// Licensed to the LF AI & Data foundation under one
// or more contributor license agreements. See the NOTICE file
// distributed with this work for additional information
// regarding copyright ownership. The ASF licenses this file
// to you 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 rootcoord

import (
	"container/heap"
	"context"
	"math/rand"
	"sync"
	"testing"

	"github.com/cockroachdb/errors"

	"github.com/milvus-io/milvus/internal/mq/msgstream"
	"github.com/milvus-io/milvus/internal/mq/msgstream/mqwrapper"
	"github.com/milvus-io/milvus/internal/util/dependency"
	"github.com/milvus-io/milvus/internal/util/funcutil"

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

func TestDmlMsgStream(t *testing.T) {
	t.Run("RefCnt", func(t *testing.T) {

		dms := &dmlMsgStream{refcnt: 0}
		assert.Equal(t, int64(0), dms.RefCnt())
		assert.Equal(t, int64(0), dms.Used())

		dms.IncRefcnt()
		assert.Equal(t, int64(1), dms.RefCnt())
		dms.BookUsage()
		assert.Equal(t, int64(1), dms.Used())

		dms.DecRefCnt()
		assert.Equal(t, int64(0), dms.RefCnt())
		assert.Equal(t, int64(1), dms.Used())

		dms.DecRefCnt()
		assert.Equal(t, int64(0), dms.RefCnt())
		assert.Equal(t, int64(1), dms.Used())
	})
}

func TestChannelsHeap(t *testing.T) {
	chanNum := 16
	var h channelsHeap
	h = make([]*dmlMsgStream, 0, chanNum)

	for i := int64(0); i < int64(chanNum); i++ {
		dms := &dmlMsgStream{
			refcnt: 0,
			used:   0,
			idx:    i,
			pos:    int(i),
		}
		h = append(h, dms)
	}

	check := func(h channelsHeap) bool {
		for i := 0; i < chanNum; i++ {
			if h[i].pos != i {
				return false
			}
			if i*2+1 < chanNum {
				if !h.Less(i, i*2+1) {
					t.Log("left", i)
					return false
				}
			}
			if i*2+2 < chanNum {
				if !h.Less(i, i*2+2) {
					t.Log("right", i)
					return false
				}
			}
		}
		return true
	}

	heap.Init(&h)

	assert.True(t, check(h))

	// add usage for all
	for i := 0; i < chanNum; i++ {
		h[0].BookUsage()
		h[0].IncRefcnt()
		heap.Fix(&h, 0)
	}

	assert.True(t, check(h))
	for i := 0; i < chanNum; i++ {
		assert.EqualValues(t, 1, h[i].RefCnt())
		assert.EqualValues(t, 1, h[i].Used())
	}

	randIdx := rand.Intn(chanNum)

	target := h[randIdx]
	h[randIdx].DecRefCnt()
	heap.Fix(&h, randIdx)
	assert.EqualValues(t, 0, target.pos)

	next := heap.Pop(&h).(*dmlMsgStream)

	assert.Equal(t, target, next)
}

func TestDmlChannels(t *testing.T) {
	const (
		dmlChanPrefix      = "rootcoord-dml"
		totalDmlChannelNum = 2
	)
	ctx, cancel := context.WithCancel(context.Background())
	defer cancel()

	factory := dependency.NewDefaultFactory(true)
	Params.Init()

	dml := newDmlChannels(ctx, factory, dmlChanPrefix, totalDmlChannelNum)
	chanNames := dml.listChannels()
	assert.Equal(t, 0, len(chanNames))

	randStr := funcutil.RandomString(8)
	assert.Panics(t, func() { dml.addChannels(randStr) })
	assert.Panics(t, func() { dml.broadcast([]string{randStr}, nil) })
	assert.Panics(t, func() { dml.broadcastMark([]string{randStr}, nil) })
	assert.Panics(t, func() { dml.removeChannels(randStr) })

	chans0 := dml.getChannelNames(2)
	dml.addChannels(chans0...)
	assert.Equal(t, 2, dml.getChannelNum())

	chans1 := dml.getChannelNames(1)
	dml.addChannels(chans1...)
	assert.Equal(t, 2, dml.getChannelNum())

	chans2 := dml.getChannelNames(totalDmlChannelNum + 1)
	assert.Nil(t, chans2)

	dml.removeChannels(chans1...)
	assert.Equal(t, 2, dml.getChannelNum())

	dml.removeChannels(chans0...)
	assert.Equal(t, 0, dml.getChannelNum())
}

func TestDmChannelsFailure(t *testing.T) {
	var wg sync.WaitGroup
	wg.Add(1)
	t.Run("Test newDmlChannels", func(t *testing.T) {
		defer wg.Done()
		mockFactory := &FailMessageStreamFactory{}
		assert.Panics(t, func() { newDmlChannels(context.TODO(), mockFactory, "test-newdmlchannel-root", 1) })
	})

	wg.Add(1)
	t.Run("Test broadcast", func(t *testing.T) {
		defer wg.Done()
		mockFactory := &FailMessageStreamFactory{errBroadcast: true}
		dml := newDmlChannels(context.TODO(), mockFactory, "test-newdmlchannel-root", 1)
		chanName0 := dml.getChannelNames(1)[0]
		dml.addChannels(chanName0)
		require.Equal(t, 1, dml.getChannelNum())

		err := dml.broadcast([]string{chanName0}, nil)
		assert.Error(t, err)

		v, err := dml.broadcastMark([]string{chanName0}, nil)
		assert.Empty(t, v)
		assert.Error(t, err)
	})
	wg.Wait()
}

// FailMessageStreamFactory mock MessageStreamFactory failure
type FailMessageStreamFactory struct {
	msgstream.Factory
	errBroadcast bool
}

func (f *FailMessageStreamFactory) NewMsgStream(ctx context.Context) (msgstream.MsgStream, error) {
	if f.errBroadcast {
		return &FailMsgStream{errBroadcast: true}, nil
	}
	return nil, errors.New("mocked failure")
}

func (f *FailMessageStreamFactory) NewTtMsgStream(ctx context.Context) (msgstream.MsgStream, error) {
	return nil, errors.New("mocked failure")
}

type FailMsgStream struct {
	msgstream.MsgStream
	errBroadcast bool
}

func (ms *FailMsgStream) Close()                                     {}
func (ms *FailMsgStream) Chan() <-chan *msgstream.MsgPack            { return nil }
func (ms *FailMsgStream) AsProducer(channels []string)               {}
func (ms *FailMsgStream) AsReader(channels []string, subName string) {}
func (ms *FailMsgStream) AsConsumer(channels []string, subName string, position mqwrapper.SubscriptionInitialPosition) {
}
func (ms *FailMsgStream) SetRepackFunc(repackFunc msgstream.RepackFunc) {}
func (ms *FailMsgStream) GetProduceChannels() []string                  { return nil }
func (ms *FailMsgStream) Produce(*msgstream.MsgPack) error              { return nil }
func (ms *FailMsgStream) Broadcast(*msgstream.MsgPack) (map[string][]msgstream.MessageID, error) {
	if ms.errBroadcast {
		return nil, errors.New("broadcast error")
	}
	return nil, nil
}
func (ms *FailMsgStream) Consume() *msgstream.MsgPack                { return nil }
func (ms *FailMsgStream) Seek(offset []*msgstream.MsgPosition) error { return nil }

func (ms *FailMsgStream) GetLatestMsgID(channel string) (msgstream.MessageID, error) {
	return nil, nil
}
