// Copyright 2017 Vector Creations Ltd
// Copyright 2017-2018 New Vector Ltd
// Copyright 2019-2020 The Matrix.org Foundation C.I.C.
//
// 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 input

import (
	"context"
	"encoding/json"
	"time"

	"github.com/matrix-org/dendrite/eduserver/api"
	"github.com/matrix-org/dendrite/eduserver/cache"
	userapi "github.com/matrix-org/dendrite/userapi/api"
	"github.com/matrix-org/gomatrixserverlib"
	"github.com/nats-io/nats.go"
	"github.com/sirupsen/logrus"
)

// EDUServerInputAPI implements api.EDUServerInputAPI
type EDUServerInputAPI struct {
	// Cache to store the current typing members in each room.
	Cache *cache.EDUCache
	// The kafka topic to output new typing events to.
	OutputTypingEventTopic string
	// kafka producer
	JetStream nats.JetStreamContext
	// Internal user query API
	UserAPI userapi.UserInternalAPI
	// our server name
	ServerName gomatrixserverlib.ServerName
}

// InputTypingEvent implements api.EDUServerInputAPI
func (t *EDUServerInputAPI) InputTypingEvent(
	ctx context.Context,
	request *api.InputTypingEventRequest,
	response *api.InputTypingEventResponse,
) error {
	ite := &request.InputTypingEvent
	if ite.Typing {
		// user is typing, update our current state of users typing.
		expireTime := ite.OriginServerTS.Time().Add(
			time.Duration(ite.TimeoutMS) * time.Millisecond,
		)
		t.Cache.AddTypingUser(ite.UserID, ite.RoomID, &expireTime)
	} else {
		t.Cache.RemoveUser(ite.UserID, ite.RoomID)
	}

	return t.sendTypingEvent(ite)
}

func (t *EDUServerInputAPI) sendTypingEvent(ite *api.InputTypingEvent) error {
	ev := &api.TypingEvent{
		Type:   gomatrixserverlib.MTyping,
		RoomID: ite.RoomID,
		UserID: ite.UserID,
		Typing: ite.Typing,
	}
	ote := &api.OutputTypingEvent{
		Event: *ev,
	}

	if ev.Typing {
		expireTime := ite.OriginServerTS.Time().Add(
			time.Duration(ite.TimeoutMS) * time.Millisecond,
		)
		ote.ExpireTime = &expireTime
	}

	eventJSON, err := json.Marshal(ote)
	if err != nil {
		return err
	}
	logrus.WithFields(logrus.Fields{
		"room_id": ite.RoomID,
		"user_id": ite.UserID,
		"typing":  ite.Typing,
	}).Tracef("Producing to topic '%s'", t.OutputTypingEventTopic)

	_, err = t.JetStream.PublishMsg(&nats.Msg{
		Subject: t.OutputTypingEventTopic,
		Header:  nats.Header{},
		Data:    eventJSON,
	})
	return err
}