Backend/routes/lp.go

package routes

import (
	"backend/database"
	"errors"
	"fmt"
	"github.com/go-chi/chi/v5"
	"net/http"
	"time"
)

func RegisterLongPollRoutes(r chi.Router) {
	r.Get("/", resolveLongPoll)
}

func resolveLongPoll(w http.ResponseWriter, r *http.Request) {
	userId, err := GetCurrentUserID(r)
	if errors.Is(err, database.ErrNotAuthorized) {
		NoToken.Ferror(w)
		return
	}
	if errors.Is(err, http.ErrNoCookie) {
		NoToken.Ferror(w)
		return
	}
	events, err := lpServer.GetEvents(userId)
	Response(w, err, events)
}

var NoEventsErr = fmt.Errorf("no events")

type LongPollServer struct {
	clients map[uint64]*LongPollClient
}

type LongPollClient struct {
	events []*LongPollEvent
}

type LongPollEvent struct {
	Action  string      `json:"action"`
	TS      int64       `json:"ts"`
	Payload interface{} `json:"payload"`
}

func InitLongPollServer() *LongPollServer {
	return &LongPollServer{
		clients: make(map[uint64]*LongPollClient),
	}
}

func (lpServer *LongPollServer) PushEvent(payload interface{}, userId uint64, action string) {
	lpClient, ok := lpServer.clients[userId]
	if !ok {
		lpClient = new(LongPollClient)
		lpServer.clients[userId] = lpClient
	}

	lpClient.events = append(lpClient.events, &LongPollEvent{
		action,
		time.Now().Unix(),
		payload,
	})
}

func (lpServer *LongPollServer) PushEventToAll(payload interface{}, action string) {
	for _, lpClient := range lpServer.clients {
		lpClient.events = append(lpClient.events, &LongPollEvent{
			action,
			time.Now().Unix(),
			payload,
		})
	}
}

func (lpServer *LongPollServer) GetEvents(userId uint64) ([]*LongPollEvent, error) {
	lpClient, ok := lpServer.clients[userId]
	if !ok {
		lpServer.clients[userId] = new(LongPollClient)
		return nil, NoEventsErr
	}

	if len(lpClient.events) == 0 {
		return nil, NoEventsErr
	}

	events := lpClient.events
	lpClient.events = make([]*LongPollEvent, 0)
	return events, nil
}