transport_event_handler.go

package mongo_watcher

import (
	"context"
	"encoding/json"
	"github.com/techpro-studio/mongo_watcher/transport"
	"go.mongodb.org/mongo-driver/v2/mongo"
	"log"
)

type RoomFormatter[T any] interface {
	Format(event *Event[T]) string
}

type RoomFormatterFunc[T any] func(event *Event[T]) string

func (r RoomFormatterFunc[T]) Format(event *Event[T]) string {
	return r(event)
}

type StaticRoomFormatter[T any] struct {
	roomName string
}

func NewStaticRoomFormatter[T any](roomName string) *StaticRoomFormatter[T] {
	return &StaticRoomFormatter[T]{roomName: roomName}
}

func (r StaticRoomFormatter[T]) Format(event *Event[T]) string {
	return r.roomName
}

type TransportEventHandler[T any] struct {
	trans           transport.RoomTransport
	objectFormatter ObjectFormatter[T]
	roomFormatter   RoomFormatter[T]
}

type ObjectFormatter[T any] interface {
	Format(event *Event[T]) (map[string]string, error)
}

type JsonPayloadObjectFormatter[T any] struct {
}

func NewJsonPayloadObjectFormatter[T any]() *JsonPayloadObjectFormatter[T] {
	return &JsonPayloadObjectFormatter[T]{}
}

func (j JsonPayloadObjectFormatter[T]) Format(event *Event[T]) (map[string]string, error) {
	jsonData, err := json.Marshal(*event.FullDocument)
	if err != nil {
		return nil, err
	}
	result := map[string]string{"payload": string(jsonData)}
	return result, nil
}

func NewTransportEventHandler[T any](trans transport.RoomTransport, roomFormatter RoomFormatter[T], formatter ObjectFormatter[T]) *TransportEventHandler[T] {
	return &TransportEventHandler[T]{trans: trans, roomFormatter: roomFormatter, objectFormatter: formatter}
}

func (t *TransportEventHandler[T]) Setup(ctx context.Context, collection *mongo.Collection) {
	log.Printf("Setting up transport event handler for %s", collection.Name())
}

func (t *TransportEventHandler[T]) HandleEvent(ctx context.Context, event *Event[T]) error {
	var sendData map[string]string
	switch event.Type {
	case MongoEventDelete:
		sendData = map[string]string{"id": event.Key}
	default:
		var err error
		sendData, err = t.objectFormatter.Format(event)
		if err != nil {
			return err
		}
	}

	room := t.roomFormatter.Format(event)

	err := t.trans.SendMessage(ctx, &transport.RoomMessage{
		Data:  sendData,
		Room:  room,
		Event: string(event.Type),
	})
	if err != nil {
		return err
	}

	return nil
}