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

#define ROUND_DOWN(X, STEP) ((X) / (STEP) * (STEP))

size_t
strlcpy (char *dst, const char *src, size_t size)
{
    size_t src_len;

    src_len = strlen (src);
    if (size > 0)
    {
        size_t dst_len = size - 1;
        if (src_len < dst_len)
            dst_len = src_len;
        memcpy (dst, src, dst_len);
        dst[dst_len] = '\0';
    }
    return src_len;
}

// assume that arguments can't exceed 128 bytes//
bool load_argument_to_stack (const char *file_name, void **esp){

    if (sizeof(file_name) > 128) return false;
    void *pointers[128];
    int arg_count = 0;
    char *parsedString = (char *)malloc(strlen(file_name)+1);
    strlcpy(parsedString, file_name,strlen(file_name));
    char *token;
    char *rest = parsedString;
    while ((token = strtok_r(rest, " ", &rest)))
    {
        int size_token = strlen(token)+1;
        printf("size_token %d\n",size_token);
        *esp -=size_token;
        printf("*esp = %x\n", *esp);
        int i;
        for (i = 0; i < size_token; i++) {
            //pushing tokens
            printf("char %d\n",token[i]);
            void *temp = *esp + i;
            //*((char *)temp) = token[i];
        }
        pointers[arg_count] = *esp;
        arg_count++;

    }
    //pushing word alignment
    void *temp = *esp;
    ROUND_DOWN((unsigned int)*esp,4);
    memset(*esp,0,(temp - *esp));
    printf("*esp after ROUND_DOWN = %x\n", *esp);
    //pushing null character
    *esp -= sizeof(char *);
    memset(*esp, 0 , 4);
    printf("*esp after NULL = %x\n", *esp);
    //pushing arg[i]
    int j;
    for (j = arg_count - 1; j>=0; j--) {
        *esp -= sizeof(char *);
        printf("*esp after each pointer to argument = %x\n", *esp);
        (*(unsigned int *)(*esp)) = pointers[j];
    }
    //pushing char**
    *esp -= 4;
    printf("*esp after pointer to argv = %x\n", *esp);
    (*(unsigned int *)(*esp)) = *esp + 4;
    printf("address of argv[0] = %x\n", (*(unsigned int *)(*esp)));
    //pushing arg_count
    *esp -= sizeof(int);
    printf("*esp after pointer to argc = %x\n", *esp);
    (*(unsigned int *)(*esp)) = arg_count;
    //pushing fake return address
    *esp -= 4;
    printf("*esp after pointer fake return address = %x\n", *esp);
    memset(*esp, 0 , 4);
    return true;
}

int main() {
    void *esp= (void*)0xc0000000;
    load_argument_to_stack("/bin/ls -l foo bar",&esp);
    return 0;
}