web-drs-lib/ServerMessage.ts

export enum MessageType {
  ACK = 0,
  TEXT = 1,
  ID_RESPONSE = 3,
}

export type ServerMessage = {
  __ctx?: string;
  type: MessageType;
  date: number;
};
export function isServerMessage(
  obj: unknown,
  type?: MessageType
): obj is ServerMessage {
  if (typeof obj !== "object") return false;
  if (obj === null) return false;
  if (
    !Object.hasOwnProperty.call(obj, "type") ||
    typeof (obj as { type: unknown }).type !== "number" ||
    (type === undefined &&
      !Object.hasOwnProperty.call(
        MessageType,
        (obj as { type: number }).type
      )) ||
    (type !== undefined && (obj as { type: number }).type !== type)
  ) {
    return false;
  }
  if (
    !Object.hasOwnProperty.call(obj, "date") ||
    typeof (obj as { date: unknown }).date !== "number"
  ) {
    return false;
  }
  if (
    Object.hasOwnProperty.call(obj, "__ctx") &&
    typeof (obj as { __ctx: unknown }).__ctx !== "string" &&
    typeof (obj as { __ctx: unknown }).__ctx !== "undefined"
  ) {
    return false;
  }

  return true;
}

export type TextMessage = ServerMessage & {
  type: MessageType.TEXT;
  author: string;
  content: string;
};
export function isTextMessage(obj: unknown): obj is TextMessage {
  if (!isServerMessage(obj, MessageType.TEXT)) return false;
  if (
    !Object.hasOwnProperty.call(obj, "author") ||
    typeof (obj as ServerMessage & { author: unknown }).author !== "string"
  ) {
    return false;
  }
  if (
    !Object.hasOwnProperty.call(obj, "author") ||
    typeof (obj as ServerMessage & { content: unknown }).content !== "string"
  ) {
    return false;
  }
  return true;
}

export type AckMessage = ServerMessage & {
  type: MessageType.ACK;
};
export function isAckMessage(obj: unknown): obj is AckMessage {
  return isServerMessage(obj, MessageType.ACK);
}

export type IdResponseMessage = ServerMessage & {
  type: MessageType.ID_RESPONSE;
  authorId: string;
};
export function isIdResponseMessage(obj: unknown): obj is IdResponseMessage {
  if (!isServerMessage(obj, MessageType.ID_RESPONSE)) return false;
  if (
    !Object.hasOwnProperty.call(obj, "authorId") ||
    typeof (obj as ServerMessage & { authorId: unknown }).authorId !== "string"
  ) {
    return false;
  }
  return true;
}