#include <stdint.h>

#include <stdio.h>

#include <string.h>

#include <stdbool.h>

//              0123456789AB

char S1[17] = {"Hello World"};  //max 16 char availabel!

char S2[17] = {""};        //Midstr

char S3[17] = {""};        //Upper-/Lowercase

char S4[17] = {"Wo"};      //Instring

char Tempstr[17];  

uint8_t x;

uint8_t position;

/* LeftStr returns the leftmost characters of a string

  Input:

    char *dst ==> pointer to the destination string

    char *src ==> pointer to the source string

    uint8_t dstsize ==> buffer size of the destination string

    uint8_t length ==> number of characters to extract. (1...n)

  Output:

    Pointer to the destination string

*/

char * LeftStr(char *dst, char *src, uint8_t dstsize, uint8_t length) {  

  if (length > (dstsize - 1)) { length = dstsize - 1; }

  strncpy(dst, src, length);

  dst[length] = '\0'; // zero terminate 

  return dst;

}

/* MidStr extracts a number of characters from a string

  Input:

    char *dst ==> pointer to the destination string

    char *src ==> pointer to the source string

    uint8_t dstlen ==> buffer size of the destination string

    uint8_t start ==> starting position within the source string. (First position is 1)

    uint8_t length ==> number of characters to extract. (1...n)

  Output:

    Pointer to the destination string

*/

char * MidStr(char *dst, char *src, uint8_t dstsize, uint8_t start, uint8_t length)  {  

  if (length > (dstsize - 1)) { length = dstsize - 1; }

  if (start > 0) { start--; } //call starts at 1..., internal start is 0...

    if (start > (strlen(src) - 1)) {

    dst[0] = '\0';   // out of range

  }

   else {

     strncpy(dst, src + start, length);

     dst[length] = '\0'; // zero terminate 

     }

   return dst;

}

/* RightStr returns the rightmost characters of a string

  Input:

    char *dst ==> pointer to the destination string

    char *src ==> pointer to the source string

    uint8_t dstlen ==> string length of the destination string

    uint8_t length ==> number of characters to extract. (1...n)

  Output:

    Pointer to the destination string

*/

char * RightStr(char *dst, char *src, uint8_t dstsize, uint8_t length) {  

  if (length > (dstsize - 1)) { length = dstsize - 1; }

  strncpy(dst, src + strlen(src) - length, length);

  dst[length] = '\0'; // zero terminate 

  return dst;

}

/* UpperCase converts characters a..z to A..Z

  Input:

    char *dst ==> pointer to the destination string

    char *src ==> pointer to the source string

    uint8_t dstlen ==> string length of the destination string

  Output:

    Pointer to the destination string

*/

char * UpperCase(char * dst, char * src, uint8_t dst_len) {

  uint8_t srclen;

  srclen= strlen(src);

  if ( (dst_len + 1) < srclen) srclen = dst_len; //ensure available space

  strncpy(dst, src, srclen); //copy max l_puffer bytes from src to dst

  dst[srclen + 1] = '\0';

  strupr(dst);

  return dst;

}  

/* LowerCase converts characters A..Z to a..z

  Input:

    char *dst ==> pointer to the destination string

    char *src ==> pointer to the source string

    uint8_t dstlen ==> string length of the destination string

  Output:

    Pointer to the destination string

*/

char * LowerCase(char * dst, char * src, uint8_t dst_len) {

  uint8_t srclen;

  srclen= strlen(src);

  if ( (dst_len + 1) < srclen) srclen = dst_len; //ensure available space

  strncpy(dst, src, srclen); //copy max l_puffer bytes from src to dst

  dst[srclen + 1] = '\0';

  strlwr(dst);

  return dst;

}  

/* InString looks for the occurrence of a substr in the source string

  Input:

    char *dst ==> pointer to the destination string

    char *src ==> pointer to the source string

    uint8_t sourcesize ==> buffer size of the source string

    uint8_t start ==> starting position within the source string. (First position is 1)

    bool CaseSensitive ==> true or false

  Output:

    Position of the first occurrence (1...)

    0 = not found

*/

uint8_t InStr(char *source,  char *substr, uint8_t sourcesize, uint8_t start, bool CaseSensitive) {  

  uint8_t position;

  char* subs;

  char* src;

  char* found;

  if (start > 0) { start--; } //call starts at 1..., internal start is 0...

  if (start > sourcesize - 2) { //string length - \0 - 1 

    position = 0;  //illegal starting position

  }

  else {

    if (CaseSensitive) {

       found = strstr(source, substr);

       if (found != 0) {

         position = found - source;   //strstr returns NULL if item not found

       }

       else {position = 0; }

    }

    else {

      src = malloc(sourcesize);

      memcpy(src, source + start, sourcesize - start);

      subs = malloc(strlen(substr) + 1);

      memcpy(subs, substr, strlen(substr) + 1);

      strupr(src);

      strupr(subs);    

      found = strstr(src, subs);     

      if (found != 0) { 

        position = found + start - src;   // strstr returns NULL if item not found 

      }

        else {position = 0; }    

      free(src);

      free(subs);

    } 

  }

  return position + 1;  //

}

/* PadString pads the destination string with a character

  Input:

    char *dst ==> pointer to the destination string

    char *src ==> pointer to the source string

    uint8_t destsize ==> buffer size of the destination string

    uint8_t start ==> starting position within the source string. (First position is 1)

    bool CaseSensitive ==> true or false

  Output:

    Position of the first occurrence

*/

char * PadStr(char *dst,  char *src, uint8_t dstsize, char padchar, bool padleft) {   //left/Right pad with a character

  uint8_t srclen;

  srclen = strlen(src);

  if (srclen > (dstsize - 1)) { srclen = dstsize - 1; }

  if (padleft) { 

    memset (dst, padchar, dstsize - srclen - 1); //insert padchar

    strncpy(dst + dstsize - srclen -1, src, srclen); 

  }

  else { 

    strncpy(dst, src, srclen);

    memset (dst + srclen, padchar, dstsize - srclen - 1); //insert padchar

  }

  dst[dstsize -1] = '\0';  

  return dst;

}

int main(void) {

   LeftStr(S2, S1, sizeof(S2), 3);            //==> "ell"

   MidStr(S2, S1, sizeof(S2), 2, 3);          //==> "ll"

   RightStr(S2, S1, sizeof(S2), 3);            //==> "rld"

   UpperCase(S3, S1, sizeof(S3));            //==> "HELLO WORLD"

   LowerCase(S3, S1, sizeof(S3));            //==> "hello world"

   PadStr(Tempstr,  S1, sizeof(Tempstr), '>', true);  //==> ">>>>>HELLO WORLD"

   PadStr(Tempstr,  S1, sizeof(Tempstr), '>', false);  //==> "HELLO WORLD>>>>>"

   x = InStr(S1, S4, sizeof(S1), 4, false);        //==> 7      

}