/*
Copyright 2014 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 etcd

import (
	"math/rand"
	"net/http/httptest"
	"testing"
	"time"

	"github.com/coreos/etcd/config"
	"github.com/coreos/etcd/store"
)

func TestKillLeader(t *testing.T) {
	tests := []int{3, 5, 9, 11}

	for i, tt := range tests {
		es, hs := buildCluster(tt, false)
		waitCluster(t, es)
		waitLeader(es)

		lead := es[0].p.node.Leader()
		es[lead].Stop()

		time.Sleep(es[0].tickDuration * defaultElection * 2)

		waitLeader(es)
		if es[1].p.node.Leader() == 0 {
			t.Errorf("#%d: lead = %d, want not 0", i, es[1].p.node.Leader())
		}

		for i := range es {
			es[len(es)-i-1].Stop()
		}
		for i := range hs {
			hs[len(hs)-i-1].Close()
		}
	}
	afterTest(t)
}

func TestRandomKill(t *testing.T) {
	tests := []int{3, 5, 9, 11}

	for _, tt := range tests {
		es, hs := buildCluster(tt, false)
		waitCluster(t, es)
		waitLeader(es)

		toKill := make(map[int64]struct{})
		for len(toKill) != tt/2-1 {
			toKill[rand.Int63n(int64(tt))] = struct{}{}
		}
		for k := range toKill {
			es[k].Stop()
		}

		time.Sleep(es[0].tickDuration * defaultElection * 2)

		waitLeader(es)

		for i := range es {
			es[len(es)-i-1].Stop()
		}
		for i := range hs {
			hs[len(hs)-i-1].Close()
		}
	}
	afterTest(t)
}

func TestJoinThroughFollower(t *testing.T) {
	tests := []int{3, 4, 5, 6}

	for _, tt := range tests {
		es := make([]*Server, tt)
		hs := make([]*httptest.Server, tt)
		for i := 0; i < tt; i++ {
			c := config.New()
			if i > 0 {
				c.Peers = []string{hs[i-1].URL}
			}
			es[i], hs[i] = initTestServer(c, int64(i), false)
		}

		go es[0].Run()

		for i := 1; i < tt; i++ {
			go es[i].Run()
			waitLeader(es[:i])
		}
		waitCluster(t, es)

		for i := range hs {
			es[len(hs)-i-1].Stop()
		}
		for i := range hs {
			hs[len(hs)-i-1].Close()
		}
	}
	afterTest(t)
}

func BenchmarkEndToEndSet(b *testing.B) {
	es, hs := buildCluster(3, false)
	waitLeader(es)
	b.ResetTimer()
	for n := 0; n < b.N; n++ {
		_, err := es[0].p.Set("foo", false, "bar", store.Permanent)
		if err != nil {
			panic("unexpect error")
		}
	}
	b.StopTimer()
	for i := range hs {
		es[len(hs)-i-1].Stop()
	}
	for i := range hs {
		hs[len(hs)-i-1].Close()
	}
}

// TODO(yichengq): cannot handle previous msgDenial correctly now
func TestModeSwitch(t *testing.T) {
	t.Skip("not passed")
	size := 5
	round := 3

	for i := 0; i < size; i++ {
		es, hs := buildCluster(size, false)
		waitCluster(t, es)

		config := config.NewClusterConfig()
		config.SyncInterval = 0
		id := int64(i)
		for j := 0; j < round; j++ {
			lead, _ := waitActiveLeader(es)
			// cluster only demotes follower
			if lead == id {
				continue
			}

			config.ActiveSize = size - 1
			if err := es[lead].p.setClusterConfig(config); err != nil {
				t.Fatalf("#%d: setClusterConfig err = %v", i, err)
			}
			if err := es[lead].p.remove(id); err != nil {
				t.Fatalf("#%d: remove err = %v", i, err)
			}

			waitMode(standbyMode, es[i])

			for k := 0; k < 4; k++ {
				if es[i].s.leader != noneId {
					break
				}
				time.Sleep(20 * time.Millisecond)
			}
			if g := es[i].s.leader; g != lead {
				t.Errorf("#%d: lead = %d, want %d", i, g, lead)
			}

			config.ActiveSize = size
			if err := es[lead].p.setClusterConfig(config); err != nil {
				t.Fatalf("#%d: setClusterConfig err = %v", i, err)
			}

			waitMode(participantMode, es[i])

			if err := checkParticipant(i, es); err != nil {
				t.Errorf("#%d: check alive err = %v", i, err)
			}
		}

		for i := range hs {
			es[len(hs)-i-1].Stop()
		}
		for i := range hs {
			hs[len(hs)-i-1].Close()
		}
	}
	afterTest(t)
}

type leadterm struct {
	lead int64
	term int64
}

func waitActiveLeader(es []*Server) (lead, term int64) {
	for {
		if l, t := waitLeader(es); l >= 0 && es[l].mode.Get() == participantMode {
			return l, t
		}
	}
}

// waitLeader waits until all alive servers are checked to have the same leader.
// WARNING: The lead returned is not guaranteed to be actual leader.
func waitLeader(es []*Server) (lead, term int64) {
	for {
		ls := make([]leadterm, 0, len(es))
		for i := range es {
			switch es[i].mode.Get() {
			case participantMode:
				ls = append(ls, getLead(es[i]))
			case standbyMode:
				//TODO(xiangli) add standby support
			case stopMode:
			}
		}
		if isSameLead(ls) {
			return ls[0].lead, ls[0].term
		}
		time.Sleep(es[0].tickDuration * defaultElection)
	}
}

func getLead(s *Server) leadterm {
	return leadterm{s.p.node.Leader(), s.p.node.Term()}
}

func isSameLead(ls []leadterm) bool {
	m := make(map[leadterm]int)
	for i := range ls {
		m[ls[i]] = m[ls[i]] + 1
	}
	if len(m) == 1 {
		if ls[0].lead == -1 {
			return false
		}
		return true
	}
	// todo(xiangli): printout the current cluster status for debugging....
	return false
}