// Copyright (C) 2015-2023 Internet Systems Consortium, Inc. ("ISC")
//
// This Source Code Form is subject to the terms of the Mozilla Public
// License, v. 2.0. If a copy of the MPL was not distributed with this
// file, You can obtain one at http://mozilla.org/MPL/2.0/.

#ifndef GENERIC_HOST_DATA_SOURCE_UNITTEST_H
#define GENERIC_HOST_DATA_SOURCE_UNITTEST_H

#include <asiolink/io_address.h>
#include <util/reconnect_ctl.h>
#include <dhcpsrv/base_host_data_source.h>
#include <dhcpsrv/cfgmgr.h>
#include <dhcpsrv/host.h>
#include <dhcpsrv/host_mgr.h>
#include <dhcpsrv/testutils/generic_backend_unittest.h>
#include <dhcp/classify.h>
#include <dhcp/option.h>
#include <boost/algorithm/string/join.hpp>
#include <boost/shared_ptr.hpp>
#include <gtest/gtest.h>
#include <sstream>
#include <vector>

namespace isc {
namespace dhcp {
namespace test {

/// @brief Test Fixture class with utility functions for HostDataSource backends
///
/// It contains utility functions for test purposes.
/// All concrete HostDataSource test classes should be derived from it.
class GenericHostDataSourceTest : public GenericBackendTest {
public:

    /// @brief Universe (V4 or V6).
    enum Universe {
        V4,
        V6
    };

    /// @brief Options to be inserted into a host.
    ///
    /// Parameter of this type is passed to the @ref addTestOptions to
    /// control which option types should be inserted into a host.
    enum AddedOptions {
        DHCP4_ONLY,
        DHCP6_ONLY,
        DHCP4_AND_DHCP6
    };

    /// @brief Default constructor.
    GenericHostDataSourceTest();

    /// @brief Virtual destructor.
    virtual ~GenericHostDataSourceTest();

    /// @brief Used to sort a host collection by IPv4 subnet id.
    /// @param host1 first host to be compared
    /// @param host2 second host to be compared
    /// @result return true if host1's subnet id is smaller than host2's
    /// subnet id
    static bool compareHostsForSort4(const ConstHostPtr& host1,
                                     const ConstHostPtr& host2);

    /// @brief Used to sort a host collection by IPv6 subnet id.
    /// @param host1 first host to be compared
    /// @param host2 second host to be compared
    /// @result return true if host1's subnet id is smaller than host2's
    /// subnet id
    static bool compareHostsForSort6(const ConstHostPtr& host1,
                                     const ConstHostPtr& host2);

    /// @brief Used to sort a host collection by host identifier.
    /// @param host1 first host to be compared
    /// @param host2 second host to be compared
    /// @result return true if host1's identifier is smaller than host2's
    /// identifier
    static bool compareHostsIdentifier(const ConstHostPtr& host1,
                                       const ConstHostPtr& host2);

    /// @brief Returns number of entries in the v4 options table.
    ///
    /// This utility method is expected to be implemented by specific backends.
    /// The code here is just a boilerplate for backends that do not store
    /// host options in a table.
    ///
    /// @param number of existing entries in options table
    virtual int countDBOptions4() {
        return (-1);
    }

    /// @brief Returns number of entries in the v6 options table.
    ///
    /// This utility method is expected to be implemented by specific backends.
    /// The code here is just a boilerplate for backends that do not store
    /// host options in a table.
    ///
    /// @param number of existing entries in options table
    virtual int countDBOptions6() {
        return (-1);
    }

    /// @brief Returns number of entries in the v6 reservations table.
    ///
    /// This utility method is expected to be implemented by specific backends.
    /// The code here is just a boilerplate for backends that do not store
    /// v6 reservations in a table.
    ///
    /// @param number of existing entries in v6_reservations table
    virtual int countDBReservations6() {
        return (-1);
    }

    /// @brief Adds multiple options into the host.
    ///
    /// This method creates the following options into the host object:
    /// - DHCPv4 boot file name option,
    /// - DHCPv4 default ip ttl option,
    /// - DHCPv4 option 1 within vendor-encapsulated-options space,
    /// - DHCPv4 option 254 with a single IPv4 address,
    /// - DHCPv4 option 1 within isc option space,
    /// - DHCPv6 boot file url option,
    /// - DHCPv6 information refresh time option,
    /// - DHCPv6 vendor option with vendor id 2495,
    /// - DHCPv6 option 1024, with a single IPv6 address,
    /// - DHCPv6 empty option 1, within isc2 option space,
    /// - DHCPv6 option 2, within isc2 option space with 3 IPv6 addresses,
    ///
    /// This method also creates option definitions for the non-standard
    /// options and registers them in the LibDHCP as runtime option
    /// definitions.
    ///
    /// @param host Host object into which options should be added.
    /// @param formatted A boolean value selecting if the formatted option
    /// value should be used (if true), or binary value (if false).
    /// @param added_options Controls which options should be inserted into
    /// a host: DHCPv4, DHCPv6 options or both.
    /// @param user_context Optional user context
    void addTestOptions(const HostPtr& host, const bool formatted,
                        const AddedOptions& added_options,
                        isc::data::ConstElementPtr user_context =
                        isc::data::ConstElementPtr()) const;

    /// @brief Adds an IPv6 address to the host.
    ///
    /// @param host pointer to the host instance.
    /// @param address an IPv6 address to be added as a string.
    void addIPv6Address(const HostPtr& host, const std::string& address) const;

    /// @brief Pointer to the host data source
    HostDataSourcePtr hdsptr_;

    /// @brief Test that backend can be started in read-only mode.
    ///
    /// Some backends can operate when the database is read only, e.g.
    /// host reservation tables are read only, or the database user has
    /// read only privileges on the entire database. In such cases, the
    /// Kea server administrator can specify in the backend configuration
    /// that the database should be opened in read only mode, i.e.
    /// INSERT, UPDATE, DELETE statements can't be issued. If any of the
    /// functions updating the database is called for the backend, the
    /// error is reported. The database running in read only mode can
    /// be merely used to retrieve existing host reservations from the
    /// database. This test verifies that this is the case.
    ///
    /// @param valid_db_type Parameter specifying type of backend to
    /// be used, e.g. type=mysql.
    void testReadOnlyDatabase(const char* valid_db_type);

    /// @brief Test that checks that simple host with IPv4 reservation
    ///        can be inserted and later retrieved.
    ///
    /// Uses gtest macros to report failures.
    /// @param id Identifier type.
    void testBasic4(const Host::IdentifierType& id);

    /// @brief Test that verifies that an IPv4 host reservation with
    /// options can have the global subnet id value.
    ///
    /// Uses gtest macros to report failures.
    void testGlobalSubnetId4();

    /// @brief Test that verifies that an IPv6 host reservation with
    /// options can have the global subnet id value.
    ///
    /// Uses gtest macros to report failures.
    void testGlobalSubnetId6();

    /// @brief Test that verifies that an IPv4 host reservation with
    /// options can have a max value for dhcp4_subnet id
    ///
    /// Uses gtest macros to report failures.
    void testMaxSubnetId4();

    /// @brief Test that Verifies that an IPv6 host reservation with
    /// options can have a max value for dhcp6_subnet id
    ///
    /// Uses gtest macros to report failures.
    void testMaxSubnetId6();

    /// @brief Test that Verifies that IPv4 host reservations in the
    /// same subnet can be retrieved properly.
    ///
    /// Uses gtest macros to report failures.
    void testGetAll4();

    /// @brief Test that Verifies that IPv6 host reservations in the
    /// same subnet can be retrieved properly.
    ///
    /// Uses gtest macros to report failures.
    void testGetAll6();

    /// @brief Test that Verifies that host reservations with the same
    /// hostname can be retrieved properly.
    ///
    /// Uses gtest macros to report failures.
    void testGetAllbyHostname();

    /// @brief Test that Verifies that IPv4 host reservations with the same
    /// hostname and in the same subnet can be retrieved properly.
    ///
    /// Uses gtest macros to report failures.
    void testGetAllbyHostnameSubnet4();

    /// @brief Test that Verifies that IPv6 host reservations with the same
    /// hostname and in the same subnet can be retrieved properly.
    ///
    /// Uses gtest macros to report failures.
    void testGetAllbyHostnameSubnet6();

    /// @brief Test that Verifies that pages of host reservations in the
    /// same subnet can be retrieved properly.
    ///
    /// Uses gtest macros to report failures.
    void testGetPage4();

    /// @brief Test that Verifies that pages of host reservations in the
    /// same subnet can be retrieved properly.
    ///
    /// Uses gtest macros to report failures.
    void testGetPage6();

    /// @brief Test that Verifies that pages of complex host reservations
    /// are not truncated, i.e. the limit applies on the number of hosts
    /// and not on the number of rows.
    ///
    /// Uses gtest macros to report failures.
    /// @param id Identifier type (hwaddr or duid).
    void testGetPageLimit4(const Host::IdentifierType& id);

    /// @brief Test that Verifies that pages of complex host reservations
    /// are not truncated, i.e. the limit applies on the number of hosts
    /// and not on the number of rows.
    ///
    /// Uses gtest macros to report failures.
    /// @param id Identifier type (hwaddr or duid).
    void testGetPageLimit6(const Host::IdentifierType& id);

    /// @brief Test that Verifies that pages of host reservations in the
    /// same subnet can be retrieved properly even with multiple subnets.
    ///
    /// Uses gtest macros to report failures.
    void testGetPage4Subnets();

    /// @brief Test that Verifies that pages of host reservations in the
    /// same subnet can be retrieved properly even with multiple subnets.
    ///
    /// Uses gtest macros to report failures.
    void testGetPage6Subnets();

    /// @brief Test that Verifies that pages of all host reservations
    /// can be retrieved properly.
    ///
    /// Uses gtest macros to report failures.
    void testGetPage4All();

    /// @brief Test that Verifies that pages of all host reservations
    /// can be retrieved properly.
    ///
    /// Uses gtest macros to report failures.
    void testGetPage6All();

    /// @brief Test inserts several hosts with unique IPv4 address and
    ///        checks that they can be retrieved properly.
    ///
    /// Uses gtest macros to report failures.
    /// @param id Identifier type.
    void testGetByIPv4(const Host::IdentifierType& id);

    /// @brief Test that hosts can be retrieved by host identifier.
    ///
    /// Uses gtest macros to report failures.
    void testGet4ByIdentifier(const Host::IdentifierType& identifier_type);

    /// @brief Test that clients with stored HW address can't be retrieved
    ///        by DUID with the same value.
    ///
    /// Test procedure: add host reservation with hardware address X, try to retrieve
    /// host by client-identifier X, verify that the reservation is not returned.
    ///
    /// Uses gtest macros to report failures.
    void testHWAddrNotClientId();

    /// @brief Test that clients with stored DUID can't be retrieved
    ///        by HW address of the same value.
    ///
    /// Test procedure: add host reservation with client identifier X, try to
    /// retrieve host by hardware address X, verify that the reservation is not
    /// returned.
    ///
    /// Uses gtest macros to report failures.
    void testClientIdNotHWAddr();

    /// @brief Test adds specified number of hosts with unique hostnames, then
    /// retrieves them and checks that the hostnames are set properly.
    ///
    /// Uses gtest macros to report failures.
    ///
    /// @param name hostname to be used (if n>1, numbers will be appended)
    /// @param num number of hostnames to be added.
    void testHostname(std::string name, int num);

    /// @brief Test insert and retrieve a host with user context.
    ///
    /// Uses gtest macros to report failures.
    ///
    /// @param user_context The user context.
    void testUserContext(isc::data::ConstElementPtr user_context);

    /// @brief Test inserts multiple reservations for the same host for different
    /// subnets and check that they can be retrieved properly.
    ///
    /// Uses gtest macros to report failures.
    ///
    /// @param subnets number of subnets to test
    /// @param id Host identifier type.
    void testMultipleSubnets(int subnets, const Host::IdentifierType& id);

    /// @brief Test inserts several hosts with unique IPv6 addresses and
    ///        checks that they can be retrieved properly.
    ///
    /// Uses gtest macros to report failures.
    /// @param id type of the identifier to be used (IDENT_HWADDR or IDENT_DUID)
    /// @param prefix true - reserve IPv6 prefix, false - reserve IPv6 address
    void testGetByIPv6(Host::IdentifierType id, bool prefix);

    /// @brief Test inserts several hosts with unique prefixes and checks
    ///        that the can be retrieved by subnet id and prefix value.
    void testGetBySubnetIPv6();

    /// @brief Test that hosts can be retrieved by hardware address.
    ///
    /// Uses gtest macros to report failures.
    void testGet6ByHWAddr();

    /// @brief Test that hosts can be retrieved by client-id
    ///
    /// Uses gtest macros to report failures.
    void testGet6ByClientId();

    /// @brief Test verifies if a host reservation can be stored with both
    ///         IPv6 address and prefix.
    /// Uses gtest macros to report failures.
    void testAddr6AndPrefix();

    /// @brief Tests if host with multiple IPv6 reservations can be added and then
    ///        retrieved correctly.
    void testMultipleReservations();

    /// @brief Tests if compareIPv6Reservations() method treats same pool of
    ///        reservations but added in different order as equal.
    void testMultipleReservationsDifferentOrder();

    /// @brief Test if host reservations made for different IPv6 subnets
    ///        are handled correctly.
    ///
    /// Uses gtest macros to report failures.
    ///
    /// @param subnets number of subnets to test
    /// @param id identifier type (IDENT_HWADDR or IDENT_DUID)
    void testSubnetId6(int subnets, Host::IdentifierType id);

    /// @brief Test if the duplicate host with same DUID can't be inserted.
    ///
    /// Uses gtest macros to report failures.
    void testAddDuplicate6WithSameDUID();

    /// @brief Test if the duplicate host with same HWAddr can't be inserted.
    ///
    /// Uses gtest macros to report failures.
    void testAddDuplicate6WithSameHWAddr();

    /// @brief Test that duplicate IPv6 reservation can't be inserted.
    ///
    /// Uses gtest macros to report failures.
    void testAddDuplicateIPv6();

    /// @brief Test if the reservation for the same IPv6 address can be
    /// inserted when allowed by the configuration.
    ///
    /// Uses gtest macros to report failures.
    void testAllowDuplicateIPv6();

    /// @brief Test that duplicate IPv4 reservation can't be inserted.
    ///
    /// Uses gtest macros to report failures.
    void testAddDuplicateIPv4();

    /// @brief Test if the reservation for the same IPv4 address can be
    /// inserted when allowed by the configuration.
    ///
    /// Uses gtest macros to report failures.
    void testAllowDuplicateIPv4();

    /// @brief Test that the backend does not support a mode in which multiple
    /// host reservations for the same IP address can be created.
    void testDisallowDuplicateIP();

    /// @brief Test that DHCPv4 options can be inserted and retrieved from
    /// the database.
    ///
    /// Uses gtest macros to report failures.
    ///
    /// @param formatted Boolean value indicating if the option values
    /// should be stored in the textual format in the database.
    /// @param user_context Optional user context.
    void testOptionsReservations4(const bool formatted,
                                  isc::data::ConstElementPtr user_context =
                                  isc::data::ConstElementPtr());

    /// @brief Test that DHCPv6 options can be inserted and retrieved from
    /// the database.
    ///
    /// Uses gtest macros to report failures.
    ///
    /// @param formatted Boolean value indicating if the option values
    /// should be stored in the textual format in the database.
    /// @param user_context Optional user context.
    void testOptionsReservations6(const bool formatted,
                                  isc::data::ConstElementPtr user_context =
                                  isc::data::ConstElementPtr());

    /// @brief Test that DHCPv4 and DHCPv6 options can be inserted and retrieved
    /// with a single query to the database.
    ///
    /// Uses gtest macros to report failures.
    ///
    /// @param formatted Boolean value indicating if the option values
    /// should be stored in the textual format in the database.
    void testOptionsReservations46(const bool formatted);

    /// @brief Test that multiple client classes for IPv4 can be inserted and
    /// retrieved for a given host reservation.
    ///
    /// Uses gtest macros to report failures.
    ///
    void testMultipleClientClasses4();

    /// @brief Test that multiple client classes for IPv6 can be inserted and
    /// retrieved for a given host reservation.
    ///
    /// Uses gtest macros to report failures.
    ///
    void testMultipleClientClasses6();

    /// @brief Test that multiple client classes for both IPv4 and IPv6 can
    /// be inserted and retrieved for a given host reservation.
    ///
    /// Uses gtest macros to report failures.
    ///
    void testMultipleClientClassesBoth();

    /// @brief Test that siaddr, sname, file fields can be retrieved
    /// from a database for a host.
    ///
    /// Uses gtest macros to report failures.
    void testMessageFields4();

    /// @brief Stress test on adding and retrieving hosts
    ///
    /// Rather than checking for correctness, this test gives interpretable
    /// performance results.
    ///
    /// @param n_of_hosts number of hosts to insert into and retrieve from the
    ///     database
    void stressTest(uint32_t n_of_hosts);
    /// @brief Tests that delete(subnet-id, addr4) call works.
    ///
    /// Uses gtest macros to report failures.
    void testDeleteByAddr4();

    /// @brief Tests that delete(subnet4-id, identifier-type, identifier) works.
    ///
    /// Uses gtest macros to report failures.
    void testDeleteById4();

    /// @brief Tests that delete(subnet4-id, id-type, id) also deletes options.
    void testDeleteById4Options();

    /// @brief Tests that delete(subnet6-id, identifier-type, identifier) works.
    ///
    /// Uses gtest macros to report failures.
    void testDeleteById6();

    /// @brief Tests that delete(subnet6-id, id-type, id) also deletes options.
    ///
    /// Uses gtest macros to report failures.
    void testDeleteById6Options();

    /// @brief Tests that multiple reservations without IPv4 addresses can be
    /// specified within a subnet.
    ///
    /// Uses gtest macros to report failures.
    void testMultipleHostsNoAddress4();

    /// @brief Tests that multiple hosts can be specified within an IPv6 subnet.
    ///
    /// Uses gtest macros to report failures.
    void testMultipleHosts6();

    /// @brief Tests that hosts can be updated.
    ///
    /// Uses gtest macros to report failures.
    void testUpdate();

    /// @brief Returns DUID with identical content as specified HW address
    ///
    /// This method does not have any sense in real life and is only useful
    /// in testing corner cases in the database backends (e.g. whether the DB
    /// is able to tell the difference between hwaddr and duid)
    ///
    /// @param hwaddr hardware address to be copied
    /// @return duid with the same value as specified HW address
    DuidPtr HWAddrToDuid(const HWAddrPtr& hwaddr);

    /// @brief Returns HW address with identical content as specified DUID
    ///
    /// This method does not have any sense in real life and is only useful
    /// in testing corner cases in the database backends (e.g. whether the DB
    /// is able to tell the difference between hwaddr and duid)
    ///
    /// @param duid DUID to be copied
    /// @return HW address with the same value as specified DUID
    HWAddrPtr DuidToHWAddr(const DuidPtr& duid);

};

class HostMgrDbLostCallbackTest : public ::testing::Test {
public:
    HostMgrDbLostCallbackTest()
        : db_lost_callback_called_(0), db_recovered_callback_called_(0),
          db_failed_callback_called_(0),
          io_service_(boost::make_shared<isc::asiolink::IOService>()) {
        isc::db::DatabaseConnection::db_lost_callback_ = 0;
        isc::db::DatabaseConnection::db_recovered_callback_ = 0;
        isc::db::DatabaseConnection::db_failed_callback_ = 0;
        isc::db::DatabaseConnection::setIOService(io_service_);
        isc::dhcp::TimerMgr::instance()->setIOService(io_service_);
        isc::dhcp::CfgMgr::instance().clear();
    }

    virtual ~HostMgrDbLostCallbackTest() {
        isc::db::DatabaseConnection::db_lost_callback_ = 0;
        isc::db::DatabaseConnection::db_recovered_callback_ = 0;
        isc::db::DatabaseConnection::db_failed_callback_ = 0;
        isc::db::DatabaseConnection::setIOService(isc::asiolink::IOServicePtr());
        isc::dhcp::TimerMgr::instance()->unregisterTimers();
        isc::dhcp::CfgMgr::instance().clear();
    }

    /// @brief Prepares the class for a test.
    ///
    /// Invoked by gtest prior test entry, we create the
    /// appropriate schema and create a basic host manager to
    /// wipe out any prior instance
    virtual void SetUp() {
        // Ensure we have the proper schema with no transient data.
        createSchema();
        // Wipe out any pre-existing mgr
        isc::dhcp::HostMgr::create();
        isc::dhcp::CfgMgr::instance().clear();
    }

    /// @brief Pre-text exit clean up
    ///
    /// Invoked by gtest upon test exit, we destroy the schema
    /// we created.
    virtual void TearDown() {
        // If data wipe enabled, delete transient data otherwise destroy the schema
        destroySchema();
        isc::dhcp::CfgMgr::instance().clear();
    }

    /// @brief Abstract method for destroying the back end specific schema
    virtual void destroySchema() = 0;

    /// @brief Abstract method for creating the back end specific schema
    virtual void createSchema() = 0;

    /// @brief Abstract method which returns the back end specific connection
    /// string
    virtual std::string validConnectString() = 0;

    /// @brief Abstract method which returns invalid back end specific connection
    /// string
    virtual std::string invalidConnectString() = 0;

    /// @brief Verifies the host manager's behavior if DB connection can not be
    /// established but succeeds on retry
    ///
    /// This function creates a host manager with a back end that supports
    /// connectivity lost callback (currently only MySQL and PostgreSQL). It
    /// verifies that connectivity is unavailable and then recovered on retry:
    /// -# The registered DbLostCallback was invoked
    /// -# The registered DbRecoveredCallback was invoked
    void testRetryOpenDbLostAndRecoveredCallback();

    /// @brief Verifies the host manager's behavior if DB connection can not be
    /// established but fails on retry
    ///
    /// This function creates a host manager with a back end that supports
    /// connectivity lost callback (currently only MySQL and PostgreSQL). It
    /// It verifies that connectivity is unavailable and then fails again on
    /// retry:
    /// -# The registered DbLostCallback was invoked
    /// -# The registered DbFailedCallback was invoked
    void testRetryOpenDbLostAndFailedCallback();

    /// @brief Verifies the host manager's behavior if DB connection can not be
    /// established but succeeds on retry
    ///
    /// This function creates a host manager with a back end that supports
    /// connectivity lost callback (currently only MySQL and PostgreSQL). It
    /// verifies that connectivity is unavailable and then recovered on retry:
    /// -# The registered DbLostCallback was invoked
    /// -# The registered DbRecoveredCallback was invoked after two reconnect
    /// attempts (once failing and second triggered by timer)
    void testRetryOpenDbLostAndRecoveredAfterTimeoutCallback();

    /// @brief Verifies the host manager's behavior if DB connection can not be
    /// established but fails on retry
    ///
    /// This function creates a host manager with a back end that supports
    /// connectivity lost callback (currently only MySQL and PostgreSQL). It
    /// It verifies that connectivity is unavailable and then fails again on
    /// retry:
    /// -# The registered DbLostCallback was invoked
    /// -# The registered DbFailedCallback was invoked after two reconnect
    /// attempts (once failing and second triggered by timer)
    void testRetryOpenDbLostAndFailedAfterTimeoutCallback();

    /// @brief Verifies open failures do NOT invoke db lost callback
    ///
    /// The db lost callback should only be invoked after successfully
    /// opening the DB and then subsequently losing it. Failing to
    /// open should be handled directly by the application layer.
    void testNoCallbackOnOpenFailure();

    /// @brief Verifies the host manager's behavior if DB connection is lost
    ///
    /// This function creates a host manager with a back end that supports
    /// connectivity lost callback (currently only MySQL and PostgreSQL). It
    /// verifies connectivity by issuing a known valid query. Next it simulates
    /// connectivity lost by identifying and closing the socket connection to
    /// the CB backend. It then reissues the query and verifies that:
    /// -# The Query throws DbOperationError (rather than exiting)
    /// -# The registered DbLostCallback was invoked
    /// -# The registered DbRecoveredCallback was invoked
    void testDbLostAndRecoveredCallback();

    /// @brief Verifies the host manager's behavior if DB connection is lost
    ///
    /// This function creates a host manager with a back end that supports
    /// connectivity lost callback (currently only MySQL and PostgreSQL). It
    /// verifies connectivity by issuing a known valid query. Next it simulates
    /// connectivity lost by identifying and closing the socket connection to
    /// the CB backend. It then reissues the query and verifies that:
    /// -# The Query throws DbOperationError (rather than exiting)
    /// -# The registered DbLostCallback was invoked
    /// -# The registered DbFailedCallback was invoked
    void testDbLostAndFailedCallback();

    /// @brief Verifies the host manager's behavior if DB connection is lost
    ///
    /// This function creates a host manager with a back end that supports
    /// connectivity lost callback (currently only MySQL and PostgreSQL). It
    /// verifies connectivity by issuing a known valid query. Next it simulates
    /// connectivity lost by identifying and closing the socket connection to
    /// the CB backend. It then reissues the query and verifies that:
    /// -# The Query throws DbOperationError (rather than exiting)
    /// -# The registered DbLostCallback was invoked
    /// -# The registered DbRecoveredCallback was invoked after two reconnect
    /// attempts (once failing and second triggered by timer)
    void testDbLostAndRecoveredAfterTimeoutCallback();

    /// @brief Verifies the host manager's behavior if DB connection is lost
    ///
    /// This function creates a host manager with a back end that supports
    /// connectivity lost callback (currently only MySQL and PostgreSQL). It
    /// verifies connectivity by issuing a known valid query. Next it simulates
    /// connectivity lost by identifying and closing the socket connection to
    /// the CB backend. It then reissues the query and verifies that:
    /// -# The Query throws DbOperationError (rather than exiting)
    /// -# The registered DbLostCallback was invoked
    /// -# The registered DbFailedCallback was invoked after two reconnect
    /// attempts (once failing and second triggered by timer)
    void testDbLostAndFailedAfterTimeoutCallback();

    /// @brief Callback function registered with the host manager
    bool db_lost_callback(util::ReconnectCtlPtr /* not_used */) {
        return (++db_lost_callback_called_);
    }

    /// @brief Flag used to detect calls to db_lost_callback function
    uint32_t db_lost_callback_called_;

    /// @brief Callback function registered with the host manager
    bool db_recovered_callback(util::ReconnectCtlPtr /* not_used */) {
        return (++db_recovered_callback_called_);
    }

    /// @brief Flag used to detect calls to db_recovered_callback function
    uint32_t db_recovered_callback_called_;

    /// @brief Callback function registered with the host manager
    bool db_failed_callback(util::ReconnectCtlPtr /* not_used */) {
        return (++db_failed_callback_called_);
    }

    /// @brief Flag used to detect calls to db_failed_callback function
    uint32_t db_failed_callback_called_;

    /// The IOService object, used for all ASIO operations.
    isc::asiolink::IOServicePtr io_service_;
};

/// @brief Test fixture class for @c HostMgr class.
class HostMgrTest : public ::testing::Test {
public:

    /// @brief Constructor
    HostMgrTest() = default;

    /// @brief Destructor
    virtual ~HostMgrTest() = default;

protected:

    /// @brief Prepares the class for a test.
    ///
    /// This method crates a handful of unique HW address and DUID objects
    /// for use in unit tests. These objects are held in the @c hwaddrs_ and
    /// @c duids_ members respectively.
    ///
    /// This method also resets the @c CfgMgr configuration and re-creates
    /// the @c HostMgr object.
    virtual void SetUp();

    /// @brief Convenience method returning a pointer to the @c CfgHosts object
    /// in the @c CfgMgr.
    CfgHostsPtr getCfgHosts() const;

    /// @brief Inserts IPv4 reservation into the host data source.
    ///
    /// @param data_source Reference to the data source to which the reservation
    /// should be inserted.
    /// @param hwaddr Pointer to the hardware address to be associated with the
    /// reservation.
    /// @param subnet_id IPv4 subnet id.
    /// @param address IPv4 address to be reserved.
    void addHost4(BaseHostDataSource& data_source,
                  const HWAddrPtr& hwaddr,
                  const SubnetID& subnet_id,
                  const isc::asiolink::IOAddress& address);

    /// @brief Inserts IPv6 reservation into the host data source.
    ///
    /// @param data_source Reference to the data source to which the reservation
    /// should be inserted.
    /// @param duid Pointer to the DUID to be associated with the reservation.
    /// @param subnet_id IPv6 subnet id.
    /// @param address IPv6 address/prefix to be reserved.
    /// @param prefix_len Prefix length. The default value is 128 which
    /// indicates that the reservation is for an IPv6 address rather than a
    /// prefix.
    void addHost6(BaseHostDataSource& data_source,
                  const DuidPtr& duid,
                  const SubnetID& subnet_id,
                  const isc::asiolink::IOAddress& address,
                  const uint8_t prefix_len = 128);

    /// @brief Inserts IPv6 reservation into the host data source.
    ///
    /// @param data_source Reference to the data source to which the reservation
    /// should be inserted.
    /// @param duid Pointer to the DUID to be associated with the reservation.
    /// @param subnet_id IPv6 subnet id.
    /// @param addresses IPv6 addresses/prefixes to be reserved.
    /// @param prefix_len Prefix length. The default value is 128 which
    /// indicates that the reservation is for an IPv6 address rather than a
    /// prefix. Notice that this is common for all addresses in given vector
    /// of addresses.
    void addHost6(BaseHostDataSource& data_source,
                  const DuidPtr& duid,
                  const SubnetID& subnet_id,
                  const std::vector<isc::asiolink::IOAddress>& addresses,
                  const uint8_t prefix_len = 128);

    /// @brief This test verifies that HostMgr returns all reservations for the
    /// specified HW address.
    ///
    /// If reservations are added to different host data sources, it is expected
    /// that the @c HostMgr will retrieve reservations from both of them.
    ///
    /// @param data_source1 Host data source to which first reservation is
    /// inserted.
    /// @param data_source2 Host data source to which second reservation is
    /// inserted.
    void testGetAll(BaseHostDataSource& data_source1,
                    BaseHostDataSource& data_source2);

    /// @brief This test verifies that HostMgr returns all reservations for the
    /// specified DHCPv4 subnet.
    ///
    /// If reservations are added to different host data sources, it is expected
    /// that the @c HostMgr will retrieve reservations from both of them.
    ///
    /// @param data_source1 Host data source to which first reservation is
    /// inserted.
    /// @param data_source2 Host data source to which second reservation is
    /// inserted.
    void testGetAll4BySubnet(BaseHostDataSource& data_source1,
                             BaseHostDataSource& data_source2);

    /// @brief This test verifies that HostMgr returns all reservations for the
    /// specified DHCPv6 subnet.
    ///
    /// If reservations are added to different host data sources, it is expected
    /// that the @c HostMgr will retrieve reservations from both of them.
    ///
    /// @param data_source1 Host data source to which first reservation is
    /// inserted.
    /// @param data_source2 Host data source to which second reservation is
    /// inserted.
    void testGetAll6BySubnet(BaseHostDataSource& data_source1,
                             BaseHostDataSource& data_source2);

    /// @brief This test verifies that HostMgr returns all reservations for the
    /// specified hostname.
    ///
    /// If reservations are added to different host data sources, it is expected
    /// that the @c HostMgr will retrieve reservations from both of them.
    ///
    /// @param data_source1 Host data source to which first reservation is
    /// inserted.
    /// @param data_source2 Host data source to which second reservation is
    /// inserted.
    void testGetAllbyHostname(BaseHostDataSource& data_source1,
                              BaseHostDataSource& data_source2);

    /// @brief This test verifies that HostMgr returns all reservations for the
    /// specified hostname and DHCPv4 subnet.
    ///
    /// If reservations are added to different host data sources, it is expected
    /// that the @c HostMgr will retrieve reservations from both of them.
    ///
    /// @param data_source1 Host data source to which first reservation is
    /// inserted.
    /// @param data_source2 Host data source to which second reservation is
    /// inserted.
    void testGetAllbyHostnameSubnet4(BaseHostDataSource& data_source1,
                                     BaseHostDataSource& data_source2);

    /// @brief This test verifies that HostMgr returns all reservations for the
    /// specified hostname and DHCPv6 subnet.
    ///
    /// If reservations are added to different host data sources, it is expected
    /// that the @c HostMgr will retrieve reservations from both of them.
    ///
    /// @param data_source1 Host data source to which first reservation is
    /// inserted.
    /// @param data_source2 Host data source to which second reservation is
    /// inserted.
    void testGetAllbyHostnameSubnet6(BaseHostDataSource& data_source1,
                                     BaseHostDataSource& data_source2);

    /// @brief This test verifies that HostMgr returns all reservations for the
    /// specified DHCPv4 subnet by pages.
    ///
    /// If reservations are added to different host data sources, it is expected
    /// that the @c HostMgr will retrieve reservations from both of them.
    ///
    /// @param use_database True when the second reservation is inserted
    /// in a database.
    void testGetPage4(bool use_database);

    /// @brief This test verifies that HostMgr returns all reservations for the
    /// specified DHCPv6 subnet by pages.
    ///
    /// If reservations are added to different host data sources, it is expected
    /// that the @c HostMgr will retrieve reservations from both of them.
    ///
    /// @param use_database True when the second reservation is inserted
    /// in a database.
    void testGetPage6(bool use_database);

    /// @brief This test verifies that HostMgr returns all reservations
    /// by pages.
    ///
    /// If reservations are added to different host data sources, it is expected
    /// that the @c HostMgr will retrieve reservations from both of them.
    ///
    /// @param use_database True when the second reservation is inserted
    /// in a database.
    void testGetPage4All(bool use_database);

    /// @brief This test verifies that HostMgr returns all reservations
    /// by pages.
    ///
    /// If reservations are added to different host data sources, it is expected
    /// that the @c HostMgr will retrieve reservations from both of them.
    ///
    /// @param use_database True when the second reservation is inserted
    /// in a database.
    void testGetPage6All(bool use_database);

    /// @brief This test verifies that it is possible to retrieve IPv4
    /// reservation for the particular host using HostMgr.
    ///
    /// If reservations are added to different host data sources, it is expected
    /// that the @c HostMgr will retrieve reservations from both of them.
    ///
    /// @param data_source1 Host data source to which first reservation is
    /// inserted.
    /// @param data_source2 Host data source to which second reservation is
    /// inserted.
    void testGetAll4(BaseHostDataSource& data_source1,
                     BaseHostDataSource& data_source2);

    /// @brief This test verifies that it is possible to retrieve an IPv4
    /// reservation for the particular host using HostMgr.
    ///
    /// @param data_source Host data source to which reservation is inserted and
    /// from which it will be retrieved.
    void testGet4(BaseHostDataSource& data_source);

    /// @brief This test verifies that it is possible to retrieve negative
    /// cached reservation with and only with get4Any.
    void testGet4Any();

    /// @brief This test verifies that it is possible to retrieve an IPv6
    /// reservation for the particular host using HostMgr.
    ///
    /// @param data_source Host data source to which reservation is inserted and
    /// from which it will be retrieved.
    void testGet6(BaseHostDataSource& data_source);

    /// @brief This test verifies that it is possible to retrieve negative
    /// cached reservation with and only with get6Any.
    void testGet6Any();

    /// @brief This test verifies that it is possible to retrieve an IPv6
    /// prefix reservation for the particular host using HostMgr.
    ///
    /// @param data_source1 Host data source to which first reservation is
    /// inserted.
    /// @param data_source2 Host data source to which second reservation is
    /// inserted.
    void testGet6ByPrefix(BaseHostDataSource& data_source1,
                          BaseHostDataSource& data_source2);

    /// @brief This test verifies that HostMgr returns all reservations for the
    /// specified DHCPv4 subnet and IPv4 address.
    ///
    /// If reservations are added to different host data sources, it is expected
    /// that the @c HostMgr will retrieve reservations from both of them.
    ///
    /// @param data_source1 Host data source to which first reservation is
    /// inserted.
    /// @param data_source2 Host data source to which second reservation is
    /// inserted.
    void testGetAll4BySubnetIP(BaseHostDataSource& data_source1,
                               BaseHostDataSource& data_source2);

    /// @brief This test verifies that HostMgr returns all reservations for the
    /// specified DHCPv6 subnet and IPv6 address.
    ///
    /// If reservations are added to different host data sources, it is expected
    /// that the @c HostMgr will retrieve reservations from both of them.
    ///
    /// @param data_source1 Host data source to which first reservation is
    /// inserted.
    /// @param data_source2 Host data source to which second reservation is
    /// inserted.
    void testGetAll6BySubnetIP(BaseHostDataSource& data_source1,
                               BaseHostDataSource& data_source2);

    /// @brief This test verifies that HostMgr returns all reservations for the
    /// specified IPv6 address.
    ///
    /// If reservations are added to different host data sources, it is expected
    /// that the @c HostMgr will retrieve reservations from both of them.
    ///
    /// @param data_source1 Host data source to which first reservation is
    /// inserted.
    /// @param data_source2 Host data source to which second reservation is
    /// inserted.
    void testGetAll6ByIP(BaseHostDataSource& data_source1,
                         BaseHostDataSource& data_source2);

    /// @brief This test verifies that HostMgr returns all reservations for the
    /// specified IPv6 prefix/es.
    ///
    /// If reservations are added to different host data sources, it is expected
    /// that the @c HostMgr will retrieve reservations from both of them.
    ///
    /// @param data_source1 Host data source to which first reservation is
    /// inserted.
    /// @param data_source2 Host data source to which second reservation is
    /// inserted.
    void testGetAll6ByIpPrefix(BaseHostDataSource& data_source1, BaseHostDataSource& data_source2);

    /// @brief This test verifies that HostMgr adds the reservations to any
    /// data source.
    ///
    /// The reservations are added to the external database (alternate sources)
    /// by default but the primary source may be changed on demand too.
    ///
    /// @param data_source1 Host data source to which first reservation is
    /// inserted.
    /// @param data_source2 Host data source to which second reservation is
    /// inserted.
    void testAdd(BaseHostDataSource& data_source1,
                 BaseHostDataSource& data_source2);

    /// @brief This test verifies that HostMgr deletes the reservations by
    /// the subnet ID and subnet address.
    ///
    /// The reservations are deleted from the external database (alternate
    /// sources) only by default but the primary source may be changed on
    /// demand too.
    ///
    /// @param data_source1 Host data source to which first reservation is
    /// inserted.
    /// @param data_source2 Host data source to which second reservation is
    /// inserted.
    void testDeleteByIDAndAddress(BaseHostDataSource& data_source1,
                                  BaseHostDataSource& data_source2);

    /// @brief This test verifies that HostMgr deletes the IPv4 reservations by
    /// the subnet ID and identifier.
    ///
    /// The reservations are deleted from the external database (alternate
    /// sources) only by default but the primary source may be changed on
    /// demand too.
    ///
    /// @param data_source1 Host data source to which first reservation is
    /// inserted.
    /// @param data_source2 Host data source to which second reservation is
    /// inserted.
    void testDelete4ByIDAndIdentifier(BaseHostDataSource& data_source1,
                                      BaseHostDataSource& data_source2);

    /// @brief This test verifies that HostMgr deletes the IPv6 reservations by
    /// the subnet ID and identifier.
    ///
    /// The reservations are deleted from the external database (alternate
    /// sources) only by default but the primary source may be changed on
    /// demand too.
    ///
    /// @param data_source1 Host data source to which first reservation is
    /// inserted.
    /// @param data_source2 Host data source to which second reservation is
    /// inserted.
    void testDelete6ByIDAndIdentifier(BaseHostDataSource& data_source1,
                                      BaseHostDataSource& data_source2);

    /// @brief Utility function that returns true if a given data source
    /// is primary (it isn't an alternate source).
    /// @param data_source Host data source to check.
    /// @return True if the data source is primary. Otherwise, false.
    bool isPrimaryDataSource(const BaseHostDataSource& data_source) const;

    /// @brief HW addresses to be used by the tests.
    std::vector<HWAddrPtr> hwaddrs_;
    /// @brief DUIDs to be used by the tests.
    std::vector<DuidPtr> duids_;
};

}  // namespace test
}  // namespace dhcp
}  // namespace isc

#endif