/* mbed Microcontroller Library
 * Copyright (c) 2018 ARM Limited
 *
 * 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.
 */

#ifndef SOCKET_STATS_H
#define SOCKET_STATS_H

#include "platform/SingletonPtr.h"
#include "platform/PlatformMutex.h"
#include "netsocket/Socket.h"
#include "SocketAddress.h"
#include "hal/ticker_api.h"

#ifndef MBED_CONF_NSAPI_SOCKET_STATS_MAX_COUNT
#define MBED_CONF_NSAPI_SOCKET_STATS_MAX_COUNT      10
#endif

/** Enum of socket states
  *
  * Can be used to specify current state of socket - open, closed, connected or listen.
  *
  * @enum socket_state
  */
typedef enum {
    SOCK_CLOSED,                    /**< Socket is closed and does not exist anymore in the system */
    SOCK_OPEN,                      /**< Socket is open but not associated to any peer address */
    SOCK_CONNECTED,                 /**< Socket is associated to peer address, either by connect() or sendto()/recvfrom() calls */
    SOCK_LISTEN,                    /**< Socket is listening for incoming connections */
} socket_state;

/** Structure to parse socket statistics
  */
typedef struct {
    Socket *reference_id;           /**< Used for identifying socket */
    SocketAddress peer;             /**< Last associated peername of this socket (Destination address) */
    socket_state state;             /**< State of this socket */
    nsapi_protocol_t proto;         /**< Specifies a protocol used with socket */
    size_t sent_bytes;              /**< Data sent through this socket */
    size_t recv_bytes;              /**< Data received through this socket */
    us_timestamp_t last_change_tick;/**< osKernelGetTick() when state last changed */
} mbed_stats_socket_t;

/**  SocketStats class
 *
 *   Class to get the network socket statistics
 */
class SocketStats {
public:

#if !defined(DOXYGEN_ONLY)
    /** Create a socket statistics object
     *
     *  Application users must not create class objects.
     *  Entities reporting network statistics create the class object.
     *  Application can fetch network statistics using static `mbed_stats_socket_get_each` API
     *  without creating an object.
     */
    constexpr SocketStats() = default;
#endif
    /**
     *  Fill the passed array of structures with the socket statistics for each created socket.
     *
     *  @param stats    A pointer to an array of mbed_stats_socket_t structures to fill
     *  @param count    The number of mbed_stats_socket_t structures in the provided array
     *  @return         The number of mbed_stats_socket_t structures that have been filled.
     *                  If the number of sockets on the system is less than or equal to count,
     *                  it will equal the number of sockets created (active or closed).
     *                  If the number of sockets on the system is greater than count,
     *                  it will equal count.
     */
    static size_t mbed_stats_socket_get_each(mbed_stats_socket_t *stats, size_t count);

#if !defined(DOXYGEN_ONLY)
    /** Add entry of newly created socket in statistics array.
     *  API used by socket (TCP or UDP) layers only, not to be used by application.
     *
     *  @param reference_id   ID to identify socket in data array.
     *
     *  @Note: The entry in the array is maintained even after the socket is closed.
     *         The entry is overwritten for sockets that were closed first, in case
     *         the socket creation count exceeds `MBED_CONF_NSAPI_SOCKET_STATS_MAX_COUNT`.
     *
     */
    void stats_new_socket_entry(const Socket *reference_id);

    /** Updates the state of the socket and records `tick_last_change`.
     *  API used by socket (TCP or UDP) layers only, not to be used by application.
     *
     *  @param reference_id   ID to identify socket in data array.
     *  @param state  Parameter to update the current state of the socket.
     *
     */
    void stats_update_socket_state(const Socket *reference_id, socket_state state);

    /** Update the peer information of the socket.
     *  API used by socket (TCP or UDP) layers only, not to be used by application.
     *
     *  @param reference_id   ID to identify socket in data array.
     *  @param peer  Parameter to update destination peer information.
     *
     */
    void stats_update_peer(const Socket *reference_id, const SocketAddress &peer);

    /** Update socket protocol.
     *  API used by socket (TCP or UDP) layers only, not to be used by application.
     *
     *  @param reference_id   ID to identify socket in data array.
     *  @param proto Parameter to update the protocol type of socket.
     *
     */
    void stats_update_proto(const Socket *reference_id, nsapi_protocol_t proto);

    /** Update bytes sent on socket, which is cumulative count per socket.
     *  API used by socket (TCP or UDP) layers only, not to be used by application.
     *
     *  @param reference_id   ID to identify socket in data array.
     *  @param sent_bytes Parameter to append bytes sent over the socket.
     *
     */
    void stats_update_sent_bytes(const Socket *reference_id, size_t sent_bytes);

    /** Update bytes received on socket, which is cumulative count per socket
     *  API used by socket (TCP or UDP) layers only, not to be used by application.
     *
     *  @param reference_id   ID to identify socket in data array.
     *  @param recv_bytes Parameter to append bytes the socket receives.
     *
     */
    void stats_update_recv_bytes(const Socket *reference_id, size_t recv_bytes);

#if MBED_CONF_NSAPI_SOCKET_STATS_ENABLED
private:
    static mbed_stats_socket_t _stats[MBED_CONF_NSAPI_SOCKET_STATS_MAX_COUNT];
    static SingletonPtr<PlatformMutex> _mutex;
    static uint32_t _size;

    /** Internal function to scan the array and get the position of the element in the list.
     *
     *  @param reference_id   ID to identify the socket in the data array.
     *
     */
    int get_entry_position(const Socket *reference_id);
#endif
#endif
};

#if !MBED_CONF_NSAPI_SOCKET_STATS_ENABLED
inline size_t SocketStats::mbed_stats_socket_get_each(mbed_stats_socket_t *, size_t)
{
    return 0;
}

inline void SocketStats::stats_new_socket_entry(const Socket *)
{
}

inline void SocketStats::stats_update_socket_state(const Socket *, socket_state)
{
}

inline void SocketStats::stats_update_peer(const Socket *, const SocketAddress &)
{
}

inline void SocketStats::stats_update_proto(const Socket *, nsapi_protocol_t)
{
}

inline void SocketStats::stats_update_sent_bytes(const Socket *, size_t)
{
}

inline void SocketStats::stats_update_recv_bytes(const Socket *, size_t)
{
}
#endif // !MBED_CONF_NSAPI_SOCKET_STATS_ENABLED

#endif