#include "stringv.h"
#include <stddef.h>
#include <stdio.h>
#include <string.h>

/*
 * @brief Create a string view from a const char* and  set their lenght
 *
 * @details This string view provides a view of a string. It does not allocate
 * memory, therefore, it lives only while the source is alive. The
 * lenght is a bytes number of the string. It does not represents the number of
 * characters.
 *
 * @param str pointer from the original string. It can be NULL.
 *
 * @return a StringView with the view of original string with corresponding
 * lenght.
 */

#define STRING_VIEW_NULL (StringView){.text = NULL, .lenght = 0}

StringView sv_from_cstr(const char *str) {
    if (str == NULL) {
        return STRING_VIEW_NULL;
    }
    return (StringView){.text = (char *)str, .lenght = strlen(str)};
}

StringView sv_left(const StringView *sv, size_t l) {
    if (sv == NULL) {
        perror("sv_left: pointer is NULL\n");
        return STRING_VIEW_NULL;
    }
    if (sv->text == NULL) {
        perror("sv_left: text pointer is NULL\n");
        return STRING_VIEW_NULL;
    }
    if (sv->lenght < l) {
        perror("sv_left: text length is less than specified length\n");
        return STRING_VIEW_NULL;
    }
    return (StringView){.text = sv->text, .lenght = l};
}

StringView sv_right(const StringView *sv, size_t r) {
    if (sv == NULL) {
        perror("sv_right: pointer is NULL\n");
        return STRING_VIEW_NULL;
    }
    if (sv->text == NULL) {
        perror("sv_right: text pointer is NULL\n");
        return STRING_VIEW_NULL;
    }
    if (sv->lenght < r) {
        perror("sv_right: text length is less than specified length\n");
        return STRING_VIEW_NULL;
    }
    size_t nlength = sv->lenght - r;
    return (StringView){.text = sv->text + nlength, .lenght = r};
}