// middleware/permissions.js —— RBAC 权限检查 + 数据范围过滤

/**
 * 检查当前用户是否拥有指定权限
 * @param {string} resource - 资源名，如 'customer'
 * @param {string} action   - 操作名，如 'read'
 */
function checkPermission(resource, action) {
  return (req, res, next) => {
    const permName = `${resource}:${action}`
    if (!req.user || !req.user.permissions || !req.user.permissions.includes(permName)) {
      return res.status(403).json({ code: 403, message: '权限不足' })
    }
    next()
  }
}

/**
 * 根据当前用户角色，返回该资源的数据范围过滤条件
 * @param {object} user     - req.user（含 roleName, id, department）
 * @param {string} resource - 资源名：customers / contracts / after_sales / products / suppliers / employees / users
 * @returns {{ where?: string, values?: any[], deny?: boolean }}
 *   - where + values：追加到 SQL WHERE 子句的条件
 *   - deny：true 表示该角色无权访问此资源
 */
function getDataScope(user, resource) {
  const { roleName, id: userId, department } = user

  // admin 和 general_manager（总经理）：全量数据，无限制
  if (roleName === 'admin' || roleName === 'general_manager') {
    return {}
  }

  switch (resource) {
    case 'customers':
      if (roleName === 'finance') return {}
      return { where: 'responsible_user_id = ?', values: [userId] }

    case 'contracts':
      if (roleName === 'finance') return {}
      if (roleName === 'procurement_manager') {
        return { where: 'c.type = ?', values: ['supply'] }
      }
      if (roleName === 'franchise_manager' || roleName === 'operations_manager') {
        return { where: 'c.responsible_user_id = ? AND c.type = ?', values: [userId, 'franchise'] }
      }
      return {}

    case 'after_sales':
      if (roleName === 'finance') return {}
      if (roleName === 'operations_manager') {
        return { where: 'responsible_user_id = ?', values: [userId], tableAlias: 'a' }
      }
      // franchise_manager 和 procurement_manager 无权限（checkPermission 已拦截）
      return {}

    case 'employees':
      if (roleName === 'finance') return {}
      // 所有非管理员/总经理角色：只能看自己部门的员工
      return { where: 'department = ?', values: [department] }

    case 'products':
    case 'suppliers':
    case 'users':
      // 无数据范围过滤，仅靠 checkPermission 控制访问
      return {}

    default:
      return {}
  }
}

module.exports = { checkPermission, getDataScope }