#include "rabincarp.h"


int rlsi_hash_reset(rol_hash_isearch *rlh)
{
  rlh->pow = 1;
  rlh->pattern_len = 0;
  rlh->pattern_hash = 0;
  rlh->text_hash = 0;
  rlh->text_len = 0;
  rlh->text = NULL;
  rlh->pattern = NULL;
  rlh->iter_pos = 0;
  rlh->count = 0;
  rlh->pre_text = NULL;
  rlh->chunk_done = 0;
  return 0;
}

int rlsi_hash_init(rol_hash_isearch *rlh, int b, int m)
{
  rlh->b = b;
  rlh->m = m;
  rlsi_hash_reset(rlh);
  return 0;
}

int rlsi_hash_precalc(rol_hash_isearch *rlh, char *pattern, int plen, char *text, int tlen)
{
  int i;

  if (tlen<plen)
  {
    return -1;
  }

  rlh->text_len    = tlen;
  rlh->text        = text;
  rlh->pattern     = pattern;
  rlh->pattern_len = plen;

  rlh->pow = 1;
  for (i=0; i<plen-1; i++)
  {
    rlh->pow = (rlh->pow * rlh->b) % rlh->m;
  }

  rlh->text_hash = 0;
  rlh->pattern_hash = 0;
  for (i=0;i<plen;i++)
  {
    rlh->pattern_hash = (rlh->pattern_hash * rlh->b + pattern[i]) % rlh->m;
    rlh->text_hash   =  (rlh->text_hash   * rlh->b + text[i])    % rlh->m;
  }

  //printf("pow %d\n",rlh->pow);
  //printf("pattern %d\n",rlh->pattern_hash);
  //printf("text %d\n",rlh->text_hash);

  //set buffer size for presaved text
  rlh->pre_text = malloc(plen);//dont check err =P, mem leak here
  rlh->count = 0;

  return 0;
}

//run after prepararion step
int rlsi_hash_search(rol_hash_isearch *rlh, char *pattern, int plen, char *text, int tlen)
{
  int j=0;

  int found=0;

  if ((rlh->text == NULL) && (rlh->pattern == NULL))
  {
    rlsi_hash_precalc(rlh, pattern, plen, text, tlen);
  }

  if (rlh->chunk_done == 1)
  {
    rlh->chunk_done = 0;
    rlh->text_len = tlen;
  }

  //printf("while %d",rlh->text_len-rlh->pattern_len);
  //while (rlh->iter_pos<=(rlh->text_len-rlh->pattern_len))
  while (rlh->iter_pos<=(rlh->text_len-rlh->pattern_len))
  {

    //hashes are matching
    if (rlh->text_hash == rlh->pattern_hash)
    {
      //printf("2\n"); 
      //check if string match
      for (j=0;j<rlh->pattern_len;j++)
      {
        //???
        char i_c=0;
        int k=rlh->iter_pos+j;
        if (k<0)
        {
          i_c = rlh->pre_text[rlh->pattern_len+k];
        } else
        {
          //i_c = rlh->text[rlh->iter_pos+j];
          i_c = text[rlh->iter_pos+j];
        }
        if (i_c != rlh->pattern[j])
          break;
      }

      if (j == rlh->pattern_len)
        {
          //???
          //printf("Found pattern at %d\n",rlh->iter_pos+1);
          //printf("Found pattern at %d\n",rlh->count);
          found = 1;
        }
      
    }

    //???
    if (rlh->iter_pos < rlh->text_len - rlh->pattern_len)
     {
      //printf("1\n"); 
      //???
      char i_c;
      if (rlh->iter_pos < 0)
      {
        i_c = rlh->pre_text[rlh->pattern_len+rlh->iter_pos];
      } else
      {
        //i_c = rlh->text[rlh->iter_pos];
        i_c = text[rlh->iter_pos];
      }
      //printf("CHAR: %c\n",i_c);
      //rlh->text_hash = ( rlh->b *( rlh->text_hash - i_c*rlh->pow) + rlh->text[rlh->iter_pos+rlh->pattern_len] ) % rlh->m;
      rlh->text_hash = ( rlh->b *( rlh->text_hash - i_c*rlh->pow) + text[rlh->iter_pos+rlh->pattern_len] ) % rlh->m;
      //printf("text %d\n",rlh->text_hash);
      if (rlh->text_hash < 0)
      {
        rlh->text_hash = rlh->text_hash + rlh->m;
      }
     }
    
    //iter over current buffer
    rlh->iter_pos += 1;
    //total data that have been iterated
    rlh->count += 1;

    if (found == 1)
    {
      //rlh->count -= 1;
      return 1;
    }
    //iter over current buffer
    //rlh->iter_pos += 1;
    //total data that have been iterated
    //rlh->count += 1;
    //printf("rlh->iter_pos %d\n",rlh->iter_pos);
    //printf("rlh->count %d\n",rlh->count);
  }
  //printf("tlen %d\n",tlen);
  //exit from while loop because end of the buffer, iter is +1 element larger
  //copy pattern to intermidiate buffer
  //if ((rlh->iter_pos)==(rlh->text_len - rlh->pattern_len+1))
  {
    //copy last bit of buffer to further processing
    //memcpy(rlh->pre_text, &rlh->text[rlh->iter_pos], rlh->pattern_len);
    memcpy(rlh->pre_text, &text[rlh->iter_pos-1], rlh->pattern_len);
    //printf("end of chunk\n");
    //rlh->count -= 1;
    //printf("count %d\n",rlh->count);

    rlh->chunk_done = 1;
    rlh->iter_pos = -rlh->pattern_len;
  }

//exit_loop:
  //chunk finished search new need to be supplied pal
  //printf("0\n");
  rlh->count -= 1;
  return 0;
}

int rlsi_hash_get(rol_hash_isearch *rlh)
{
  //return rlh->iter_pos;
  return rlh->count;
}