const { BillPayment, Bill } = require('../models');
const { Op, fn, col } = require('sequelize');
const response = require('../utils/response');
const rentalBillingService = require('../services/rentalBillingService');

// 获取账单的所有支付流水
const getPaymentsByBillId = async (req, res) => {
  try {
    const { billId } = req.params;
    const tenantId = req.user.tenantId;

    const payments = await BillPayment.findAll({
      where: {
        billId,
        tenantId,
        isDeleted: 0
      },
      order: [['paymentTime', 'DESC']]
    });

    response.success(res, '获取成功', payments);
  } catch (error) {
    console.error('获取支付流水失败:', error);
    response.serverError(res, '获取支付流水失败', error);
  }
};

// 创建支付流水（收款）
const createPayment = async (req, res) => {
  const transaction = await require('../config/db').transaction();
  try {
    const { billId } = req.params;
    const { amount, paymentMethod, paymentTime, transactionNo, remark } = req.body;
    const tenantId = req.user.tenantId;
    const createBy = req.user.id;

    const bill = await Bill.findOne({
      where: { id: billId, tenantId, isDeleted: 0 },
      transaction
    });

    if (!bill) {
      await transaction.rollback();
      return response.notFound(res, '账单不存在');
    }

    if (transactionNo) {
      const existingPayment = await BillPayment.findOne({
        where: { transactionNo, billId, tenantId, isDeleted: 0 },
        transaction
      });
      if (existingPayment) {
        await transaction.rollback();
        return response.badRequest(res, '该交易流水号已存在，请勿重复提交');
      }
    }

    let paymentInfo;
    try {
      paymentInfo = rentalBillingService.validatePaymentAmount(bill, amount);
    } catch (validationError) {
      await transaction.rollback();
      return response.badRequest(res, validationError.message);
    }

    const payment = await BillPayment.create({
      billId,
      amount: paymentInfo.paymentAmount,
      paymentMethod,
      paymentTime: paymentTime || new Date(),
      transactionNo: transactionNo || null,
      remark: remark || null,
      tenantId,
      createBy,
      isDeleted: 0
    }, { transaction });

    await bill.update({
      receivedAmount: paymentInfo.newReceivedAmount,
      status: paymentInfo.newStatus,
      updateBy: createBy
    }, { transaction });

    await transaction.commit();

    response.created(res, '收款成功', {
      payment,
      bill: {
        id: bill.id,
        receivedAmount: paymentInfo.newReceivedAmount,
        status: paymentInfo.newStatus
      }
    });
  } catch (error) {
    await transaction.rollback();
    console.error('创建支付流水失败:', error);
    response.serverError(res, '创建支付流水失败', error);
  }
};

// 删除支付流水（退款/撤销）
const deletePayment = async (req, res) => {
  const transaction = await require('../config/db').transaction();
  try {
    const { id } = req.params;
    const tenantId = req.user.tenantId;
    const updateBy = req.user.id;

    const payment = await BillPayment.findOne({
      where: { id, tenantId, isDeleted: 0 },
      transaction
    });

    if (!payment) {
      await transaction.rollback();
      return response.notFound(res, '支付流水不存在');
    }

    const bill = await Bill.findOne({
      where: { id: payment.billId, tenantId, isDeleted: 0 },
      transaction
    });

    if (!bill) {
      await transaction.rollback();
      return response.notFound(res, '关联账单不存在');
    }

    await payment.update({ isDeleted: 1 }, { transaction });

    const remainingPayments = await BillPayment.findAll({
      where: { billId: bill.id, tenantId, isDeleted: 0 },
      transaction
    });

    const newReceivedAmount = remainingPayments.reduce((sum, p) => sum + parseFloat(p.amount), 0);
    let newStatus = 'unpaid';
    if (newReceivedAmount >= parseFloat(bill.receivableAmount)) {
      newStatus = 'paid';
    } else if (newReceivedAmount > 0) {
      newStatus = 'partial';
    }

    await bill.update({
      receivedAmount: newReceivedAmount,
      status: newStatus,
      updateBy
    }, { transaction });

    await transaction.commit();

    response.success(res, '支付流水已撤销，账单状态已更新', {
      bill: { id: bill.id, receivedAmount: newReceivedAmount, status: newStatus }
    });
  } catch (error) {
    await transaction.rollback();
    console.error('撤销支付流水失败:', error);
    response.serverError(res, '撤销支付流水失败', error);
  }
};

// 获取支付流水统计
const getPaymentStatistics = async (req, res) => {
  try {
    const tenantId = req.user.tenantId;
    const { startDate, endDate } = req.query;

    const where = {
      tenantId,
      isDeleted: 0
    };

    if (startDate && endDate) {
      where.paymentTime = {
        [Op.between]: [new Date(startDate), new Date(endDate)]
      };
    }

    const payments = await BillPayment.findAll({
      where,
      attributes: ['paymentMethod', [fn('SUM', col('amount')), 'totalAmount'], [fn('COUNT', col('id')), 'count']],
      group: ['paymentMethod']
    });

    response.success(res, '获取成功', payments);
  } catch (error) {
    console.error('获取支付统计失败:', error);
    response.serverError(res, '获取支付统计失败', error);
  }
};

module.exports = {
  getPaymentsByBillId,
  createPayment,
  deletePayment,
  getPaymentStatistics
};