Snake/src/SnakePkg/Board.java

package SnakePkg;

import java.lang.Math;

/**
 * @class Board
 * @brief The game's board representation.
 * 
 * The board in a square collection of tiles numbered in a
 * boustrophedon (zig-zag) way. A number of snakes, ladders
 * and apples which called elements are placed on the board
 * for each game. 
 * 
 * @author Christos Choutouridis 8997
 * @email  cchoutou@ece.auth.gr
 */
public class Board {
   /** Constants */
   /**@{ */
   static final int POINTS_MAX = 20;   /**< The maximum absolute number of points for each apple */
   static final int POINTS_STEP = 5;   /**< The difference between different apple points */
   /**@} */

   /** @name Constructors */
   /** @{ */
   /** A doing nothing default constructor
    * @warining Avoid using this constructor as it requires all setters(or copy)
    * and @ref createBoard() to be called after.
    */
   Board () {
      N = M   =0;
      tiles   = null;
      snakes  = null;
      ladders = null;
      apples  = null;
   }
   
   /**
    * @brief Creates a board for game
    * 
    * This constructor allocates the memory for the board and elements and
    * creates a board by placing all required elements on the board.
    * 
    * @param N             The row for the board
    * @param M             The columns of the board
    * @param numOfSnakes   Number of snakes to place
    * @param numOfLadders  Number of ladders to place
    * @param numOfApples   Number of Apples to place
    * 
    * @warning
    *    We call @ref createBoard() inside this constructor in order for
    *    the board to be in "playable condition". This is preferable by the author.
    *    A constructor should(if possible) to leave the object in a usable condition.
    *    In order to follow the project requirements we create this functionality in a
    *    separate function @ref createBoard(). We believe that if a user can make a
    *    mistake he eventually will do it sometime. Here, if we leave the createBoard()
    *    call to user we are enabling him to make it.
    */
   Board (int N, int M, int numOfSnakes, int numOfLadders, int numOfApples) {
      // Init the board object
      setN (N);         // Input checked version (may throw)
      setM (M);         // Input checked version (may throw)
      tiles   = new int[N][M];
      snakes  = new Snake[numOfSnakes];
      ladders = new Ladder[numOfLadders];
      apples  = new Apple[numOfApples];
      createBoard ();   // Complete board preparation and make all the element memory allocations
   }
   
   /**
    * @brief Copy constructor.
    * We make a deep copy of B and we trust B's data to be valid.
    * @param B The board we want to copy
    * @note We don't use clone as long as we don't inherit Cloneable iface
    * @note This requires Snake, Apple and Ladder copy constructors
    */
   Board (Board B) {
      N  = B.getN();
      M  = B.getM();
      tiles   = new int[N][M];
      snakes  = new Snake[B.getSnakes().length];
      ladders = new Ladder[B.getLadders().length];
      apples  = new Apple[B.getApples().length];
      // Copy B's guts into new memory
      setTiles(B.getTiles());       // primitive
      copySnakes(B.getSnakes());
      copyLadders(B.getLadders());
      copyApples(B.getApples());
   }
   /** @} */
   
   /** @name Get/Set interface */
   /** @{ */
   
   /** Get value N */
   int getN () { return N; }
   /** Set value N  */
   void setN (int N) { this.N = N; }
   
   /** Get value M */
   int getM () { return M; }
   /** Set value M  */
   void setM (int M) { this.M = M; }

   /** Get reference to tiles */
   int[][] getTiles () { return tiles; }  
   
   /**
    * Set tiles
    * @param   tiles    Source of tiles to use
    * @note This has to be called if the board is default constructed
    */
   void setTiles (int[][] tiles) {
      // Check if we need allocation
      if (this.tiles == null)
         this.tiles = new int[N][M];
      // Assign values
      for (int i =0 ; i<N ; ++i)
         for (int j =0 ; j<M ; ++j)
            this.tiles[i][j] = tiles[i][j];
   }
   
   /** Get reference to snakes */
   Snake[] getSnakes() { return snakes; }
   /**   
    * Set snakes
    * @param   snakes  Reference to snakes to use
    * @note    This requires snakes must be allocated elsewhere.
    */
   void setSnakes(Snake[] snakes) { this.snakes = snakes; }
   
   /** Get reference to ladders */
   Ladder[] getLadders() { return ladders; }
   /**   
    * Set ladders
    * @param   ladders  Reference to ladders to use
    * @note    This requires ladders must be allocated elsewhere.
    */
   void setLadders(Ladder[] ladders) { this.ladders = ladders; }

   /** Get reference to apples */
   Apple[] getApples() { return apples; }
   /**   
    * Set apples
    * @param   apples  Reference to apples to use
    * @note    This requires apples must be allocated elsewhere.
    */
   void setApples(Apple[] apples) { this.apples = apples; }
   
   /**
    * Copy snakes (deep copy)
    * @param snakes  Source of snakes to use 
    * @note Requires Snake copy constructor
    * @note This has to be called if the board is default constructed
    */
   void copySnakes(Snake[] snakes) {
      // Check if we need allocation
      if (this.snakes == null)
         this.snakes = new Snake[snakes.length];
      // Assign values (deep copy)
      for (int i =0 ; i<this.snakes.length ; ++i)
         this.snakes[i] = new Snake(snakes[i]);
   }
   /**
    * Copy ladders (deep copy)
    * @param ladders  Source of ladders to use 
    * @note Requires Ladder copy constructor
    * @note This has to be called if the board is default constructed
    */
   void copyLadders (Ladder[] ladders) {
      // Check if we need allocation
      if (this.ladders == null)
         this.ladders = new Ladder[ladders.length];
      // Assign values (deep copy)
      for (int i =0 ; i<this.ladders.length ; ++i)
         this.ladders[i] = new Ladder(ladders[i]);
   }
   /**
    * Copy apples (deep copy)
    * @param apples  Source of apples to use 
    * @note Requires Apple copy constructor
    * @note This has to be called if the board is default constructed
    */
   void copyApples (Apple[] apples) {
      // Check if we need allocation
      if (this.apples == null)
         this.apples = new Apple[apples.length];
      // Assign values (deep copy)
      for (int i =0 ; i<this.apples.length ; ++i)
         this.apples[i] = new Apple(apples[i]);
   }
   /** @} */

   /** @name Exposed API members */
   /** @{ */

   /**
    * Check if the tile is a snake head. If so return the snake's
    * tails tile. If not return the same tile
    * @param tile    The tile to check
    * @return        The result tile
    */
   int checkSnake (int tile) {
      for (int i =0 ; i<snakes.length ; ++i) {
         if (snakes[i].getHeadId() == tile)
            return snakes[i].getTailId();
      }
      return tile;
   }

   /**
    * Check if the tile is a ladder down step. If so return the ladder's
    * up step tile. If not return the same tile.
    * @note
    *    This also break the ladder if used
    * @param tile    The tile to check
    * @return        The result tile
    */
   int checkLadder (int tile) {
      for (int i =0 ; i<ladders.length ; ++i) {
         if (ladders[i].getDownStepId() == tile &&
             ladders[i].getBroken() == false) {
            ladders[i].setBroken(true);
            return ladders[i].getUpStepId();
         }
      }
      return tile;
   }

   /**
    * Check if the tile is an apple tile. If so eat it and return the score difference
    * @param tile    The tile to check
    * @return        The score difference
    */
   int checkApple (int tile) {
      int ds =0;  // delta-score
      for (int i =0 ; i<apples.length ; ++i) {
         if (apples[i].getAppleTileId() == tile) {
            // eat it
            ds = apples[i].getPoints();
            apples[i].setPoints(0);
         }
      }
      return ds;
   }

   /**
    * Create a playable board for the game.
    * @warning
    *    This is not required to be called after construction in order to ensure board's playable
    *    condition. In fact this function SHOULD NOT CALLED AT ALL.
    *    The project requirements expect this to be public. The preferable mode would be private.
    *    @see Board() constructor.
    */
   void createBoard () {
      _tileNumbering ();  // Create tile numbering
      _placeSnakes ();    // Place snakes
      _placeApples ();    // Place Apples
      _placeLadders ();   // place ladders
   }

   /**
    * @brief 
    *    make and print element boards
    * This is not required in order for the board to be playable
    * It just produce a stdout output for convenience.
    */
   void createElementBoard () {
      String[][] elementBoardSnakes    = new String[N][M];
      String[][] elementBoardLadders   = new String[N][M];
      String[][] elementBoardApples    = new String[N][M];

      _makeElementSnakes (elementBoardSnakes);
      _makeElementLadders (elementBoardLadders);
      _makeElementApples (elementBoardApples);
      
      _printElement (elementBoardSnakes, "elementBoardSnakes");
      _printElement (elementBoardLadders, "elementBoardLadders");
      _printElement (elementBoardApples, "elementBoardApples");
   }
   /** @} */


   /** @name Private api */
   /**@{ */
   
   /**
    * @brief
    *    Create the tile numbering in a boustrophedon (zig-zag) way.
    * We use a starting point the tile[0][0] and as finish point
    * the tile[N-1][M-1]
    */
   private void _tileNumbering () {
      for (int i=0, tile =1 ; i<N ; ++i) {
         if (i%2 == 0) {
            // Even row, go right
            for (int j=0 ; j<M ; ++j)
               tiles[i][j] = tile++;
         }
         else {
            // Odd row, go left
            for (int j=M-1 ; j>=0 ; --j)
               tiles[i][j] = tile++;
         }
      }
   }

   /**
    * @brief
    *    Place the snakes on the board
    * The only constrain at this point is that snake tails must be placed
    * below heads and heads must be placed in separate tiles
    */
   private void _placeSnakes () {
      int [] head = new int [snakes.length];    // temporary place holder for heads
      int [] tail = new int [snakes.length];    // temporary place holder for tails
      for (int i =0, tile =0 ; i<snakes.length ; ++i) {
         // Keep getting heads until they are different from the previous
         do
            tile = _pickRandom (M+1, M*N);      // Don't use first row for heads
         while (_search (head, tile) >= 0);
         head[i] = tile;
         tail[i] = _pickRandom (1, head[i]-head[i]%M);   // Don't use heads row and up for tail
         snakes[i] = new Snake(i, head[i], tail[i]);     // Allocate snake
      }
   }

   /**
    * @brief
    *    Place apples on the board
    * The constrains here are
    * that apples have to lie on different tiles and not in some
    * snake's head.
    * @note We require we have snakes.
    */
   private void _placeApples () {
      int [] apple_tiles = new int [apples.length];   // temporary placeholder for apples
      int [] snake_tiles = new int [snakes.length];   // array with snake head tiles
      for (int i =0 ; i<snakes.length ; ++i)          // Load snake head tiles
         snake_tiles[i] = snakes[i].getHeadId();

      for (int i =0, tile =0 ; i<apples.length ; ++i) {
         // Keep getting tiles until they are different from the previous
         // and not in some snake's head
         do
            tile = _pickRandom (1, M*N);
         while ((_search (apple_tiles, tile) >= 0) ||
                (_search (snake_tiles, tile) >= 0));
         apple_tiles[i] = tile;
         // get points
         int points = _pickRandom (1, (POINTS_MAX/POINTS_STEP)) * POINTS_STEP;
         boolean red = (boolean)(Math.random() >=0.5);   // get color
         // Allocate apple
         if (red)
            apples[i] = new Apple(i, tile, "red", points);
         else
            apples[i] = new Apple(i, tile, "black", -points);
      }
   }

   /**
    * @brief
    *    Place ladders on board
    *    
    *    We add constrains so each ladder's up-step tile has to be different from:
    *    * A snake's head tile. This ensures ladders and snakes are independent
    *    * A ladders's down-step. This ensure we eliminate ladder chains.
    *    * One other ladder's up-step. This is not critical but helps the printElement functionality
    *    
    *    We add constrains so each ladder's down-step tile has to be different from:
    *    * A snake's head tile. This ensures ladders and snakes are independent
    *    * A ladders's down-step. This is not critical but helps the printElement functionality
    *    * One other ladder's up-step. This ensure we eliminate ladder chains. 
    * @note We require we have snakes.
    */
   private void _placeLadders () {
      int [] up_step    = new int [ladders.length];   // temporary place holder for up-steps
      int [] down_step  = new int [ladders.length];   // temporary place holder for down-step
      int [] snake_tiles= new int [snakes.length];    // array with snake head tiles
      for (int i =0 ; i<snakes.length ; ++i)          // Load snake head tiles
         snake_tiles[i] = snakes[i].getHeadId();

      for (int i =0, tile =0 ; i<ladders.length ; ++i) {
         // Keep getting up-steps until they are different from the previous ladder tiles
         // and not in some snake's head
         do
            tile = _pickRandom (M+1, M*N);            // Don't use first row for up-steps
         while ((_search (up_step, tile) >= 0)
             || (_search (down_step, tile) >= 0)
             || (_search (snake_tiles, tile) >= 0));
         up_step[i] = tile;
         // Keep getting down-steps until they are different from the previous ladder tiles
         // and not in some snake's head
         do
            // Don't use up-step row and up for down-step
            tile = _pickRandom (1, up_step[i]-up_step[i]%M);
         while ((_search (up_step, tile) >= 0)
             || (_search (down_step, tile) >= 0)
             || (_search (snake_tiles, tile) >= 0));
         down_step[i] = tile;
         ladders[i] = new Ladder (i, up_step[i], down_step[i]);   // Allocate ladder
      }
   }

   /**
    * Make element array of snakes as required by the project
    * @param elemSnakes
    */
   private void _makeElementSnakes (String[][] elemSnakes) {
      int [] head_tiles = new int [snakes.length];   // array with snake head tiles
      int [] tail_tiles = new int [snakes.length];   // array with snake head tiles
      int sn =-1;
      // Load snake head tiles
      for (int i =0 ; i<snakes.length ; ++i) {
         head_tiles[i] = snakes[i].getHeadId();
         tail_tiles[i] = snakes[i].getTailId();
      }

      // Search all tiles for snake heads and tails
      for (int i =0; i<N ; ++i) {
         for (int j =0 ; j<M ; ++j) {
            if ((sn = _search (head_tiles, tiles[i][j])) >= 0)
               elemSnakes[i][j] = "SH" + sn;
            else if ((sn = _search (tail_tiles, tiles[i][j])) >= 0)
               elemSnakes[i][j] = "ST" + sn;
            else
               elemSnakes[i][j] = "___";
         }
      }
   }

   /**
    * Make element array of ladders as required by the project
    * @param elemLadders
    */
   private void _makeElementLadders (String[][] elemLadders) {
      int [] up_tiles   = new int [ladders.length];   // array with ladder up-step tiles
      int [] down_tiles = new int [ladders.length];   // array with ladder down-step tiles
      int sn =-1;
      // Load ladder tiles
      for (int i =0 ; i<ladders.length ; ++i) {
         up_tiles[i] = ladders[i].getUpStepId();
         down_tiles[i] = ladders[i].getDownStepId();
      }

      // Search all tiles for snake heads and tails
      for (int i =0; i<N ; ++i) {
         for (int j =0 ; j<M ; ++j) {
            if ((sn = _search (up_tiles, tiles[i][j])) >= 0)
               elemLadders[i][j] = "LU" + sn;
            else if ((sn = _search (down_tiles, tiles[i][j])) >= 0)
               elemLadders[i][j] = "LD" + sn;
            else
               elemLadders[i][j] = "___";
         }
      }
   }

   /**
    * Make element array of apples as required by the project
    * @param elemApples
    */
   private void _makeElementApples (String[][] elemApples) {
      int [] red_tiles   = new int [apples.length];   // array with red apple tiles
      int [] black_tiles = new int [apples.length];   // array with black apple tiles
      int sn =-1;
      // Load apple tiles
      for (int i =0 ; i<apples.length ; ++i) {
         if (apples[i].getColor() == "red")
            red_tiles[i] = apples[i].getAppleTileId();
         else
            black_tiles[i] = apples[i].getAppleTileId();
      }

      // Search all tiles for snake heads and tails
      for (int i =0; i<N ; ++i) {
         for (int j =0 ; j<M ; ++j) {
            if ((sn = _search (red_tiles, tiles[i][j])) >= 0)
               elemApples[i][j] = "AR" + sn;
            else if ((sn = _search (black_tiles, tiles[i][j])) >= 0)
               elemApples[i][j] = "AB" + sn;
            else
               elemApples[i][j] = "___";
         }
      }
   }

   /**
    * Print element array
    * @param elem    The element array to print
    * @param caption The caption
    * @note
    *    As long as we use tiles[0][0] for first tile, this method
    *    has to print in reverse Y-axis order. For ex:
    *    <pre>
    *    16 15 14 13
    *    09 10 11 12
    *    08 07 06 05
    *    01 02 03 04
    *    </pre>
    */
   private void _printElement (String[][] elem, String caption) {
      System.out.print(caption);
      for (int i=N-1 ; i>=0 ; --i) {
         System.out.println("");
         System.out.print(" ");
         for (int j =0 ; j<M ; ++j)
            System.out.print(elem[i][j] + " ");
      }
      System.out.println("");
      System.out.println("");
   }

   /**
    * Pick a random tile in range [from..to]
    * @param from    The first tile to consider
    * @param to      The last tile to consider
    * @return        The random pick
    */
   private int _pickRandom (int from, int to) {
      return from + (int)(Math.random() * (to - from));
   }

   /** Search algorithm
    * @param array   Array to search
    * @param elem    Element of type T to find inside of array
    * @return        The status of the operation
    *    @arg  -1    Element not found
    *    @arg  >=0   Element found
    */
   private int _search (int[] array, int elem) {
      for (int i=0 ; i<array.length ; ++i)
         if (elem == array[i])
            return i;
      return -1;
   }
   /**@} */
   
   /** @name Data members */
   /** @{ */
   private int N;             /**< Board's row count */
   private int M;             /**< Board's Column count */
   private int[][]  tiles;    /**< Board's tiles */
   private Snake[]  snakes;   /**< Board's snakes */
   private Ladder[] ladders;  /**< Board's ladders */
   private Apple[]  apples;   /**< Board's apples */
   /** @} */
}