/****************************************************************************
 * apps/modbus/mb.c
 *
 * FreeModbus Library: A portable Modbus implementation for Modbus ASCII/RTU.
 * Copyright (c) 2006 Christian Walter <wolti@sil.at>
 * 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. The name of the author may not be used to endorse or promote products
 *    derived from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``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 AUTHOR 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.
 *
 ****************************************************************************/

/****************************************************************************
 * Included Files
 ****************************************************************************/

#include <nuttx/config.h>
#include <stdlib.h>
#include <string.h>

#include "port.h"

#include "modbus/mb.h"
#include "modbus/mbframe.h"
#include "modbus/mbproto.h"
#include "modbus/mbfunc.h"

#include "modbus/mbport.h"

#ifdef CONFIG_MB_RTU_ENABLED
#  include "mbrtu.h"
#endif

#ifdef CONFIG_MB_ASCII_ENABLED
#  include "mbascii.h"
#endif

#ifdef CONFIG_MB_TCP_ENABLED
#  include "mbtcp.h"
#endif

/****************************************************************************
 * Private Data
 ****************************************************************************/

static uint8_t  ucMBAddress;
static eMBMode  eMBCurrentMode;

static enum
{
  STATE_ENABLED,
  STATE_DISABLED,
  STATE_NOT_INITIALIZED
} eMBState = STATE_NOT_INITIALIZED;

/* Functions pointer which are initialized in eMBInit(). Depending on the
 * mode (RTU or ASCII) the are set to the correct implementations.
 */

static peMBFrameSend peMBFrameSendCur;
static pvMBFrameStart pvMBFrameStartCur;
static pvMBFrameStop pvMBFrameStopCur;
static peMBFrameReceive peMBFrameReceiveCur;
static pvMBFrameClose pvMBFrameCloseCur;

/* Callback functions required by the porting layer. They are called when
 * an external event has happened which includes a timeout or the reception
 * or transmission of a character.
 */

bool(*pxMBFrameCBByteReceived)(void);
bool(*pxMBFrameCBTransmitterEmpty)(void);
bool(*pxMBPortCBTimerExpired)(void);

bool(*pxMBFrameCBReceiveFSMCur)(void);
bool(*pxMBFrameCBTransmitFSMCur)(void);

/* An array of Modbus functions handlers which associates Modbus function
 * codes with implementing functions.
 */

static xMBFunctionHandler xFuncHandlers[CONFIG_MB_FUNC_HANDLERS_MAX] =
{
#ifdef CONFIG_MB_FUNC_OTHER_REP_SLAVEID_ENABLED
  {MB_FUNC_OTHER_REPORT_SLAVEID, eMBFuncReportSlaveID},
#endif
#ifdef CONFIG_MB_FUNC_READ_INPUT_ENABLED
  {MB_FUNC_READ_INPUT_REGISTER, eMBFuncReadInputRegister},
#endif
#ifdef CONFIG_MB_FUNC_READ_HOLDING_ENABLED
  {MB_FUNC_READ_HOLDING_REGISTER, eMBFuncReadHoldingRegister},
#endif
#ifdef CONFIG_MB_FUNC_WRITE_MULTIPLE_HOLDING_ENABLED
  {MB_FUNC_WRITE_MULTIPLE_REGISTERS, eMBFuncWriteMultipleHoldingRegister},
#endif
#ifdef CONFIG_MB_FUNC_WRITE_HOLDING_ENABLED
  {MB_FUNC_WRITE_REGISTER, eMBFuncWriteHoldingRegister},
#endif
#ifdef CONFIG_MB_FUNC_READWRITE_HOLDING_ENABLED
  {MB_FUNC_READWRITE_MULTIPLE_REGISTERS, eMBFuncReadWriteMultipleHoldingRegister},
#endif
#ifdef CONFIG_MB_FUNC_READ_COILS_ENABLED
  {MB_FUNC_READ_COILS, eMBFuncReadCoils},
#endif
#ifdef CONFIG_MB_FUNC_WRITE_COIL_ENABLED
  {MB_FUNC_WRITE_SINGLE_COIL, eMBFuncWriteCoil},
#endif
#ifdef CONFIG_MB_FUNC_WRITE_MULTIPLE_COILS_ENABLED
  {MB_FUNC_WRITE_MULTIPLE_COILS, eMBFuncWriteMultipleCoils},
#endif
#ifdef CONFIG_MB_FUNC_READ_DISCRETE_INPUTS_ENABLED
  {MB_FUNC_READ_DISCRETE_INPUTS, eMBFuncReadDiscreteInputs},
#endif
};

/****************************************************************************
 * Public Functions
 ****************************************************************************/

eMBErrorCode eMBInit(eMBMode eMode, uint8_t ucSlaveAddress, uint8_t ucPort,
                     speed_t ulBaudRate, eMBParity eParity)
{
  eMBErrorCode eStatus = MB_ENOERR;

  /* check preconditions */

  if ((ucSlaveAddress == MB_ADDRESS_BROADCAST) ||
      (ucSlaveAddress < MB_ADDRESS_MIN) || (ucSlaveAddress > MB_ADDRESS_MAX))
    {
      eStatus = MB_EINVAL;
    }
  else
    {
      ucMBAddress = ucSlaveAddress;

      switch (eMode)
        {
#ifdef CONFIG_MB_RTU_ENABLED
        case MB_RTU:
          pvMBFrameStartCur = eMBRTUStart;
          pvMBFrameStopCur = eMBRTUStop;
          peMBFrameSendCur = eMBRTUSend;
          peMBFrameReceiveCur = eMBRTUReceive;
          pvMBFrameCloseCur = vMBPortClose;
          pxMBFrameCBByteReceived = xMBRTUReceiveFSM;
          pxMBFrameCBTransmitterEmpty = xMBRTUTransmitFSM;
          pxMBPortCBTimerExpired = xMBRTUTimerT35Expired;

          eStatus = eMBRTUInit(ucMBAddress, ucPort, ulBaudRate, eParity);
          break;
#endif
#ifdef CONFIG_MB_ASCII_ENABLED
        case MB_ASCII:
          pvMBFrameStartCur = eMBASCIIStart;
          pvMBFrameStopCur = eMBASCIIStop;
          peMBFrameSendCur = eMBASCIISend;
          peMBFrameReceiveCur = eMBASCIIReceive;
          pvMBFrameCloseCur = vMBPortClose;
          pxMBFrameCBByteReceived = xMBASCIIReceiveFSM;
          pxMBFrameCBTransmitterEmpty = xMBASCIITransmitFSM;
          pxMBPortCBTimerExpired = xMBASCIITimerT1SExpired;

          eStatus = eMBASCIIInit(ucMBAddress, ucPort, ulBaudRate, eParity);
          break;
#endif
        default:
          eStatus = MB_EINVAL;
        }

      if (eStatus == MB_ENOERR)
        {
          if (!xMBPortEventInit())
            {
              /* port dependent event module initialization failed. */

              eStatus = MB_EPORTERR;
            }
          else
            {
              eMBCurrentMode = eMode;
              eMBState = STATE_DISABLED;
            }
        }
    }

  return eStatus;
}

#ifdef CONFIG_MB_TCP_ENABLED
eMBErrorCode eMBTCPInit(uint16_t ucTCPPort)
{
  eMBErrorCode eStatus = MB_ENOERR;

  if ((eStatus = eMBTCPDoInit(ucTCPPort)) != MB_ENOERR)
    {
      eMBState = STATE_DISABLED;
    }
  else if (!xMBPortEventInit())
    {
      /* Port dependent event module initialization failed. */

      eStatus = MB_EPORTERR;
    }
  else
    {
      pvMBFrameStartCur = eMBTCPStart;
      pvMBFrameStopCur = eMBTCPStop;
      peMBFrameReceiveCur = eMBTCPReceive;
      peMBFrameSendCur = eMBTCPSend;
#ifdef CONFIG_MB_HAVE_CLOSE
      pvMBFrameCloseCur = vMBTCPPortClose;
#else
      pvMBFrameCloseCur = NULL;
#endif
      ucMBAddress = MB_TCP_PSEUDO_ADDRESS;
      eMBCurrentMode = MB_TCP;
      eMBState = STATE_DISABLED;
    }

  return eStatus;
}
#endif

eMBErrorCode eMBRegisterCB(uint8_t ucFunctionCode, pxMBFunctionHandler pxHandler)
{
  eMBErrorCode  eStatus;
  int           i;

  if ((0 < ucFunctionCode) && (ucFunctionCode <= 127))
    {
      ENTER_CRITICAL_SECTION();
      if (pxHandler != NULL)
        {
          for (i = 0; i < CONFIG_MB_FUNC_HANDLERS_MAX; i++)
            {
              if ((xFuncHandlers[i].pxHandler == NULL) ||
                  (xFuncHandlers[i].pxHandler == pxHandler))
                {
                  xFuncHandlers[i].ucFunctionCode = ucFunctionCode;
                  xFuncHandlers[i].pxHandler = pxHandler;
                  break;
                }
            }
          eStatus = (i != CONFIG_MB_FUNC_HANDLERS_MAX) ? MB_ENOERR : MB_ENORES;
        }
      else
        {
          for (i = 0; i < CONFIG_MB_FUNC_HANDLERS_MAX; i++)
            {
              if (xFuncHandlers[i].ucFunctionCode == ucFunctionCode)
                {
                  xFuncHandlers[i].ucFunctionCode = 0;
                  xFuncHandlers[i].pxHandler = NULL;
                  break;
                }
            }

          /* Remove can't fail. */

          eStatus = MB_ENOERR;
        }

      EXIT_CRITICAL_SECTION();
    }
  else
    {
      eStatus = MB_EINVAL;
    }

  return eStatus;
}

eMBErrorCode eMBClose(void)
{
  eMBErrorCode eStatus = MB_ENOERR;

  if (eMBState == STATE_DISABLED)
    {
      if (pvMBFrameCloseCur != NULL)
        {
          pvMBFrameCloseCur();
        }
    }
  else
    {
      eStatus = MB_EILLSTATE;
    }

  return eStatus;
}

eMBErrorCode eMBEnable(void)
{
  eMBErrorCode eStatus = MB_ENOERR;

  if (eMBState == STATE_DISABLED)
    {
      /* Activate the protocol stack. */

      pvMBFrameStartCur();
      eMBState = STATE_ENABLED;
    }
  else
    {
      eStatus = MB_EILLSTATE;
    }

  return eStatus;
}

eMBErrorCode eMBDisable(void)
{
  eMBErrorCode  eStatus;

  if (eMBState == STATE_ENABLED)
    {
      pvMBFrameStopCur();
      eMBState = STATE_DISABLED;
      eStatus = MB_ENOERR;
    }
  else if (eMBState == STATE_DISABLED)
    {
      eStatus = MB_ENOERR;
    }
  else
    {
      eStatus = MB_EILLSTATE;
    }

  return eStatus;
}

eMBErrorCode eMBPoll(void)
{
  static uint8_t     *ucMBFrame;
  static uint8_t      ucRcvAddress;
  static uint8_t      ucFunctionCode;
  static uint16_t     usLength;
  static eMBException eException;

  int             i;
  eMBErrorCode    eStatus = MB_ENOERR;
  eMBEventType    eEvent;

  /* Check if the protocol stack is ready. */

  if (eMBState != STATE_ENABLED)
    {
      return MB_EILLSTATE;
    }

  /* Check if there is a event available. If not return control to caller.
   * Otherwise we will handle the event.
   */

  if (xMBPortEventGet(&eEvent) == true)
    {
      switch (eEvent)
        {
        case EV_READY:
          break;

        case EV_FRAME_RECEIVED:
          eStatus = peMBFrameReceiveCur(&ucRcvAddress, &ucMBFrame, &usLength);
          if (eStatus == MB_ENOERR)
            {
              /* Check if the frame is for us. If not ignore the frame. */

              if ((ucRcvAddress == ucMBAddress) || (ucRcvAddress == MB_ADDRESS_BROADCAST))
                {
                  xMBPortEventPost(EV_EXECUTE);
                }
            }
            break;

        case EV_EXECUTE:
          ucFunctionCode = ucMBFrame[MB_PDU_FUNC_OFF];
          eException = MB_EX_ILLEGAL_FUNCTION;
          for( i = 0; i < CONFIG_MB_FUNC_HANDLERS_MAX; i++)
            {
              /* No more function handlers registered. Abort. */

              if (xFuncHandlers[i].ucFunctionCode == 0)
                {
                  break;
                }
              else if (xFuncHandlers[i].ucFunctionCode == ucFunctionCode)
                {
                  eException = xFuncHandlers[i].pxHandler(ucMBFrame, &usLength);
                  break;
                }
            }

          /* If the request was not sent to the broadcast address we
           * return a reply.
           */

          if (ucRcvAddress != MB_ADDRESS_BROADCAST)
            {
              if (eException != MB_EX_NONE)
                {
                  /* An exception occurred. Build an error frame. */

                  usLength = 0;
                  ucMBFrame[usLength++] = (uint8_t)(ucFunctionCode | MB_FUNC_ERROR);
                  ucMBFrame[usLength++] = eException;
                }

#ifdef CONFIG_MB_ASCII_ENABLED
              if ((eMBCurrentMode == MB_ASCII) && CONFIG_MB_ASCII_TIMEOUT_WAIT_BEFORE_SEND_MS)
                {
                  vMBPortTimersDelay(CONFIG_MB_ASCII_TIMEOUT_WAIT_BEFORE_SEND_MS);
                }
#endif
              peMBFrameSendCur(ucMBAddress, ucMBFrame, usLength);
            }
            break;

        case EV_FRAME_SENT:
            break;
        }
    }

  return MB_ENOERR;
}