#include "utils.h"
#include <stdbool.h>
#include <stdio.h>
#include <stdlib.h>
#include <time.h>

#define SEPARATOR_CHAR '-'
#define SEPARATOR_WIDTH 50
#define NEWLINE_CHAR '\n'
#define INPUT_BUFFER_SIZE 16
#define TIME_FORMAT_STRING "%Y-%m-%d %H:%M:%S"
#define ASK_YES_NO_PROMPT "Please enter 'y' or 'n': "

/** Clear leftover input from stdin */
static void flush_stdin(void)
{
	int input_char;
	do
		input_char = getchar();
	while (input_char != NEWLINE_CHAR && input_char != EOF);
}

/** Print a horizontal separator line for the quiz UI */
static void print_separator_line(void)
{
	for (size_t current_column = 0; current_column < SEPARATOR_WIDTH;
	     ++current_column)
		putchar(SEPARATOR_CHAR);

	putchar(NEWLINE_CHAR);
}

/** Print a horizontal separator line */
void print_line(void)
{
	print_separator_line();
}

/**
 * Pause until the user presses ENTER
 *
 * @param prompt Optional message to display before waiting
 */
void wait_for_enter(const char* prompt)
{
	if (prompt != NULL)
		fputs(prompt, stdout);

	flush_stdin();
}

/**
 * Ask a yes/no question and return a boolean answer
 *
 * @param prompt Question message to display
 * @return true if user answered 'y' or 'Y', false if 'n', default false
 */
bool ask_yes_no(const char* prompt)
{
	char input_line[INPUT_BUFFER_SIZE];

	while (1) {
		if (prompt != NULL)
			fputs(prompt, stdout);

		if (fgets(input_line, sizeof(input_line), stdin) == NULL)
			return false;

		const char first_char = input_line[0];

		if (first_char == 'y' || first_char == 'Y')
			return true;

		if (first_char == 'n' || first_char == 'N')
			return false;

		fputs(ASK_YES_NO_PROMPT, stdout);
	}
}

/**
 * Get the current timestamp for recording when a question was answered
 *
 * @param answer_time_buffer Buffer to store the formatted timestamp
 * @param buffer_capacity Size of the buffer in bytes
 */
void get_answer_timestamp(char* answer_time_buffer,
			  const size_t buffer_capacity)
{
	if (answer_time_buffer == NULL || buffer_capacity == 0)
		return;

	const time_t current_time = time(NULL);
	const struct tm* local_time = localtime(&current_time);
	if (local_time != NULL)
		strftime(answer_time_buffer,
			 buffer_capacity,
			 TIME_FORMAT_STRING,
			 local_time);
}

/**
 * Get a random question index in the quiz (thread-safe)
 *
 * @param seed Pointer to an unsigned int seed (per-thread)
 * @param total_questions Number of questions in the current quiz session
 * @return Random index in the range [0, total_questions-1]
 */
size_t get_random_question_index(unsigned int* seed,
				 const size_t total_questions)
{
	if (total_questions == 0 || seed == NULL)
		return 0;

	const unsigned long random_value = (unsigned long)rand_r(seed);
	return random_value % total_questions;
}