/**
 * Session todo list: merge-by-id, grok-shaped statuses. No Bare imports.
 */

const STATUSES = ['pending', 'in_progress', 'completed', 'cancelled'];

function normalizeStatus(s) {
  const v = String(s || 'pending')
    .toLowerCase()
    .replace(/[\s-]+/g, '_');
  if (v === 'done' || v === 'complete') return 'completed';
  if (v === 'progress' || v === 'doing' || v === 'inprogress') return 'in_progress';
  if (v === 'cancel' || v === 'canceled') return 'cancelled';
  if (STATUSES.indexOf(v) >= 0) return v;
  return 'pending';
}

function normalizeItem(t, i) {
  t = t || {};
  return {
    id: String(t.id || 'todo_' + (i + 1)),
    content: String(t.content || t.text || t.title || ''),
    status: normalizeStatus(t.status),
  };
}

function merge(existing, incoming, mode) {
  const next = Array.isArray(incoming) ? incoming.map(normalizeItem) : [];
  if (mode === 'replace' || !existing || !existing.length) return next;
  const byId = new Map();
  for (const t of existing) {
    const n = normalizeItem(t, 0);
    byId.set(n.id, n);
  }
  for (const t of next) {
    const prev = byId.get(t.id) || {};
    const merged = Object.assign({}, prev, t);
    if (!t.content && prev.content) merged.content = prev.content;
    byId.set(t.id, merged);
  }
  return Array.from(byId.values());
}

function hasOpen(list) {
  return (list || []).some((t) => t.status === 'pending' || t.status === 'in_progress');
}

function formatBlock(list) {
  const todos = list || [];
  if (!todos.length) return '[todos]\n(none)';
  return (
    '[todos]\n' +
    todos.map((t) => '- [' + t.status + '] ' + t.id + ': ' + t.content).join('\n')
  );
}

module.exports = { STATUSES, normalizeStatus, normalizeItem, merge, hasOpen, formatBlock };