2025/xmas.c

#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <string.h>
#include <signal.h>
#include <ncurses.h>
#include <sys/ioctl.h>
#include <errno.h>

#define ARRAY_SIZE(x) (sizeof(x) / sizeof(x[0]))

typedef struct {
	struct winsize ws;

	/* m middle */
	size_t mx;
	size_t my;
} SCREEN_SIZE;
static SCREEN_SIZE ss;

typedef struct {
	char *str;
	int color;
	int x;
	int y;
} ENTITY;
static ENTITY names[10];
static ENTITY stars[25];

enum {
	COL_RED = 1,
	COL_GREEN,
	COL_BLUE,
	COL_YELLOW,
	COL_CYAN,
	COL_MAGENTA,
	COL_WHITE,
	COL_COUNT
};

char *persons[] = {
	"PseudoCube",
	"wonderfox",
	"DwarfX",
	"prahou",
	"8nl",
	"blit",
	"kir4ik52",
	"cybertailor",
	"ej",
	"Sarotar",
	"continue",
	"mittorn",
	"edges",
	"mirsusarch",
	"Worst",
	"Timukra",
	"mnnwwn",
	"dlmk",
	"vlnst",
	"KindFoxie",
	"leca",
	"kurator88",
	"SiberiaBread"
};

void add_entity(ENTITY *ent, int y, int x, char *str, int color) {
	ent->y = y;
	ent->x = x;
	ent->color = color;
	ent->str = str;
}

void init_names(int i, int y) {
	int color = rand() % COL_COUNT;
	while (color == COL_GREEN)
		color = rand() % COL_COUNT;

	add_entity(&names[i], y, ss.mx + (-6 + rand() % 12), persons[rand() % ARRAY_SIZE(persons)], color);
}

void update_names(void) {
	for (size_t i = 0; i < ARRAY_SIZE(names); i++) {
		names[i].x += -3 + rand() % 6;
		names[i].y++;

		if (names[i].y >= ss.ws.ws_row)
			init_names(i, 1);
	}
}

void color_print(const int y, const int x, const char *str, const int color) {
	attron(COLOR_PAIR(color));
	mvprintw(y, x, "%s", str);
	attroff(COLOR_PAIR(color));
}

void draw_tree(void) {
	mvprintw(ss.ws.ws_row - 1, ss.mx - 3, "|_____|");

	for (size_t i = ss.ws.ws_row - 2; i > 0; i--) {
		for (size_t j = 0; j < i; j++) {
			color_print(i, (int)(ss.mx + j), "-", COL_GREEN);
			color_print(i, (int)(ss.mx - j), "-", COL_GREEN);
		}

		if (i == 1)
			color_print(i, ss.mx, "@", COL_YELLOW);
	}
}

void sig_handler(int sig) {
	(void)sig;

	endwin();
	exit(0);
}

int main(void) {
	srand(getpid());

	/* Fill SCREEN_SIZE struct */
	if (ioctl(STDOUT_FILENO, TIOCGWINSZ, &ss.ws) < 0) {
		fprintf(stderr, "ioctl failed: %s\n", strerror(errno));
		return 1;
	}

	ss.mx = ss.ws.ws_col / 2;
	ss.my = ss.ws.ws_row / 2;

	/* Init ncurses */
	initscr();
	noecho();
	cbreak();
	curs_set(0);

	/* Colors */
	start_color();
	init_pair(1, COLOR_RED, COLOR_BLACK);
	init_pair(2, COLOR_GREEN, COLOR_BLACK);
	init_pair(3, COLOR_BLUE, COLOR_BLACK);
	init_pair(4, COLOR_YELLOW, COLOR_BLACK);
	init_pair(5, COLOR_CYAN, COLOR_BLACK);
	init_pair(6, COLOR_MAGENTA, COLOR_BLACK);
	init_pair(7, COLOR_WHITE, COLOR_BLACK);

	if (!has_colors()) {
		endwin();

		fputs("colors are not supported by the terminal", stderr);
		return 1;
	}

	/* Update siganls */
	signal(SIGINT, sig_handler);
	signal(SIGKILL, sig_handler);

	/* Update names */
	for (size_t i = 0; i < ARRAY_SIZE(names); i++)
		init_names(i, i);

	/* Add stars */
	for (size_t i = 0; i < ARRAY_SIZE(stars); i++)
		add_entity(&stars[i], rand() % ss.my, rand() % ss.ws.ws_col, ".", COLOR_WHITE);

	/* Main */
	while (1) {
		clear();

		/* Stars */
		for (size_t i = 0; i < ARRAY_SIZE(stars); i++)
			color_print(stars[i].y, stars[i].x, stars[i].str, stars[i].color);

		/* Title */
		char *msg = "HAPPY NEW YEAR!";
		mvprintw(0, ss.mx - strlen(msg) / 2, "%s", msg);

		/* Tree */
		draw_tree();

		/* Names */
		update_names();
		for (size_t i = 0; i < ARRAY_SIZE(names); i++)
			color_print(names[i].y, names[i].x, names[i].str, names[i].color);

		refresh();
		usleep(600000);
	}
}