// WHY: sections are identified by emoji header; order defines generated layout
const SECTIONS = [
  { key: 'completed', header: /^## ✅/, emoji: '✅', hasNote: false },
  { key: 'todo', header: /^## 🚀/, emoji: '⏳', hasNote: true },
  { key: 'inProgress', header: /^## 🔄/, emoji: '🔄', hasNote: true },
  { key: 'backlog', header: /^## 📋/, emoji: '📋', hasNote: false }
];

const SECTION_LABEL = {
  completed: 'Befejezett',
  todo: 'TODO',
  inProgress: 'In Progress',
  backlog: 'Backlog'
};

function parseTodoFile(content) {
  const sections = {
    completed: { header: null, rows: [] },
    todo: { header: null, rows: [] },
    inProgress: { header: null, rows: [] },
    backlog: { header: null, rows: [] }
  };
  const rows = [];
  let current = null;

  for (const line of content.split('\n')) {
    const sec = SECTIONS.find(s => s.header.test(line));
    if (sec) {
      current = sec.key;
      if (!sections[current].header) sections[current].header = line;
      continue;
    }
    if (!current || !line.trim().startsWith('|')) continue;
    const cols = line.split('|').map(c => c.trim()).filter(c => c !== '');
    if (cols.length < 3) continue;
    if (cols[0] === 'Plane' || /^[-]+$/.test(cols[0])) continue;
    const row = { id: cols[0], name: cols[1], status: cols[2], note: cols[3] || '' };
    sections[current].rows.push(row);
    rows.push({ section: current, ...row });
  }

  return { sections, rows };
}

function seqNum(id) {
  const match = id.match(/(\d+)$/);
  return match ? parseInt(match[1], 10) : 0;
}

function buildTable(sec, rows) {
  const header = sec.hasNote
    ? '| Plane | Feladat | Státusz | Megjegyzés |'
    : '| Plane | Feladat | Státusz |';
  const separator = sec.hasNote
    ? '|-------|---------|---------|-----------|'
    : '|-------|---------|---------|';
  const body = rows
    .slice()
    .sort((a, b) => seqNum(a.id) - seqNum(b.id))
    .map(row => {
      if (sec.hasNote) return `| ${row.id} | ${row.name} | ${sec.emoji} | ${row.note || ''} |`;
      return `| ${row.id} | ${row.name} | ${sec.emoji} |`;
    });
  return [header, separator, ...body].join('\n');
}

// WHY: only the section region is regenerated, prefix/suffix (overview, commands) are preserved.
// Prefix/suffix are trimmed and rejoined with normalized separators so that a previous run
// that dropped the blank line after `---` cannot corrupt the section headers (`---## ✅`).
function regenerate(content, finalSections) {
  const lines = content.split('\n');
  const firstIdx = lines.findIndex(l => SECTIONS[0].header.test(l));
  const backlogIdx = lines.findIndex(l => SECTIONS[3].header.test(l));
  if (firstIdx === -1 || backlogIdx === -1) throw new Error('TODO.md section headers not found');

  let endIdx = lines.length;
  for (let i = backlogIdx + 1; i < lines.length; i++) {
    if (lines[i].trim() === '---') {
      endIdx = i;
      break;
    }
  }

  const prefix = lines.slice(0, firstIdx).join('\n').trimEnd();
  const suffix = lines.slice(endIdx + 1).join('\n').trimStart();

  const headerOf = key => {
    const sec = SECTIONS.find(s => s.key === key);
    const idx = lines.findIndex(l => sec.header.test(l));
    return idx >= 0 ? lines[idx].replace(/^## /, '') : key;
  };

  const blocks = SECTIONS.map(sec => {
    const rows = finalSections[sec.key] || [];
    return `## ${headerOf(sec.key)}\n\n${buildTable(sec, rows)}`;
  });
  const middle = blocks.join('\n\n---\n\n');
  const result = `${prefix}\n\n${middle}\n\n---\n\n${suffix}`;
  return result.endsWith('\n') ? result : `${result}\n`;
}

module.exports = { SECTIONS, SECTION_LABEL, parseTodoFile, buildTable, regenerate, seqNum };