cloud-game/pkg/worker/coordinator.go

package worker

import (
	"encoding/json"
	"log"
	"strconv"

	"github.com/giongto35/cloud-game/pkg/cws"
	"github.com/giongto35/cloud-game/pkg/util"
	"github.com/giongto35/cloud-game/pkg/webrtc"
	"github.com/giongto35/cloud-game/pkg/worker/room"
	"github.com/gorilla/websocket"
)

// CoordinatorClient maintans connection to coordinator
// We expect only one CoordinatorClient for each server
type CoordinatorClient struct {
	*cws.Client
}

// NewCoordinatorClient returns a client connecting to coordinator for coordiation between different server
func NewCoordinatorClient(oc *websocket.Conn) *CoordinatorClient {
	if oc == nil {
		return nil
	}

	oClient := &CoordinatorClient{
		Client: cws.NewClient(oc),
	}
	return oClient
}

// RouteCoordinator are all routes server received from coordinator
func (h *Handler) RouteCoordinator() {
	// iceCandidates := map[string][]string{}
	oClient := h.oClient

	/* Coordinator */

	// Received from coordinator the serverID
	oClient.Receive(
		"serverID",
		func(response cws.WSPacket) (request cws.WSPacket) {
			// Stick session with serverID got from coordinator
			log.Println("Received serverID ", response.Data)
			h.serverID = response.Data

			return cws.EmptyPacket
		},
	)

	/* WebRTC Connection */

	oClient.Receive(
		"initwebrtc",
		func(resp cws.WSPacket) (req cws.WSPacket) {
			log.Println("Received a request to createOffer from browser via coordinator")

			peerconnection := webrtc.NewWebRTC()
			var initPacket struct {
				IsMobile bool `json:"is_mobile"`
			}
			err := json.Unmarshal([]byte(resp.Data), &initPacket)
			if err != nil {
				log.Println("Error: Cannot decode json:", err)
				return cws.EmptyPacket
			}

			localSession, err := peerconnection.StartClient(
				initPacket.IsMobile,
				func(candidate string) {
					// send back candidate string to browser
					oClient.Send(cws.WSPacket{
						ID:        "candidate",
						Data:      candidate,
						SessionID: resp.SessionID,
					}, nil)
				},
			)

			// localSession, err := peerconnection.StartClient(initPacket.IsMobile, iceCandidates[resp.SessionID])
			// h.peerconnections[resp.SessionID] = peerconnection

			// Create new sessions when we have new peerconnection initialized
			session := &Session{
				peerconnection: peerconnection,
			}
			h.sessions[resp.SessionID] = session
			log.Println("Start peerconnection", resp.SessionID)

			if err != nil {
				log.Println("Error: Cannot create new webrtc session", err)
				return cws.EmptyPacket
			}

			return cws.WSPacket{
				ID:   "offer",
				Data: localSession,
			}
		},
	)

	oClient.Receive(
		"answer",
		func(resp cws.WSPacket) (req cws.WSPacket) {
			log.Println("Received answer SDP from browser")
			session := h.getSession(resp.SessionID)

			if session != nil {
				peerconnection := session.peerconnection

				err := peerconnection.SetRemoteSDP(resp.Data)
				if err != nil {
					log.Println("Error: Cannot set RemoteSDP of client: " + resp.SessionID)
				}
			} else {
				log.Printf("Error: No session for ID: %s\n", resp.SessionID)
			}

			return cws.EmptyPacket
		},
	)

	oClient.Receive(
		"candidate",
		func(resp cws.WSPacket) (req cws.WSPacket) {
			log.Println("Received remote Ice Candidate from browser")
			session := h.getSession(resp.SessionID)

			if session != nil {
				peerconnection := session.peerconnection

				err := peerconnection.AddCandidate(resp.Data)
				if err != nil {
					log.Println("Error: Cannot add IceCandidate of client: " + resp.SessionID)
				}
			} else {
				log.Printf("Error: No session for ID: %s\n", resp.SessionID)
			}

			return cws.EmptyPacket
		},
	)

	/* Game Logic */

	oClient.Receive(
		"start",
		func(resp cws.WSPacket) (req cws.WSPacket) {
			log.Println("Received a start request from coordinator")
			session := h.getSession(resp.SessionID)
			if session == nil {
				log.Printf("Error: No session for ID: %s\n", resp.SessionID)
				return cws.EmptyPacket
			}

			peerconnection := session.peerconnection
			// TODO: Standardize for all types of packet. Make WSPacket generic
			var startPacket struct {
				GameName string `json:"game_name"`
				IsMobile bool   `json:"is_mobile"`
			}

			err := json.Unmarshal([]byte(resp.Data), &startPacket)
			if err != nil {
				log.Println("Error: Cannot decode json:", err)
				return cws.EmptyPacket
			}

			room := h.startGameHandler(startPacket.GameName, resp.RoomID, resp.PlayerIndex, peerconnection, util.GetVideoEncoder(startPacket.IsMobile))
			session.RoomID = room.ID
			// TODO: can data race
			h.rooms[room.ID] = room

			return cws.WSPacket{
				ID:     "start",
				RoomID: room.ID,
			}
		},
	)

	oClient.Receive(
		"quit",
		func(resp cws.WSPacket) (req cws.WSPacket) {
			log.Println("Received a quit request from coordinator")
			session := h.getSession(resp.SessionID)

			if session != nil {
				room := h.getRoom(session.RoomID)
				// Defensive coding, check if the peerconnection is in room
				if room.IsPCInRoom(session.peerconnection) {
					h.detachPeerConn(session.peerconnection)
				}
			} else {
				log.Printf("Error: No session for ID: %s\n", resp.SessionID)
			}

			return cws.EmptyPacket
		},
	)

	oClient.Receive(
		"save",
		func(resp cws.WSPacket) (req cws.WSPacket) {
			log.Println("Received a save game from coordinator")
			log.Println("RoomID:", resp.RoomID)
			req.ID = "save"
			req.Data = "ok"
			if resp.RoomID != "" {
				room := h.getRoom(resp.RoomID)
				if room == nil {
					return
				}
				err := room.SaveGame()
				if err != nil {
					log.Println("[!] Cannot save game state: ", err)
					req.Data = "error"
				}
			} else {
				req.Data = "error"
			}

			return req
		})

	oClient.Receive(
		"load",
		func(resp cws.WSPacket) (req cws.WSPacket) {
			log.Println("Received a load game from coordinator")
			log.Println("Loading game state")
			req.ID = "load"
			req.Data = "ok"
			if resp.RoomID != "" {
				room := h.getRoom(resp.RoomID)
				err := room.LoadGame()
				if err != nil {
					log.Println("[!] Cannot load game state: ", err)
					req.Data = "error"
				}
			} else {
				req.Data = "error"
			}

			return req
		})

	oClient.Receive(
		"playerIdx",
		func(resp cws.WSPacket) (req cws.WSPacket) {
			log.Println("Received an update player index event from coordinator")
			req.ID = "playerIdx"

			room := h.getRoom(resp.RoomID)
			session := h.getSession(resp.SessionID)
			idx, err := strconv.Atoi(resp.Data)
			log.Printf("Got session %v and room %v", session, room)

			if room != nil && session != nil && err == nil {
				room.UpdatePlayerIndex(session.peerconnection, idx)
				req.Data = strconv.Itoa(idx)
			} else {
				req.Data = "error"
			}

			return req
		})

	oClient.Receive(
		"terminateSession",
		func(resp cws.WSPacket) (req cws.WSPacket) {
			log.Println("Received a terminate session ", resp.SessionID)
			session := h.getSession(resp.SessionID)
			if session != nil {
				session.Close()
				delete(h.sessions, resp.SessionID)
				h.detachPeerConn(session.peerconnection)
			} else {
				log.Printf("Error: No session for ID: %s\n", resp.SessionID)
			}

			return cws.EmptyPacket
		},
	)
}

func getServerIDOfRoom(oc *CoordinatorClient, roomID string) string {
	log.Println("Request coordinator roomID ", roomID)
	packet := oc.SyncSend(
		cws.WSPacket{
			ID:   "getRoom",
			Data: roomID,
		},
	)
	log.Println("Received roomID from coordinator ", packet.Data)

	return packet.Data
}

// startGameHandler starts a game if roomID is given, if not create new room
func (h *Handler) startGameHandler(gameName, existedRoomID string, playerIndex int, peerconnection *webrtc.WebRTC, videoEncoderType string) *room.Room {
	log.Println("Starting game", gameName)
	// If we are connecting to coordinator, request corresponding serverID based on roomID
	// TODO: check if existedRoomID is in the current server
	room := h.getRoom(existedRoomID)
	// If room is not running
	if room == nil {
		log.Println("Got Room from local ", room, " ID: ", existedRoomID)
		// Create new room and update player index
		room = h.createNewRoom(gameName, existedRoomID, videoEncoderType)
		room.UpdatePlayerIndex(peerconnection, playerIndex)

		// Wait for done signal from room
		go func() {
			<-room.Done
			h.detachRoom(room.ID)
			// send signal to coordinator that the room is closed, coordinator will remove that room
			h.oClient.Send(cws.WSPacket{
				ID:   "closeRoom",
				Data: room.ID,
			}, nil)
		}()
	}

	// Attach peerconnection to room. If PC is already in room, don't detach
	log.Println("Is PC in room", room.IsPCInRoom(peerconnection))
	if !room.IsPCInRoom(peerconnection) {
		h.detachPeerConn(peerconnection)
		room.AddConnectionToRoom(peerconnection)
	}

	// Register room to coordinator if we are connecting to coordinator
	if room != nil && h.oClient != nil {
		h.oClient.Send(cws.WSPacket{
			ID:   "registerRoom",
			Data: room.ID,
		}, nil)
	}

	return room
}