// What crosses the terminal's channel. Bytes from the server lead with what they are; bytes to it are typed input.

/** The first byte of the server's binary messages. */
export const OUTPUT = 0;
export const SNAPSHOT = 1;

/** The server's other messages. */
export type ServerMessage =
  /** No shell has run in this conversation since the server started. */
  | { t: "none" }
  /** The shell exited, with its code, or `null` when a signal ended it; its last screen stays. */
  | { t: "exit"; code: number | null }
  /** The session's size, which whoever resized it last chose. */
  | { t: "size"; cols: number; rows: number }
  /** Starting a shell failed. */
  | { t: "error"; message: string };

export type ClientMessage =
  /** Start a shell, unless one is running. */
  | { t: "start"; cols: number; rows: number }
  | { t: "resize"; cols: number; rows: number };

export const tagged = (tag: number, data: Uint8Array) => {
  const out = new Uint8Array(data.length + 1);
  out[0] = tag;
  out.set(data, 1);
  return out;
};