// lib/util/autonomy-gate.mjs
// The --gates flag parser for /trekbrief, /trekresearch, /trekplan and
// /trekexecute: maps the flag's value to gates on or off.
//
// CLI:
//   node lib/util/autonomy-gate.mjs [--gates [true|false|closed|open]]
//   (bare --gates = on; true|closed = on, false|open = off; no flag = off.
//   Any other value is a usage error, exit 1; case-sensitive. One token
//   --gates=<value> is read as --gates <value>; an empty value is the same
//   usage error. Any other argument is a usage error.)
//   → JSON: { ok: true, gates: true|false }   (exit 0)
//   → JSON: { ok: false, error: "usage: ..." } (exit 1)
//
// Pure data; no I/O beyond the CLI's stdout.

import { isMain } from './is-main.mjs';

/** A --gates value: true|closed = on, false|open = off, else undefined. */
function gatesValue(v) {
  if (v === 'true' || v === 'closed') return true;
  if (v === 'false' || v === 'open') return false;
  return undefined;
}

const GATES_USAGE = 'usage: --gates takes true, false, closed or open';
const USAGE = 'usage: autonomy-gate.mjs [--gates [true|false|closed|open]]';

/**
 * Parse the CLI arguments.
 *
 * @param {string[]} argv
 * @returns {{ ok: true, gates: boolean } | { ok: false, error: string }}
 */
export function parseGatesArgs(argv) {
  let gates = false;
  for (let i = 0; i < argv.length; i++) {
    const a = argv[i];
    let v;
    if (a.startsWith('--gates=')) {
      // The one-token form, read as `--gates <value>`; an empty value is no value.
      v = a.slice('--gates='.length);
    } else if (a === '--gates') {
      // Bare `--gates` (last, or followed by another flag) means on and
      // consumes nothing.
      const next = argv[i + 1];
      if (next === undefined || next.startsWith('--')) {
        gates = true;
        continue;
      }
      v = next;
      i++;
    } else {
      return { ok: false, error: USAGE };
    }
    const g = gatesValue(v);
    if (g === undefined) return { ok: false, error: GATES_USAGE };
    gates = g;
  }
  return { ok: true, gates };
}

if (isMain(import.meta.url)) {
  const result = parseGatesArgs(process.argv.slice(2));
  process.stdout.write(JSON.stringify(result) + '\n');
  process.exit(result.ok ? 0 : 1);
}