#!/usr/bin/env bun
/**
 * gstack-issue-links — issue links by intent for /ship Step 18 (plan C6).
 *
 *   gstack-issue-links [--base <ref>] [--issue <n>]... [--ci-run <id>]... [--repo <owner/repo>] [--out <issues.json>] [--json]
 *
 * Reads `git log origin/<base>..HEAD` and classifies every issue mention:
 * `Fixes #N` only on explicit closure intent (a Fixes/Closes/Resolves trailer
 * or --issue), `Refs #N` for everything else (bare mentions, partial fixes,
 * deferred asks, cross-repo ids). Each closure issue is read through
 * gstack-issue-guard; unreadable ones are downgraded to Refs
 * (ISSUE_UNREADABLE). Each --ci-run id is searched among open issues whose
 * body names it (bot flake issues) and rendered `Flake: #N (run <id>)`.
 * Prints the `## Issues` lines; --json / --out emit the receipt's `issues`
 * object for `gstack-ship-receipt write --issues @file`. Logic: lib/issue-links.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 { mentionsIn, receiptIssues, renderIssueLines, resolveLinks, type IssueMention } from '../lib/issue-links';
import { resultLine } from '../lib/result-codes';
import { resolveBaseBranch } from '../lib/ship-policy';

const HELP = `gstack-issue-links — Fixes only on explicit closure intent; everything else is Refs (docs/pregate.md#issue-links)

  --base <ref>        base branch (default: origin/HEAD, else main); commits origin/<base>..HEAD are read
  --issue <n>         explicit closure intent (repeatable); still read through gstack-issue-guard
  --ci-run <id>       a failing CI run id (repeatable); open issues naming it become Flake: #N (run <id>)
  --repo <owner/repo> repository for gh (default: the current remote)
  --out <file>        write the issues object (fixes, refs, flakes) for gstack-ship-receipt write --issues @file
  --json              JSON only on stdout

Exit 0 with links or none; 1 when a closure issue was unreadable (its link is Refs); 2 usage.
${exitTableHelp()}`;

function flags(args: string[], name: string): string[] {
  const out: string[] = [];
  for (let i = 0; i < args.length; i++) if (args[i] === name && args[i + 1] !== undefined) out.push(args[++i]!);
  return out;
}
function git(args: string[], cwd: string): string | undefined {
  const r = spawnSync('git', args, { cwd, encoding: 'utf8', timeout: 30_000, maxBuffer: 64 * 1024 * 1024 });
  return r.status === 0 ? r.stdout : undefined;
}

function main(argv: string[]): number {
  if (argv.includes('--help') || argv.includes('-h')) { process.stdout.write(HELP + '\n'); return EXIT.ok; }
  const json = argv.includes('--json');
  const repoRoot = git(['rev-parse', '--show-toplevel'], process.cwd())?.trim() ?? process.cwd();
  const base = flags(argv, '--base')[0] ?? resolveBaseBranch(repoRoot);
  const explicit: number[] = [];
  for (const raw of flags(argv, '--issue')) {
    if (!/^\d+$/.test(raw)) { process.stderr.write(`gstack-issue-links: --issue must be a positive integer, got ${JSON.stringify(raw)}\n`); return EXIT.usage; }
    explicit.push(Number(raw));
  }
  const runs = flags(argv, '--ci-run');
  if (runs.some(r => !/^[A-Za-z0-9_.-]{1,64}$/.test(r))) { process.stderr.write('gstack-issue-links: --ci-run ids are alphanumeric\n'); return EXIT.usage; }
  const repoFlag = flags(argv, '--repo')[0];
  const repoArgs = repoFlag ? ['--repo', repoFlag] : [];
  const binDir = path.dirname(Bun.fileURLToPath(import.meta.url));

  const log = git(['log', '--format=%H%n%B%x00', `origin/${base}..HEAD`], repoRoot) ?? git(['log', '--format=%H%n%B%x00', `${base}..HEAD`], repoRoot);
  if (log === undefined) { process.stderr.write(`gstack-issue-links: cannot read commits ${base}..HEAD (fetch origin/${base} first)\n`); return EXIT.usage; }
  const mentions: IssueMention[] = [];
  for (const entry of log.split('\0')) {
    const nl = entry.indexOf('\n');
    if (nl < 0) continue;
    mentions.push(...mentionsIn(entry.slice(nl + 1), `commit ${entry.slice(0, nl).trim().slice(0, 12)}`));
  }
  const readable = (issue: number): boolean => {
    const r = spawnSync(path.join(binDir, 'gstack-issue-guard'), ['issue', String(issue)], { cwd: repoRoot, encoding: 'utf8', timeout: 60_000, maxBuffer: 16 * 1024 * 1024 });
    return r.status === 0 && r.stdout.length > 0;
  };
  const flakes: Array<{ issue: number; run: string }> = [];
  for (const run of runs) {
    const r = spawnSync('gh', ['issue', 'list', ...repoArgs, '--state', 'open', '--search', `"${run}" in:body`, '--limit', '20', '--json', 'number'], { cwd: repoRoot, encoding: 'utf8', timeout: 60_000 });
    if (r.status !== 0) { process.stderr.write(`gstack-issue-links: flake search for run ${run} failed: ${(r.stderr ?? '').trim()}\n`); continue; }
    try { for (const row of JSON.parse(r.stdout) as Array<{ number: number }>) flakes.push({ issue: row.number, run }); }
    catch { process.stderr.write(`gstack-issue-links: flake search for run ${run} returned no JSON\n`); }
  }
  const links = resolveLinks(mentions, explicit, readable, flakes);
  for (const n of links.unreadable) process.stderr.write(resultLine('gstack-issue-links', 'ISSUE_UNREADABLE', `#${n}`) + '\n');
  const out = flags(argv, '--out')[0];
  if (out) { fs.mkdirSync(path.dirname(out), { recursive: true }); fs.writeFileSync(out, JSON.stringify(receiptIssues(links), null, 2) + '\n'); }
  if (json) process.stdout.write(JSON.stringify({ ...receiptIssues(links), cross: links.cross, unreadable: links.unreadable, lines: renderIssueLines(links) }) + '\n');
  else {
    const lines = renderIssueLines(links);
    process.stdout.write(lines.length ? lines.join('\n') + '\n' : 'ISSUE_LINKS: none\n');
    for (const m of mentions) process.stderr.write(`  ${m.intent === 'fixes' ? 'closure' : 'reference'} ${m.repo ? `${m.repo}#` : '#'}${m.issue} ← ${m.source}\n`);
  }
  return links.unreadable.length ? EXIT.fail : EXIT.ok;
}

process.exit(main(process.argv.slice(2)));