// -----------------------------------------------------
// lightbot simulator to check Light-bot level solutions
// Fritz Ruehr, WU CS 141, Fall 2011
// (original Light-bot by Coolio-Niato and Armor Games)
// -----------------------------------------------------


#include <stdio.h>
#include <string.h>


// -------------------- constants

#define prefix   "lev"
#define suffix   ".dat"
#define SIZE     8
#define Off      2


// -------------------- macros  (enum { East, North, West, South } d; )
//                              (ints vs. enums for modular arithmetic)

#define left     d=(d+1)%4
#define right    d=(d+3)%4
#define dx       ((1-d)%2)
#define dy       ((2-d)%2)
#define curr     board[x][y]
#define next     board[x+dx][y+dy]
#define target   ((d%2)?y+dy:x+dx)
#define forward  { x+=dx; y+=dy; }
#define safe     (0<=target && target<SIZE)
#define diff     (next.h - curr.h)
#define even     (diff==0)
#define easy     (diff == 1 || diff < 0)
#define togg(l)  if (l>0) (l)=(3-l)%3


// -------------------- global data

typedef struct {int h; int l;} tile;            // enum { None, On, Off } l ;
tile board[SIZE][SIZE];                         // board of heights and lights
int x, y, d;                                    // start position & direction


// -------------------- readBoard

int readBoard(char* fname) {

    FILE* boardfile=fopen(fname,"r");
	int i, j;
	
	for(i=0; i<SIZE; i++)
		for(j=0; j<SIZE; j++)
			fscanf(boardfile, "%d %d", &(board[i][j].h), &(board[i][j].l));
			
	fscanf(boardfile, "%d %d %d", &x, &y, &d);
	fclose(boardfile);
}


// -------------------- checkSolution

int checkSolution() {

    int move;

	while((move=getchar())!=EOF) {
		
		switch(move) {
		
			case  'F':  case 'f':       if (safe && even)  forward;  break;
			case  'J':  case 'j':       if (safe && easy)  forward;  break;
			
			case  'R':  case 'r':       right;  break;
			case  'L':  case 'l':       left;   break;
			
			case  'S':  case 's':       togg(board[x][y].l);    break;
			
			case  ' ':  case '\t':  case  '\n':      break;
			
			default:    printf("** Error; bad move code: %c **\n", move);
		}	
	}
}


// -------------------- allLitUp

int allLitUp() {

	int good = 1;
    int i, j;
	
	for(i=0; i<SIZE; i++)
		for(j=0; j<SIZE; j++)
		    
		    if((board[i][j].l) == Off) {
		        good = 0;
		        printf("\n\t... light on at (%d,%d) ...", i, j);
		    }
	return good;
}


// -------------------- getLevel

int getLevel() {
    int level;
    
    printf("\nPlease input desired level number (1-12), or 0 to quit: ");
    scanf("%d", &level);
    return(level);
}


// -------------------- moreSolutions

int moreSolutions() {
    char input[100];

    printf("\nCheck another solution against this board (y or n)?: ");
    scanf("%s", input);
    return(input[0]=='y');
}


// -------------------- fexists

int fexists(char* fname) {
    FILE* fp;
    if(fp=fopen(fname,"r")) {
        fclose(fp);
        return 1;
    }
    else
        return 0;
}


// -------------------- main (outer loops for user interaction)

int main() {

    int   level;
    char  fname[20];
    
    printf("\n-----------------------------");
    printf("\nLight-bot simulator, ver. 0.3\n");
    
    while((level=getLevel())!=0) {
    
        // generate standard filename from parts
        
        strcpy(fname,prefix);
        sprintf(&fname[strlen(prefix)],"%d",level);
        strcat(fname,suffix);
        
        if(!fexists(fname))
            printf("\nSorry, no valid board file found as: %s\n", fname);
            
        else
            do {
                readBoard(fname);
                printf("\nEnter a solution string; EOF to stop (i.e., ctrl-d): \n\n");
                checkSolution();
		        printf("\n\nSolution %s\n", allLitUp() ? "succeeds :)" : "fails :(");
                clearerr(stdin);
            }
            while(moreSolutions());
    }
    
    printf("\nLight-bot simulator over and out!\n");
    printf("---------------------------------\n\n");
}

// end lightbot program