Domain Modeling - Design Workflow: join room

[kayac-chang]

implement design of https://hackmd.io/KvV2Ou3HS9uN11OUpsAUzA?both#Workflow-join-room

[JohnsonMao]

Command

type JoinRoomCommand = {
    playerId: string;
    roomId: string;
}

Event

type JoinRoomEvent = {
    playerId: string;
    roomId: string;
}

Error

type PlayerLimitError = Error & {
    name: 'PlayerLimitError'
    message: 'Exceeded game player limit'
}

type JoinRoomError =
    | PlayerLimitError
    | EventSourceReadError
    | EventSourceWriteError

Model

type GameRoom = {
    playerIds: string[];
    roomId: string;
    status: 'wait for join' | 'game started';
};

Type

type JoinRoom = (eventsource: EventSource, command: JoinRoomCommand) => ResultAsync<JoinRoomEvent, JoinRoomError>

Workflow

workflow: join room
    input:
        event source
        join room command
    output:
        async result of 
            ok -> game room
            err -> join room error
    step:
        read all events from event source
            if error occured:
                return event source read error
        checkPlayerCountAgainstGameLimit
            if exceeded game player limit:
                return player limit error
        append event to event source
            if error occured:
                return event source write error
            otherwise:
                return game room

[kayac-chang]

@JohnsonMao
I also consider that
should we add the current status of the game room, such like 'wait for join' | 'game started' ?
because I think we should not let player joined if game already started.

[JohnsonMao]

I agree with your consideration.