import { execFile } from "node:child_process";

/**
 * Minimal child-process runner shared by the stages. Array-args only —
 * never a shell — so URLs and paths cannot be interpreted, and secrets
 * can only travel via `env` (spec §6/§10).
 */
export interface CommandResult {
  exitCode: number;
  stdout: string;
  stderr: string;
}

export type RunCommand = (
  command: string,
  args: string[],
  options: { cwd: string; env?: Record<string, string> },
) => Promise<CommandResult>;

const MAX_OUTPUT_BYTES = 64 * 1024 * 1024;

/** Ten minutes: covers a cold `npm install` of a real repo; prevents hangs. */
const COMMAND_TIMEOUT_MS = 10 * 60 * 1000;

export const runCommand: RunCommand = (command, args, options) =>
  new Promise((resolve, reject) => {
    execFile(
      command,
      args,
      {
        cwd: options.cwd,
        env: { ...process.env, ...options.env },
        maxBuffer: MAX_OUTPUT_BYTES,
        timeout: COMMAND_TIMEOUT_MS,
      },
      (error, stdout, stderr) => {
        if (error === null) {
          resolve({ exitCode: 0, stdout, stderr });
          return;
        }
        // Non-zero exit is a result, not an exception — stages map it to
        // named protocol errors. Spawn-level failures still reject.
        const exitCode = typeof error.code === "number" ? error.code : null;
        if (exitCode !== null) {
          resolve({ exitCode, stdout, stderr });
          return;
        }
        if (error.killed === true) {
          resolve({ exitCode: 124, stdout, stderr: `${stderr}\n(timed out)` });
          return;
        }
        reject(error);
      },
    );
  });