Updated A LOT

server/services/leases.js

@@ -0,0 +1,146 @@
+const { all, audit, now, one, run } = require('../db');
+const { money } = require('../depreciation');
+
+const FREQUENCIES = { monthly: 12, quarterly: 4, semiannual: 2, annual: 1 };
+
+function periodsPerYear(frequency) {
+  return FREQUENCIES[frequency] || 12;
+}
+
+function addMonths(date, count) {
+  const next = new Date(date.getTime());
+  next.setMonth(next.getMonth() + count);
+  return next;
+}
+
+function listLeases(query = {}) {
+  return all(
+    `SELECT l.*, a.asset_id AS asset_code, a.description AS asset_description
+     FROM leases l
+     LEFT JOIN assets a ON a.id = l.asset_id
+     WHERE (? IS NULL OR l.asset_id = ?)
+     ORDER BY l.start_date DESC, l.id DESC`,
+    [query.asset_id || null, query.asset_id || null]
+  );
+}
+
+function getLease(id) {
+  return one('SELECT * FROM leases WHERE id = ?', [id]);
+}
+
+function createLease(input, userId) {
+  const timestamp = now();
+  const result = run(
+    `INSERT INTO leases (asset_id, lessor, contract_value, start_date, end_date, discount_rate, payment_frequency, notes, created_at, updated_at)
+     VALUES (?, ?, ?, ?, ?, ?, ?, ?, ?, ?)`,
+    [
+      input.asset_id || null,
+      input.lessor || null,
+      Number(input.contract_value || 0),
+      input.start_date || null,
+      input.end_date || null,
+      Number(input.discount_rate || 0),
+      input.payment_frequency || 'monthly',
+      input.notes || null,
+      timestamp,
+      timestamp
+    ]
+  );
+  audit(userId, 'create', 'lease', result.lastInsertRowid, null, input);
+  return getLease(result.lastInsertRowid);
+}
+
+function updateLease(id, input, userId) {
+  const before = getLease(id);
+  if (!before) return null;
+  run(
+    `UPDATE leases SET
+      lessor = ?, contract_value = ?, start_date = ?, end_date = ?, discount_rate = ?,
+      payment_frequency = ?, notes = ?, updated_at = ?
+     WHERE id = ?`,
+    [
+      input.lessor ?? before.lessor,
+      Number(input.contract_value ?? before.contract_value),
+      input.start_date ?? before.start_date,
+      input.end_date ?? before.end_date,
+      Number(input.discount_rate ?? before.discount_rate),
+      input.payment_frequency ?? before.payment_frequency,
+      input.notes ?? before.notes,
+      now(),
+      id
+    ]
+  );
+  audit(userId, 'update', 'lease', id, before, input);
+  return getLease(id);
+}
+
+function deleteLease(id, userId) {
+  const before = getLease(id);
+  if (!before) return false;
+  run('DELETE FROM leases WHERE id = ?', [id]);
+  audit(userId, 'delete', 'lease', id, before, null);
+  return true;
+}
+
+// Straight-line ROU amortization with an ASC 842-style liability schedule.
+function leaseSchedule(lease) {
+  if (!lease) return null;
+  const ppy = periodsPerYear(lease.payment_frequency);
+  const monthsPerPeriod = 12 / ppy;
+  const start = lease.start_date ? new Date(`${lease.start_date}T00:00:00`) : new Date();
+  const end = lease.end_date ? new Date(`${lease.end_date}T00:00:00`) : addMonths(start, 12);
+
+  const totalMonths = Math.max(monthsPerPeriod, (end.getFullYear() - start.getFullYear()) * 12 + (end.getMonth() - start.getMonth()));
+  const periods = Math.max(1, Math.round(totalMonths / monthsPerPeriod));
+
+  const contractValue = Number(lease.contract_value || 0);
+  const payment = contractValue / periods;
+  const rate = Number(lease.discount_rate || 0) / 100 / ppy;
+  const presentValue = rate > 0 ? payment * (1 - (1 + rate) ** -periods) / rate : contractValue;
+
+  const rouAmortization = presentValue / periods;
+  let liability = presentValue;
+  let rouBalance = presentValue;
+  let totalInterest = 0;
+  const rows = [];
+
+  for (let period = 1; period <= periods; period += 1) {
+    const interest = liability * rate;
+    const principal = payment - interest;
+    liability = Math.max(0, liability - principal);
+    rouBalance = Math.max(0, rouBalance - rouAmortization);
+    totalInterest += interest;
+    rows.push({
+      period,
+      date: addMonths(start, period * monthsPerPeriod).toISOString().slice(0, 10),
+      payment: money(payment),
+      interest: money(interest),
+      principal: money(principal),
+      liability_balance: money(liability),
+      rou_amortization: money(rouAmortization),
+      rou_balance: money(rouBalance)
+    });
+  }
+
+  return {
+    summary: {
+      periods,
+      frequency: lease.payment_frequency,
+      periodic_payment: money(payment),
+      present_value: money(presentValue),
+      total_payments: money(payment * periods),
+      total_interest: money(totalInterest)
+    },
+    rows
+  };
+}
+
+module.exports = {
+  FREQUENCIES,
+  createLease,
+  deleteLease,
+  getLease,
+  leaseSchedule,
+  listLeases,
+  updateLease
+};