// Runs one CLI command for `bin/quak.ts` and exits with its code.

import type { Writable } from "node:stream";

// Run a command and exit with its code once stdout/stderr have drained.
// Exiting before the drain can truncate piped output, and the library can keep
// the event loop alive after a command returns, so a plain return could hang.
// An error the command throws is printed as one `quak: MESSAGE` line, without
// the stack trace, and exits 1.
export const run = async (
    command: Promise<number>,
    stdout: Writable,
    stderr: Writable,
    exit: (code: number) => void,
): Promise<void> => {
    let code: number;
    try {
        code = await command;
    } catch (err) {
        stderr.write(
            `quak: ${err instanceof Error ? err.message : String(err)}\n`,
        );
        code = 1;
    }
    const pending = [stdout, stderr].filter((s) => s.writableLength > 0);
    if (pending.length === 0) {
        exit(code);
        return;
    }
    let remaining = pending.length;
    for (const s of pending) {
        s.once("drain", () => {
            if (--remaining === 0) exit(code);
        });
    }
};