#!/usr/bin/env node
// okf-index.mjs
// Genererer OKF-kompatible `index.md` per nivaa i en bundle-rot (prosjekt
// `.claude/okr/` eller home `~/.claude/okr/org/`). Verbatim OKF-«Documents/kb
// Layout»-index-form:
//   # Overskrift
//
//   okf_version: <ver>      (KUN rot-index)
//
//   * [title](relativ.md) - description
// Ingen frontmatter paa index.md (OKF-reservert). Konsept-filers `title`/
// `description` leses via lib/frontmatter.mjs. Underkataloger faar en peker til
// sin egen index.md. Kjoeres PER ROT (de to bundlene har ulik livssyklus).
//
// Idempotens / vedlikehold (NFR): en eksisterende index.md sin `# overskrift`,
// rotens `okf_version`-verdi, og menneske-skrevne beskrivelser for underkatalog-
// pekere bevares; konsept-entries regenereres alltid fra frontmatter (autoritativ
// kilde). Skriving er atomisk (temp + renameSync), jf. write-org-profile.mjs.
//
// Zero npm dependencies (node:-builtins).

import { readdirSync, readFileSync, writeFileSync, existsSync, renameSync } from 'node:fs';
import { join, basename } from 'node:path';
import { fileURLToPath } from 'node:url';
import { parseFrontmatter } from '../lib/frontmatter.mjs';

export const OKF_VERSION = 'kb-layout-2026-06';

// "strategisk-kontekst" -> "Strategisk kontekst"
function titleFromName(name) {
  const spaced = name.replace(/[-_]+/g, ' ').trim();
  return spaced.charAt(0).toUpperCase() + spaced.slice(1);
}

// Parse en eksisterende index.md for bevaring: overskrift, okf_version, og
// beskrivelser pr. lenke (for underkatalog-pekere). Kaster aldri.
function parseExistingIndex(path) {
  const result = { heading: null, okfVersion: null, descByLink: {} };
  if (!existsSync(path)) return result;
  for (const line of readFileSync(path, 'utf8').split('\n')) {
    if (result.heading === null && line.startsWith('# ')) {
      result.heading = line.slice(2).trim();
    }
    const ver = line.match(/^okf_version:\s*(.+)$/);
    if (ver) result.okfVersion = ver[1].trim();
    const entry = line.match(/^\*\s*\[([^\]]*)\]\(([^)]+)\)(?:\s*-\s*(.*))?$/);
    if (entry) result.descByLink[entry[2]] = { title: entry[1], desc: (entry[3] || '').trim() };
  }
  return result;
}

// Bygg en enkelt entry-linje paa OKF-form. Tom beskrivelse -> dropp ` - d`.
function entryLine(title, link, desc) {
  return desc ? `* [${title}](${link}) - ${desc}` : `* [${title}](${link})`;
}

// Generer og skriv index.md for EN katalog (ikke rekursivt). isRoot styrer okf_version.
function writeIndexFor(dir, isRoot, okfVersion) {
  const existing = parseExistingIndex(join(dir, 'index.md'));
  const dirents = readdirSync(dir, { withFileTypes: true });
  const subdirs = dirents.filter((e) => e.isDirectory()).map((e) => e.name).sort();
  const concepts = dirents
    .filter((e) => e.isFile() && e.name.endsWith('.md') && e.name !== 'index.md')
    .map((e) => e.name)
    .sort();

  const heading = existing.heading
    || (isRoot ? 'OKF second brain' : titleFromName(basename(dir)));

  const lines = [`# ${heading}`, ''];
  if (isRoot) {
    lines.push(`okf_version: ${existing.okfVersion || okfVersion}`, '');
  }

  for (const sd of subdirs) {
    const link = `${sd}/index.md`;
    const prev = existing.descByLink[link];
    lines.push(entryLine(prev?.title || titleFromName(sd), link, prev?.desc || 'Underkatalog.'));
  }
  for (const c of concepts) {
    const { get } = parseFrontmatter(readFileSync(join(dir, c), 'utf8'));
    const title = get('title') || titleFromName(basename(c, '.md'));
    lines.push(entryLine(title, c, get('description') || ''));
  }

  const content = `${lines.join('\n')}\n`;
  const tmp = join(dir, `.index.md.${process.pid}.tmp`);
  writeFileSync(tmp, content);
  renameSync(tmp, join(dir, 'index.md'));
}

// Generer index.md for rot + alle underkataloger, rekursivt.
export function generateIndexes(root, opts = {}) {
  const okfVersion = opts.okfVersion || OKF_VERSION;
  const walk = (dir, isRoot) => {
    writeIndexFor(dir, isRoot, okfVersion);
    for (const e of readdirSync(dir, { withFileTypes: true })) {
      if (e.isDirectory()) walk(join(dir, e.name), false);
    }
  };
  if (!existsSync(root)) throw new Error(`Bundle-rot finnes ikke: ${root}`);
  walk(root, true);
}

// --- CLI ---
const isMain = process.argv[1]
  && fileURLToPath(import.meta.url) === process.argv[1];
if (isMain) {
  const root = process.argv[2];
  if (!root) {
    process.stderr.write('Bruk: node okf-index.mjs <bundle-rot> [--okf-version <ver>]\n');
    process.exit(2);
  }
  const vi = process.argv.indexOf('--okf-version');
  const okfVersion = vi !== -1 ? process.argv[vi + 1] : undefined;
  generateIndexes(root, { okfVersion });
  process.stdout.write(`OKF-index generert for ${root}\n`);
}