#include <stdio.h>
#include <string.h>

#include "sml.h"
#include "smlCrcTable.h"

#ifdef SML_DEBUG
char logBuff[200];

#ifdef SML_NATIVE
#define SML_LOG(...)                                                           \
  do {                                                                         \
    printf(__VA_ARGS__);                                                       \
  } while (0)
#define SML_TREELOG(level, ...)                                                \
  do {                                                                         \
    printf("%.*s", level, "        ");                                         \
    printf(__VA_ARGS__);                                                       \
  } while (0)
#elif ARDUINO
#include <Arduino.h>
#define SML_LOG(...)                                                           \
  do {                                                                         \
    sprintf(logBuff, __VA_ARGS__);                                             \
    Serial.print(logBuff);                                                     \
  } while (0)
#define SML_TREELOG(level, ...)                                                \
  do {                                                                         \
    sprintf(logBuff, __VA_ARGS__);                                             \
    Serial.print(logBuff);                                                     \
  } while (0)
#endif

#else
#define SML_LOG(...)                                                           \
  do {                                                                         \
  } while (0)
#define SML_TREELOG(level, ...)                                                \
  do {                                                                         \
  } while (0)
#endif

#define MAX_LIST_SIZE 80
#define MAX_TREE_SIZE 10

static sml_states_t currentState = SML_START;
static char nodes[MAX_TREE_SIZE];
static unsigned char currentLevel = 0;
static unsigned short crc = 0xFFFF;
static signed char sc;
static unsigned short crcMine = 0xFFFF;
static unsigned short crcReceived = 0x0000;
static unsigned char len = 4;
static unsigned char listBuffer[MAX_LIST_SIZE]; /* keeps a list
                                                   as length + state + data  */
static unsigned char listPos = 0;

void crc16(unsigned char &byte)
{
#ifdef ARDUINO
  crc =
      pgm_read_word_near(&smlCrcTable[(byte ^ crc) & 0xff]) ^ (crc >> 8 & 0xff);
#else
  crc = smlCrcTable[(byte ^ crc) & 0xff] ^ (crc >> 8 & 0xff);
#endif
}

void setState(sml_states_t state, int byteLen)
{
  currentState = state;
  len = byteLen;
}

void pushListBuffer(unsigned char byte)
{
  if (listPos < MAX_LIST_SIZE) {
    listBuffer[listPos++] = byte;
  }
}

void reduceList()
{
  if (currentLevel < MAX_TREE_SIZE && nodes[currentLevel] > 0)
    nodes[currentLevel]--;
}

void smlNewList(unsigned char size)
{
  reduceList();
  if (currentLevel < MAX_TREE_SIZE)
    currentLevel++;
  nodes[currentLevel] = size;
  SML_TREELOG(currentLevel, "LISTSTART on level %i with %i nodes\n",
              currentLevel, size);
  setState(SML_LISTSTART, size);
  // @todo workaround for lists inside obis lists
  if (size > 5) {
    listPos = 0;
    memset(listBuffer, '\0', MAX_LIST_SIZE);
  }
  else {
    pushListBuffer(size);
    pushListBuffer(currentState);
  }
}

void checkMagicByte(unsigned char &byte)
{
  unsigned int size = 0;
  while (currentLevel > 0 && nodes[currentLevel] == 0) {
    /* go back in tree if no nodes remaining */
    SML_TREELOG(currentLevel, "back to previous list\n");
    currentLevel--;
  }
  if (byte > 0x70 && byte <= 0x7F) {
    /* new list */
    size = byte & 0x0F;
    smlNewList(size);
  }
  else if (byte >= 0x01 && byte <= 0x6F && nodes[currentLevel] > 0) {
    if (byte == 0x01) {
      /* no data, get next */
      SML_TREELOG(currentLevel, " Data %i (empty)\n", nodes[currentLevel]);
      pushListBuffer(0);
      pushListBuffer(currentState);
      if (nodes[currentLevel] == 1) {
        setState(SML_LISTEND, 1);
        SML_TREELOG(currentLevel, "LISTEND\n");
      }
      else {
        setState(SML_NEXT, 1);
      }
    }
    else {
      size = (byte & 0x0F) - 1;
      setState(SML_DATA, size);
      if ((byte & 0xF0) == 0x50) {
        setState(SML_DATA_SIGNED_INT, size);
      }
      else if ((byte & 0xF0) == 0x60) {
        setState(SML_DATA_UNSIGNED_INT, size);
      }
      else if ((byte & 0xF0) == 0x00) {
        setState(SML_DATA_OCTET_STRING, size);
      }
      SML_TREELOG(currentLevel,
                  " Data %i (length = %i%s): ", nodes[currentLevel], size,
                  (currentState == SML_DATA_SIGNED_INT)     ? ", signed int"
                  : (currentState == SML_DATA_UNSIGNED_INT) ? ", unsigned int"
                  : (currentState == SML_DATA_OCTET_STRING) ? ", octet string"
                                                            : "");
      pushListBuffer(size);
      pushListBuffer(currentState);
    }
    reduceList();
  }
  else if (byte == 0x00) {
    /* end of block */
    reduceList();
    SML_TREELOG(currentLevel, "End of block at level %i\n", currentLevel);
    if (currentLevel == 0) {
      setState(SML_NEXT, 1);
    }
    else {
      setState(SML_BLOCKEND, 1);
    }
  }
  else if (byte & 0x80) {
    // MSB bit is set, another TL byte will follow
    if (byte >= 0x80 && byte <= 0x8F) {
      // Datatype Octet String
      setState(SML_HDATA, (byte & 0x0F) << 4);
    }
    else if (byte >= 0xF0 /*&& byte <= 0xFF*/) {
      /* Datatype List of ...*/
      setState(SML_LISTEXTENDED, (byte & 0x0F) << 4);
    }
  }
  else if (byte == 0x1B && currentLevel == 0) {
    /* end sequence */
    setState(SML_END, 3);
  }
  else {
    /* Unexpected Byte */
    SML_TREELOG(currentLevel,
                "UNEXPECTED magicbyte >%02X< at currentLevel %i\n", byte,
                currentLevel);
    setState(SML_UNEXPECTED, 4);
  }
}

sml_states_t smlState(unsigned char &currentByte)
{
  unsigned char size;
  if (len > 0)
    len--;
  crc16(currentByte);
  switch (currentState) {
  case SML_UNEXPECTED:
  case SML_CHECKSUM_ERROR:
  case SML_FINAL:
  case SML_START:
    currentState = SML_START;
    currentLevel = 0; // Reset current level at the begin of a new transmission
                      // to prevent problems
    if (currentByte != 0x1b)
      setState(SML_UNEXPECTED, 4);
    if (len == 0) {
      SML_TREELOG(0, "START\n");
      /* completely clean any garbage from crc checksum */
      crc = 0xFFFF;
      currentByte = 0x1b;
      crc16(currentByte);
      crc16(currentByte);
      crc16(currentByte);
      crc16(currentByte);
      setState(SML_VERSION, 4);
    }
    break;
  case SML_VERSION:
    if (currentByte != 0x01)
      setState(SML_UNEXPECTED, 4);
    if (len == 0) {
      setState(SML_BLOCKSTART, 1);
    }
    break;
  case SML_END:
    if (currentByte != 0x1b) {
      SML_LOG("UNEXPECTED char >%02X< at SML_END\n", currentByte);
      setState(SML_UNEXPECTED, 4);
    }
    if (len == 0) {
      setState(SML_CHECKSUM, 4);
    }
    break;
  case SML_CHECKSUM:
    // SML_LOG("CHECK: %02X\n", currentByte);
    if (len == 2) {
      crcMine = crc ^ 0xFFFF;
    }
    if (len == 1) {
      crcReceived += currentByte;
    }
    if (len == 0) {
      crcReceived = crcReceived | (currentByte << 8);
      SML_LOG("Received checksum: %02X\n", crcReceived);
      SML_LOG("Calculated checksum: %02X\n", crcMine);
      if (crcMine == crcReceived) {
        setState(SML_FINAL, 4);
      }
      else {
        setState(SML_CHECKSUM_ERROR, 4);
      }
      crc = 0xFFFF;
      crcReceived = 0x000; /* reset CRC */
    }
    break;
  case SML_HDATA:
    size = len + currentByte - 1;
    setState(SML_DATA, size);
    pushListBuffer(size);
    pushListBuffer(currentState);
    SML_TREELOG(currentLevel, " Data (length = %i): ", size);
    break;
  case SML_LISTEXTENDED:
    size = len + (currentByte & 0x0F);
    SML_TREELOG(currentLevel, "Extended List with Size=%i\n", size);
    smlNewList(size);
    break;
  case SML_DATA:
  case SML_DATA_SIGNED_INT:
  case SML_DATA_UNSIGNED_INT:
  case SML_DATA_OCTET_STRING:
    SML_LOG("%02X ", currentByte);
    pushListBuffer(currentByte);
    if (nodes[currentLevel] == 0 && len == 0) {
      SML_LOG("\n");
      SML_TREELOG(currentLevel, "LISTEND on level %i\n", currentLevel);
      currentState = SML_LISTEND;
    }
    else if (len == 0) {
      currentState = SML_DATAEND;
      SML_LOG("\n");
    }
    break;
  case SML_DATAEND:
  case SML_NEXT:
  case SML_LISTSTART:
  case SML_LISTEND:
  case SML_BLOCKSTART:
  case SML_BLOCKEND:
    checkMagicByte(currentByte);
    break;
  }
  return currentState;
}

bool smlOBISCheck(const unsigned char *obis)
{
  return (memcmp(obis, &listBuffer[2], 6) == 0);
}

void smlOBISManufacturer(unsigned char *str, int maxSize)
{
  int i = 0, pos = 0, size = 0;
  while (i < listPos) {
    size = (int)listBuffer[i];
    i++;
    pos++;
    if (pos == 6) {
      /* get manufacturer at position 6 in list */
      size = (size > maxSize - 1) ? maxSize : size;
      memcpy(str, &listBuffer[i + 1], size);
      str[size + 1] = 0;
    }
    i += size + 1;
  }
}

void smlPow(float &val, signed char &scaler)
{
  if (scaler < 0) {
    while (scaler++) {
      val /= 10;
    }
  }
  else {
    while (scaler--) {
      val *= 10;
    }
  }
}

void smlOBISByUnit(long long int &val, signed char &scaler, sml_units_t unit)
{
  unsigned char i = 0, pos = 0, size = 0, y = 0, skip = 0;
  sml_states_t type;
  val = -1; /* unknown or error */
  while (i < listPos) {
    pos++;
    size = (int)listBuffer[i++];
    type = (sml_states_t)listBuffer[i++];
    if (type == SML_LISTSTART && size > 0) {
      // skip a list inside an obis list
      skip = size;
      while (skip > 0) {
        size = (int)listBuffer[i++];
        type = (sml_states_t)listBuffer[i++];
        i += size;
        skip--;
      }
      size = 0;
    }
    if (pos == 4 && listBuffer[i] != unit) {
      /* return unknown (-1) if unit does not match */
      return;
    }
    if (pos == 5) {
      scaler = listBuffer[i];
    }
    if (pos == 6) {
      y = size;
      // initialize 64bit signed integer based on MSB from received value
      val =
          (type == SML_DATA_SIGNED_INT && (listBuffer[i] & (1 << 7))) ? ~0 : 0;
      for (y = 0; y < size; y++) {
        // left shift received bytes to 64 bit signed integer
        val = (val << 8) | listBuffer[i + y];
      }
    }
    i += size;
  }
}

void smlOBISWh(float &wh)
{
  long long int val;
  smlOBISByUnit(val, sc, SML_WATT_HOUR);
  wh = val;
  smlPow(wh, sc);
}

void smlOBISW(float &w)
{
  long long int val;
  smlOBISByUnit(val, sc, SML_WATT);
  w = val;
  smlPow(w, sc);
}

void smlOBISVolt(float &v)
{
  long long int val;
  smlOBISByUnit(val, sc, SML_VOLT);
  v = val;
  smlPow(v, sc);
}

void smlOBISAmpere(float &a)
{
  long long int val;
  smlOBISByUnit(val, sc, SML_AMPERE);
  a = val;
  smlPow(a, sc);
}