import { parseDuration } from "./duration";

/** Parsed `/kg` command, decoupled from any Pi context for unit testing. */
export type KgCommand =
  | { kind: "schedule"; seconds: number; message: string }
  | { kind: "auto"; message: string }
  | { kind: "list" }
  | { kind: "cancel" }
  | { kind: "help" }
  | { kind: "error"; reason: string };

/**
 * Parse the raw argument string of `/kg`.
 *
 * Grammar: `<duration|auto|list|cancel|help> [message...]`. An empty input is
 * treated as `help`. The first token is a subcommand or a duration; the
 * remainder is the message (defaulting to `defaultMessage`).
 */
export function parseKgCommand(args: string, defaultMessage: string): KgCommand {
  const trimmed = args.trim();
  if (trimmed === "") return { kind: "help" };

  const [first, ...rest] = trimmed.split(/\s+/);
  const message = rest.join(" ").trim() || defaultMessage;

  switch (first.toLowerCase()) {
    case "help":
      return { kind: "help" };
    case "list":
      return { kind: "list" };
    case "cancel":
      return { kind: "cancel" };
    case "auto":
      return { kind: "auto", message };
  }

  const seconds = parseDuration(first);
  if (seconds === null) {
    return {
      kind: "error",
      reason: `Invalid duration "${first}". Use e.g. 40m, 2h30m, 90s, or "auto".`,
    };
  }
  return { kind: "schedule", seconds, message };
}