/*
 *  spreadspace avr utils
 *
 *
 *  Copyright (C) 2013-2018 Christian Pointner <equinox@spreadspace.org>
 *
 *  This file is part of spreadspace avr utils.
 *
 *  spreadspace avr utils is free software: you can redistribute it and/or modify
 *  it under the terms of the GNU General Public License as published by
 *  the Free Software Foundation, either version 3 of the License, or
 *  any later version.
 *
 *  spreadspace avr utils is distributed in the hope that it will be useful,
 *  but WITHOUT ANY WARRANTY; without even the implied warranty of
 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *  GNU General Public License for more details.
 *
 *  You should have received a copy of the GNU General Public License
 *  along with spreadspace avr utils. If not, see <http://www.gnu.org/licenses/>.
 */

#include <avr/io.h>
#include <avr/wdt.h>
#include <avr/interrupt.h>
#include <avr/power.h>

#include "util.h"
#include "led.h"

/*
             LUFA Library
     Copyright (C) Dean Camera, 2014.

  dean [at] fourwalledcubicle [dot] com
           www.lufa-lib.org
*/
#include <LUFA/Version.h>
#include <LUFA/Drivers/Peripheral/SPI.h>
#include <LUFA/Drivers/Misc/RingBuffer.h>
#include <LUFA/Drivers/USB/USB.h>
#include "lufa-descriptor-usbserial.h"

    /* Global I/O Buffers: */
static RingBuffer_t USBtoSPI_Buffer;
static uint8_t      USBtoSPI_Buffer_Data[128];
static RingBuffer_t SPItoUSB_Buffer;
static uint8_t      SPItoUSB_Buffer_Data[128];

/** LUFA CDC Class driver interface configuration and state information. This structure is
 *  passed to all CDC Class driver functions, so that multiple instances of the same class
 *  within a device can be differentiated from one another.
 */
USB_ClassInfo_CDC_Device_t VirtualSerial_CDC_Interface =
  {
    .Config =
      {
        .ControlInterfaceNumber         = INTERFACE_ID_CDC_CCI,
        .DataINEndpoint                 =
          {
            .Address                = CDC_TX_EPADDR,
            .Size                   = CDC_TXRX_EPSIZE,
            .Banks                  = 1,
          },
        .DataOUTEndpoint                =
          {
            .Address                = CDC_RX_EPADDR,
            .Size                   = CDC_TXRX_EPSIZE,
            .Banks                  = 1,
          },
        .NotificationEndpoint           =
          {
            .Address                = CDC_NOTIFICATION_EPADDR,
            .Size                   = CDC_NOTIFICATION_EPSIZE,
            .Banks                  = 1,
          },
      },
  };

void EVENT_USB_Device_ConfigurationChanged(void)
{
  CDC_Device_ConfigureEndpoints(&VirtualSerial_CDC_Interface);
}

void EVENT_USB_Device_ControlRequest(void)
{
  CDC_Device_ProcessControlRequest(&VirtualSerial_CDC_Interface);
}

/* end LUFA CDC-ACM specific definitions */

    /* Hardware Defines: */
#define SPI_CS_DDR DDRB
#define SPI_CS_PORT PORTB
#define CS   0

#define RESET_DDR DDRB
#define RESET_PORT PORTB
#define RESET   7

void SetupHardware(void)
{
  MCUSR &= ~(1 << WDRF);
  wdt_disable();

  cpu_init();
  led_init();
  USB_Init();

  SPI_Init(SPI_SPEED_FCPU_DIV_16  | SPI_MODE_MASTER | SPI_ORDER_MSB_FIRST |
           SPI_SCK_LEAD_RISING | SPI_SAMPLE_LEADING);
  SPI_CS_DDR |= (1<<CS);
  SPI_CS_PORT |= (1<<CS);

  RESET_DDR |= (1<<RESET);
  RESET_PORT |= (1<<RESET);

/* INT0 as input with pull-up */
  DDRD &= ~(1<<0);
  PORTD |= (1<<0);
  EICRA |= (1<<ISC01);
  EIFR |= (1<<INTF0);
  EIMSK |= (1<<INT0);
}

void EVENT_CDC_Device_ControLineStateChanged(USB_ClassInfo_CDC_Device_t* const CDCInterfaceInfo)
{
  if(CDCInterfaceInfo->State.ControlLineStates.HostToDevice & CDC_CONTROL_LINE_OUT_DTR)
    RESET_PORT &= ~(1<<RESET);
  else
    RESET_PORT |= (1<<RESET);
}

void EVENT_CDC_Device_BreakSent(USB_ClassInfo_CDC_Device_t* const CDCInterfaceInfo, const uint8_t Duration)
{
  SPI_CS_PORT ^= (1<<CS);
}

ISR(INT0_vect)
{
  SPI_CS_PORT &= ~(1<<CS);
  led_on();

  uint8_t ReceivedByte = SPI_ReceiveByte();
  RingBuffer_Insert(&SPItoUSB_Buffer, ReceivedByte);

  led_off();
  SPI_CS_PORT |= (1<<CS);
}

void SPI_SendBuffer(void)
{
  SPI_CS_PORT &= ~(1<<CS);
  led_on();

  while(!(RingBuffer_IsEmpty(&USBtoSPI_Buffer))) {
    SPI_SendByte(RingBuffer_Remove(&USBtoSPI_Buffer));
  }

  led_off();
  SPI_CS_PORT |= (1<<CS);
}

int main(void)
{
  SetupHardware();

  RingBuffer_InitBuffer(&USBtoSPI_Buffer, USBtoSPI_Buffer_Data, sizeof(USBtoSPI_Buffer_Data));
  RingBuffer_InitBuffer(&SPItoUSB_Buffer, SPItoUSB_Buffer_Data, sizeof(SPItoUSB_Buffer_Data));

  sei();

  for (;;) {
    /* Only try to read in bytes from the CDC interface if the transmit buffer is not full */
    if(!(RingBuffer_IsFull(&USBtoSPI_Buffer))) {
      int16_t ReceivedByte = CDC_Device_ReceiveByte(&VirtualSerial_CDC_Interface);
      if (!(ReceivedByte < 0))
        RingBuffer_Insert(&USBtoSPI_Buffer, ReceivedByte);
    }


    uint16_t BufferCount = RingBuffer_GetCount(&SPItoUSB_Buffer);
    if (BufferCount) {
      Endpoint_SelectEndpoint(VirtualSerial_CDC_Interface.Config.DataINEndpoint.Address);
      if (Endpoint_IsINReady()) {
        uint8_t BytesToSend = MIN(BufferCount, (CDC_TXRX_EPSIZE - 1));

        while (BytesToSend--) {
          if (CDC_Device_SendByte(&VirtualSerial_CDC_Interface,
                      RingBuffer_Peek(&SPItoUSB_Buffer)) != ENDPOINT_READYWAIT_NoError) {
            break;
          }

          RingBuffer_Remove(&SPItoUSB_Buffer);
        }
      }
    }

    if (!(RingBuffer_IsEmpty(&USBtoSPI_Buffer)))
      SPI_SendBuffer();

    CDC_Device_USBTask(&VirtualSerial_CDC_Interface);
    USB_USBTask();
  }
}