/*
 *  Copyright (c) 2018, 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
 * @brief
 *   This file implements the posix simulation.
 */

#include "openthread-posix-config.h"
#include "platform-posix.h"

#include <arpa/inet.h>
#include <stddef.h>
#include <stdio.h>
#include <string.h>
#include <sys/select.h>
#include <unistd.h>

#if OPENTHREAD_POSIX_VIRTUAL_TIME

static const int kMaxNetworkSize = 33;      ///< Well-known ID used by a simulated radio supporting promiscuous mode.
static const int kBasePort       = 18000;   ///< This base port for posix app simulation.
static const int kUsPerSecond    = 1000000; ///< Number of microseconds per second.

static uint64_t sNow        = 0;  ///< Time of simulation.
static int      sSockFd     = -1; ///< Socket used to communicating with simulator.
static uint16_t sPortOffset = 0;  ///< Port offset for simulation.

void virtualTimeInit(uint16_t aNodeId)
{
    struct sockaddr_in sockaddr;
    char              *offset;

    memset(&sockaddr, 0, sizeof(sockaddr));
    sockaddr.sin_family = AF_INET;

    offset = getenv("PORT_OFFSET");

    if (offset)
    {
        char *endptr;

        sPortOffset = (uint16_t)strtol(offset, &endptr, 0);

        if (*endptr != '\0')
        {
            const uint8_t kMsgSize = 40;
            char          msg[kMsgSize];

            snprintf(msg, sizeof(msg), "Invalid PORT_OFFSET: %s", offset);
            DieNowWithMessage(msg, OT_EXIT_INVALID_ARGUMENTS);
        }

        sPortOffset *= (kMaxNetworkSize + 1);
    }

    sockaddr.sin_port        = htons(kBasePort + sPortOffset + aNodeId);
    sockaddr.sin_addr.s_addr = INADDR_ANY;

    sSockFd = SocketWithCloseExec(AF_INET, SOCK_DGRAM, IPPROTO_UDP, kSocketBlock);

    if (sSockFd == -1)
    {
        DieNowWithMessage("socket", OT_EXIT_ERROR_ERRNO);
    }

    if (bind(sSockFd, (struct sockaddr *)&sockaddr, sizeof(sockaddr)) == -1)
    {
        DieNowWithMessage("bind", OT_EXIT_ERROR_ERRNO);
    }
}

void virtualTimeDeinit(void)
{
    if (sSockFd != -1)
    {
        close(sSockFd);
        sSockFd = -1;
    }
}

static void virtualTimeSendEvent(struct VirtualTimeEvent *aEvent, size_t aLength)
{
    ssize_t            rval;
    struct sockaddr_in sockaddr;

    memset(&sockaddr, 0, sizeof(sockaddr));
    sockaddr.sin_family = AF_INET;
    inet_pton(AF_INET, "127.0.0.1", &sockaddr.sin_addr);
    sockaddr.sin_port = htons(9000 + sPortOffset);

    rval = sendto(sSockFd, aEvent, aLength, 0, (struct sockaddr *)&sockaddr, sizeof(sockaddr));

    if (rval < 0)
    {
        DieNowWithMessage("sendto", OT_EXIT_ERROR_ERRNO);
    }
}

void virtualTimeReceiveEvent(struct VirtualTimeEvent *aEvent)
{
    ssize_t rval = recvfrom(sSockFd, aEvent, sizeof(*aEvent), 0, nullptr, nullptr);

    if (rval < 0 || (uint16_t)rval < offsetof(struct VirtualTimeEvent, mData))
    {
        DieNowWithMessage("recvfrom", (rval < 0) ? OT_EXIT_ERROR_ERRNO : OT_EXIT_FAILURE);
    }

    sNow += aEvent->mDelay;
}

void virtualTimeSendSleepEvent(const struct timeval *aTimeout)
{
    struct VirtualTimeEvent event;

    event.mDelay      = (uint64_t)aTimeout->tv_sec * kUsPerSecond + (uint64_t)aTimeout->tv_usec;
    event.mEvent      = OT_SIM_EVENT_ALARM_FIRED;
    event.mDataLength = 0;

    virtualTimeSendEvent(&event, offsetof(struct VirtualTimeEvent, mData));
}

void virtualTimeSendRadioSpinelWriteEvent(const uint8_t *aData, uint16_t aLength)
{
    struct VirtualTimeEvent event;

    event.mDelay      = 0;
    event.mEvent      = OT_SIM_EVENT_RADIO_SPINEL_WRITE;
    event.mDataLength = aLength;

    memcpy(event.mData, aData, aLength);

    virtualTimeSendEvent(&event, offsetof(struct VirtualTimeEvent, mData) + event.mDataLength);
}

void virtualTimeUpdateFdSet(otSysMainloopContext *aContext)
{
    FD_SET(sSockFd, &aContext->mReadFdSet);
    if (aContext->mMaxFd < sSockFd)
    {
        aContext->mMaxFd = sSockFd;
    }
}

void virtualTimeProcess(otInstance *aInstance, const otSysMainloopContext *aContext)
{
    struct VirtualTimeEvent event;

    memset(&event, 0, sizeof(event));

    OT_UNUSED_VARIABLE(aInstance);

    if (FD_ISSET(sSockFd, &aContext->mReadFdSet))
    {
        virtualTimeReceiveEvent(&event);
    }

    virtualTimeSpinelProcess(aInstance, &event);
    virtualTimeRadioProcess(aInstance, &event);
}

uint64_t otPlatTimeGet(void) { return sNow; }

#endif // OPENTHREAD_POSIX_VIRTUAL_TIME