/*
Copyright (c) 2018 Intel Corporation

Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at

      http://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.
*/
#pragma once

#include "logging.hpp"
#include "sessions.hpp"

#include <boost/beast/http/verb.hpp>
#include <boost/container/flat_map.hpp>
#include <boost/container/vector.hpp>

#include <array>
#include <bitset>
#include <cstddef>
#include <functional>
#include <initializer_list>
#include <string>
#include <string_view>
#include <utility>
#include <vector>

namespace redfish
{

enum class PrivilegeType
{
    BASE,
    OEM
};

/** @brief A fixed array of compile time privileges  */
constexpr std::array<std::string_view, 5> basePrivileges{
    "Login", "ConfigureManager", "ConfigureComponents", "ConfigureSelf",
    "ConfigureUsers"};

constexpr const size_t basePrivilegeCount = basePrivileges.size();

/** @brief Max number of privileges per type  */
constexpr const size_t maxPrivilegeCount = 32;

/**
 * @brief A vector of all privilege names and their indexes
 * The privilege "OpenBMCHostConsole" is added to users who are members of the
 * "hostconsole" user group. This privilege is required to access the host
 * console.
 */
constexpr std::array<std::string_view, maxPrivilegeCount> privilegeNames{
    "Login",         "ConfigureManager", "ConfigureComponents",
    "ConfigureSelf", "ConfigureUsers",   "OpenBMCHostConsole"};

/**
 * @brief Redfish privileges
 *
 *        This implements a set of Redfish privileges.  These directly represent
 *        user privileges and help represent entity privileges.
 *
 *        Each incoming Connection requires a comparison between privileges held
 *        by the user issuing a request and the target entity's privileges.
 *
 *        To ensure best runtime performance of this comparison, privileges
 *        are represented as bitsets. Each bit in the bitset corresponds to a
 *        unique privilege name.
 *
 *        A bit is set if the privilege is required (entity domain) or granted
 *        (user domain) and false otherwise.
 *
 */
class Privileges
{
  public:
    /**
     * @brief Constructs object without any privileges active
     *
     */
    Privileges() = default;

    /**
     * @brief Constructs object with given privileges active
     *
     * @param[in] privilegeList  List of privileges to be activated
     *
     */
    Privileges(std::initializer_list<const char*> privilegeList)
    {
        for (const char* privilege : privilegeList)
        {
            if (!setSinglePrivilege(privilege))
            {
                BMCWEB_LOG_CRITICAL("Unable to set privilege {} in constructor",
                                    privilege);
            }
        }
    }

    /**
     * @brief Sets given privilege in the bitset
     *
     * @param[in] privilege  Privilege to be set
     *
     * @return               None
     *
     */
    bool setSinglePrivilege(std::string_view privilege)
    {
        for (size_t searchIndex = 0; searchIndex < privilegeNames.size();
             searchIndex++)
        {
            if (privilege == privilegeNames[searchIndex])
            {
                privilegeBitset.set(searchIndex);
                return true;
            }
        }

        return false;
    }

    /**
     * @brief Resets the given privilege in the bitset
     *
     * @param[in] privilege  Privilege to be reset
     *
     * @return               None
     *
     */
    bool resetSinglePrivilege(const char* privilege)
    {
        for (size_t searchIndex = 0; searchIndex < privilegeNames.size();
             searchIndex++)
        {
            if (privilege == privilegeNames[searchIndex])
            {
                privilegeBitset.reset(searchIndex);
                return true;
            }
        }
        return false;
    }

    /**
     * @brief Retrieves names of all active privileges for a given type
     *
     * @param[in] type    Base or OEM
     *
     * @return            Vector of active privileges.  Pointers are valid until
     * the setSinglePrivilege is called, or the Privilege structure is destroyed
     *
     */
    std::vector<std::string>
        getActivePrivilegeNames(const PrivilegeType type) const
    {
        std::vector<std::string> activePrivileges;

        size_t searchIndex = 0;
        size_t endIndex = basePrivilegeCount;
        if (type == PrivilegeType::OEM)
        {
            searchIndex = basePrivilegeCount;
            endIndex = privilegeNames.size();
        }

        for (; searchIndex < endIndex; searchIndex++)
        {
            if (privilegeBitset.test(searchIndex))
            {
                activePrivileges.emplace_back(privilegeNames[searchIndex]);
            }
        }

        return activePrivileges;
    }

    /**
     * @brief Determines if this Privilege set is a superset of the given
     * privilege set
     *
     * @param[in] privilege  Privilege to be checked
     *
     * @return               None
     *
     */
    bool isSupersetOf(const Privileges& p) const
    {
        return (privilegeBitset & p.privilegeBitset) == p.privilegeBitset;
    }

    /**
     * @brief Returns the intersection of two Privilege sets.
     *
     * @param[in] privilege  Privilege set to intersect with.
     *
     * @return               The new Privilege set.
     *
     */
    Privileges intersection(const Privileges& p) const
    {
        return Privileges{privilegeBitset & p.privilegeBitset};
    }

  private:
    explicit Privileges(const std::bitset<maxPrivilegeCount>& p) :
        privilegeBitset{p}
    {}
    std::bitset<maxPrivilegeCount> privilegeBitset = 0;
};

inline Privileges getUserPrivileges(const persistent_data::UserSession& session)
{
    // default to no access
    Privileges privs;

    // Check if user is member of hostconsole group
    for (const auto& userGroup : session.userGroups)
    {
        if (userGroup == "hostconsole")
        {
            // Redfish privilege : host console access
            privs.setSinglePrivilege("OpenBMCHostConsole");
            break;
        }
    }

    if (session.userRole == "priv-admin")
    {
        // Redfish privilege : Administrator
        privs.setSinglePrivilege("Login");
        privs.setSinglePrivilege("ConfigureManager");
        privs.setSinglePrivilege("ConfigureSelf");
        privs.setSinglePrivilege("ConfigureUsers");
        privs.setSinglePrivilege("ConfigureComponents");
    }
    else if (session.userRole == "priv-operator")
    {
        // Redfish privilege : Operator
        privs.setSinglePrivilege("Login");
        privs.setSinglePrivilege("ConfigureSelf");
        privs.setSinglePrivilege("ConfigureComponents");
    }
    else if (session.userRole == "priv-user")
    {
        // Redfish privilege : Readonly
        privs.setSinglePrivilege("Login");
        privs.setSinglePrivilege("ConfigureSelf");
    }

    return privs;
}

/**
 * @brief The OperationMap represents the privileges required for a
 * single entity (URI).  It maps from the allowable verbs to the
 * privileges required to use that operation.
 *
 * This represents the Redfish "Privilege AND and OR syntax" as given
 * in the spec and shown in the Privilege Registry.  This does not
 * implement any Redfish property overrides, subordinate overrides, or
 * resource URI overrides.  This does not implement the limitation of
 * the ConfigureSelf privilege to operate only on your own account or
 * session.
 **/
using OperationMap = boost::container::flat_map<boost::beast::http::verb,
                                                std::vector<Privileges>>;

/* @brief Checks if user is allowed to call an operation
 *
 * @param[in] operationPrivilegesRequired   Privileges required
 * @param[in] userPrivileges                Privileges the user has
 *
 * @return                 True if operation is allowed, false otherwise
 */
inline bool isOperationAllowedWithPrivileges(
    const std::vector<Privileges>& operationPrivilegesRequired,
    const Privileges& userPrivileges)
{
    // If there are no privileges assigned, there are no privileges required
    if (operationPrivilegesRequired.empty())
    {
        return true;
    }
    for (const auto& requiredPrivileges : operationPrivilegesRequired)
    {
        BMCWEB_LOG_DEBUG("Checking operation privileges...");
        if (userPrivileges.isSupersetOf(requiredPrivileges))
        {
            BMCWEB_LOG_DEBUG("...success");
            return true;
        }
    }
    return false;
}

/**
 * @brief Checks if given privileges allow to call an HTTP method
 *
 * @param[in] method       HTTP method
 * @param[in] user         Privileges
 *
 * @return                 True if method allowed, false otherwise
 *
 */
inline bool isMethodAllowedWithPrivileges(const boost::beast::http::verb method,
                                          const OperationMap& operationMap,
                                          const Privileges& userPrivileges)
{
    const auto& it = operationMap.find(method);
    if (it == operationMap.end())
    {
        return false;
    }

    return isOperationAllowedWithPrivileges(it->second, userPrivileges);
}

} // namespace redfish