#include <ncurses.h>
#include <stdlib.h>
#include <stdio.h>
#include <time.h>
#include <unistd.h>
#include <stdbool.h>

#define CHAR_COUNT 17

#define COLOR_LIGHT_GREEN 8
#define COLOR_MID_GREEN 9
#define COLOR_DARK_GREEN 10
#define COLOR_BLACK_GREEN 11

#define WHITE 1
#define LIGHT_GREEN 2
#define MID_GREEN 3
#define DARK_GREEN 4
#define BLACK_GREEN 5


const char CHARS[] = "!$%&?#@Y0123456789";


struct Cursor {
	int x;
	int y;
	int speed;
	int length;
	char string[256];
	bool is_expanding;
	bool is_active;
};


int get_random_number(int max_number)
{
	double index = (rand() / (double)RAND_MAX) * max_number;

	return (int)index % max_number;
}


char get_random_char()
{
	return CHARS[get_random_number(CHAR_COUNT)];
}


void generate_random_string(char * string, int length)
{
	int index = 0;

	for (int c = 0; c < length; c++) {
		string[c] = get_random_char();
		index = c;
	}

	string[index + 1] = '\0';
}


void print_with_color(char c, int x, int y, int color_pair)
{
	attron(COLOR_PAIR(color_pair));
	mvaddch(y, x, c);
	attroff(COLOR_PAIR(color_pair));
}


void draw_cursor(struct Cursor * cursor, int * screen_height)
{
	print_with_color(cursor->string[cursor->y], cursor->x, cursor->y, WHITE);

	if (cursor->y > 0) {
		print_with_color(cursor->string[cursor->y - 1], cursor->x, cursor->y - 1, LIGHT_GREEN);
	}

	++cursor->y;

	/*
	if (cursor->y > 4 && cursor->length > 4 && get_random_number(100) > 90) {
		char random_char = get_random_char();
		int char_index = cursor->y - get_random_number(cursor->length - 4);

		cursor->string[char_index] = random_char;
	}
	*/

	if (cursor->is_expanding) {
		++cursor->length;

		if (cursor->length > *screen_height * 0.1) {
			cursor->is_expanding = get_random_number(10) > 1;
		}
	} else {
		mvaddch(cursor->y - cursor->length - 4, cursor->x, ' ');
		print_with_color(cursor->string[cursor->y - cursor->length - 3], cursor->x, cursor->y - cursor->length - 3, BLACK_GREEN);
		print_with_color(cursor->string[cursor->y - cursor->length - 2], cursor->x, cursor->y - cursor->length - 2, DARK_GREEN);
		print_with_color(cursor->string[cursor->y - cursor->length - 1], cursor->x, cursor->y - cursor->length - 1, MID_GREEN);
	}

	if (cursor->y > *screen_height + cursor->length + 3) {
		cursor->length = 0;
		cursor->y = 0;
		cursor->is_active = false;
		cursor->is_expanding = true;
	}
}


void control_cursor(struct Cursor * cursor, int * screen_height)
{
	if (cursor->is_active) {
		draw_cursor(cursor, screen_height);
	} else {
		cursor->is_active = get_random_number(*screen_height) > *screen_height * 0.5;

		if (cursor->is_active) {
			generate_random_string(cursor->string, *screen_height + 4);
		}
	}
}


int main()
{
	int screen_width = 0;
	int screen_height = 0;

	srand(time(NULL));

	initscr();

	if (!has_colors()) {
		printf("Your shell does not support colors!\n");
		return 1;
	}

	getmaxyx(stdscr, screen_height, screen_width);

	struct Cursor cursors[screen_width];

	for (int c = 0; c < screen_width; c++) {
		struct Cursor cursor;

		cursor.x = c;
		cursor.y = -1 * get_random_number(screen_height);
		cursor.speed = 0;
		cursor.length = 0;
		cursor.is_active = false;
		cursor.is_expanding = true;

		cursors[c] = cursor;
	}

	cbreak();
	curs_set(0);
	noecho();
	keypad(stdscr, 1);
	start_color();

	init_color(COLOR_WHITE, 1000, 1000, 1000);
	init_color(COLOR_BLACK, 0, 0, 0);
	init_color(COLOR_LIGHT_GREEN, 500, 1000, 500);
	init_color(COLOR_MID_GREEN, 0, 600, 0);
	init_color(COLOR_DARK_GREEN, 0, 200, 0);
	init_color(COLOR_BLACK_GREEN, 0, 50, 0);


	init_pair(WHITE, COLOR_WHITE, COLOR_BLACK);
	init_pair(LIGHT_GREEN, COLOR_LIGHT_GREEN, COLOR_BLACK);
	init_pair(MID_GREEN, COLOR_MID_GREEN, COLOR_BLACK);
	init_pair(DARK_GREEN, COLOR_DARK_GREEN, COLOR_BLACK);
	init_pair(BLACK_GREEN, COLOR_DARK_GREEN, COLOR_BLACK);

	while (true) {
		for (int c = 0; c < screen_width; c++) {
			control_cursor(&cursors[c], &screen_height);
		}

		refresh();

		usleep(90000);
	}

	endwin();

	return 0;
}