#include <tigcclib.h>
#define LCD_BYTES_COLS		20
#define LCD_ROW_BYTES			30
#define LCD_BOTTOM_ROW 		(void *)0x579A
#define ARROW_ROW					0xFFFE
#define ESCROW 						0xFFBF  // the ESC row on the TI-89 keyboard matrix
#define ESCKEY 						0x0001  // the ESC key inside that row
#define NDKEY							0x0010
#define KEYLEFT 					0x0002
#define KEYRIGHT					0x0008

unsigned long blocks = 0;
char spacing_count = 38, max_spacing = 40, max_spacing_count = 0, platform_row = 4;
char speed = 0;

unsigned char ball_x = 77, ball_y = 50;
unsigned char ball[] = {0x78,0x9C,0xBC,0xFC,0xFC,0x78};

void draw_speed() {
	char buffer[5];
	sprintf (buffer, "%d", speed);
	DrawStr(60, 38, buffer, A_NORMAL);
}

void draw_menu() {
	ClrScr();
	FontSetSys(F_8x10);
	DrawStr(4, 2, "Falldown Impossible", A_NORMAL); 
	FontSetSys(F_4x6);
	DrawStr(135, 12, "v1.0a", A_NORMAL);
	FontSetSys(F_6x8);
	DrawStr(0, 30, "2nd  -  Start Game", A_NORMAL);
	DrawStr(0, 38, "Speed  \x11     \x12", A_NORMAL);
	draw_speed();
	DrawStr(0, 46, "F1  -  Help", A_NORMAL);
}

void delay(int len) {
	int i, randnum;
	for (i = 0; i < len; i++) {
		randnum = random(0xFF);
	}
}

void scroll_up() {
	memcpy(LCD_MEM, LCD_MEM + LCD_ROW_BYTES, LCD_ROW_BYTES * LCD_HEIGHT);
}

void draw_platform() {
	if (platform_row == 4) {   // If we have drawn all four lines of a platform
		spacing_count++;  // Increase our count of the space between each platform
		if (spacing_count == max_spacing) {  // If it is time to draw a new block...
			platform_row = 0;
			randomize();
			blocks = ((long)random(0xFFFF) << 16) | ((long)random(0xFFFF));  // Generate a new random platform 
			spacing_count = 0;   // Reset the spacing count
			max_spacing_count++;  // And add one to max spacing count
			if (max_spacing_count == 6) {   // Its time to decrease the spacing between platforms
				max_spacing -= 2; 
				if (max_spacing <= 8) {  // Unless the spacing is too thin, then dont change it
					max_spacing = 8;
				} 
				max_spacing_count = 0;
			}
		}
	} else {
		int i;
		unsigned long bits = 0x00080000;
		char *lcd = LCD_BOTTOM_ROW;
		for (i = 0; i < 20; i++){
			if (blocks & bits) {
				if (platform_row == 0 || platform_row == 3) {
					lcd[i] = 0xFF;  // Fill ones with lines
				} else {
					lcd[i] = random(0xFF);  // or with randomness
				}
			}
			bits >>= 1;
		}
		platform_row++;
	}
}

void move_up() {
	ball_y--; 
}

void move_down() {
	Sprite8(ball_x, ball_y - 1, 6, ball, LCD_MEM, SPRT_XOR);
	if (ball_y < 94) {
		ball_y++;
	}
	Sprite8(ball_x, ball_y, 6, ball, LCD_MEM, SPRT_XOR);	
}

void move_left() {
	if (ball_x <= 0) { return; }
	int i;
	char *check;
	if (ball_x % 8 == 0) {
		for (i = 0; i < 6; i++) {
			check = LCD_MEM + (LCD_ROW_BYTES * (ball_y + i)) + (ball_x / 8) - 1;
			if (*check) { return; }
		}
	}
	Sprite8(ball_x, ball_y, 6, ball, LCD_MEM, SPRT_XOR);
	ball_x--;
	Sprite8(ball_x, ball_y, 6, ball, LCD_MEM, SPRT_XOR);
}

void move_right() {
	if (ball_x >= 153) { return; }
	int i;
	char *check;
	if (ball_x % 8 == 2) {
		for (i = 0; i < 6; i++) {
			check = LCD_MEM + (LCD_ROW_BYTES * (ball_y + i)) + (ball_x / 8) + 1;
			if (*check) { return; }
		}
	}
	Sprite8(ball_x, ball_y, 6, ball, LCD_MEM, SPRT_XOR);
	ball_x++;
	Sprite8(ball_x, ball_y, 6, ball, LCD_MEM, SPRT_XOR);
}

void move_ball() {
	// Gravitty
	unsigned char *check = LCD_MEM + (LCD_ROW_BYTES * (ball_y + 5)) + (ball_x / 8);
//	*check = 0x02;
	if (ball_x % 8 < 3) {
		if (!*check) { 
			move_down();
		} else {
			move_up();
		}
	} else {
		if (!(check[0] | check[1])) {
			move_down();
		} else {
			move_up();
		}
	}
	int key;
	
	//Left and right
	key = _rowread(ARROW_ROW);
	
	if ((key & (KEYLEFT | KEYRIGHT)) == (KEYLEFT | KEYRIGHT)) return; // Dont you dare press both at the same time. Im watching you
	
	if (key & KEYLEFT) {
		move_left();
	}

	if (key & KEYRIGHT) {
		move_right();
	}
}

void _main(void) {
	blocks = 0;
	spacing_count = 38; max_spacing = 40; max_spacing_count = 0; platform_row = 4;
	ball_x = 77; ball_y = 50;
	draw_menu();
	ngetchx();
	INT_HANDLER interrupt1 = GetIntVec(AUTO_INT_1); // save auto-interrupt 1
	INT_HANDLER interrupt5 = GetIntVec(AUTO_INT_5); // save auto-interrupt 5
	SetIntVec(AUTO_INT_1,DUMMY_HANDLER);
	SetIntVec(AUTO_INT_5,DUMMY_HANDLER);
	int key;
	while (!(_rowread(ARROW_ROW) & NDKEY)) {
		key = _rowread(ARROW_ROW);
		
		if (key & KEYLEFT) {
			speed -= 2;
			draw_speed();
		}
		
		if (key & KEYRIGHT) {
			speed += 2;
			draw_speed();
		}
		
		delay(5000);
	}
  Sprite8(ball_x, ball_y, 6, ball, LCD_MEM, SPRT_XOR); 
	while (!(_rowread(ESCROW) & ESCKEY) && (ball_y > 0)) {
		scroll_up();
		draw_platform();
		move_ball();
		delay(600);
	}
	
	SetIntVec(AUTO_INT_1,interrupt1);
	SetIntVec(AUTO_INT_5,interrupt5);
	while ((key = ngetchx()) != KEY_ESC) {
	}
//	ngetchx();
	ClrScr();
}