#include <conio.h> //콘솔 제어용 헤더
#include <dos.h> //delay() 등의 사용을 위한

//화면 사이즈
#define MAX_WIDTH				80
#define MAX_HEIGHT				24

//시작 좌표
#define LEFT_POS				1
#define TOP_POS					1

//바깥라인과 안쪽라인의 차이
#define INNER_OFFSET			1

//좌표의 배열 처리를 위한 인덱스값 등록
#define OUT_CHAR_IDX			0
#define IN_CHAR_IDX				1

//방향값 등록
#define DIRECTION_LEFT_RIGHT	1
#define DIRECTION_RIGHT_LEFT	2
#define DIRECTION_TOP_DOWN		3
#define DIRECTION_DOWN_TOP		4

void main()
{
	int x[] = {1, 79};//{out x, in x}
	int y[] = {1, 2};//{out y, in y}

	int dir[] = {DIRECTION_LEFT_RIGHT, DIRECTION_RIGHT_LEFT};//{out direction, in direction}

	clrscr();

	//while(!kbhit()) //키입력으로 수행 중단...
	for(;;)
	{
		/*
			만약 일정 횟수만 돌기 원한다면 for 문을 (i=0; i<이동칸수; i++) 설정합니다....	
		*/
		if(kbhit()) break; //키입력으로 수행 중단...

		//이전 위치에 공백 출력...
		gotoxy(x[OUT_CHAR_IDX], y[OUT_CHAR_IDX]);
		cprintf(" ");

		gotoxy(x[IN_CHAR_IDX], y[IN_CHAR_IDX]);
		cprintf(" ");

		//새로운 위치 계산...

		//바깥 문자처리
		/*
		switch(dir[OUT_CHAR_IDX])
		{
			case DIRECTION_LEFT_RIGHT :
				x[OUT_CHAR_IDX]++;
				if(x[OUT_CHAR_IDX] == MAX_WIDTH) dir[OUT_CHAR_IDX] = DIRECTION_TOP_DOWN;
				break;
			case DIRECTION_RIGHT_LEFT :
				x[OUT_CHAR_IDX]--;
				if(x[OUT_CHAR_IDX] == INNER_OFFSET) dir[OUT_CHAR_IDX] = DIRECTION_DOWN_TOP;
				break;
			case DIRECTION_TOP_DOWN :
				y[OUT_CHAR_IDX]++;
				if(y[OUT_CHAR_IDX] == MAX_HEIGHT) dir[OUT_CHAR_IDX] = DIRECTION_RIGHT_LEFT;
				break;
			case DIRECTION_DOWN_TOP :
				y[OUT_CHAR_IDX]--;
				if(y[OUT_CHAR_IDX] == INNER_OFFSET) dir[OUT_CHAR_IDX] = DIRECTION_LEFT_RIGHT;
				break;
		}
		*/
		if(dir[OUT_CHAR_IDX] == DIRECTION_LEFT_RIGHT)
		{
			x[OUT_CHAR_IDX]++;
			if(x[OUT_CHAR_IDX] == MAX_WIDTH) dir[OUT_CHAR_IDX] = DIRECTION_TOP_DOWN;
		}
		else if(dir[OUT_CHAR_IDX] == DIRECTION_RIGHT_LEFT)
		{
			x[OUT_CHAR_IDX]--;
			if(x[OUT_CHAR_IDX] == INNER_OFFSET) dir[OUT_CHAR_IDX] = DIRECTION_DOWN_TOP;
		}
		else if(dir[OUT_CHAR_IDX] == DIRECTION_TOP_DOWN)
		{
			y[OUT_CHAR_IDX]++;
			if(y[OUT_CHAR_IDX] == MAX_HEIGHT) dir[OUT_CHAR_IDX] = DIRECTION_RIGHT_LEFT;
		}
		else if(dir[OUT_CHAR_IDX] == DIRECTION_DOWN_TOP)
		{
			y[OUT_CHAR_IDX]--;
			if(y[OUT_CHAR_IDX] == INNER_OFFSET) dir[OUT_CHAR_IDX] = DIRECTION_LEFT_RIGHT;
		}

		//안쪽 문자처리
		/*
		switch(dir[IN_CHAR_IDX])
		{
			case DIRECTION_LEFT_RIGHT :
				x[IN_CHAR_IDX]++;
				if(x[IN_CHAR_IDX] == (MAX_WIDTH - 1)) dir[IN_CHAR_IDX] = DIRECTION_DOWN_TOP;
				break;
			case DIRECTION_RIGHT_LEFT :
				x[IN_CHAR_IDX]--;
				if(x[IN_CHAR_IDX] == (LEFT_POS + INNER_OFFSET)) dir[IN_CHAR_IDX] = DIRECTION_TOP_DOWN;
				break;
			case DIRECTION_TOP_DOWN :
				y[IN_CHAR_IDX]++;
				if(y[IN_CHAR_IDX] == (MAX_HEIGHT - 1)) dir[IN_CHAR_IDX] = DIRECTION_LEFT_RIGHT;
				break;
			case DIRECTION_DOWN_TOP :
				y[IN_CHAR_IDX]--;
				if(y[IN_CHAR_IDX] == (TOP_POS + INNER_OFFSET)) dir[IN_CHAR_IDX] = DIRECTION_RIGHT_LEFT;
				break;
		}
		*/
		if(dir[OUT_CHAR_IDX] == DIRECTION_LEFT_RIGHT)
		{
			x[IN_CHAR_IDX]++;
			if(x[IN_CHAR_IDX] == (MAX_WIDTH - 1)) dir[IN_CHAR_IDX] = DIRECTION_DOWN_TOP;
		}
		else if(dir[OUT_CHAR_IDX] == DIRECTION_RIGHT_LEFT)
		{
			x[IN_CHAR_IDX]--;
			if(x[IN_CHAR_IDX] == (LEFT_POS + INNER_OFFSET)) dir[IN_CHAR_IDX] = DIRECTION_TOP_DOWN;
		}
		else if(dir[OUT_CHAR_IDX] == DIRECTION_TOP_DOWN)
		{
			y[IN_CHAR_IDX]++;
			if(y[IN_CHAR_IDX] == (MAX_HEIGHT - 1)) dir[IN_CHAR_IDX] = DIRECTION_LEFT_RIGHT;
		}
		else if(dir[OUT_CHAR_IDX] == DIRECTION_DOWN_TOP)
		{
			y[IN_CHAR_IDX]--;
			if(y[IN_CHAR_IDX] == (TOP_POS + INNER_OFFSET)) dir[IN_CHAR_IDX] = DIRECTION_RIGHT_LEFT;
		}

		//계산된 위치에 문자 출력
		gotoxy(x[OUT_CHAR_IDX], y[OUT_CHAR_IDX]);
		cprintf("*");

		gotoxy(x[IN_CHAR_IDX], y[IN_CHAR_IDX]);
		cprintf("@");

		//너무 빠른 진행을 막기위해 지연 시킴
	    delay(100); //밀리초 단위의 지연시간...
	}
}