// message types between daemon and adapters

export type ClientMessage =
  | { type: "join"; room: string }
  | { type: "leave" }
  | { type: "update"; data: number[] } // yjs update as byte array
  | { type: "awareness"; data: number[] };

export type AwarenessState = {
  clientId: number;
  cursor?: { line: number; col: number };
  selection?: { startLine: number; startCol: number; endLine: number; endCol: number };
  name?: string;
};

export type ServerMessage =
  | { type: "sync"; data: number[] } // full yjs state
  | { type: "update"; data: number[] }
  | { type: "awareness"; data: AwarenessState }
  | { type: "peers"; count: number }
  | { type: "error"; message: string };

export type BridgeMessage =
  | { type: "ready" }
  | { type: "connected"; room: string }
  | { type: "disconnected" }
  | { type: "content"; text: string }
  | { type: "peers"; count: number }
  | { type: "error"; message: string };

export function encode(msg: ServerMessage): string {
  return JSON.stringify(msg);
}

function isClientMessage(obj: unknown): obj is ClientMessage {
  if (typeof obj !== "object" || obj === null) return false;
  const msg = obj as Record<string, unknown>;

  switch (msg.type) {
    case "join":
      return typeof msg.room === "string";
    case "leave":
      return true;
    case "update":
      return (
        Array.isArray(msg.data) && msg.data.every((n) => typeof n === "number")
      );
    case "awareness":
      return (
        Array.isArray(msg.data) && msg.data.every((n) => typeof n === "number")
      );
    default:
      return false;
  }
}

export function decode(raw: string): ClientMessage | null {
  try {
    const parsed = JSON.parse(raw);
    if (!isClientMessage(parsed)) return null;
    return parsed;
  } catch {
    return null;
  }
}