/**
 * 贷款申请控制器
 * @file loanApplicationController.js
 * @description 银行系统贷款申请相关API控制器
 */
const { LoanApplication, AuditRecord, User } = require('../models');
const { Op } = require('sequelize');
const { validationResult } = require('express-validator');

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

    // 构建查询条件
    const where = {};
    
    // 搜索条件
    if (searchValue) {
      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}%` };
      }
    }

    // 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
    const order = [[sortField, sortOrder.toUpperCase()]];

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

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

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

/**
 * 获取贷款申请详情
 * @param {Object} req - 请求对象
 * @param {Object} res - 响应对象
 */
const getApplicationById = async (req, res) => {
  try {
    const { id } = req.params;

    const application = await LoanApplication.findByPk(id, {
      include: [
        {
          model: User,
          as: 'applicant',
          attributes: ['id', 'username', 'real_name', 'email', 'phone']
        },
        {
          model: User,
          as: 'approver',
          attributes: ['id', 'username', 'real_name']
        },
        {
          model: User,
          as: 'rejector',
          attributes: ['id', 'username', 'real_name']
        },
        {
          model: AuditRecord,
          as: 'auditRecords',
          include: [
            {
              model: User,
              as: 'auditorUser',
              attributes: ['id', 'username', 'real_name']
            }
          ],
          order: [['auditTime', 'DESC']]
        }
      ]
    });

    if (!application) {
      return res.status(404).json({
        success: false,
        message: '贷款申请不存在'
      });
    }

    // 格式化数据
    const formattedApplication = {
      id: application.id,
      applicationNumber: application.applicationNumber,
      productName: application.productName,
      farmerName: application.farmerName,
      borrowerName: application.borrowerName,
      borrowerIdNumber: application.borrowerIdNumber,
      assetType: application.assetType,
      applicationQuantity: application.applicationQuantity,
      amount: parseFloat(application.amount),
      status: application.status,
      type: application.type,
      term: application.term,
      interestRate: parseFloat(application.interestRate),
      phone: application.phone,
      purpose: application.purpose,
      remark: application.remark,
      applicationTime: application.applicationTime,
      approvedTime: application.approvedTime,
      rejectedTime: application.rejectedTime,
      applicant: application.applicant,
      approver: application.approver,
      rejector: application.rejector,
      auditRecords: application.auditRecords.map(record => ({
        id: record.id,
        action: record.action,
        auditor: record.auditorUser?.real_name || record.auditor,
        auditorId: record.auditorId,
        comment: record.comment,
        time: record.auditTime,
        previousStatus: record.previousStatus,
        newStatus: record.newStatus
      }))
    };

    res.json({
      success: true,
      data: formattedApplication
    });
  } catch (error) {
    console.error('获取贷款申请详情失败:', error);
    res.status(500).json({
      success: false,
      message: '获取贷款申请详情失败'
    });
  }
};

/**
 * 审核贷款申请
 * @param {Object} req - 请求对象
 * @param {Object} res - 响应对象
 */
const auditApplication = 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 { action, comment } = req.body;
    const userId = req.user?.id;

    // 获取申请信息
    const application = await LoanApplication.findByPk(id);
    if (!application) {
      return res.status(404).json({
        success: false,
        message: '贷款申请不存在'
      });
    }

    // 检查申请状态
    if (application.status === 'approved' || application.status === 'rejected') {
      return res.status(400).json({
        success: false,
        message: '该申请已完成审核，无法重复操作'
      });
    }

    const previousStatus = application.status;
    let newStatus = application.status;

    // 根据审核动作更新状态
    if (action === 'approve') {
      newStatus = 'approved';
      application.approvedTime = new Date();
      application.approvedBy = userId;
    } else if (action === 'reject') {
      newStatus = 'rejected';
      application.rejectedTime = new Date();
      application.rejectedBy = userId;
      application.rejectionReason = comment;
    }

    // 更新申请状态
    application.status = newStatus;
    await application.save();

    // 创建审核记录
    await AuditRecord.create({
      applicationId: id,
      action,
      auditor: req.user?.real_name || req.user?.username || '系统',
      auditorId: userId,
      comment,
      auditTime: new Date(),
      previousStatus,
      newStatus
    });

    res.json({
      success: true,
      message: action === 'approve' ? '审核通过' : '审核拒绝',
      data: {
        id: application.id,
        status: newStatus,
        action,
        comment
      }
    });
  } catch (error) {
    console.error('审核贷款申请失败:', error);
    res.status(500).json({
      success: false,
      message: '审核贷款申请失败'
    });
  }
};

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

    const totalApplications = await LoanApplication.count();
    const totalAmount = await LoanApplication.sum('amount') || 0;

    const statusStats = {
      pending_review: 0,
      verification_pending: 0,
      pending_binding: 0,
      approved: 0,
      rejected: 0
    };

    const amountStats = {
      pending_review: 0,
      verification_pending: 0,
      pending_binding: 0,
      approved: 0,
      rejected: 0
    };

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

    res.json({
      success: true,
      data: {
        total: {
          applications: totalApplications,
          amount: parseFloat(totalAmount)
        },
        byStatus: {
          counts: statusStats,
          amounts: amountStats
        }
      }
    });
  } catch (error) {
    console.error('获取申请统计失败:', error);
    res.status(500).json({
      success: false,
      message: '获取申请统计失败'
    });
  }
};

/**
 * 批量更新申请状态
 * @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: '请选择要操作的申请'
      });
    }

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

    // 更新申请状态
    const [updatedCount] = await LoanApplication.update(
      {
        status,
        ...(status === 'approved' && { approvedTime: new Date(), approvedBy: userId }),
        ...(status === 'rejected' && { rejectedTime: new Date(), rejectedBy: userId })
      },
      {
        where: {
          id: { [Op.in]: ids }
        }
      }
    );

    // 为每个申请创建审核记录
    for (const id of ids) {
      await AuditRecord.create({
        applicationId: id,
        action: status === 'approved' ? 'approve' : 'reject',
        auditor: req.user?.real_name || req.user?.username || '系统',
        auditorId: userId,
        comment: `批量${status === 'approved' ? '通过' : '拒绝'}`,
        auditTime: new Date(),
        newStatus: status
      });
    }

    res.json({
      success: true,
      message: `成功更新${updatedCount}个申请的状态`,
      data: {
        updatedCount,
        status
      }
    });
  } catch (error) {
    console.error('批量更新申请状态失败:', error);
    res.status(500).json({
      success: false,
      message: '批量更新申请状态失败'
    });
  }
};

module.exports = {
  getApplications,
  getApplicationById,
  auditApplication,
  getApplicationStats,
  batchUpdateStatus
};