const { all, audit, now, one, parseJson, run } = require('../db');

const SOURCES = ['common', 'industry', 'business', 'custom'];

// How many asset categories reference a given class number (categories store it in metadata).
function categoryUsage() {
  const counts = {};
  for (const row of all("SELECT metadata FROM reference_values WHERE type = 'category'")) {
    const num = parseJson(row.metadata, {}).asset_class_number;
    if (num) counts[num] = (counts[num] || 0) + 1;
  }
  return counts;
}

function fromRow(row, usage) {
  if (!row) return null;
  return {
    id: row.id,
    class_number: row.class_number,
    description: row.description,
    gds: row.gds,
    ads: row.ads,
    source: row.source,
    table: row.source, // back-compat alias used by the category picker
    category_count: row.class_number ? (usage[row.class_number] || 0) : 0
  };
}

function list() {
  const usage = categoryUsage();
  return all('SELECT * FROM asset_classes ORDER BY description').map((row) => fromRow(row, usage));
}

function getClass(id) {
  return fromRow(one('SELECT * FROM asset_classes WHERE id = ?', [id]), categoryUsage());
}

function normalize(body) {
  const num = (value) => {
    if (value === '' || value === null || value === undefined) return null;
    const n = Number(value);
    return Number.isFinite(n) ? n : null;
  };
  return {
    class_number: body.class_number ? String(body.class_number).trim() : null,
    description: String(body.description || '').trim(),
    gds: num(body.gds),
    ads: num(body.ads),
    source: SOURCES.includes(body.source) ? body.source : 'custom'
  };
}

function createClass(body, userId) {
  const input = normalize(body);
  if (!input.description) throw Object.assign(new Error('A description is required'), { status: 400 });
  const ts = now();
  const result = run(
    'INSERT INTO asset_classes (class_number, description, gds, ads, source, created_at, updated_at) VALUES (?, ?, ?, ?, ?, ?, ?)',
    [input.class_number, input.description, input.gds, input.ads, input.source, ts, ts]
  );
  audit(userId, 'create', 'asset_class', result.lastInsertRowid, null, input);
  return getClass(result.lastInsertRowid);
}

function updateClass(id, body, userId) {
  const before = one('SELECT * FROM asset_classes WHERE id = ?', [id]);
  if (!before) return null;
  const input = normalize({ ...before, ...body });
  if (!input.description) throw Object.assign(new Error('A description is required'), { status: 400 });
  run(
    'UPDATE asset_classes SET class_number = ?, description = ?, gds = ?, ads = ?, source = ?, updated_at = ? WHERE id = ?',
    [input.class_number, input.description, input.gds, input.ads, input.source, now(), id]
  );
  audit(userId, 'update', 'asset_class', id, before, input);
  return getClass(id);
}

function deleteClass(id, userId) {
  const before = one('SELECT * FROM asset_classes WHERE id = ?', [id]);
  if (!before) return false;
  run('DELETE FROM asset_classes WHERE id = ?', [id]);
  audit(userId, 'delete', 'asset_class', id, before, null);
  return true;
}

module.exports = {
  SOURCES,
  createClass,
  deleteClass,
  getClass,
  list,
  updateClass
};