/**
 * @file Node89978445.java
 * @brief
 *    File containing the Node class witch represents
 *    the moves of Pacman 
 * 
 * @author  Christos Choutouridis   8997 cchoutou@ece.auth.gr
 * @author  Konstantina Tsechelidou 8445 konstsec@ece.auth.gr
 */

package gr.auth.ee.dsproject.node;

import java.util.ArrayList;

import gr.auth.ee.dsproject.pacman.PacmanUtilities;
import gr.auth.ee.dsproject.pacman.Room;


/**
 * @class   Node89978445
 * @brief
 *    This class holds each move of the current round and it's evaluation
 *    
 */
public class Node89978445
{
   double nodeEvaluation;     /**
                               * Pacman's current move evaluation as return value of evaluation ()
                               * This is used also as the "return status" of the object
                               * @note
                               *    The variable is initialized to Globals.NO_EVAL and calculated only
                               *    after the getEvaluation () call
                               */
   int[] nodeXY;              // Pacman's current x,y coordinate
   int[][] curGhostPos;       // Array holding the Ghost (x,y) pairs
   
   int[][] flagPos;           // Array holding the flag (x,y) pairs
   boolean[] curFlagStatus;   // Array holding the flag capture status
   Room[][] Maze;             // copy of the current Maze

   /*
    * Tree navigation references. These variables are handled by
    * PacTree
    */
   Node89978445            parent;     // reference to parent node in search tree
   ArrayList<Node89978445> children;   // references to children nodes in search tree
   int depth;                          // the depth of the node in search tree

   /*
    * ============ Constructors ==============
    */
   /**
    * @brief
    *    The simple constructor. Just initialize the data
    * @note
    *    Using this constructor means that the user MUST call setMaze() 
    *    and setPosition() manually after the creation of the Node89978445 object
    */
   public Node89978445 ()
   {
      this.Maze      = null;  // Fill members
      nodeXY         = Globals.POSITION_FALSE;
      nodeEvaluation = Globals.NO_EVAL;
      parent         = null;

      // allocate objects
      curGhostPos    = new int [PacmanUtilities.numberOfGhosts][2];
      flagPos        = new int [PacmanUtilities.numberOfFlags][2];
      curFlagStatus  = new boolean[PacmanUtilities.numberOfFlags];
      children       = new ArrayList<Node89978445> ();
   }

   /**
    * @brief
    *    Constructor for the Node89978445
    * @param Maze    The current maze object
    * @param curXY   The current pacman's (x, y) position
    */
   public Node89978445 (Room[][] Maze, int[] curXY)
   {
      this.Maze      = Maze; // Fill members
      nodeXY         = curXY;
      nodeEvaluation = Globals.NO_EVAL;
      parent         = null;

      // allocate objects
      curGhostPos    = new int [PacmanUtilities.numberOfGhosts][2];
      flagPos        = new int [PacmanUtilities.numberOfFlags][2];
      curFlagStatus  = new boolean[PacmanUtilities.numberOfFlags];
      children       = new ArrayList<Node89978445> ();
   }

   /*
    * ============== Setters ===============
    */
   /**
    * @brief
    *    SetMaze (Room) to Node object
    * @param maze    The room to set 
    */
   public void setMaze (Room[][] maze) {
      this.Maze = maze;
   }

   /**
    * @brief
    *    Set pacman's position
    * @param curXY   Pacman's current X, Y position
    */
   public void setPosition (int[] curXY) {
      nodeXY = curXY;
   }

   /*
    * ============== getters =================
    */

   /**
    * @brief
    *    If not done calls the evaluation algorithm and returns the result
    * @return  The evaluation result (also stored inside object)
    * @note
    *    We assume the current position was a valid position.
    *    This routine is not called upon creation of the class
    */
   public double getEvaluation ()
   {
      // If already evaluated do not re-evaluate the move
      if (nodeEvaluation == Globals.NO_EVAL) {
         // Safety filters
         if (Maze == null)
            return Globals.NO_EVAL;
         if (nodeXY == Globals.POSITION_FALSE)
            return Globals.NO_EVAL;
         // calculate helper arrays
         curGhostPos = findGhosts ();
         flagPos = findFlags ();
         curFlagStatus = checkFlags ();
         
         return nodeEvaluation = evaluate ();
      }
      else
         return nodeEvaluation;
    }

   /**
    * @return  Nodes position in maze
    */
   public int[] getCurrentPacmanPos () {
      return nodeXY;
   }
   /**
    * @return  Current ghost position ina maze
    */
   public int[][] getCurrentGhostPos () {
      return curGhostPos;
   }
   /**
    * @return  The depth of the node tin the min-max tree
    */
   public int getDepth () {
      return depth;
   }

   /*
    * ============= Helper API ============
    */
   /**
    * @brief
    *    Convert back a maze position to Room's direction format 
    * @param nextPos    The intention (x, y) coordinates
    * @param curPos     The current coordinates
    * @return        The direction
    *    @arg  Room.NORTH  (x decreases)
    *    @arg  Room.SOUTH  (x increases)
    *    @arg  Room.WEST   (y decreases)
    *    @arg  Room.EAST   (y increases)
    */
   public static int moveConv (int[] nextPos, int[] curPos)
   {
      int dx = nextPos[0] - curPos[0];
      int dy = nextPos[1] - curPos[1];
           
      if      (dx == -1 || dx ==  PacmanUtilities.numberOfRows-1)
         return Room.NORTH;
      else if (dx == 1  || dx == -PacmanUtilities.numberOfRows+1)
         return Room.SOUTH;
      else if (dy == -1 || dy ==  PacmanUtilities.numberOfColumns-1)
         return Room.WEST;
      else if (dy == 1  || dy ==  -PacmanUtilities.numberOfColumns+1)
         return Room.EAST;
      else
         return Globals.INVALID_MOVE;
   }

   /**
    * @param creature   creature's (x,y)
    * @return
    *    Return true if the creature is inside the maze boxes
    */
   public static boolean isInsideBox (int[] creature)
   {
      boolean ret = false; //have faith
      for (int i=0 ; i<4 ; ++i) {
         if ((creature[0]>=Globals.BOXES[i][0][0] && creature[0]<=Globals.BOXES[i][1][0]) &&
             (creature[1]>=Globals.BOXES[i][0][1] && creature[1]<=Globals.BOXES[i][1][1]))
            ret = true;
      }
      return ret;
   }

   /**
    * @brief
    *    Torus borders are the squares in the outer limits of the maze where
    *    there are no walls. Pacman's gravity can curve the maze plane to
    *    a torus through these squares. This function check if a position is
    *    a torus border position
    * @param creature   creature's (x,y)
    * @return
    *    Return true if the creature is in a border position.
    */
   public static boolean isTorusSquare (int[] creature)
   {
      for (int i=0 ; i<Globals.TORUS_BORDERS.length ; ++i) {
         if (creature[0] == Globals.TORUS_BORDERS[i][0] &&
             creature[1] == Globals.TORUS_BORDERS[i][1]) {
            return true;
         }
      }
      return false;
   }

   /**
    * @brief
    *    Static version of move validation to use outside of the class
    *    Check if the requested move for a node is valid
    */
   public static int[] pacmanValidMove (Node89978445 node, int move) {
      return node.pacmanValidMove (node.nodeXY, move);
   }


   /*
    * ============= Node's private methods =============
    */
   /**
    * @brief
    *    Loop entire maze and return an object that holds Ghost positions
    * @param   none
    * @return  Object with Ghost position
    *          The first dimension holds the number of the ghost
    *          The 2nd dimension holds the (x, y) coordinates of the ghost
    */
   private int[][] findGhosts ()
   {
      int [][] ret = new int [PacmanUtilities.numberOfGhosts][2]; // Make an object to return
      int g = 0;                    // Ghost index
      boolean  keepGoing = true;    // Boundary check helper variable

      // Loop entire Maze (i, j)
      for (int x=0 ; keepGoing && x<PacmanUtilities.numberOfRows ; ++x) {
         for (int y=0 ; keepGoing && y<PacmanUtilities.numberOfColumns ; ++y) {
            if (Maze[x][y].isGhost ()) {
               // In case of a Ghost save its position to return object
               ret[g][0] = x;
               ret[g][1] = y;
               // boundary check
               if (++g >= PacmanUtilities.numberOfGhosts)
                  keepGoing = false;
            }
         }
      }
      return ret;
   }
   
   /**
    * @brief
    *    Loop entire maze and return an object that holds flags positions
    * @param   none
    * @return  Object with flag positions
    *          The first dimension holds the number of the flag
    *          The 2nd dimension holds the (x, y) coordinates of the flag
    */
   private int[][] findFlags ()
   {
      int [][] ret = new int [PacmanUtilities.numberOfFlags][2]; // Make an object to return
      int f = 0;                    // Flag index
      boolean  keepGoing = true;    // Boundary check helper variable

      // Loop entire Maze (i, j)
      for (int x=0 ; keepGoing && x<PacmanUtilities.numberOfRows ; ++x) {
         for (int y=0 ; keepGoing && y<PacmanUtilities.numberOfColumns ; ++y) {
            if (Maze[x][y].isFlag()) {
               // In case of a Ghost save its position to return object
               ret[f][0] = x;
               ret[f][1] = y;
               // boundary check
               if (++f >= PacmanUtilities.numberOfFlags)
                  keepGoing = false;
            }
         }
      }
      return ret;
   }

   /**
    * @brief
    *    Loop through flags and check their status
    * @return  Object with flag status
    */
   private boolean[] checkFlags ()
   {
      boolean[] ret = new boolean [PacmanUtilities.numberOfFlags];
      int x, y;
      
     for (int i=0 ; i<PacmanUtilities.numberOfFlags ; ++i) {
        x = flagPos[i][0]; // Get row,col coordinates
        y = flagPos[i][1];
        ret[i] = (Maze[x][y].isCapturedFlag()) ? true : false;
     }
     return ret;
   }

   /*
    * ============ private evaluation helper methods ==============
    */

   /**
    * Helper enumerator to make a function pointer like trick
    * inside @ref moveDist()
    */
   private enum Creature {
      GHOST, PACMAN
   }

   /**
    * @brief
    *    Check if the requested ghost move is valid
    * @param   ghost    ghost coordinates to check the move validation
    * @param   move     the move to check
    * @return
    *    @arg  The resulting position in maze if the move is valid.
    *    @arg  If it is not valid return Globals.POSITION_FALSE 
    */
   private int[] ghostValidMove (int[] ghost, int move)
   {
      int[] newPos = new int[2];

      // find hypothetical new position
      newPos[0] = ghost[0];
      newPos[1] = ghost[1];
      newPos[0] += (move == Room.SOUTH) ? 1:0;
      newPos[0] -= (move == Room.NORTH) ? 1:0;
      newPos[1] += (move == Room.EAST) ? 1:0;
      newPos[1] -= (move == Room.WEST) ? 1:0;

      // Valid filters
      if (!((newPos[0] >= 0 && newPos[0] < PacmanUtilities.numberOfRows) &&
          (newPos[1] >= 0 && newPos[1] < PacmanUtilities.numberOfColumns)))
         return Globals.POSITION_FALSE;
      /*
       * else if (Maze[newPos[0]][newPos[1]].isFlag ())
       *    return Globals.POSITION_FALSE;
       * @note
       *    We comment out the flag part...
       *    This incorrect behavior help evaluation routine to stop treat
       *    flag position as asylum. In other words we remove the discontinuity
       *    of shortestMoveDist() for ghost function.
       */
      else if (!isInsideBox(ghost) && (Maze[ghost[0]][ghost[1]].walls[move] == 0))
         return Globals.POSITION_FALSE;
      else
         return newPos;
   }

   /**
    * @brief
    *    Check if the requested pacman move is valid
    * @param   pacman   pacman coordinates to check the move validation
    * @param   move     the move to check
    * @return
    *    @arg  The resulting position in maze if the move is valid.
    *    @arg  If it is not valid return Globals.POSITION_FALSE 
    */
   private int[] pacmanValidMove (int[] pacman, int move)
   {
      int[] newPos = new int[2];

      // find hypothetical new position
      newPos[0] = pacman[0];
      newPos[1] = pacman[1];
      newPos[0] += (move == Room.SOUTH) ? 1:0;
      newPos[0] -= (move == Room.NORTH) ? 1:0;
      newPos[1] += (move == Room.EAST) ? 1:0;
      newPos[1] -= (move == Room.WEST) ? 1:0;

      // Pacman curves Maze plane to a Torus
      if (newPos[0] < 0)   newPos[0] = PacmanUtilities.numberOfRows-1;
      if (newPos[0] >= PacmanUtilities.numberOfRows ) newPos[0] = 0;
      if (newPos[1] < 0)   newPos[1] = PacmanUtilities.numberOfColumns-1;
      if (newPos[1] >= PacmanUtilities.numberOfColumns ) newPos[1] = 0;

      // Valid filters
      if (Maze[pacman[0]][pacman[1]].walls[move] == 0)
         return Globals.POSITION_FALSE;
      else if (Maze[newPos[0]][newPos[1]].isGhost ())
         return Globals.POSITION_FALSE;
      else
         return newPos;
   }

   /**
    * @brief
    *    A Breadth-first search to find the shortest path distance
    *    from an origin point to another point in the maze as if
    *    a creature could walk through origin to xy
    * @param origin     origin's x, y (starting point)
    * @param xy         destination's x, y
    * @param creature   The type of creature for whom the path is for.
    *                   This helper variable let us decide which validation
    *                   function should call.
    * @return           The number of steps from origin to xy
    * @note
    *    As long as Java have not function pointers. I prefer this
    *    as a work around over interfaces and lambdas.
    */
   private int shortestMoveDist (int[] origin, int[] xy, Creature creature)
   {
      int move;                     // move direction
      int steps, qStepItems;        // distance and group counters
      boolean done = false;         // algo ending flag
      int[] xyItem = new int [2];   // Coordinates of the current position of the algo
      int[] xyNext = new int [2];   // Coordinates of the next valid position of the algo
      // Queue to feed with possible position
      Queue2D q = new Queue2D (Globals.DISTANCE_MAX - 1);
      // 2D array holding all the distances from the origin to each square of the maze
      int[][] dist = new int [PacmanUtilities.numberOfRows][PacmanUtilities.numberOfColumns];

      /*
       *  If target square is inside a box abort with max DISTANCE_FALSE
       *  This is for speeding thing up, as the algorithm would return
       *  the same thing anyway.
       */
      if (isInsideBox(xy))
         return Globals.DISTANCE_FALSE;

      /*
       *  initialize data for algorithm
       */
      for (int i=0 ; i<PacmanUtilities.numberOfRows ; ++i)
         for (int j=0 ; j<PacmanUtilities.numberOfColumns ; ++j)
            dist[i][j] = Globals.DISTANCE_FALSE;   // dist array starts with -1
      dist [origin[0]][origin[1]] = 0;             //starting point is the origin position
      q.insert (origin);                           // feed first loop data
      qStepItems = 1;                              // init counters
      steps = 1;

      /*
       * Main loop of the algorithm.
       * For every position pulled from queue with the same "steps" value:
       * - check all the valid moves around current's position
       * - mark them with the current "steps" value in dist[][] array
       * - push them to queue
       * - count the pushed position with the same "steps" value in queue
       * If no other queued position with the current "steps" value remained
       * increase "steps" value and continue.
       */
      while (done == false) {
         if (qStepItems>0) {           // Have we any item on the current group?
            xyItem = q.remove ();      //load an item of the current group
            --qStepItems;              // mark the removal of the item
            // loop every valid next position for the current position
            for (move=0 ; move<4 ; ++move) {
               switch (creature) {
                  case GHOST:    xyNext = ghostValidMove (xyItem, move);   break;
                  case PACMAN:   xyNext = pacmanValidMove (xyItem, move);  break;
                  default:       xyNext = Globals.POSITION_FALSE;
                  /*
                   * Function pointer - like behavior
                   */
               }
               if (xyNext != Globals.POSITION_FALSE) {
                  if (dist[xyNext[0]][xyNext[1]] == Globals.DISTANCE_FALSE) {
                     // If we haven't been there
                     dist[xyNext[0]][xyNext[1]] = steps; // mark the distance
                     if ((xyNext[0] == xy[0]) && (xyNext[1] == xy[1])) {
                        /*
                         *  first match: The first time we reach destination we
                         *  have measured the distance. No need any other try
                         */
                        done = true;
                        break;
                     }
                     else {
                        // If we are not there yet, feed queue with another position
                        q.insert (xyNext);
                     }
                  }
               }
            }
         }
         else {
            // We are done with group, mark how many are for the next one
            if ((qStepItems = q.size()) <= 0)
               done = true;   // There is no path to destination, abort
            ++steps;          // Update distance counter
         }
      }
      return dist[xy[0]][xy[1]];
   }

   /**
    * @brief
    *    Normalize a distance to our evaluation interval.
    * @param v       The value to normalize
    * @param max     The maximum input limit value
    * @param out_min The minimum output limit value
    * @param out_max The maximum output limit value
    */
   private double normalize (double v, double max, double out_min, double out_max) {
      return (v / max) * (out_max - out_min) + out_min;
   }

   /**
    * @brief
    *    Evaluate the current move.
    * The position evaluation is based on shortestMoveDist() results.
    * We measure the move distance of:
    * 1) Ghosts to current position, as a ghost path, which represent the minimum steps
    *    needed by a ghost in order to reach the current position avoiding all obstacles
    * 2) Pacman to all the flags, which represent the minimum steps needed by pacman
    *    in order to reach the flags avoiding all obstacles including the curving
    *    of the plane in the borders
    * 3) Pacman to all the torus border squares, which represent the minimum steps needed
    *    by pacman in order to reach the torus border squares. @ref Globals.TORUS_BORDERS
    * 
    * We mix these values in order to produce the final evaluation value
    */
   private double evaluate ()
   {
      double eval       = 0;     // mixed evaluation value
      double ghostEval  = 0, gd; // ghost evaluation value
      double flagEval   = 0;     // flag evaluation value
      double torusEval  = 0;     // torus evaluation value
      int[] ghostDist   = new int[PacmanUtilities.numberOfGhosts];   // hold the ghost distances
      int[] flagDist    = new int[PacmanUtilities.numberOfFlags];    // hold the flag distances
      int[] torusDist   = new int[Globals.TORUS_BORDERS.length];     // hold the torus square distances
      int minGhostDist  = Globals.DISTANCE_MAX+1;     // hold the minimum ghost distance
      int averGhostDist = Globals.DISTANCE_MAX;       // hold the average ghost distance
      int minFlagDist   = Globals.DISTANCE_MAX+1;     // hold the minimum flag distance
      int minTorusDist  = Globals.DISTANCE_MAX+1;     // hold the minimum torus square distance
      int i;   // loop counter

      /*
       *  === Ghost distances part ===
       */
      for (i=0, averGhostDist=0 ; i<PacmanUtilities.numberOfGhosts ; ++i) {
         if ((ghostDist [i] = shortestMoveDist (curGhostPos[i], nodeXY, Creature.GHOST)) >= 1) {
            averGhostDist += ghostDist [i];
            if (minGhostDist > ghostDist[i])
               minGhostDist = ghostDist[i];
         }
      }
      averGhostDist /= PacmanUtilities.numberOfGhosts;
      // extract the ghostEval as a combination of the minimum distance and the average
      gd = Globals.EVAL_GHOSTDIST_MIN_FACTOR * minGhostDist + Globals.EVAL_GHOSTDIST_AVER_FACTOR * averGhostDist;
      // normalize the ghostEval to our interval
      if (minGhostDist <= Globals.EVAL_GHOST_BOOST)
         ghostEval = normalize (gd, Globals.DISTANCE_MAX ,Globals.EVAL_MIN+Globals.EVAL_GHOSTBOOST_OFFSET, Globals.EVAL_MAX);
      else if (minGhostDist <= Globals.EVAL_GHOST_TERRITORY)
         ghostEval = normalize (gd, Globals.DISTANCE_MAX, Globals.EVAL_MIN, Globals.EVAL_MAX - Globals.EVAL_GHOSTTERRITORY_OFFSET);
      else
         ghostEval = normalize (gd, Globals.DISTANCE_MAX, Globals.EVAL_MIN, Globals.EVAL_MAX);

      /*
       *  === Flag distances part ===
       */
      for (i=0 ; i<PacmanUtilities.numberOfFlags ; ++i) {
         if (curFlagStatus[i] == false) {
            if ((flagDist[i] = shortestMoveDist (nodeXY, flagPos[i], Creature.PACMAN)) >= 0) {
               if (minFlagDist > flagDist[i])
                  minFlagDist = flagDist[i];
            }
         }
      }
      // normalize the flagEval to our interval
      if (minFlagDist <= Globals.EVAL_FLAG_BOOST)
         flagEval = normalize ((double)Globals.FLAGDIST_MAX - minFlagDist, Globals.FLAGDIST_MAX, Globals.EVAL_MIN, Globals.EVAL_MAX+Globals.EVAL_FLAGBOOST_OFFSET);
      else
         flagEval = normalize ((double)Globals.FLAGDIST_MAX - minFlagDist, Globals.FLAGDIST_MAX, Globals.EVAL_MIN, Globals.EVAL_MAX);

      /*
       *  === Torus borders distances part ===
       */
      for (i=0 ; i<Globals.TORUS_BORDERS.length ; ++i) {
         if ((torusDist[i] = shortestMoveDist (nodeXY, Globals.TORUS_BORDERS[i], Creature.PACMAN)) >= 0) {
            if (minTorusDist > torusDist[i])
               minTorusDist = torusDist[i];
         }
      }
      // normalize the flagEval to our interval
      torusEval = normalize (Globals.BORDERDIST_MAX-minTorusDist, Globals.BORDERDIST_MAX, Globals.EVAL_MIN, Globals.EVAL_MAX);

      /*
       * === Mix up the values and return the normalized value back to caller ===
       */
      eval = ghostEval * Globals.EVAL_GHOSTDIST_FACTOR
           + flagEval * Globals.EVAL_FLAGDIST_FACTOR
           + torusEval * Globals.EVAL_TORUSDIST_FACTOR;
      return normalize (eval, Globals.EVAL_FINAL_MAX, Globals.EVAL_FINAL_MIN, Globals.EVAL_FINAL_MAX);
   }

}