// /components/expenses/expenseService.js
'use strict';

const Expense = require('./expenseModel');
const AppError = require('../../utils/AppError');
const { parsePaginationAndSort, buildFilterQuery, calculateMeta } = require('../../utils/pagination');
const { resolveDateRange } = require('../../utils/financialRange');

const sanitizePayload = (body = {}) => {
  const payload = {
    title: String(body.title || '').trim(),
    category: body.category ? String(body.category).trim() : 'عمومی',
    amount: Math.max(0, Number(body.amount) || 0),
    date: body.date ? new Date(body.date) : new Date(),
    notes: body.notes ? String(body.notes).trim().slice(0, 2000) : ''
  };
  return payload;
};

const createExpense = async (body, actorId = null) => {
  const payload = sanitizePayload(body);
  const expense = await Expense.create({ ...payload, recordedBy: actorId || undefined });
  return expense;
};

const getAllExpenses = async (queryParams) => {
  const { page, limit, skip, sort } = parsePaginationAndSort(queryParams, 'date', 'desc');
  const filter = buildFilterQuery(queryParams, ['title', 'category', 'notes'], [
    'page', 'limit', 'sortBy', 'sortOrder', 'q', 'search', 'lang', 'startDate', 'endDate'
  ]);

  if (queryParams.startDate || queryParams.endDate) {
    const { start, end } = resolveDateRange(queryParams);
    filter.date = { $gte: start, $lte: end };
  }

  const [items, total] = await Promise.all([
    Expense.find(filter).populate('recordedBy', 'name').sort(sort).skip(skip).limit(limit).lean(),
    Expense.countDocuments(filter)
  ]);

  return { data: items, meta: calculateMeta(total, page, limit) };
};

const getExpenseById = async (id) => {
  const expense = await Expense.findById(id).populate('recordedBy', 'name').lean();
  if (!expense) throw new AppError('EXPENSE_NOT_FOUND');
  return expense;
};

const updateExpense = async (id, body) => {
  const expense = await Expense.findById(id);
  if (!expense) throw new AppError('EXPENSE_NOT_FOUND');

  if (body.title !== undefined) expense.title = String(body.title).trim();
  if (body.category !== undefined) expense.category = String(body.category).trim() || 'عمومی';
  if (body.amount !== undefined) expense.amount = Math.max(0, Number(body.amount) || 0);
  if (body.date !== undefined) expense.date = new Date(body.date);
  if (body.notes !== undefined) expense.notes = String(body.notes).trim().slice(0, 2000);

  await expense.save();
  return expense;
};

const deleteExpense = async (id) => {
  const expense = await Expense.findByIdAndDelete(id);
  if (!expense) throw new AppError('EXPENSE_NOT_FOUND');
  return null;
};

/** Sum of expense amounts whose `date` falls within [start, end] — used by date-range financial reports. */
const sumExpensesInRange = async (start, end) => {
  const result = await Expense.aggregate([
    { $match: { date: { $gte: start, $lte: end } } },
    { $group: { _id: null, total: { $sum: '$amount' } } }
  ]);
  return result[0]?.total || 0;
};

module.exports = {
  createExpense,
  getAllExpenses,
  getExpenseById,
  updateExpense,
  deleteExpense,
  sumExpensesInRange
};