// Copyright 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 consumers

import (
	"context"
	"encoding/json"

	"github.com/Shopify/sarama"
	"github.com/matrix-org/dendrite/eduserver/api"
	"github.com/matrix-org/dendrite/internal"
	"github.com/matrix-org/dendrite/internal/config"
	"github.com/matrix-org/dendrite/syncapi/storage"
	"github.com/matrix-org/dendrite/syncapi/sync"
	"github.com/matrix-org/dendrite/syncapi/types"
	"github.com/matrix-org/gomatrixserverlib"
	"github.com/matrix-org/util"
	log "github.com/sirupsen/logrus"
)

// OutputSendToDeviceEventConsumer consumes events that originated in the EDU server.
type OutputSendToDeviceEventConsumer struct {
	sendToDeviceConsumer *internal.ContinualConsumer
	db                   storage.Database
	serverName           gomatrixserverlib.ServerName // our server name
	notifier             *sync.Notifier
}

// NewOutputSendToDeviceEventConsumer creates a new OutputSendToDeviceEventConsumer.
// Call Start() to begin consuming from the EDU server.
func NewOutputSendToDeviceEventConsumer(
	cfg *config.SyncAPI,
	kafkaConsumer sarama.Consumer,
	n *sync.Notifier,
	store storage.Database,
) *OutputSendToDeviceEventConsumer {

	consumer := internal.ContinualConsumer{
		Topic:          string(cfg.Matrix.Kafka.Topics.OutputSendToDeviceEvent),
		Consumer:       kafkaConsumer,
		PartitionStore: store,
	}

	s := &OutputSendToDeviceEventConsumer{
		sendToDeviceConsumer: &consumer,
		db:                   store,
		serverName:           cfg.Matrix.ServerName,
		notifier:             n,
	}

	consumer.ProcessMessage = s.onMessage

	return s
}

// Start consuming from EDU api
func (s *OutputSendToDeviceEventConsumer) Start() error {
	return s.sendToDeviceConsumer.Start()
}

func (s *OutputSendToDeviceEventConsumer) onMessage(msg *sarama.ConsumerMessage) error {
	var output api.OutputSendToDeviceEvent
	if err := json.Unmarshal(msg.Value, &output); err != nil {
		// If the message was invalid, log it and move on to the next message in the stream
		log.WithError(err).Errorf("EDU server output log: message parse failure")
		return err
	}

	_, domain, err := gomatrixserverlib.SplitID('@', output.UserID)
	if err != nil {
		return err
	}
	if domain != s.serverName {
		return nil
	}

	util.GetLogger(context.TODO()).WithFields(log.Fields{
		"sender":     output.Sender,
		"user_id":    output.UserID,
		"device_id":  output.DeviceID,
		"event_type": output.Type,
	}).Info("sync API received send-to-device event from EDU server")

	streamPos := s.db.AddSendToDevice()

	_, err = s.db.StoreNewSendForDeviceMessage(
		context.TODO(), streamPos, output.UserID, output.DeviceID, output.SendToDeviceEvent,
	)
	if err != nil {
		log.WithError(err).Errorf("failed to store send-to-device message")
		return err
	}

	s.notifier.OnNewSendToDevice(
		output.UserID,
		[]string{output.DeviceID},
		types.NewStreamToken(0, streamPos, nil),
	)

	return nil
}