/**
 * 贷款合同控制器
 * @file loanContractController.js
 * @description 银行系统贷款合同相关API控制器
 */
const { LoanContract, User } = require('../models');
const { Op } = require('sequelize');
const { validationResult } = require('express-validator');

/**
 * 获取贷款合同列表
 * @param {Object} req - 请求对象
 * @param {Object} res - 响应对象
 */
const getContracts = async (req, res) => {
  try {
    const {
      page = 1,
      pageSize = 10,
      searchField = 'contractNumber',
      searchValue = '',
      status = '',
      sortField = 'createdAt',
      sortOrder = 'DESC'
    } = req.query;

    // 构建查询条件
    const where = {};
    
    // 搜索条件
    if (searchValue) {
      if (searchField === 'contractNumber') {
        where.contract_number = { [Op.like]: `%${searchValue}%` };
      } else if (searchField === 'customerName') {
        where.customer_name = { [Op.like]: `%${searchValue}%` };
      } else if (searchField === 'customerPhone') {
        where.customer_phone = { [Op.like]: `%${searchValue}%` };
      } else if (searchField === 'customerIdCard') {
        where.customer_id_card = { [Op.like]: `%${searchValue}%` };
      } else if (searchField === 'applicationNumber') {
        // 数据库中实际没有applicationNumber字段，使用id作为替代
        where.id = { [Op.like]: `%${searchValue}%` };
      }
    }

    // 状态筛选
    if (status) {
      where.status = status;
    }

    // 分页参数
    const offset = (parseInt(page) - 1) * parseInt(pageSize);
    const limit = parseInt(pageSize);

    // 排序参数 - 映射字段名
    const fieldMapping = {
      'createdAt': 'created_at',
      'updatedAt': 'updated_at',
      'contractDate': 'contract_date',
      'loanAmount': 'loan_amount',
      'loanTerm': 'loan_term',
      'interestRate': 'interest_rate'
    };
    const dbSortField = fieldMapping[sortField] || sortField;
    const order = [[dbSortField, sortOrder.toUpperCase()]];

    // 查询数据
    const { count, rows } = await LoanContract.findAndCountAll({
      where,
      order,
      offset,
      limit
    });

    // 格式化数据
    const contracts = rows.map(contract => ({
      id: contract.id,
      contract_number: contract.contract_number,
      customer_name: contract.customer_name,
      customer_phone: contract.customer_phone,
      customer_id_card: contract.customer_id_card,
      loan_amount: parseFloat(contract.loan_amount),
      loan_term: contract.loan_term,
      interest_rate: parseFloat(contract.interest_rate),
      contract_date: contract.contract_date,
      status: contract.status,
      created_at: contract.created_at,
      updated_at: contract.updated_at
    }));

    res.json({
      success: true,
      data: {
        contracts,
        pagination: {
          current: parseInt(page),
          pageSize: parseInt(pageSize),
          total: count,
          totalPages: Math.ceil(count / parseInt(pageSize))
        }
      }
    });
  } catch (error) {
    console.error('获取贷款合同列表失败:', error);
    res.status(500).json({
      success: false,
      message: '获取贷款合同列表失败'
    });
  }
};

/**
 * 获取贷款合同详情
 * @param {Object} req - 请求对象
 * @param {Object} res - 响应对象
 */
const getContractById = async (req, res) => {
  try {
    const { id } = req.params;

    const contract = await LoanContract.findByPk(id, {
      include: [
        {
          model: User,
          as: 'creator',
          attributes: ['id', 'username', 'real_name', 'email', 'phone']
        },
        {
          model: User,
          as: 'updater',
          attributes: ['id', 'username', 'real_name']
        }
      ]
    });

    if (!contract) {
      return res.status(404).json({
        success: false,
        message: '贷款合同不存在'
      });
    }

    // 格式化数据
    const formattedContract = {
      id: contract.id,
      contractNumber: contract.contractNumber,
      applicationNumber: contract.applicationNumber,
      productName: contract.productName,
      farmerName: contract.farmerName,
      borrowerName: contract.borrowerName,
      borrowerIdNumber: contract.borrowerIdNumber,
      assetType: contract.assetType,
      applicationQuantity: contract.applicationQuantity,
      amount: parseFloat(contract.amount),
      paidAmount: parseFloat(contract.paidAmount),
      status: contract.status,
      type: contract.type,
      term: contract.term,
      interestRate: parseFloat(contract.interestRate),
      phone: contract.phone,
      purpose: contract.purpose,
      remark: contract.remark,
      contractTime: contract.contractTime,
      disbursementTime: contract.disbursementTime,
      maturityTime: contract.maturityTime,
      completedTime: contract.completedTime,
      remainingAmount: parseFloat(contract.amount - contract.paidAmount),
      repaymentProgress: contract.getRepaymentProgress(),
      creator: contract.creator,
      updater: contract.updater
    };

    res.json({
      success: true,
      data: formattedContract
    });
  } catch (error) {
    console.error('获取贷款合同详情失败:', error);
    res.status(500).json({
      success: false,
      message: '获取贷款合同详情失败'
    });
  }
};

/**
 * 创建贷款合同
 * @param {Object} req - 请求对象
 * @param {Object} res - 响应对象
 */
const createContract = async (req, res) => {
  try {
    const errors = validationResult(req);
    if (!errors.isEmpty()) {
      return res.status(400).json({
        success: false,
        message: '请求参数错误',
        errors: errors.array()
      });
    }

    const contractData = {
      ...req.body,
      createdBy: req.user?.id
    };

    const contract = await LoanContract.create(contractData);

    res.status(201).json({
      success: true,
      message: '贷款合同创建成功',
      data: contract
    });
  } catch (error) {
    console.error('创建贷款合同失败:', error);
    res.status(500).json({
      success: false,
      message: '创建贷款合同失败'
    });
  }
};

/**
 * 更新贷款合同
 * @param {Object} req - 请求对象
 * @param {Object} res - 响应对象
 */
const updateContract = async (req, res) => {
  try {
    const errors = validationResult(req);
    if (!errors.isEmpty()) {
      return res.status(400).json({
        success: false,
        message: '请求参数错误',
        errors: errors.array()
      });
    }

    const { id } = req.params;
    const updateData = {
      ...req.body,
      updatedBy: req.user?.id
    };

    const [updatedCount] = await LoanContract.update(updateData, {
      where: { id }
    });

    if (updatedCount === 0) {
      return res.status(404).json({
        success: false,
        message: '贷款合同不存在'
      });
    }

    const updatedContract = await LoanContract.findByPk(id);

    res.json({
      success: true,
      message: '贷款合同更新成功',
      data: updatedContract
    });
  } catch (error) {
    console.error('更新贷款合同失败:', error);
    res.status(500).json({
      success: false,
      message: '更新贷款合同失败'
    });
  }
};

/**
 * 删除贷款合同
 * @param {Object} req - 请求对象
 * @param {Object} res - 响应对象
 */
const deleteContract = async (req, res) => {
  try {
    const { id } = req.params;

    const deletedCount = await LoanContract.destroy({
      where: { id }
    });

    if (deletedCount === 0) {
      return res.status(404).json({
        success: false,
        message: '贷款合同不存在'
      });
    }

    res.json({
      success: true,
      message: '贷款合同删除成功'
    });
  } catch (error) {
    console.error('删除贷款合同失败:', error);
    res.status(500).json({
      success: false,
      message: '删除贷款合同失败'
    });
  }
};

/**
 * 获取合同统计信息
 * @param {Object} req - 请求对象
 * @param {Object} res - 响应对象
 */
const getContractStats = async (req, res) => {
  try {
    const stats = await LoanContract.findAll({
      attributes: [
        'status',
        [LoanContract.sequelize.fn('COUNT', '*'), 'count'],
        [LoanContract.sequelize.fn('SUM', LoanContract.sequelize.col('amount')), 'totalAmount'],
        [LoanContract.sequelize.fn('SUM', LoanContract.sequelize.col('paidAmount')), 'totalPaidAmount']
      ],
      group: ['status'],
      raw: true
    });

    const totalContracts = await LoanContract.count();
    const totalAmount = await LoanContract.sum('amount') || 0;
    const totalPaidAmount = await LoanContract.sum('paidAmount') || 0;

    const statusStats = {
      active: 0,
      pending: 0,
      completed: 0,
      defaulted: 0,
      cancelled: 0
    };

    const amountStats = {
      active: 0,
      pending: 0,
      completed: 0,
      defaulted: 0,
      cancelled: 0
    };

    const paidAmountStats = {
      active: 0,
      pending: 0,
      completed: 0,
      defaulted: 0,
      cancelled: 0
    };

    stats.forEach(stat => {
      statusStats[stat.status] = parseInt(stat.count);
      amountStats[stat.status] = parseFloat(stat.totalAmount) || 0;
      paidAmountStats[stat.status] = parseFloat(stat.totalPaidAmount) || 0;
    });

    res.json({
      success: true,
      data: {
        total: {
          contracts: totalContracts,
          amount: parseFloat(totalAmount),
          paidAmount: parseFloat(totalPaidAmount),
          remainingAmount: parseFloat(totalAmount - totalPaidAmount)
        },
        byStatus: {
          counts: statusStats,
          amounts: amountStats,
          paidAmounts: paidAmountStats
        }
      }
    });
  } catch (error) {
    console.error('获取合同统计失败:', error);
    res.status(500).json({
      success: false,
      message: '获取合同统计失败'
    });
  }
};

/**
 * 批量更新合同状态
 * @param {Object} req - 请求对象
 * @param {Object} res - 响应对象
 */
const batchUpdateStatus = async (req, res) => {
  try {
    const { ids, status } = req.body;
    const userId = req.user?.id;

    if (!ids || !Array.isArray(ids) || ids.length === 0) {
      return res.status(400).json({
        success: false,
        message: '请选择要操作的合同'
      });
    }

    if (!status) {
      return res.status(400).json({
        success: false,
        message: '请指定目标状态'
      });
    }

    // 更新合同状态
    const updateData = {
      status,
      updatedBy: userId
    };

    // 根据状态设置相应的时间字段
    if (status === 'active') {
      updateData.disbursementTime = new Date();
    } else if (status === 'completed') {
      updateData.completedTime = new Date();
    }

    const [updatedCount] = await LoanContract.update(updateData, {
      where: {
        id: { [Op.in]: ids }
      }
    });

    res.json({
      success: true,
      message: `成功更新${updatedCount}个合同的状态`,
      data: {
        updatedCount,
        status
      }
    });
  } catch (error) {
    console.error('批量更新合同状态失败:', error);
    res.status(500).json({
      success: false,
      message: '批量更新合同状态失败'
    });
  }
};

module.exports = {
  getContracts,
  getContractById,
  createContract,
  updateContract,
  deleteContract,
  getContractStats,
  batchUpdateStatus
};