// Runs berry, and runs it again when it exits to restart, or crashes.

import { fromFileUrl } from "@std/path";
import { denoExecutable } from "./deno.ts";

/** The exit code berry restarts with. */
export const RESTART = 75;

if (import.meta.main) {
  const main = fromFileUrl(new URL("./main.ts", import.meta.url));
  let stopping = false;
  let child: Deno.ChildProcess | undefined;
  // the terminal's ^C reaches berry too; either way, berry stops and then so does this
  for (const signal of ["SIGINT", "SIGTERM"] as const) {
    Deno.addSignalListener(signal, () => {
      stopping = true;
      try {
        child?.kill(signal);
      } catch {
        // already gone
      }
    });
  }

  let backoff = 1_000;
  while (true) {
    const started = Date.now();
    child = new Deno.Command(denoExecutable(), { args: ["run", "-A", main] }).spawn();
    const { code } = await child.status;
    if (stopping || code === 0) Deno.exit(code);
    if (code === RESTART) {
      console.log("[berry] restarting");
      backoff = 1_000;
      continue;
    }
    // a long run means the crash is news, not the same broken code again
    if (Date.now() - started > 60_000) backoff = 1_000;
    console.error(`[berry] exited with ${code}; starting again in ${backoff / 1000}s`);
    await new Promise((resolve) => setTimeout(resolve, backoff));
    backoff = Math.min(backoff * 2, 30_000);
  }
}