// Copyright 2017 Vector Creations Ltd
//
// 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 contains the code processes new room events
package internal

import (
	"context"
	"encoding/json"
	"sync"

	"github.com/Shopify/sarama"
	"github.com/matrix-org/dendrite/roomserver/api"
	log "github.com/sirupsen/logrus"

	fsAPI "github.com/matrix-org/dendrite/federationsender/api"
)

// SetFederationSenderInputAPI passes in a federation sender input API reference
// so that we can avoid the chicken-and-egg problem of both the roomserver input API
// and the federation sender input API being interdependent.
func (r *RoomserverInternalAPI) SetFederationSenderAPI(fsAPI fsAPI.FederationSenderInternalAPI) {
	r.fsAPI = fsAPI
}

// WriteOutputEvents implements OutputRoomEventWriter
func (r *RoomserverInternalAPI) WriteOutputEvents(roomID string, updates []api.OutputEvent) error {
	messages := make([]*sarama.ProducerMessage, len(updates))
	for i := range updates {
		value, err := json.Marshal(updates[i])
		if err != nil {
			return err
		}
		logger := log.WithFields(log.Fields{
			"room_id": roomID,
			"type":    updates[i].Type,
		})
		if updates[i].NewRoomEvent != nil {
			logger = logger.WithFields(log.Fields{
				"event_type":     updates[i].NewRoomEvent.Event.Type(),
				"event_id":       updates[i].NewRoomEvent.Event.EventID(),
				"adds_state":     len(updates[i].NewRoomEvent.AddsStateEventIDs),
				"removes_state":  len(updates[i].NewRoomEvent.RemovesStateEventIDs),
				"send_as_server": updates[i].NewRoomEvent.SendAsServer,
				"sender":         updates[i].NewRoomEvent.Event.Sender(),
			})
		}
		logger.Infof("Producing to topic '%s'", r.OutputRoomEventTopic)
		messages[i] = &sarama.ProducerMessage{
			Topic: r.OutputRoomEventTopic,
			Key:   sarama.StringEncoder(roomID),
			Value: sarama.ByteEncoder(value),
		}
	}
	return r.Producer.SendMessages(messages)
}

// InputRoomEvents implements api.RoomserverInternalAPI
func (r *RoomserverInternalAPI) InputRoomEvents(
	ctx context.Context,
	request *api.InputRoomEventsRequest,
	response *api.InputRoomEventsResponse,
) (err error) {
	for i, e := range request.InputRoomEvents {
		roomID := "global"
		if r.DB.SupportsConcurrentRoomInputs() {
			roomID = e.Event.RoomID()
		}
		mutex, _ := r.mutexes.LoadOrStore(roomID, &sync.Mutex{})
		mutex.(*sync.Mutex).Lock()
		if response.EventID, err = r.processRoomEvent(ctx, request.InputRoomEvents[i]); err != nil {
			mutex.(*sync.Mutex).Unlock()
			return err
		}
		mutex.(*sync.Mutex).Unlock()
	}
	return nil
}