#!/usr/bin/env bun
/**
 * gstack-gate-diff — list the gate edits in a candidate so a human can
 * disposition each one (W1 of docs/designs/HONEST_WORK_GATE_INTEGRITY.md).
 *
 *   gstack-gate-diff [base-ref] [--format table|jsonl] [--commit <sha>] [--help]
 *
 * The tool produces the inventory and the tags; it never judges and never
 * suppresses. stdout, first line always:
 *
 *   GATE_SUMMARY: listed=N eligible=N inspected=N unread=N tagged={RH-1:2,RH-15:1}
 *     unmatched=N coverage=RH-1,… languages_unlisted=<csv|none>
 *     candidate=<merge-base-short>+<wtree-short> artifact=<absolute path>
 *
 * then the read-level listing (table) or one JSON object per listed hunk
 * (jsonl). Diagnostics go to stderr. The full jsonl is always written to
 * $GSTACK_STATE_ROOT/projects/<slug>/gate-diff/<candidate>.jsonl (mode 0600,
 * never inside the working tree: an untracked file under the repo would flip
 * /review's review_binding and make /ship loop).
 *
 * Exit: 0 with or without hunks. 2 only when the base is unresolvable
 * (`GATE_ERROR=no_base ref=<ref> fix=<git command>` as the only stdout line)
 * or the tool itself failed (`GATE_ERROR=internal …`). Unmatched paths are
 * counted, never an exit 2.
 */
import * as fs from 'node:fs';
import * as path from 'node:path';
import * as os from 'node:os';
import { scanCandidate, parseGateIntegrityBlock, specDirectoryHoldsSpecs, type FileDiff, type CommitInfo } from '../lib/gate-diff/index';
import {
  commitInfo, commitsInRange, defaultBase, diffCommit, diffWorkingTree, firstParent, headSha, mergeBase, noBaseFix, readClaudeMd, repoRoot,
  resolvesToCommit, treePaths, untrackedAsAdded,
} from '../lib/gate-diff/git';
import { renderDiagnostics, renderJsonl, renderJsonlBody, renderTable } from '../lib/gate-diff/render';
import { resolveStateRoot } from '../lib/state-root';
import { runScriptSync, wtreeFingerprint } from '../lib/script-invocation';

const BIN_DIR = path.dirname(Bun.fileURLToPath(import.meta.url));
const USAGE = `usage: gstack-gate-diff [base-ref] [--format table|jsonl] [--commit <sha>] [--help]

Lists every hunk in a test, CI, runner/lint-config, snapshot or golden path of the
candidate (merge-base of <base-ref> and HEAD -> working tree + untracked files),
tags the gate edits it recognises (RH-1 RH-3 RH-4 RH-12 RH-13 RH-14 RH-15 RH-16),
and prints the read-level listing after one GATE_SUMMARY: line. --commit <sha>
scans that commit's first-parent delta instead of the working tree.
Exit 0 with or without hunks; 2 only for an unresolvable base (GATE_ERROR=no_base)
or a tool failure (GATE_ERROR=internal). Full jsonl artifact path is in the summary.`;

interface Args {
  base?: string;
  format: 'table' | 'jsonl';
  commit?: string;
  help: boolean;
}

function parseArgs(argv: string[]): Args | string {
  const args: Args = { format: 'table', help: false };
  for (let i = 0; i < argv.length; i++) {
    const a = argv[i];
    if (a === '--help' || a === '-h') args.help = true;
    else if (a === '--format') {
      const v = argv[++i];
      if (v !== 'table' && v !== 'jsonl') return `--format must be table or jsonl, got ${JSON.stringify(v ?? '')}`;
      args.format = v;
    } else if (a.startsWith('--format=')) {
      const v = a.slice(9);
      if (v !== 'table' && v !== 'jsonl') return `--format must be table or jsonl, got ${JSON.stringify(v)}`;
      args.format = v;
    } else if (a === '--commit') {
      const v = argv[++i];
      if (!v || v.startsWith('-')) return '--commit requires a <sha>';
      args.commit = v;
    } else if (a.startsWith('-')) return `unknown option ${a}`;
    else if (args.base !== undefined) return `unexpected extra argument ${a}`;
    else args.base = a;
  }
  return args;
}

function projectSlug(cwd: string): string {
  try {
    const r = runScriptSync(path.join(BIN_DIR, 'gstack-slug'), [], { cwd, encoding: 'utf-8', timeout: 30_000 });
    if (r.error) console.error(`gstack-gate-diff: gstack-slug failed (${r.error.message}); artifact filed under projects/unknown`);
    const m = (r.stdout || '').match(/^SLUG=(.+)$/m);
    return m ? m[1].trim() : 'unknown';
  } catch (e: any) {
    console.error(`gstack-gate-diff: gstack-slug failed (${e?.message ?? e}); artifact filed under projects/unknown`);
    return 'unknown';
  }
}

/** The artifact directory: the state root, or the OS temp dir when no home resolves (never the working tree). */
function artifactDir(cwd: string): string {
  const root = resolveStateRoot();
  const base = root === '.gstack' ? path.join(os.tmpdir(), 'gstack-gate-diff') : root;
  if (root === '.gstack') console.error(`gstack-gate-diff: no HOME/GSTACK_HOME — artifact goes to ${base} instead of the state root`);
  return path.join(base, 'projects', projectSlug(cwd), 'gate-diff');
}

function writeArtifact(file: string, body: string): void {
  fs.mkdirSync(path.dirname(file), { recursive: true, mode: 0o700 });
  fs.writeFileSync(file, body, { mode: 0o600 });
  fs.chmodSync(file, 0o600);
}

function main(argv: string[]): number {
  const parsed = parseArgs(argv);
  if (typeof parsed === 'string') {
    console.error(`gstack-gate-diff: ${parsed}\n${USAGE}`);
    process.stdout.write(`GATE_ERROR=internal reason=usage detail=${JSON.stringify(parsed)}\n`);
    return 2;
  }
  if (parsed.help) {
    console.log(USAGE);
    return 0;
  }
  const cwd = process.cwd();
  const root = repoRoot(cwd);
  if (!root) {
    process.stdout.write(`GATE_ERROR=internal reason=not_a_git_repository cwd=${cwd}\n`);
    return 2;
  }

  let files: FileDiff[];
  let commits: CommitInfo[];
  let candidate: string;
  let specIsTestPath: boolean;
  if (parsed.commit) {
    const sha = resolvesToCommit(parsed.commit, root);
    if (!sha) {
      process.stdout.write(`GATE_ERROR=no_base ref=${parsed.commit} fix=${noBaseFix(parsed.commit, root)}\n`);
      return 2;
    }
    if (!firstParent(sha, root)) {
      process.stdout.write(`GATE_ERROR=no_base ref=${sha.slice(0, 12)}^ fix=${noBaseFix(`${sha}^`, root)}\n`);
      return 2;
    }
    files = diffCommit(sha, root);
    const info = commitInfo(sha, root);
    commits = info ? [info] : [];
    candidate = sha.slice(0, 12);
    specIsTestPath = specDirectoryHoldsSpecs(treePaths(root, sha));
  } else {
    const baseRef = parsed.base ?? defaultBase(root);
    const baseSha = resolvesToCommit(baseRef, root);
    const head = headSha(root);
    if (!baseSha || !head) {
      process.stdout.write(`GATE_ERROR=no_base ref=${baseRef} fix=${noBaseFix(baseRef, root)}\n`);
      return 2;
    }
    const mb = mergeBase(baseSha, head, root);
    if (!mb) {
      process.stdout.write(`GATE_ERROR=no_base ref=${baseRef} fix=${noBaseFix(baseRef, root)}\n`);
      return 2;
    }
    files = [...diffWorkingTree(mb, root), ...untrackedAsAdded(root, root)];
    commits = commitsInRange(mb, head, root);
    const fp = wtreeFingerprint({ cwd: root });
    if ('error' in fp) console.error(`gstack-gate-diff: working-tree fingerprint unavailable (${fp.error}); candidate recorded without it`);
    candidate = `${mb.slice(0, 12)}+${'tree' in fp ? fp.tree.slice(0, 12) : 'nowtree'}`;
    specIsTestPath = specDirectoryHoldsSpecs(treePaths(root));
  }

  const artifact = path.join(artifactDir(root), `${candidate}.jsonl`);
  const result = scanCandidate({
    files, commits, candidate, artifact, specIsTestPath,
    project: parseGateIntegrityBlock(readClaudeMd(root)),
  });
  writeArtifact(artifact, renderJsonlBody(result));
  for (const line of renderDiagnostics(result)) console.error(line);
  process.stdout.write(parsed.format === 'jsonl' ? renderJsonl(result) : renderTable(result));
  return 0;
}

try {
  // exitCode, not process.exit(): a large listing may still be in flight on the stdout pipe.
  process.exitCode = main(process.argv.slice(2));
} catch (e: any) {
  console.error(`gstack-gate-diff: ${e?.stack ?? e}`);
  process.stdout.write(`GATE_ERROR=internal reason=exception detail=${JSON.stringify(String(e?.message ?? e))}\n`);
  process.exitCode = 2;
}