/*
 *  spreadspace avr utils
 *
 *
 *  Copyright (C) 2013 Christian Pointner <equinox@spreadspace.org>
 *                     Othmar Gsenger <otti@wirdorange.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 <stdio.h>
#include <string.h>

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

#include "heartbeat.h"
#include "stepper.h"
#include "ledmatrix.h"
#include "sl018.h"

#include "LUFA/Drivers/Peripheral/TWI.h"
#include "LUFA/Drivers/Peripheral/Serial.h"
#include "LUFA/Drivers/Misc/RingBuffer.h"

#include <avr/eeprom.h>
#define EEPROM_SIZE 1024
typedef uint8_t keyslot_t[8];
keyslot_t EEMEM keystore[EEPROM_SIZE/sizeof(keyslot_t)];

FILE usb_stream;
FILE serial_stream;
FILE * stdio = &serial_stream;

/*
             LUFA Library
     Copyright (C) Dean Camera, 2012.

  dean [at] fourwalledcubicle [dot] com
           www.lufa-lib.org
*/


#include <LUFA/Drivers/USB/USB.h>
#include "lufa-descriptor-usbserial.h"

USB_ClassInfo_CDC_Device_t VirtualSerial_CDC_Interface =
  {
    .Config =
      {
        .ControlInterfaceNumber         = 0,

        .DataINEndpointNumber           = CDC_TX_EPNUM,
        .DataINEndpointSize             = CDC_TXRX_EPSIZE,
        .DataINEndpointDoubleBank       = false,

        .DataOUTEndpointNumber          = CDC_RX_EPNUM,
        .DataOUTEndpointSize            = CDC_TXRX_EPSIZE,
        .DataOUTEndpointDoubleBank      = false,

        .NotificationEndpointNumber     = CDC_NOTIFICATION_EPNUM,
        .NotificationEndpointSize       = CDC_NOTIFICATION_EPSIZE,
        .NotificationEndpointDoubleBank = false,
      },
  };

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

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

void EVENT_CDC_Device_ControLineStateChanged(USB_ClassInfo_CDC_Device_t* const CDCInterfaceInfo)	
{
  if(CDCInterfaceInfo->State.ControlLineStates.HostToDevice & CDC_CONTROL_LINE_OUT_DTR)
    stdio = &usb_stream;
  else
    stdio = &serial_stream;
}

void EVENT_USB_Device_Disconnect(void)
{
  stdio = &serial_stream;
}
/* end LUFA CDC-ACM specific definitions*/



int16_t stdio_bytes_received(void)
{
  if(stdio == &usb_stream)
    return CDC_Device_BytesReceived(&VirtualSerial_CDC_Interface);
  else
    return (int16_t)Serial_IsCharReceived();
}


void flash_keystore_from_stdio(void)
{
  keyslot_t ks;
  uint8_t byte_pos=0;
  fprintf(stdio,"Flashing keys:\n\r");
  fflush(stdio);
  for(uint8_t ks_pos=0;ks_pos<EEPROM_SIZE/sizeof(ks);) {
    CDC_Device_USBTask(&VirtualSerial_CDC_Interface);
    USB_USBTask();

    int16_t bytes_received = stdio_bytes_received();
    while(bytes_received > 0) {
      ks[byte_pos++]=fgetc(stdio);
      bytes_received--;
      if (byte_pos == sizeof(ks)) {
        byte_pos=0;
        eeprom_update_block(&ks,&keystore[ks_pos],sizeof(ks));
        ks_pos++;
        fputc('.', stdio);
        fflush(stdio);
        led_toggle();
      }
    }
  }
  fprintf(stdio,"\n");
  fputc(0, stdio);
  led_off();
}

void dump_keystore_to_stdio(void)
{
  keyslot_t ks;
  for(uint8_t ks_pos=0;ks_pos<EEPROM_SIZE/sizeof(ks);ks_pos++) {
    eeprom_read_block(&ks,&keystore[ks_pos],sizeof(ks));
    for (uint8_t i=0; i< sizeof(ks); i++)
      fprintf(stdio,"%02X",ks[i]);
    fprintf(stdio,"\n\r");
  }
}

void handle_stdio(uint8_t cmd)
{  
  switch(cmd) {
    case 'r': 
             reset2bootloader(); 
             break;
    case 'R': 
             if(!sl018_reset(stdio))
               fprintf(stdio, "ok\n\r");
             break;
    case 'f': //get cardreader firmware version
             do {
               unsigned char * firmware_str = sl018_get_firmware_version(stdio);
               if(firmware_str)
                 fprintf(stdio, "%s\n\r",firmware_str);
             } while(0);    
             break;
    case 'e': //flash eeprom
             flash_keystore_from_stdio();
             break;
    case 'd': //dump eeprom - this breaks security!
             dump_keystore_to_stdio();
             break;
    case 'o': 
             if(start_stepper(dir_open))
               fprintf(stdio, "ok\n\r");
             else
               fprintf(stdio, "error: already in progress\n\r");
             break;
    case 'c': 
             if(start_stepper(dir_close))
               fprintf(stdio, "ok\n\r");
             else
               fprintf(stdio, "error: already in progress\n\r");
             break;
    case '0': ledmatrix(off); break;
    case '1': ledmatrix(red); break;
    case '2': ledmatrix(red_moving); break;
    case '3': ledmatrix(red_blink); break;
    case '4': ledmatrix(green); break;
    case '5': ledmatrix(green_moving); break;
    case '6': ledmatrix(green_blink); break;
    case '7': ledmatrix(rg_moving); break;
    case '8': ledmatrix(rg_blink); break;
    default: fprintf(stdio, "error, unknown command %02X '%c'\n\r",cmd, cmd); return;
  }
}



/* this generates a Fletcher8 checksum  */
/* code from: http://stackoverflow.com/questions/13491700/8-bit-fletcher-checksum-of-16-byte-data */
uint8_t generate_csum(uint8_t* data)
{
  uint16_t sum1 = 0xf, sum2 = 0xf, len = sizeof(keyslot_t) - 1;
  do { sum2 += ( sum1 += *data++ ); } while (--len);
  return sum2<<4 | sum1;
}

uint8_t compare_keyslots(const keyslot_t a, const keyslot_t b)
{
  uint8_t tmp=0;
      // constant time compare
  for(uint8_t i=0; i<sizeof(keyslot_t); ++i)
    tmp |= a[i] ^ b[i];
  return tmp;
}

bool check_card(const uint8_t * uid, uint8_t uid_len)
{
  keyslot_t card, ks;
  memset(card, 0, sizeof(card));
  for (uint8_t pos=0; pos<uid_len; pos++)
    card[pos]=uid[uid_len-pos-1];
  card[sizeof(keyslot_t)-1]=generate_csum(card);
  bool valid=0;
  for(uint8_t ks_pos=0;ks_pos<(EEPROM_SIZE/sizeof(ks));ks_pos++) {
    eeprom_read_block(&ks,&keystore[ks_pos],sizeof(ks));
    if(!compare_keyslots(card, ks)) {
      valid=1;
      // break;  // this would break security (not constant time)
    }
  }
  return valid;
}

void handle_card(void)
{
  uid_t uid;
  sl018_read_card_uid(&uid,stdio);
  if (uid.length)
  {
    if(check_card(uid.buffer,uid.length)) {  
      sl018_set_led(1,stdio);
      _delay_ms(255);  
      fprintf(stdio,"Card allowed - opening/closing door\n\r"); // TODO: open/close door!  
      sl018_set_led(0,stdio);
    } else {  
      fprintf(stdio,"Card not found in Database\n\r");  
    } 
  }
}

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

  cpu_init();
  led_init();
  USB_Init();
  TWI_Init(TWI_BIT_PRESCALE_1, TWI_BITLENGTH_FROM_FREQ(1, 200000));
  Serial_Init(115200,false);
  Serial_CreateStream(&serial_stream);
  CDC_Device_CreateStream(&VirtualSerial_CDC_Interface,&usb_stream);

  sei();  

  init_heartbeat();
  init_stepper();
  init_ledmatrix();

  sl018_reset(stdio);

  for(;;) {
    CDC_Device_USBTask(&VirtualSerial_CDC_Interface);
    USB_USBTask();

    int16_t bytes_received = stdio_bytes_received();
    if(bytes_received > 0)
      handle_stdio(fgetc(stdio));

    if (sl018_check_for_new_card(stdio))
      handle_card();
    handle_heartbeat();
  }
}