#!/usr/bin/env -S bun --no-env-file --config=/dev/null
/**
 * gstack-ship-policy — read, validate and explain `.gstack/ship-policy.json` (plan C1).
 *
 *   gstack-ship-policy init [--explain] [--force]              write the example (every key at its default)
 *   gstack-ship-policy validate [--policy-from head|base] [--base <ref>] [--json]
 *   gstack-ship-policy show-effective [--policy-from base|head] [--base <ref>] [--json]
 *   gstack-ship-policy check-history [--base <ref>] [--branch <name>] [--plan merge|squash|rebase] [--json]
 *
 * `show-effective` reads the committed copy on origin/<base> by default (the
 * reviewed policy); `validate` reads the working tree by default (the file
 * you are editing). Query commands: no GSTACK_RESULT line; `--json` means
 * JSON only on stdout. Logic: lib/ship-policy.ts; codes: lib/result-codes.ts.
 */
import { spawnSync } from 'node:child_process';
import * as fs from 'node:fs';
import * as path from 'node:path';
import { EXIT, exitTableHelp } from '../lib/headless-artifacts';
import { resultLine } from '../lib/result-codes';
import {
  BUMP_NEVER_KEY_VERSION, POLICY_KEYS, POLICY_KEY_INTRODUCED, SHIP_POLICY_PATH, examplePolicyJson, explainPolicy, isUnavailable, loadPolicyFromBase, loadPolicyFromHead,
  minimumReader, policyUnavailableLine, renderEffective, resolveBaseBranch, type LoadedPolicy,
} from '../lib/ship-policy';

const HELP = `gstack-ship-policy — the repo ship policy (docs/ship-policy.md)

  init [--explain] [--force]                         write ${SHIP_POLICY_PATH} with every key at its default
  validate [--policy-from head|base] [--base <ref>]  schema and containment check (default: the working tree)
  show-effective [--policy-from base|head] [--base <ref>]
                                                     resolved values with the source of each (default: origin/<base>)
  check-history [--base <ref>] [--branch <name>] [--plan merge|squash|rebase]
                                                     under history: merge-only, refuse a squash/rebase plan or a rewritten branch

--json: JSON only on stdout. Error lines end in (<CODE>) with a fix: clause.
${exitTableHelp()}`;

function flag(args: string[], name: string): string | undefined {
  const i = args.indexOf(name);
  return i >= 0 ? args[i + 1] : undefined;
}
function usage(message: string): number {
  process.stderr.write(`gstack-ship-policy: ${message}\n${HELP}\n`);
  return EXIT.usage;
}
function repoRoot(): string {
  const r = spawnSync('git', ['rev-parse', '--show-toplevel'], { encoding: 'utf8', timeout: 15_000 });
  return r.status === 0 && r.stdout.trim() ? r.stdout.trim() : process.cwd();
}

function load(root: string, args: string[], defaultFrom: 'base' | 'head'): LoadedPolicy | number {
  const from = flag(args, '--policy-from') ?? defaultFrom;
  if (from !== 'base' && from !== 'head') return usage('--policy-from needs base or head');
  if (from === 'head') return loadPolicyFromHead(root);
  const base = resolveBaseBranch(root, flag(args, '--base'));
  const loaded = loadPolicyFromBase(root, base);
  if (isUnavailable(loaded)) {
    process.stderr.write(policyUnavailableLine('gstack-ship-policy', base, loaded.detail) + '\n');
    return EXIT.refused;
  }
  return loaded;
}

function printErrors(loaded: LoadedPolicy): void {
  for (const e of loaded.errors) process.stderr.write(resultLine('gstack-ship-policy', e.code, `${e.message} at ${e.path || SHIP_POLICY_PATH}`) + '\n');
}

function main(argv: string[]): number {
  const [cmd, ...rest] = argv;
  const json = rest.includes('--json');
  if (!cmd || cmd === '--help' || cmd === '-h' || cmd === 'help') { process.stdout.write(HELP + '\n'); return cmd ? EXIT.ok : EXIT.usage; }
  const root = repoRoot();

  if (cmd === 'init') {
    if (rest.includes('--explain')) { process.stdout.write(explainPolicy()); if (rest.length === 1) return EXIT.ok; }
    const file = path.join(root, SHIP_POLICY_PATH);
    if (fs.existsSync(file) && !rest.includes('--force')) {
      process.stderr.write(resultLine('gstack-ship-policy init', 'POLICY_EXISTS', file) + '\n');
      return EXIT.refused;
    }
    fs.mkdirSync(path.dirname(file), { recursive: true });
    fs.writeFileSync(file, examplePolicyJson());
    process.stdout.write(`POLICY_WRITTEN: ${SHIP_POLICY_PATH} (edit it, then gstack-ship-policy validate; commit it on the base branch before /ship reads it)\n`);
    return EXIT.ok;
  }

  if (cmd === 'validate' || cmd === 'show-effective') {
    const loaded = load(root, rest, cmd === 'validate' ? 'head' : 'base');
    if (typeof loaded === 'number') return loaded;
    const set = POLICY_KEYS.filter(k => loaded.values[k] && loaded.values[k] !== 'default');
    const introduced = Object.fromEntries(set.map(k => [k, k === 'bump' && loaded.policy.bump === 'never' ? BUMP_NEVER_KEY_VERSION : POLICY_KEY_INTRODUCED[k]]));
    const minReader = set.length ? minimumReader(Object.fromEntries(set.map(k => [k, loaded.policy[k]]))) : null;
    if (json) {
      process.stdout.write(JSON.stringify({ valid: loaded.errors.length === 0, present: loaded.present, source: loaded.source, policy: loaded.policy, values: loaded.values, introduced, min_reader: minReader, errors: loaded.errors }) + '\n');
      return loaded.errors.length ? EXIT.fail : EXIT.ok;
    }
    printErrors(loaded);
    if (cmd === 'validate') {
      process.stdout.write(loaded.errors.length ? `POLICY_INVALID: ${loaded.errors.length} error(s) in ${loaded.source.label}\n` : `POLICY_VALID: ${loaded.present ? loaded.source.label : `no ${SHIP_POLICY_PATH} (defaults apply)`}\n`);
      for (const k of set) process.stdout.write(`KEY: ${k} introduced=${introduced[k]}\n`);
      if (minReader) process.stdout.write(`MIN_READER: gstack ${minReader} (every lane that reads this policy needs at least this version)\n`);
      return loaded.errors.length ? EXIT.fail : EXIT.ok;
    }
    process.stdout.write(renderEffective(loaded, { base: flag(rest, '--base') ?? resolveBaseBranch(root) }));
    return loaded.errors.length ? EXIT.fail : EXIT.ok;
  }

  if (cmd === 'check-history') {
    const loaded = load(root, rest, 'base');
    if (typeof loaded === 'number') return loaded;
    const branch = flag(rest, '--branch') ?? (spawnSync('git', ['branch', '--show-current'], { cwd: root, encoding: 'utf8', timeout: 15_000 }).stdout ?? '').trim();
    const policy = loaded.policy.history;
    const plan = flag(rest, '--plan') ?? 'merge';
    if (!['merge', 'squash', 'rebase'].includes(plan)) return usage(`--plan must be merge, squash or rebase (got ${plan})`);
    const result: Record<string, unknown> = { history: policy, branch: branch || null, plan };
    let verdict: string;
    let code = EXIT.ok;
    if (policy !== 'merge-only') verdict = `HISTORY: squash-ok (no check; policy history=${policy}; plan=${plan})`;
    else if (plan !== 'merge') {
      verdict = `HISTORY: refused (plan=${plan} rewrites history; policy history=merge-only keeps every reviewed commit reachable so gate evidence and preregistration ancestry stay bound to the shas that were gated) — fix: integrate with a merge commit, or set history: squash-ok in .gstack/ship-policy.json on the base branch (HISTORY_POLICY_VIOLATION)`;
      code = EXIT.refused;
    }
    else if (!branch) { verdict = 'HISTORY: merge-only (detached HEAD; no pushed branch to compare)'; }
    else {
      const remote = spawnSync('git', ['rev-parse', '--verify', '--quiet', `refs/remotes/origin/${branch}`], { cwd: root, encoding: 'utf8', timeout: 15_000 });
      if (remote.status !== 0) verdict = `HISTORY: merge-only (origin/${branch} not pushed yet; nothing to rewrite)`;
      else {
        const anc = spawnSync('git', ['merge-base', '--is-ancestor', remote.stdout.trim(), 'HEAD'], { cwd: root, timeout: 15_000 });
        result.remote = remote.stdout.trim();
        if (anc.status === 0) verdict = `HISTORY: ok (merge-only; origin/${branch} is an ancestor of HEAD)`;
        else {
          verdict = `HISTORY: rewritten (origin/${branch} ${remote.stdout.trim().slice(0, 12)} is not an ancestor of HEAD) — fix: ${'merge origin/<base> instead of rebasing or squashing; never force-push under history: merge-only'} (HISTORY_POLICY_VIOLATION)`;
          code = EXIT.fail;
        }
      }
    }
    result.ok = code === EXIT.ok;
    result.verdict = verdict;
    process.stdout.write(json ? JSON.stringify(result) + '\n' : verdict + '\n');
    return code;
  }

  return usage(`unknown command ${cmd}`);
}

process.exitCode = main(process.argv.slice(2));