// routes/contracts.js —— 合同管理 CRUD（纯数据库操作，权限由中间件层控制）
const { pool } = require('../db')

// 格式化日期为 YYYY-MM-DD
function formatDate(dateStr) {
  if (!dateStr) return null
  if (typeof dateStr === 'string' && /^\d{4}-\d{2}-\d{2}$/.test(dateStr)) {
    return dateStr
  }
  try {
    const date = new Date(dateStr)
    if (isNaN(date.getTime())) return null
    const year = date.getFullYear()
    const month = String(date.getMonth() + 1).padStart(2, '0')
    const day = String(date.getDate()).padStart(2, '0')
    return `${year}-${month}-${day}`
  } catch {
    return null
  }
}

function pagination(query) {
  const page = Math.max(Number(query.page) || 1, 1)
  const pageSize = Math.min(Math.max(Number(query.pageSize) || 10, 1), 100)
  const offset = (page - 1) * pageSize
  return { page, pageSize, offset }
}

// 列表查询时 JOIN 客户名、供应商名、员工名和负责人姓名
const LIST_SELECT = `
  SELECT
    c.*,
    cu.name AS customer_name,
    s.name  AS supplier_name,
    e.name  AS employee_name,
    ru.name AS responsible_user_name
  FROM contracts c
    LEFT JOIN customers cu ON c.customer_id = cu.id
    LEFT JOIN suppliers s  ON c.supplier_id = s.id
    LEFT JOIN employees e  ON c.employee_id = e.id
    LEFT JOIN users u ON c.responsible_user_id = u.id
    LEFT JOIN employees ru ON u.employee_id = ru.id
`

// 单条查询时用同样的 JOIN
const DETAIL_SELECT = LIST_SELECT

// GET /api/contracts —— 列表
async function list(req, res) {
  try {
    const { page, pageSize, offset } = pagination(req.query)
    const { status, customer_name, contract_no, contract_name, employee_name, id, effective_date_start, effective_date_end } = req.query

    let where = 'WHERE 1=1'
    const params = []

    // 数据范围过滤（由中间件注入 req.scope，无别名；list/detail 需机械加 c. 前缀）
    if (req.scope && req.scope.sql) {
      where += ' ' + req.scope.sql.replace(/\btype\b/g, 'c.type')
      params.push(...req.scope.params)
    }

    if (id) {
      where += ' AND c.id = ?'
      params.push(id)
    }
    if (status) {
      where += ' AND c.status = ?'
      params.push(status)
    }
    if (contract_name) {
      where += ' AND c.contract_name LIKE ?'
      params.push(`%${contract_name}%`)
    }
    if (customer_name) {
      where += ' AND cu.name LIKE ?'
      params.push(`%${customer_name}%`)
    }
    if (contract_no) {
      where += ' AND c.contract_no LIKE ?'
      params.push(`%${contract_no}%`)
    }
    if (employee_name) {
      where += ' AND e.name LIKE ?'
      params.push(`%${employee_name}%`)
    }
    if (effective_date_start) {
      where += ' AND c.effective_date >= ?'
      params.push(effective_date_start)
    }
    if (effective_date_end) {
      where += ' AND c.effective_date <= ?'
      params.push(effective_date_end)
    }

    const [[{ total }]] = await pool.query(
      `SELECT COUNT(*) AS total FROM contracts c
         LEFT JOIN customers cu ON c.customer_id = cu.id
         LEFT JOIN suppliers s  ON c.supplier_id = s.id
         LEFT JOIN employees e  ON c.employee_id = e.id
         LEFT JOIN users u ON c.responsible_user_id = u.id
         LEFT JOIN employees ru ON u.employee_id = ru.id
       ${where}`,
      params
    )

    const [rows] = await pool.query(
      `${LIST_SELECT} ${where} ORDER BY c.id DESC LIMIT ? OFFSET ?`,
      [...params, pageSize, offset]
    )

    res.json({
      code: 0,
      message: 'ok',
      data: {
        list: rows,
        total,
        page,
        pageSize,
        totalPages: Math.ceil(total / pageSize),
      },
    })
  } catch (e) {
    console.error('[contracts list] error:', e)
    res.status(500).json({ code: 500, message: e.message })
  }
}

// GET /api/contracts/:id —— 详情
async function detail(req, res) {
  try {
    let sql = `${DETAIL_SELECT} WHERE c.id = ?`
    const params = [req.params.id]

    // 数据范围过滤（由中间件注入 req.scope，无别名；detail 需机械加 c. 前缀）
    if (req.scope && req.scope.sql) {
      sql += ' ' + req.scope.sql.replace(/\btype\b/g, 'c.type')
      params.push(...req.scope.params)
    }

    const [rows] = await pool.query(sql, params)
    if (rows.length === 0) {
      return res.status(404).json({ code: 404, message: '合同不存在' })
    }
    res.json({ code: 0, message: 'ok', data: rows[0] })
  } catch (e) {
    console.error('[contracts detail] error:', e)
    res.status(500).json({ code: 500, message: e.message })
  }
}

// POST /api/contracts —— 新增
async function create(req, res) {
  const {
    customer_id, supplier_id, contract_name, contract_no, contract_content,
    amount, effective_date, expiry_date, employee_id, status, remark,
  } = req.body || {}

  // 合同类型默认值（类型校验由中间件层控制）
  const contractType = req.body.type || 'franchise'

  if (contractType === 'supply' && !supplier_id) {
    return res.status(400).json({ code: 400, message: '采购合同必须选择供应商' })
  }
  if (contractType !== 'supply' && !customer_id) {
    return res.status(400).json({ code: 400, message: '加盟合同必须选择客户' })
  }
  if (!contract_name) {
    return res.status(400).json({ code: 400, message: '合同名称必填' })
  }

  try {
    // 校验客户是否存在（非采购合同必填）
    if (customer_id) {
      const [cust] = await pool.query('SELECT id FROM customers WHERE id = ?', [customer_id])
      if (cust.length === 0) {
        return res.status(400).json({ code: 400, message: '关联客户不存在' })
      }
    }
    // 校验供应商是否存在（采购合同必填）
    if (supplier_id) {
      const [sup] = await pool.query('SELECT id FROM suppliers WHERE id = ?', [supplier_id])
      if (sup.length === 0) {
        return res.status(400).json({ code: 400, message: '关联供应商不存在' })
      }
    }
    // 校验业务员（如果填了），并通过 employee_id 自动推导负责人
    let responsibleUserId = req.user.id
    if (employee_id) {
      const [emp] = await pool.query('SELECT id FROM employees WHERE id = ?', [employee_id])
      if (emp.length === 0) {
        return res.status(400).json({ code: 400, message: '关联业务员不存在' })
      }
      // 业务员即负责人：查找该员工对应的系统用户
      const [userRows] = await pool.query('SELECT id FROM users WHERE employee_id = ? LIMIT 1', [employee_id])
      if (userRows.length > 0) {
        responsibleUserId = userRows[0].id
      }
    }

    const [result] = await pool.query(
      `INSERT INTO contracts
         (customer_id, supplier_id, contract_name, contract_no, contract_content, amount, effective_date, expiry_date, employee_id, status, remark, type, responsible_user_id)
       VALUES (?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?)`,
      [customer_id || null, supplier_id || null, contract_name,
        contract_no || null,
        contract_content || null,
        amount !== undefined ? amount : null,
        formatDate(effective_date),
        formatDate(expiry_date),
        employee_id || null,
        status || '生效中',
        remark || null,
        contractType,
        responsibleUserId]
    )

    const [rows] = await pool.query(`${DETAIL_SELECT} WHERE c.id = ?`, [result.insertId])
    res.json({ code: 0, message: 'ok', data: rows[0] })
  } catch (e) {
    console.error('[contracts create] error:', e)
    res.status(500).json({ code: 500, message: e.message })
  }
}

// PUT /api/contracts/:id —— 更新
async function update(req, res) {
  const { id } = req.params
  const fields = [
    'customer_id', 'supplier_id', 'contract_name', 'contract_no', 'contract_content',
    'amount', 'effective_date', 'expiry_date', 'employee_id', 'status', 'remark', 'type',
    'responsible_user_id',
  ]

  try {
    // 确认记录存在且在数据范围内（detail/update/delete 不用表别名）
    let checkSql = 'SELECT id, employee_id FROM contracts WHERE id = ?'
    let checkParams = [id]
    if (req.scope && req.scope.sql) {
      checkSql += ' ' + req.scope.sql
      checkParams.push(...req.scope.params)
    }
    const [existing] = await pool.query(checkSql, checkParams)
    if (existing.length === 0) {
      return res.status(404).json({ code: 404, message: '合同不存在或无权操作' })
    }

    // 如果更新了 customer_id 或 employee_id，需要校验
    if (req.body.customer_id) {
      const [cust] = await pool.query('SELECT id FROM customers WHERE id = ?', [req.body.customer_id])
      if (cust.length === 0) {
        return res.status(400).json({ code: 400, message: '关联客户不存在' })
      }
    }
    if (req.body.employee_id) {
      const [emp] = await pool.query('SELECT id FROM employees WHERE id = ?', [req.body.employee_id])
      if (emp.length === 0) {
        return res.status(400).json({ code: 400, message: '关联业务员不存在' })
      }
    }

    // 业务员即负责人：当 employee_id 变更时自动推导 responsible_user_id
    if (req.body.employee_id !== undefined) {
      if (req.body.employee_id) {
        const [userRows] = await pool.query('SELECT id FROM users WHERE employee_id = ? LIMIT 1', [req.body.employee_id])
        if (userRows.length > 0) {
          req.body.responsible_user_id = userRows[0].id
        } else {
          // 该员工无对应系统用户时，设为当前登录用户
          req.body.responsible_user_id = req.user.id
        }
      } else {
        // 业务员被清空时，清空负责人
        req.body.responsible_user_id = null
      }
    }
    if (req.body.supplier_id) {
      const [sup] = await pool.query('SELECT id FROM suppliers WHERE id = ?', [req.body.supplier_id])
      if (sup.length === 0) {
        return res.status(400).json({ code: 400, message: '关联供应商不存在' })
      }
    }

    const sets = []
    const params = []
    for (const f of fields) {
      if (req.body[f] !== undefined) {
        sets.push(`${f} = ?`)
        // 日期字段需要格式化
        if (['effective_date', 'expiry_date'].includes(f)) {
          params.push(formatDate(req.body[f]))
        } else {
          params.push(req.body[f])
        }
      }
    }
    if (sets.length === 0) {
      return res.status(400).json({ code: 400, message: '没有需要更新的字段' })
    }

    params.push(id)
    await pool.query(`UPDATE contracts SET ${sets.join(', ')} WHERE id = ?`, params)

    const [rows] = await pool.query(`${DETAIL_SELECT} WHERE c.id = ?`, [id])
    res.json({ code: 0, message: 'ok', data: rows[0] })
  } catch (e) {
    console.error('[contracts update] error:', e)
    res.status(500).json({ code: 500, message: e.message })
  }
}

// DELETE /api/contracts/:id —— 删除
async function remove(req, res) {
  const { id } = req.params
  try {
    let checkSql = 'SELECT id FROM contracts WHERE id = ?'
    let checkParams = [id]
    if (req.scope && req.scope.sql) {
      checkSql += ' ' + req.scope.sql
      checkParams.push(...req.scope.params)
    }
    const [existing] = await pool.query(checkSql, checkParams)
    if (existing.length === 0) {
      return res.status(404).json({ code: 404, message: '合同不存在或无权操作' })
    }
    await pool.query('DELETE FROM contracts WHERE id = ?', [id])
    res.json({ code: 0, message: 'ok' })
  } catch (e) {
    console.error('[contracts delete] error:', e)
    // 如果因为外键约束（customer_id 被 after_sales 引用）导致删除失败
    if (e.code === 'ER_ROW_IS_REFERENCED_2') {
      return res.status(400).json({ code: 400, message: '该合同关联了售后记录，无法删除' })
    }
    res.status(500).json({ code: 500, message: e.message })
  }
}

module.exports = { list, detail, create, update, remove }