// Copyright (C) 2019-2020 Zilliz. All rights reserved.
//
// 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 querynode

import (
	"errors"
	"fmt"
	"strconv"
	"sync"

	"github.com/milvus-io/milvus/internal/log"
)

// TSafeReplicaInterface is the interface wrapper of tSafeReplica
type TSafeReplicaInterface interface {
	getTSafe(vChannel VChannel) Timestamp
	setTSafe(vChannel VChannel, timestamp Timestamp)
	addTSafe(vChannel VChannel)
	removeTSafe(vChannel VChannel)
	registerTSafeWatcher(vChannel VChannel, watcher *tSafeWatcher)
}

type tSafeReplica struct {
	mu     sync.Mutex        // guards tSafes
	tSafes map[string]tSafer // map[vChannel]tSafer
}

func (t *tSafeReplica) getTSafe(vChannel VChannel) Timestamp {
	t.mu.Lock()
	defer t.mu.Unlock()
	safer, err := t.getTSaferPrivate(vChannel)
	if err != nil {
		return 0
	}
	return safer.get()
}

func (t *tSafeReplica) setTSafe(vChannel VChannel, timestamp Timestamp) {
	t.mu.Lock()
	defer t.mu.Unlock()
	safer, err := t.getTSaferPrivate(vChannel)
	if err != nil {
		return
	}
	safer.set(timestamp)
}

func (t *tSafeReplica) getTSaferPrivate(vChannel VChannel) (tSafer, error) {
	if _, ok := t.tSafes[vChannel]; !ok {
		err := errors.New("cannot found tSafer, vChannel = " + vChannel)
		log.Error(err.Error())
		return nil, err
	}
	return t.tSafes[vChannel], nil
}

func (t *tSafeReplica) addTSafe(vChannel VChannel) {
	t.mu.Lock()
	defer t.mu.Unlock()
	t.tSafes[vChannel] = newTSafe()
}

func (t *tSafeReplica) removeTSafe(vChannel VChannel) {
	t.mu.Lock()
	defer t.mu.Unlock()
	safer, err := t.getTSaferPrivate(vChannel)
	if err != nil {
		return
	}
	safer.close()
	delete(t.tSafes, vChannel)
}

func (t *tSafeReplica) registerTSafeWatcher(vChannel VChannel, watcher *tSafeWatcher) {
	t.mu.Lock()
	defer t.mu.Unlock()
	safer, err := t.getTSaferPrivate(vChannel)
	if err != nil {
		return
	}
	safer.registerTSafeWatcher(watcher)
}

// TODO: remove and use real vChannel
func collectionIDToChannel(collectionID UniqueID) VChannel {
	return fmt.Sprintln(collectionID)
}

// TODO: remove and use real vChannel
func channelTOCollectionID(channel VChannel) UniqueID {
	collectionID, err := strconv.ParseInt(channel, 10, 64)
	if err != nil {
		return 0
	}
	return collectionID
}

func newTSafeReplica() TSafeReplicaInterface {
	var replica TSafeReplicaInterface = &tSafeReplica{
		tSafes: make(map[string]tSafer),
	}
	return replica
}