#include "syntax_essentials.h"
#include <stdio.h>

/**
 *
 * TASK 1: validate_first_name
 * Check if the first name is valid.
 * - Cannot be NULL or empty
 * - Only letters (a-z, A-Z)
 * - Minimum length: 2
 *
 * @param first_name
 * @return
 */
int validate_first_name(const char* first_name)
{
	if (!first_name)
		return 0;

	int length = 0;
	for (const char* p = first_name; *p; p++) {
		if ((*p >= 'A' && *p <= 'Z') || (*p >= 'a' && *p <= 'z'))
			length++;
		else
			return 0;
	}
	return length >= 2;
}

/**
 *
 * TASK 2: validate_last_name
 * Check if the last name is valid.
 * - Cannot be NULL or empty
 * - Only letters (a-z, A-Z)
 * - Minimum length: 2
 *
 * @param last_name
 * @return
 */
int validate_last_name(const char* last_name)
{
	if (!last_name)
		return 0;

	int length = 0;

	for (const char* p = last_name; *p; p++) {
		if ((*p >= 'A' && *p <= 'Z') || (*p >= 'a' && *p <= 'z'))
			length++;
		else
			return 0;
	}

	return length >= 2;
}

/**
 *
 * TASK 3: validate_full_name
 * Check if a full name "First Last" is valid.
 * Use TASK 1 and TASK 2 internally.
 * @param full_name
 * @return
 */
int validate_full_name(const char* full_name)
{
	if (!full_name)
		return 0;

	char first_name[64], last_name[64];
	if (sscanf(full_name, "%63s %63s", first_name, last_name) != 2)
		return 0;

	return validate_first_name(first_name) && validate_last_name(last_name);
}

/**
 *
 * @param index
 * @return
 */
int validate_index(const char* index)
{
	if (!index)
		return 0;

	int length = 0;
	for (const char* p = index; *p; p++) {
		if (*p >= '0' && *p <= '9')
			length++;
		else
			return 0;
	}

	return length == 6;
}

/**
 *
 * @param full_name
 * @param index
 * @return
 */
int register_student(const char* full_name, const char* index)
{
	if (!validate_full_name(full_name))
		return 1;
	if (!validate_index(index))
		return 2;
	return 0;
}

/**
 *
 * @param name
 * @return
 */
int name_length(const char* name)
{
	if (!name)
		return 0;

	int length = 0;
	while (*name++)
		length++;
	return length;
}

/**
 *
 * @param array
 * @param max_size
 * @param name
 * @param index
 * @return
 */
int add_student(Student* array,
		const int max_size,
		const char* name,
		const char* index)
{
	if (!name || !index || !array)
		return 2;

	int len = 0;
	while (len < max_size && array[len].full_name[0] != '\0')
		len++;

	if (len >= max_size)
		return 1;

	snprintf(
	    array[len].full_name, sizeof(array[len].full_name), "%s", name);
	snprintf(array[len].index, sizeof(array[len].index), "%s", index);
	return 0;
}

/**
 *
 * @param code
 * @return
 */
const char* get_error_message(const int code)
{
	switch (code) {
		case 0:
			return "Success";
		case 1:
			return "Invalid name";
		case 2:
			return "Invalid index";
		default:
			return "Unknown error";
	}
}