/*
 * A very simple maze game.
 *
 * Author: Zach Tomaszewski
 */

#include <stdio.h>
#include <ctype.h>

//size of room
#define WIDTH 6
#define HEIGHT 6

//chars used when printing the room
#define FLOOR '.'
#define PLAYER '@'
#define EXIT '#'

//game controls (set to lowercase values only)
#define UP 'n'
#define DOWN 's'
#define LEFT 'w'
#define RIGHT 'e'

void printRoom(int playerX, int playerY, int exitX, int exitY);
char getUserMove(void);


/*
 * Repeatedly prints a room map showing the player's current location
 * and an exit.  Each turn, asks the user to move.  When the player
 * reaches the exit, the game ends.
 */
int main() {
  
  //player starts in center of room.
  //(x increases left-to-right; y increases top-to-bottom)
  int playerX = WIDTH / 2;
  int playerY = HEIGHT / 2;
  
  //exit is in lower right corner
  int exitX = WIDTH - 1;
  int exitY = HEIGHT - 1;
  
  //Explain game to user
  printf("Try to escape the maze!  Move yourself (%c) to the exit (%c).\n", 
      PLAYER, EXIT);

  //play the game
  while (!(playerX == exitX && playerY == exitY)) {
    int move;
    
    //show room and get user's move
    printRoom(playerX, playerY, exitX, exitY);
    move = getUserMove();

    //update player position based on move choice
    switch (move) {
      case UP:    playerY--; break;
      case DOWN:  playerY++; break; 
      case LEFT:  playerX--; break;
      case RIGHT: playerX++; break;
    }
    
    //if now outside of maze, roll back move and report error
    if (playerX < 0 || playerY < 0 || playerX >= WIDTH || playerY >= HEIGHT) {      
      puts("Invalid move: You can only leave the room through the exit.");
      switch (move) {
        case UP:    playerY++; break;
        case DOWN:  playerY--; break; 
        case LEFT:  playerX++; break;
        case RIGHT: playerX--; break;
      }      
    }
  }

  //loop only exits when player makes it to exit, so: congrats
  printf("\nCongratulations!  You made it out alive.\n");

  return 0;
}


/*
 * Gets a valid move from the user.
 * 
 * Prompts the user to enter one of the valid move constant values: 
 * UP, DOWN, LEFT, RIGHT.  Will continue to ask until the user
 * enters a valid move.  Accepts either upper or lowercase versions.
 * 
 * Returns the move the user entered.
 */
char getUserMove() {
  char move = '\0';
  for (;;) { 
    //ask user until they get it right
    printf("Enter a move (%c/%c/%c/%c): ", UP, DOWN, LEFT, RIGHT);
    move = getchar();
    while (getchar() != '\n');  //clear remaining input from stream
    move = tolower(move);
    if (move == UP || move == DOWN || move == LEFT || move == RIGHT) {
      return move;
    }else { 
      puts("Sorry, that is not a valid move option. Please try again.");
    }
  }
}


/*
 * Prints the room containing a player and an exit at the given locations.
 * 
 * The characters used to print the room are set by the PLAYER, FLOOR, and
 * EXIT constants.
 *
 * playerX and exitX must be >= 0 and < WIDTH.  playerY and exitY must be
 * >= 0 and < HEIGHT.  If any of these coordinates place the player or
 * exit outside of the room, that character (player or exit) will not be
 * printed.  If the player and exit are at the same location, it will 
 * be printed as a player character.
 */
void printRoom(int playerX, int playerY, int exitX, int exitY) {
  int row, col;
  for (row = 0; row < HEIGHT; row++) {
    for (col = 0; col < WIDTH; col++) {
      if (row == playerY && col == playerX) {
        printf ("%c", PLAYER);
      }else if (row == exitY && col == exitX) {
        printf ("%c", EXIT);
      }else {
        printf("%c", FLOOR);
      }
    }
    printf("\n");  //end row
  }
}