/*************************************************************************/
// Maze:  A class for implementing operations on a maze.  The maze is a
//  character matrix of type CharMatrix.  The characters must be of
//  in the set of characters indicated under "Admissible maze characters"
//  in the constant definitions below.  The topmost and bottommost rows
//  and the leftmost and rightmost columns must consist exclusively of
//  WALL characters.
//
// See CharMatrix class for other restrictions on the input file format.
/*************************************************************************/

import java.io.*;
public class Maze extends CharMatrix implements MazeInterface
{

    /********************************************************************/
    // default constructor
    /********************************************************************/
    public Maze()
    {
        super();
    }

    /********************************************************************/
    // Constructor that reads a maze from a file.  The file must be in
    // the file format of the CharMatrix class; see comments preceding
    // the constructor in that class.  In addition, the borders of the matrix
    // must consist exclusively of WALL characters (see constant definitions
    // above) and all characters must have values from the set
    // {WALL, OPEN, GOAL, MARKED, PATHMARK}.
    /********************************************************************/
    public Maze(String filename) 
    {
        super(filename);
    }


    /*************************************************************************/
    /*   Count the empty cells that are reachable from the current location. */
    /*   FILL IN THE BODY OF THIS FUNCTION                                   */
    /*************************************************************************/
    public int countCellsFrom (int curRow, int curColumn)
    {
       setEntry(curRow, curColumn, MARKED); 
       int total = 1;
       if (getEntry(curRow, curColumn-1) == OPEN)
           total += countCellsFrom (curRow, curColumn-1);
       if (getEntry(curRow, curColumn+1) == OPEN)
           total += countCellsFrom (curRow, curColumn+1);
       if (getEntry(curRow-1,curColumn) == OPEN)
           total += countCellsFrom (curRow-1, curColumn);
       if (getEntry(curRow+1, curColumn) == OPEN)
           total += countCellsFrom (curRow+1, curColumn);
       return total;
    }

    /**********************************************************************/
    //  Find and mark a path from the current location to the to the goal */
    /*  cell, if there is one.  Cells on the path should be marked with   */
    /*  PATHMARK.  Other cells visited may be marked with MARKED          */
    /**********************************************************************/
    public boolean findGoal(int curRow, int curColumn)
    {
       if (getEntry(curRow, curColumn) == GOAL)
           return FOUND;
       setEntry(curRow, curColumn, MARKED);
       if (getEntry(curRow - 1, curColumn) == OPEN 
           || getEntry(curRow - 1, curColumn) == GOAL)
          if (findGoal (curRow - 1, curColumn) == FOUND)
          {
              setEntry(curRow, curColumn, PATHMARK);
              return FOUND;
          }
       if (getEntry(curRow, curColumn + 1) == OPEN
          || getEntry(curRow, curColumn + 1) == GOAL)
          if (findGoal(curRow, curColumn + 1) == FOUND)
          {
              setEntry(curRow, curColumn, PATHMARK);
              return FOUND;
          }
       if (getEntry(curRow + 1, curColumn) == OPEN 
           || getEntry(curRow + 1, curColumn) == GOAL)
          if (findGoal (curRow + 1, curColumn) == FOUND)
          {
              setEntry(curRow, curColumn, PATHMARK);
              return FOUND;
          }
       if (getEntry(curRow, curColumn - 1) == OPEN
          || getEntry(curRow, curColumn - 1) == GOAL)
          if (findGoal(curRow, curColumn - 1) == FOUND)
          {
              setEntry(curRow, curColumn, PATHMARK);
              return FOUND;
          }
       return NOTFOUND;
    }
}