for i := 0; i < watchTotal; i++ {
			requests <- watched[i%len(watched)]
		}
		close(requests)
	}()

	<-watchCompletedNotifier
	bar.Finish()

	fmt.Printf("Watch creation summary:\n")
	close(results)
	<-pdoneC

	// put phase
	// total number of puts * number of watchers on each key
	eventsTotal = watchPutTotal * (watchTotal / watchedKeyTotal)
	results = make(chan result)
	bar = pb.New(eventsTotal)

	bar.Format("Bom !")
	bar.Start()

	atomic.StoreInt32(&nrRecvCompleted, 0)
	recvCompletedNotifier = make(chan struct{})
	close(putStartNotifier)

	putreqc := make(chan v3.Op)

	for i := 0; i < watchPutTotal; i++ {
		go doPutForWatch(context.TODO(), clients[i%len(clients)].KV, putreqc)
	}

	pdoneC = printRate(results)

	go func() {
		for i := 0; i < eventsTotal; i++ {
			putreqc <- v3.OpPut(watched[i%(len(watched))], "data")
			// TODO: use a real rate-limiter instead of sleep.
			time.Sleep(time.Second / time.Duration(watchPutRate))
		}
		close(putreqc)
	}()

	<-recvCompletedNotifier
	bar.Finish()
	fmt.Printf("Watch events received summary:\n")
	close(results)
	<-pdoneC
}

func doWatch(stream v3.Watcher, requests <-chan string) {
	for r := range requests {
		st := time.Now()
		wch := stream.Watch(context.TODO(), r)
		var errStr string
		if wch == nil {
			errStr = "could not open watch channel"
		}
		results <- result{errStr: errStr, duration: time.Since(st), happened: time.Now()}
		bar.Increment()
		go recvWatchChan(wch)
	}
	atomic.AddInt32(&nrWatchCompleted, 1)
	if atomic.LoadInt32(&nrWatchCompleted) == int32(watchTotalStreams) {
		watchCompletedNotifier <- struct{}{}
	}

	<-putStartNotifier
}

func recvWatchChan(wch v3.WatchChan) {
	for range wch {
		if atomic.LoadInt32(&nrRecvCompleted) == int32(eventsTotal) {
			recvCompletedNotifier <- struct{}{}
			break
		}

		st := time.Now()
		results <- result{duration: time.Since(st), happened: time.Now()}
		bar.Increment()

		atomic.AddInt32(&nrRecvCompleted, 1)
	}
}

func doPutForWatch(ctx context.Context, client v3.KV, requests <-chan v3.Op) {
	for op := range requests {
		_, err := client.Do(ctx, op)
		if err != nil {
			fmt.Fprintf(os.Stderr, "failed to Put for watch benchmark: %v\n", err)
			os.Exit(1)
		}
	}
}
