/*!
 * \file      RegionCommon.c
 *
 * \brief     LoRa MAC common region implementation
 *
 * \copyright Revised BSD License, see section \ref LICENSE.
 *
 * \code
 *                ______                              _
 *               / _____)             _              | |
 *              ( (____  _____ ____ _| |_ _____  ____| |__
 *               \____ \| ___ |    (_   _) ___ |/ ___)  _ \
 *               _____) ) ____| | | || |_| ____( (___| | | |
 *              (______/|_____)_|_|_| \__)_____)\____)_| |_|
 *              (C)2013-2017 Semtech
 *
 *               ___ _____ _   ___ _  _____ ___  ___  ___ ___
 *              / __|_   _/_\ / __| |/ / __/ _ \| _ \/ __| __|
 *              \__ \ | |/ _ \ (__| ' <| _| (_) |   / (__| _|
 *              |___/ |_/_/ \_\___|_|\_\_| \___/|_|_\\___|___|
 *              embedded.connectivity.solutions===============
 *
 * \endcode
 *
 * \author    Miguel Luis ( Semtech )
 *
 * \author    Gregory Cristian ( Semtech )
 *
 * \author    Daniel Jaeckle ( STACKFORCE )
 */
#include <math.h>
#include "node/utilities.h"
#include "RegionCommon.h"

#define BACKOFF_DC_1_HOUR       100
#define BACKOFF_DC_10_HOURS     1000
#define BACKOFF_DC_24_HOURS     10000

static uint8_t CountChannels( uint16_t mask, uint8_t nbBits )
{
    uint8_t nbActiveBits = 0;

    for( uint8_t j = 0; j < nbBits; j++ )
    {
        if( ( mask & ( 1 << j ) ) == ( 1 << j ) )
        {
            nbActiveBits++;
        }
    }
    return nbActiveBits;
}

uint16_t RegionCommonGetJoinDc( TimerTime_t elapsedTime )
{
    uint16_t dutyCycle = 0;

    if( elapsedTime < 3600000 )
    {
        dutyCycle = BACKOFF_DC_1_HOUR;
    }
    else if( elapsedTime < ( 3600000 + 36000000 ) )
    {
        dutyCycle = BACKOFF_DC_10_HOURS;
    }
    else
    {
        dutyCycle = BACKOFF_DC_24_HOURS;
    }
    return dutyCycle;
}

bool RegionCommonChanVerifyDr( uint8_t nbChannels, uint16_t* channelsMask, int8_t dr, int8_t minDr, int8_t maxDr, ChannelParams_t* channels )
{
    if( RegionCommonValueInRange( dr, minDr, maxDr ) == 0 )
    {
        return false;
    }

    for( uint8_t i = 0, k = 0; i < nbChannels; i += 16, k++ )
    {
        for( uint8_t j = 0; j < 16; j++ )
        {
            if( ( ( channelsMask[k] & ( 1 << j ) ) != 0 ) )
            {// Check datarate validity for enabled channels
                if( RegionCommonValueInRange( dr, ( channels[i + j].DrRange.Fields.Min & 0x0F ),
                                                  ( channels[i + j].DrRange.Fields.Max & 0x0F ) ) == 1 )
                {
                    // At least 1 channel has been found we can return OK.
                    return true;
                }
            }
        }
    }
    return false;
}

uint8_t RegionCommonValueInRange( int8_t value, int8_t min, int8_t max )
{
    if( ( value >= min ) && ( value <= max ) )
    {
        return 1;
    }
    return 0;
}

bool RegionCommonChanDisable( uint16_t* channelsMask, uint8_t id, uint8_t maxChannels )
{
    uint8_t index = id / 16;

    if( ( index > ( maxChannels / 16 ) ) || ( id >= maxChannels ) )
    {
        return false;
    }

    // Deactivate channel
    channelsMask[index] &= ~( 1 << ( id % 16 ) );

    return true;
}

uint8_t RegionCommonCountChannels( uint16_t* channelsMask, uint8_t startIdx, uint8_t stopIdx )
{
    uint8_t nbChannels = 0;

    if( channelsMask == NULL )
    {
        return 0;
    }

    for( uint8_t i = startIdx; i < stopIdx; i++ )
    {
        nbChannels += CountChannels( channelsMask[i], 16 );
    }

    return nbChannels;
}

void RegionCommonChanMaskCopy( uint16_t* channelsMaskDest, uint16_t* channelsMaskSrc, uint8_t len )
{
    if( ( channelsMaskDest != NULL ) && ( channelsMaskSrc != NULL ) )
    {
        for( uint8_t i = 0; i < len; i++ )
        {
            channelsMaskDest[i] = channelsMaskSrc[i];
        }
    }
}

void RegionCommonSetBandTxDone( bool joined, Band_t* band, TimerTime_t lastTxDone )
{
    if( joined == true )
    {
        band->LastTxDoneTime = lastTxDone;
    }
    else
    {
        band->LastTxDoneTime = lastTxDone;
        band->LastJoinTxDoneTime = lastTxDone;
    }
}

TimerTime_t RegionCommonUpdateBandTimeOff( bool joined, bool dutyCycle, Band_t* bands, uint8_t nbBands )
{
    TimerTime_t nextTxDelay = ( TimerTime_t )( -1 );

    // Update bands Time OFF
    for( uint8_t i = 0; i < nbBands; i++ )
    {
        if( joined == false )
        {
            uint32_t txDoneTime =  MAX( TimerGetElapsedTime( bands[i].LastJoinTxDoneTime ),
                                        ( dutyCycle == true ) ? TimerGetElapsedTime( bands[i].LastTxDoneTime ) : 0 );

            if( bands[i].TimeOff <= txDoneTime )
            {
                bands[i].TimeOff = 0;
            }
            if( bands[i].TimeOff != 0 )
            {
                nextTxDelay = MIN( bands[i].TimeOff - txDoneTime, nextTxDelay );
            }
        }
        else
        {
            if( dutyCycle == true )
            {
                if( bands[i].TimeOff <= TimerGetElapsedTime( bands[i].LastTxDoneTime ) )
                {
                    bands[i].TimeOff = 0;
                }
                if( bands[i].TimeOff != 0 )
                {
                    nextTxDelay = MIN( bands[i].TimeOff - TimerGetElapsedTime( bands[i].LastTxDoneTime ),
                                       nextTxDelay );
                }
            }
            else
            {
                nextTxDelay = 0;
                bands[i].TimeOff = 0;
            }
        }
    }
    return nextTxDelay;
}

uint8_t RegionCommonParseLinkAdrReq( uint8_t* payload, RegionCommonLinkAdrParams_t* linkAdrParams )
{
    uint8_t retIndex = 0;

    if( payload[0] == SRV_MAC_LINK_ADR_REQ )
    {
        // Parse datarate and tx power
        linkAdrParams->Datarate = payload[1];
        linkAdrParams->TxPower = linkAdrParams->Datarate & 0x0F;
        linkAdrParams->Datarate = ( linkAdrParams->Datarate >> 4 ) & 0x0F;
        // Parse ChMask
        linkAdrParams->ChMask = ( uint16_t )payload[2];
        linkAdrParams->ChMask |= ( uint16_t )payload[3] << 8;
        // Parse ChMaskCtrl and nbRep
        linkAdrParams->NbRep = payload[4];
        linkAdrParams->ChMaskCtrl = ( linkAdrParams->NbRep >> 4 ) & 0x07;
        linkAdrParams->NbRep &= 0x0F;

        // LinkAdrReq has 4 bytes length + 1 byte CMD
        retIndex = 5;
    }
    return retIndex;
}

uint8_t RegionCommonLinkAdrReqVerifyParams( RegionCommonLinkAdrReqVerifyParams_t* verifyParams, int8_t* dr, int8_t* txPow, uint8_t* nbRep )
{
    uint8_t status = verifyParams->Status;
    int8_t datarate = verifyParams->Datarate;
    int8_t txPower = verifyParams->TxPower;
    int8_t nbRepetitions = verifyParams->NbRep;

    // Handle the case when ADR is off.
    if( verifyParams->AdrEnabled == false )
    {
        // When ADR is off, we are allowed to change the channels mask and the NbRep,
        // if the datarate and the TX power of the LinkAdrReq are set to 0x0F.
        if( ( verifyParams->Datarate != 0x0F ) || ( verifyParams->TxPower != 0x0F ) )
        {
            status = 0;
            nbRepetitions = verifyParams->CurrentNbRep;
        }
        // Get the current datarate and tx power
        datarate = verifyParams->CurrentDatarate;
        txPower = verifyParams->CurrentTxPower;
    }

    if( status != 0 )
    {
        // Verify datarate. The variable phyParam. Value contains the minimum allowed datarate.
        if( RegionCommonChanVerifyDr( verifyParams->NbChannels, verifyParams->ChannelsMask, datarate,
                                      verifyParams->MinDatarate, verifyParams->MaxDatarate, verifyParams->Channels  ) == false )
        {
            status &= 0xFD; // Datarate KO
        }

        // Verify tx power
        if( RegionCommonValueInRange( txPower, verifyParams->MaxTxPower, verifyParams->MinTxPower ) == 0 )
        {
            // Verify if the maximum TX power is exceeded
            if( verifyParams->MaxTxPower > txPower )
            { // Apply maximum TX power. Accept TX power.
                txPower = verifyParams->MaxTxPower;
            }
            else
            {
                status &= 0xFB; // TxPower KO
            }
        }
    }

    // If the status is ok, verify the NbRep
    if( status == 0x07 )
    {
        if( nbRepetitions == 0 )
        { // Restore the default value according to the LoRaWAN specification
            nbRepetitions = 1;
        }
    }

    // Apply changes
    *dr = datarate;
    *txPow = txPower;
    *nbRep = nbRepetitions;

    return status;
}

double RegionCommonComputeSymbolTimeLoRa( uint8_t phyDr, uint32_t bandwidth )
{
    return ( ( double )( 1 << phyDr ) / ( double )bandwidth ) * 1000;
}

double RegionCommonComputeSymbolTimeFsk( uint8_t phyDr )
{
    return ( 8.0 / ( double )phyDr ); // 1 symbol equals 1 byte
}

void RegionCommonComputeRxWindowParameters( double tSymbol, uint8_t minRxSymbols, uint32_t rxError, uint32_t wakeUpTime, uint32_t* windowTimeout, int32_t* windowOffset )
{
/* XXX: I do not understand this */
#if 0
    *windowTimeout = MAX( ( uint32_t )ceil( ( ( 2 * minRxSymbols - 8 ) * tSymbol + 2 * rxError ) / tSymbol ), minRxSymbols ); // Computed number of symbols
    *windowOffset = ( int32_t )ceil( ( 4.0 * tSymbol ) - ( ( *windowTimeout * tSymbol ) / 2.0 ) - wakeUpTime );
#else
    uint16_t add_symbols;

    *windowTimeout = MAX( ( uint32_t )ceil( ( ( 2 * minRxSymbols - 8 ) * tSymbol + 2 * rxError ) / tSymbol ), minRxSymbols ); // Computed number of symbols
    add_symbols = 1;
    if (wakeUpTime >= tSymbol) {
        add_symbols += ((double)wakeUpTime / tSymbol);
    }
    *windowTimeout += add_symbols;
    *windowOffset = -1 * wakeUpTime;
#endif
}

int8_t RegionCommonComputeTxPower( int8_t txPowerIndex, float maxEirp, float antennaGain )
{
    int8_t phyTxPower = 0;

    phyTxPower = ( int8_t )floor( ( maxEirp - ( txPowerIndex * 2U ) ) - antennaGain );

    return phyTxPower;
}

void RegionCommonCalcBackOff( RegionCommonCalcBackOffParams_t* calcBackOffParams )
{
    uint8_t bandIdx = calcBackOffParams->Channels[calcBackOffParams->Channel].Band;
    uint16_t dutyCycle = calcBackOffParams->Bands[bandIdx].DCycle;
    uint16_t joinDutyCycle = 0;

    // Reset time-off to initial value.
    calcBackOffParams->Bands[bandIdx].TimeOff = 0;

    if( calcBackOffParams->Joined == false )
    {
        // Get the join duty cycle
        joinDutyCycle = RegionCommonGetJoinDc( calcBackOffParams->ElapsedTime );
        // Apply the most restricting duty cycle
        dutyCycle = MAX( dutyCycle, joinDutyCycle );
        // Reset the timeoff if the last frame was not a join request and when the duty cycle is not enabled
        if( ( calcBackOffParams->DutyCycleEnabled == false ) && ( calcBackOffParams->LastTxIsJoinRequest == false ) )
        {
            // This is the case when the duty cycle is off and the last uplink frame was not a join.
            // This could happen in case of a rejoin, e.g. in compliance test mode.
            // In this special case we have to set the time off to 0, since the join duty cycle shall only
            // be applied after the first join request.
            calcBackOffParams->Bands[bandIdx].TimeOff = 0;
        }
        else
        {
            // Apply band time-off.
            calcBackOffParams->Bands[bandIdx].TimeOff = calcBackOffParams->TxTimeOnAir * dutyCycle - calcBackOffParams->TxTimeOnAir;
        }
    }
    else
    {
        if( calcBackOffParams->DutyCycleEnabled == true )
        {
            calcBackOffParams->Bands[bandIdx].TimeOff = calcBackOffParams->TxTimeOnAir * dutyCycle - calcBackOffParams->TxTimeOnAir;
        }
        else
        {
            calcBackOffParams->Bands[bandIdx].TimeOff = 0;
        }
    }
}