#include <string.h>
#include "types.h"
#include "string_utils.h"
#include "interpreter.h"

int is_string_ptr(long val) {
    if (val < 0) {
        return 0;
    }
    if (val > MEM_SIZE * 8) {
        return 1;
    }
    return 0;
}

long concat_strings(long ptr1, long ptr2) {
    static char empty_str[] = "";
    char *s1 = (char*)ptr1;
    char *s2 = (char*)ptr2;

    if (!s1 || !s2) {
        return (long)empty_str;
    }

    if (str_pool_idx >= STR_POOL_SIZE) {
        error("String pool overflow");
        return (long)empty_str;
    }

    char *result = &str_pool[str_pool_idx];

    int len1 = strlen(s1);
    int len2 = strlen(s2);

    if (str_pool_idx + len1 + len2 + 1 >= STR_POOL_SIZE) {
        error("String pool overflow");
        return (long)empty_str;
    }

    strcpy(result, s1);
    strcat(result, s2);

    str_pool_idx += len1 + len2 + 1;

    return (long)result;
}

long slice_string(long str_ptr, int start, int end) {
    static char empty_str[] = "";
    char *str = (char*)str_ptr;

    if (!str) {
        return (long)empty_str;
    }

    if (str_pool_idx >= STR_POOL_SIZE) {
        error("String pool overflow");
        return (long)empty_str;
    }

    char *result = &str_pool[str_pool_idx];
    int str_len = strlen(str);

    if (start < 0) start = 0;
    if (end < 0) end = str_len;
    if (end > str_len) end = str_len;
    if (start > end) start = end;
    if (start > str_len) start = str_len;

    int length = end - start;
    if (length < 0) length = 0;

    if (str_pool_idx + length + 1 >= STR_POOL_SIZE) {
        error("String pool overflow");
        return (long)empty_str;
    }

    if (length > 0 && start < str_len) {
        strncpy(result, str + start, length);
    }
    result[length] = 0;

    str_pool_idx += length + 1;
    return (long)result;
}