/*
 *  Copyright (c) 2019-2021, 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
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 */

/**
 * @file
 *   This file includes definitions for Thread Radio Encapsulation Link (TREL) interface.
 */

#ifndef TREL_INTERFACE_HPP_
#define TREL_INTERFACE_HPP_

#include "openthread-core-config.h"

#if OPENTHREAD_CONFIG_RADIO_LINK_TREL_ENABLE

#include <openthread/trel.h>
#include <openthread/platform/trel.h>

#include "common/array.hpp"
#include "common/locator.hpp"
#include "common/tasklet.hpp"
#include "common/time.hpp"
#include "mac/mac_types.hpp"
#include "net/ip6_address.hpp"
#include "net/socket.hpp"
#include "radio/trel_packet.hpp"
#include "thread/mle_types.hpp"

namespace ot {
namespace Trel {

class Link;

extern "C" void otPlatTrelHandleReceived(otInstance *aInstance, uint8_t *aBuffer, uint16_t aLength);
extern "C" void otPlatTrelHandleDiscoveredPeerInfo(otInstance *aInstance, const otPlatTrelPeerInfo *aInfo);

/**
 * This class represents a TREL link interface.
 *
 */
class Interface : public InstanceLocator
{
    friend class Link;
    friend void otPlatTrelHandleReceived(otInstance *aInstance, uint8_t *aBuffer, uint16_t aLength);
    friend void otPlatTrelHandleDiscoveredPeerInfo(otInstance *aInstance, const otPlatTrelPeerInfo *aInfo);

public:
    /**
     * This class represents information about a discovered TREL peer.
     *
     */
    class Peer : public otTrelPeer
    {
        friend class Interface;
        friend void otPlatTrelHandleDiscoveredPeerInfo(otInstance *aInstance, const otPlatTrelPeerInfo *aInfo);

    public:
        /**
         * This method returns the Extended MAC Address of the discovered TREL peer.
         *
         * @returns The Extended MAC Address of the TREL peer.
         *
         */
        const Mac::ExtAddress &GetExtAddress(void) const { return static_cast<const Mac::ExtAddress &>(mExtAddress); }

        /**
         * This method returns the Extended PAN Identifier of the discovered TREL peer.
         *
         * @returns The Extended PAN Identifier of the TREL peer.
         *
         */
        const MeshCoP::ExtendedPanId &GetExtPanId(void) const
        {
            return static_cast<const MeshCoP::ExtendedPanId &>(mExtPanId);
        }

        /**
         * This method returns the IPv6 socket address of the discovered TREL peer.
         *
         * @returns The IPv6 socket address of the TREP peer.
         *
         */
        const Ip6::SockAddr &GetSockAddr(void) const { return static_cast<const Ip6::SockAddr &>(mSockAddr); }

        /**
         * This method indicates whether the peer matches a given Extended Address.
         *
         * @param[in] aExtAddress   A Extended Address to match with.
         *
         * @retval TRUE if the peer matches @p aExtAddress.
         * @retval FALSE if the peer does not match @p aExtAddress.
         *
         */
        bool Matches(const Mac::ExtAddress &aExtAddress) const { return GetExtAddress() == aExtAddress; }

        /**
         * This method indicates whether the peer matches a given Socket Address.
         *
         * @param[in] aSockAddr   A Socket Address to match with.
         *
         * @retval TRUE if the peer matches @p aSockAddr.
         * @retval FALSE if the peer does not match @p aSockAddr.
         *
         */
        bool Matches(const Ip6::SockAddr &aSockAddr) const { return GetSockAddr() == aSockAddr; }

    private:
        class Info : public otPlatTrelPeerInfo
        {
        public:
            bool                 IsRemoved(void) const { return mRemoved; }
            const uint8_t *      GetTxtData(void) const { return mTxtData; }
            uint16_t             GetTxtLength(void) const { return mTxtLength; }
            const Ip6::SockAddr &GetSockAddr(void) const { return static_cast<const Ip6::SockAddr &>(mSockAddr); }
        };

        void SetExtAddress(const Mac::ExtAddress &aExtAddress) { mExtAddress = aExtAddress; }
        void SetExtPanId(const MeshCoP::ExtendedPanId &aExtPanId) { mExtPanId = aExtPanId; }
        void SetSockAddr(const Ip6::SockAddr &aSockAddr) { mSockAddr = aSockAddr; }
        void Log(const char *aAction) const;
    };

    /**
     * This type represents an iterator for iterating over TREL peer table entries.
     *
     */
    typedef otTrelPeerIterator PeerIterator;

    /**
     * This method enables the TREL interface.
     *
     * This call initiates an ongoing DNS-SD browse on the service name "_trel._udp" within the local browsing domain
     * to discover other devices supporting TREL. Device also registers a new service to be advertised using DNS-SD,
     * with the service name is "_trel._udp" indicating its support for TREL. Device is ready to receive TREL messages
     * from peers.
     *
     */
    void Enable(void);

    /**
     * This method disables the TREL interface.
     *
     * This call stops the DNS-SD browse on the service name "_trel._udp", stops advertising TREL DNS-SD service, and
     * clears the TREL peer table.
     *
     */
    void Disable(void);

    /**
     * This method indicates whether the TREL interface is enabled.
     *
     * @retval TRUE if the TREL interface is enabled.
     * @retval FALSE if the TREL interface is disabled.
     *
     */
    bool IsEnabled(void) const { return mEnabled; }

    /**
     * This method initializes a peer table iterator.
     *
     * @param[in] aIterator   The iterator to initialize.
     *
     */
    void InitIterator(PeerIterator &aIterator) const { aIterator = 0; }

    /**
     * This method iterates over the peer table entries.
     *
     * @param[in] aIterator   The iterator. MUST be initialized.
     *
     * @returns A pointer to the next `Peer` entry or `nullptr` if no more entries in the table.
     *
     */
    const Peer *GetNextPeer(PeerIterator &aIterator) const;

    /**
     * This method sets the filter mode (enables/disables filtering).
     *
     * When filtering is enabled, any rx and tx traffic through TREL interface is silently dropped. This is mainly
     * intended for use during testing.
     *
     * Unlike `Enable()/Disable()` which fully start/stop the TREL interface operation, when filter mode is enabled the
     * TREL interface continues to be enabled.
     *
     * @param[in] aFiltered  TRUE to enable filter mode, FALSE to disable filter mode.
     *
     */
    void SetFilterEnabled(bool aEnable) { mFiltered = aEnable; }

    /**
     * This method indicates whether or not the filter mode is enabled.
     *
     * @retval TRUE if the TREL filter mode is enabled.
     * @retval FALSE if the TREL filter mode is disabled.
     *
     */
    bool IsFilterEnabled(void) const { return mFiltered; }

private:
    static constexpr uint16_t kPeerTableExtraEntries = 32;
    static constexpr uint16_t kPeerTableSize         = Mle::kMaxRouters + Mle::kMaxChildren + kPeerTableExtraEntries;

    static const char kTxtRecordExtAddressKey[];
    static const char kTxtRecordExtPanIdKey[];

    typedef Array<Peer, kPeerTableSize, uint16_t> PeerTable;

    explicit Interface(Instance &aInstance);

    // Methods used by `Trel::Link`.
    void  Init(void);
    void  HandleExtAddressChange(void);
    void  HandleExtPanIdChange(void);
    Error Send(const Packet &aPacket, bool aIsDiscovery = false);

    // Callbacks from `otPlatTrel`.
    void HandleReceived(uint8_t *aBuffer, uint16_t aLength);
    void HandleDiscoveredPeerInfo(const Peer::Info &aInfo);

    static void HandleRegisterServiceTask(Tasklet &aTasklet);
    void        RegisterService(void);
    Error       ParsePeerInfoTxtData(const Peer::Info &      aInfo,
                                     Mac::ExtAddress &       aExtAddress,
                                     MeshCoP::ExtendedPanId &aExtPanId) const;
    Peer *      GetNewPeerEntry(void);
    void        RemovePeerEntry(Peer &aEntry);

    bool      mInitialized : 1;
    bool      mEnabled : 1;
    bool      mFiltered : 1;
    Tasklet   mRegisterServiceTask;
    uint16_t  mUdpPort;
    Packet    mRxPacket;
    PeerTable mPeerTable;
};

} // namespace Trel
} // namespace ot

#endif // #if OPENTHREAD_CONFIG_RADIO_LINK_TREL_ENABLE

#endif // TREL_INTERFACE_HPP_