/*
 * Copyright (C) 2024  Tristan Riehs
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */

#include "config.h"

#include <assert.h>
#include <stdint.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <time.h>

#include "linenoise.h"

static int lower = 0;
static int upper = 100;

static FILE *logfile;
static char logbuf[64];
#define LOGBUF_OFFSET 11

/* Return a random number x such that lower <= x < upper. */
static int
calculer_rand(void)
{
	return lower + rand()%(upper-lower);
}

static intptr_t
tp_ms(struct timespec const *tp)
{
	return tp->tv_sec*1000 + tp->tv_nsec/1000000;
}

static void *
measure_before(void)
{
	struct timespec tp;
	clock_gettime(CLOCK_REALTIME, &tp);
	return (void *)tp_ms(&tp);
}

int
measure_after(void *data, int correct)
{
	int t0 = (intptr_t) data;
	struct timespec tp;
	clock_gettime(CLOCK_REALTIME, &tp);
	int t1 = tp_ms(&tp);
	int dt = t1 - t0;
	size_t bytes_written =
		LOGBUF_OFFSET + sprintf(logbuf + LOGBUF_OFFSET,
					"%d\t%d\n", dt, correct);

	return bytes_written != fwrite(logbuf, 1, bytes_written, logfile);
}

int
main(void)
{
	srand(time(NULL));
	logfile = fopen("./calculer.log", "a");
	assert(logfile);

	time_t now = time(NULL);
	struct tm *tm = localtime(&now);
	size_t bytes_written = strftime(logbuf, sizeof(logbuf), "%F\t", tm);
	assert(bytes_written);

	while (1)
	{
		char prompt[32] = {0};
		int x, y, res;
		char *input;
		int input_val;

		x = calculer_rand();
		y = calculer_rand();
		res = x+y;

		sprintf(prompt, "%d + %d = ", x, y);
		void *measure_data = measure_before();
		input = linenoise(prompt);

		if ((!input) || (*input == '\0'))
		{
			free(input);
			fclose(logfile);
			exit(0);
		}

		input_val = atoi(input);
		if (measure_after(measure_data, input_val == res))
		{
			free(input);
			fclose(logfile);
			exit(1);
		}

		if (input_val == res)
			printf("RIGHT\n");
		else
			printf("WRONG\n");

		free(input);
	}

	fclose(logfile);
	return 0;
}