#!/usr/bin/env node
/**
 * Stamp every staged `docs/work/**\/*.md` file's frontmatter `updated:` field
 * to the current ISO 8601 timestamp. Runs from `.husky/pre-commit` before
 * `pnpm work rebuild-state`, so `_state.json` sees the fresh value.
 *
 * Idempotent: re-running produces the same result. The script silently no-ops
 * on files without frontmatter or without an `updated:` line to replace —
 * adds the field after `created:` if missing.
 *
 * Only stamps files explicitly listed in the staged diff; never walks the
 * tree. That way the timestamp tracks "the last commit that actually
 * modified the file," not "the last commit period."
 */
import { execSync } from "node:child_process";
import fs from "node:fs";
import path from "node:path";

const REPO_ROOT = execSync("git rev-parse --show-toplevel", {
  encoding: "utf8",
}).trim();

function stagedWorkDocs() {
  const out = execSync("git diff --cached --name-only --diff-filter=ACMR", {
    cwd: REPO_ROOT,
    encoding: "utf8",
  });
  return out
    .split("\n")
    .map((p) => p.trim())
    .filter(
      (p) =>
        p.startsWith("docs/work/") &&
        p.endsWith(".md") &&
        !p.endsWith("README.md"),
    );
}

function stampUpdated(content, isoNow) {
  const fmMatch = content.match(/^(---\n)([\s\S]+?)(\n---)/);
  if (!fmMatch) return content;
  const [full, openDelim, body, closeDelim] = fmMatch;

  let newBody;
  if (/^updated:\s*/m.test(body)) {
    newBody = body.replace(/^updated:\s*.*$/m, `updated: ${isoNow}`);
  } else if (/^created:\s*/m.test(body)) {
    // Insert `updated:` immediately after the `created:` line.
    newBody = body.replace(/^(created:\s*.*)$/m, `$1\nupdated: ${isoNow}`);
  } else {
    return content;
  }
  return content.replace(full, `${openDelim}${newBody}${closeDelim}`);
}

function main() {
  const files = stagedWorkDocs();
  if (files.length === 0) return;
  const isoNow = new Date().toISOString();
  let touched = 0;
  for (const rel of files) {
    const abs = path.join(REPO_ROOT, rel);
    if (!fs.existsSync(abs)) continue;
    const original = fs.readFileSync(abs, "utf8");
    const next = stampUpdated(original, isoNow);
    if (next === original) continue;
    fs.writeFileSync(abs, next);
    execSync(`git add ${JSON.stringify(rel)}`, { cwd: REPO_ROOT });
    touched++;
  }
  if (touched > 0) {
    console.log(
      `bump-updated-timestamps: stamped ${touched} file(s) at ${isoNow}`,
    );
  }
}

main();