'use strict';
// Minimal YAML front matter: flat `key: value`, inline `[a, b]` lists and `- item` lists.
// Unknown keys are kept and written back, so notes from Obsidian survive a round trip.

const FM = /^?---\r?\n([\s\S]*?)\r?\n---[ \t]*(?:\r?\n|$)/;

function unquote(v) {
  v = v.trim();
  if (v.length >= 2 && v.startsWith('"') && v.endsWith('"')) {
    try { return JSON.parse(v); } catch { return v.slice(1, -1); }
  }
  if (v.length >= 2 && v.startsWith("'") && v.endsWith("'")) return v.slice(1, -1).replace(/''/g, "'");
  return v;
}

function parseFrontMatter(raw) {
  const m = raw.match(FM);
  if (!m) return { meta: {}, body: raw };
  const meta = {};
  let last = null;
  for (const line of m[1].split(/\r?\n/)) {
    const kv = line.match(/^([A-Za-z0-9_-]+):\s*(.*)$/);
    if (kv) {
      last = kv[1];
      const v = kv[2].trim();
      if (v.startsWith('[') && v.endsWith(']')) {
        meta[last] = v.slice(1, -1).split(',').map(unquote).filter(Boolean);
      } else {
        meta[last] = v === '' ? [] : unquote(v);
      }
      continue;
    }
    const item = line.match(/^\s*-\s+(.*)$/);
    if (item && last) {
      if (!Array.isArray(meta[last])) meta[last] = [];
      meta[last].push(unquote(item[1]));
    }
  }
  // An empty `key:` with no list items below it is just an empty string.
  for (const k of Object.keys(meta)) if (Array.isArray(meta[k]) && !meta[k].length && k !== 'tags') meta[k] = '';
  return { meta, body: raw.slice(m[0].length).replace(/^\r?\n/, '') };
}

function quote(s) {
  s = String(s);
  return /^[\p{L}\p{N}_ .\/@#+-]+$/u.test(s) && s.trim() === s && !/^[-#@]/.test(s) ? s : JSON.stringify(s);
}

const ORDER = ['icon', 'cover', 'tags', 'created'];

function serializeFrontMatter(meta = {}) {
  const keys = Object.keys(meta).filter((k) => {
    const v = meta[k];
    return v !== undefined && v !== null && v !== '' && !(Array.isArray(v) && !v.length);
  });
  if (!keys.length) return '';
  keys.sort((a, b) => {
    const ia = ORDER.indexOf(a), ib = ORDER.indexOf(b);
    return (ia < 0 ? 99 : ia) - (ib < 0 ? 99 : ib);
  });
  const lines = keys.map((k) => {
    const v = meta[k];
    return Array.isArray(v) ? `${k}: [${v.map(quote).join(', ')}]` : `${k}: ${quote(v)}`;
  });
  return `---\n${lines.join('\n')}\n---\n\n`;
}

module.exports = { parseFrontMatter, serializeFrontMatter };