/*
 *    Copyright (c) 2017, The OpenThread Authors.
 *    All rights reserved.
 *
 *    Redistribution and use in source and binary forms, with or without
 *    modification, are permitted provided that the following conditions are met:
 *    1. Redistributions of source code must retain the above copyright
 *       notice, this list of conditions and the following disclaimer.
 *    2. Redistributions in binary form must reproduce the above copyright
 *       notice, this list of conditions and the following disclaimer in the
 *       documentation and/or other materials provided with the distribution.
 *    3. Neither the name of the copyright holder nor the
 *       names of its contributors may be used to endorse or promote products
 *       derived from this software without specific prior written permission.
 *
 *    THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
 *    AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 *    IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 *    ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
 *    LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
 *    CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
 *    SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
 *    INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
 *    CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 *    ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
 *    POSSIBILITY OF SUCH DAMAGE.
 */

/**
 * @file
 *   This file includes definition for Thread border agent.
 */

#ifndef OTBR_AGENT_BORDER_AGENT_HPP_
#define OTBR_AGENT_BORDER_AGENT_HPP_

#include "openthread-br/config.h"

#include <vector>

#include <stdint.h>

#include "backbone_router/backbone_agent.hpp"
#include "common/code_utils.hpp"
#include "common/mainloop.hpp"
#include "host/rcp_host.hpp"
#include "mdns/mdns.hpp"
#include "sdp_proxy/advertising_proxy.hpp"
#include "sdp_proxy/discovery_proxy.hpp"
#include "trel_dnssd/trel_dnssd.hpp"

#ifndef OTBR_VENDOR_NAME
#define OTBR_VENDOR_NAME "OpenThread"
#endif

#ifndef OTBR_PRODUCT_NAME
#define OTBR_PRODUCT_NAME "BorderRouter"
#endif

#ifndef OTBR_MESHCOP_SERVICE_INSTANCE_NAME
#define OTBR_MESHCOP_SERVICE_INSTANCE_NAME (OTBR_VENDOR_NAME " " OTBR_PRODUCT_NAME)
#endif

namespace otbr {

/**
 * @addtogroup border-router-border-agent
 *
 * @brief
 *   This module includes definition for Thread border agent
 *
 * @{
 */

/**
 * This class implements Thread border agent functionality.
 */
class BorderAgent : public Mdns::StateObserver, private NonCopyable
{
public:
    /** The callback for receiving ephemeral key changes. */
    using EphemeralKeyChangedCallback = std::function<void(void)>;

    /**
     * The constructor to initialize the Thread border agent.
     *
     * @param[in] aHost       A reference to the Thread controller.
     * @param[in] aPublisher  A reference to the mDNS Publisher.
     */
    BorderAgent(otbr::Host::RcpHost &aHost, Mdns::Publisher &aPublisher);

    ~BorderAgent(void) = default;

    /**
     * Initializes the Thread Border Agent.
     */
    void Init(void);

    /**
     * Deinitializes the Thread Border Agent.
     */
    void Deinit(void);

    /**
     * Overrides MeshCoP service (i.e. _meshcop._udp) instance name, product name, vendor name and vendor OUI.
     *
     * This method must be called before this BorderAgent is enabled by SetEnabled.
     *
     * @param[in] aServiceInstanceName    The service instance name; suffix may be appended to this value to avoid
     *                                    name conflicts.
     * @param[in] aProductName            The product name; must not exceed length of kMaxProductNameLength
     *                                    and an empty string will be ignored.
     * @param[in] aVendorName             The vendor name; must not exceed length of kMaxVendorNameLength
     *                                    and an empty string will be ignored.
     * @param[in] aVendorOui              The vendor OUI; must have length of 3 bytes or be empty and ignored.
     * @param[in] aNonStandardTxtEntries  Non-standard (vendor-specific) TXT entries whose key MUST start with "v"
     *
     * @returns OTBR_ERROR_INVALID_ARGS  If aVendorName, aProductName or aVendorOui exceeds the
     *                                   allowed ranges or invalid keys are found in aNonStandardTxtEntries
     * @returns OTBR_ERROR_NONE          If successfully set the meshcop service values.
     */
    otbrError SetMeshCopServiceValues(const std::string              &aServiceInstanceName,
                                      const std::string              &aProductName,
                                      const std::string              &aVendorName,
                                      const std::vector<uint8_t>     &aVendorOui             = {},
                                      const Mdns::Publisher::TxtList &aNonStandardTxtEntries = {});

    /**
     * This method enables/disables the Border Agent.
     *
     * @param[in] aIsEnabled  Whether to enable the Border Agent.
     */
    void SetEnabled(bool aIsEnabled);

    /**
     * This method enables/disables the Border Agent Ephemeral Key feature.
     *
     * @param[in] aIsEnabled  Whether to enable the BA Ephemeral Key feature.
     */
    void SetEphemeralKeyEnabled(bool aIsEnabled);

    /**
     * This method returns the Border Agent Ephemeral Key feature state.
     */
    bool GetEphemeralKeyEnabled(void) const { return mIsEphemeralKeyEnabled; }

    /**
     * This method handles mDNS publisher's state changes.
     *
     * @param[in] aState  The state of mDNS publisher.
     */
    void HandleMdnsState(Mdns::Publisher::State aState) override;

    /**
     * This method creates ephemeral key in the Border Agent.
     *
     * @param[out] aEphemeralKey  The ephemeral key digit string of length 9 with first 8 digits randomly
     *                            generated, and the last 9th digit as verhoeff checksum.
     *
     * @returns OTBR_ERROR_INVALID_ARGS  If Verhoeff checksum calculate returns error.
     * @returns OTBR_ERROR_NONE          If successfully generate the ePSKc.
     */
    static otbrError CreateEphemeralKey(std::string &aEphemeralKey);

    /**
     * This method adds a callback for ephemeral key changes.
     *
     * @param[in] aCallback  The callback to receive ephemeral key changed events.
     */
    void AddEphemeralKeyChangedCallback(EphemeralKeyChangedCallback aCallback);

private:
    void ClearState(void);
    void Start(void);
    void Stop(void);
    bool IsEnabled(void) const { return mIsEnabled; }
    void PublishMeshCopService(void);
    void UpdateMeshCopService(void);
    void UnpublishMeshCopService(void);
#if OTBR_ENABLE_DBUS_SERVER
    void HandleUpdateVendorMeshCoPTxtEntries(std::map<std::string, std::vector<uint8_t>> aUpdate);
#endif

    void HandleThreadStateChanged(otChangedFlags aFlags);

    bool        IsThreadStarted(void) const;
    std::string GetServiceInstanceNameWithExtAddr(const std::string &aServiceInstanceName) const;
    std::string GetAlternativeServiceInstanceName() const;

    static void HandleEpskcStateChanged(void *aContext);
    void        HandleEpskcStateChanged(void);
    void        PublishEpskcService(void);
    void        UnpublishEpskcService(void);

    otbr::Host::RcpHost &mHost;
    Mdns::Publisher     &mPublisher;
    bool                 mIsEnabled;
    bool                 mIsEphemeralKeyEnabled;

    std::map<std::string, std::vector<uint8_t>> mMeshCopTxtUpdate;

    std::vector<uint8_t> mVendorOui;

    std::string mVendorName;
    std::string mProductName;

    // The base service instance name typically consists of the vendor and product name. But it can
    // also be overridden by `OTBR_MESHCOP_SERVICE_INSTANCE_NAME` or method `SetMeshCopServiceValues()`.
    // For example, this value can be "OpenThread Border Router".
    std::string mBaseServiceInstanceName;

    // The actual instance name advertised in the mDNS service. This is usually the value of
    // `mBaseServiceInstanceName` plus the Extended Address and optional random number for avoiding
    // conflicts. For example, this value can be "OpenThread Border Router #7AC3" or
    // "OpenThread Border Router #7AC3 (14379)".
    std::string mServiceInstanceName;

    std::vector<EphemeralKeyChangedCallback> mEphemeralKeyChangedCallbacks;
};

/**
 * @}
 */

} // namespace otbr

#endif // OTBR_AGENT_BORDER_AGENT_HPP_