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

// §280F passenger-automobile annual depreciation caps, keyed by placed-in-service year (IRS Rev. Proc.,
// indexed annually). Mirrors the §179-limits reference service: cached for the engine, CRUD for admins.

let cache = null;

function clearCache() {
  cache = null;
}

function rows() {
  if (!cache) cache = all('SELECT * FROM section_280f_limits ORDER BY pis_year');
  return cache;
}

// Caps for a placed-in-service year: the most recent configured year at or before it, or null.
function getLimit(year) {
  const y = Number(year);
  if (!y) return null;
  let match = null;
  for (const row of rows()) {
    if (row.pis_year <= y) match = row;
    else break;
  }
  return match;
}

function fromRow(row) {
  return {
    id: row.id,
    pis_year: row.pis_year,
    year1_no_bonus: row.year1_no_bonus,
    year1_bonus: row.year1_bonus,
    year2: row.year2,
    year3: row.year3,
    year4plus: row.year4plus
  };
}

function list() {
  return all('SELECT * FROM section_280f_limits ORDER BY pis_year DESC').map(fromRow);
}

function normalize(body) {
  return {
    pis_year: Math.trunc(Number(body.pis_year)) || 0,
    year1_no_bonus: Number(body.year1_no_bonus) || 0,
    year1_bonus: Number(body.year1_bonus) || 0,
    year2: Number(body.year2) || 0,
    year3: Number(body.year3) || 0,
    year4plus: Number(body.year4plus) || 0
  };
}

function createLimit(body, userId) {
  const input = normalize(body);
  if (!input.pis_year) throw Object.assign(new Error('A valid placed-in-service year is required'), { status: 400 });
  if (one('SELECT id FROM section_280f_limits WHERE pis_year = ?', [input.pis_year])) {
    throw Object.assign(new Error('Caps for that year already exist'), { status: 400 });
  }
  const ts = now();
  run(
    `INSERT INTO section_280f_limits (pis_year, year1_no_bonus, year1_bonus, year2, year3, year4plus, created_at, updated_at)
     VALUES (?, ?, ?, ?, ?, ?, ?, ?)`,
    [input.pis_year, input.year1_no_bonus, input.year1_bonus, input.year2, input.year3, input.year4plus, ts, ts]
  );
  clearCache();
  audit(userId, 'create', 'section_280f_limit', String(input.pis_year), null, input);
  return fromRow(one('SELECT * FROM section_280f_limits WHERE pis_year = ?', [input.pis_year]));
}

function updateLimit(year, body, userId) {
  const before = one('SELECT * FROM section_280f_limits WHERE pis_year = ?', [Number(year)]);
  if (!before) return null;
  const input = normalize({ ...fromRow(before), ...body, pis_year: before.pis_year });
  run(
    'UPDATE section_280f_limits SET year1_no_bonus = ?, year1_bonus = ?, year2 = ?, year3 = ?, year4plus = ?, updated_at = ? WHERE pis_year = ?',
    [input.year1_no_bonus, input.year1_bonus, input.year2, input.year3, input.year4plus, now(), before.pis_year]
  );
  clearCache();
  audit(userId, 'update', 'section_280f_limit', String(before.pis_year), fromRow(before), input);
  return fromRow(one('SELECT * FROM section_280f_limits WHERE pis_year = ?', [before.pis_year]));
}

function deleteLimit(year, userId) {
  const before = one('SELECT * FROM section_280f_limits WHERE pis_year = ?', [Number(year)]);
  if (!before) return false;
  run('DELETE FROM section_280f_limits WHERE pis_year = ?', [before.pis_year]);
  clearCache();
  audit(userId, 'delete', 'section_280f_limit', String(before.pis_year), fromRow(before), null);
  return true;
}

module.exports = { clearCache, createLimit, deleteLimit, getLimit, list, updateLimit };