#include "EMatoi.h"

static char *str_swap(char *str, int size);
static void sanitize(char *buff,const char *str, int size);

/** \brief
 *
 * \param
 * \param
 * \return
 *
 */

int EMatoi(const char *str)
{
    short unsigned int size = sizeof(int) == 4 ? 11 /*max : 2 147 483 647 (10 characters + 1 for \0)*/: 6/*max : 32 768 (5 characters + 1 for \0)*/;
    char buff[size];
    int val = 0, index = 0;
    unsigned int power_of_ten = 1;
    char done = 0;

    sanitize(buff, str, size);

    str_swap(buff,strlen(buff)-1);

    for(;*(buff+index) != '\0' && !done;index++)
    {
        switch(*(buff+index))
        {
        case '+':
            done = 1;
            break;
        case '-':
            val = -val;
            done = 1;
            break;
        default:
            if(*(buff+index) >= '0' && *(buff+index) <= '9' )
            {
                val += (*(buff+index) - '1'+1) * power_of_ten;
                power_of_ten *= 10;
            }
            else
                done = 1;
            break;
        }
    }

    return val;
}

static char *str_swap(char *str, int size)
{
    int left_pos = 0, right_pos = 0;
    char c_temp, *p_start = str, *p_end = str + size;

    for(;left_pos + right_pos < size;left_pos++,right_pos++)
    {
        c_temp = *(p_start+left_pos);
        *(p_start+left_pos) = *(p_end-right_pos);
        *(p_end-right_pos) = c_temp;
    }

    return str;
}

/** \brief Remove blanks at the beginning of the string and replace the first non numeric character with '\0' except + or -
 *
 * \param char *str -> string to be sanitized
 * \return char *p -> pointing to the string
 *
 */

static void sanitize(char *buff,const char *str, int size)
{
    unsigned char number_of_white_space = 0, index = 0;

    for(;*(str+index) == ' ';index++)number_of_white_space++;

    EMstrncpy(buff, str+number_of_white_space,size-1);

    if(*buff == '-' || *buff == '+' || (*(buff) >= '0' && *(buff) <= '9'))
    {
        for(index = 1;(*(buff+index) >= '0' && *(buff+index) <= '9');index++);
        buff[index] = '\0';
    }
    else
        *buff = '\0';
}