/***************************************************************************
                          astar.cpp  -  description
                             -------------------
    begin                : Die Jul 26 2005
    copyright            : (C) 2005 by Krippel Harald
    email                : neuro.harald@surfeu.at
 ***************************************************************************/

/***************************************************************************
 *                                                                         *
 *   This program is free software; you can redistribute it and/or modify  *
 *   it under the terms of the GNU General Public License as published by  *
 *   the Free Software Foundation; either version 2 of the License, or     *
 *   (at your option) any later version.                                   *
 *                                                                         *
 ***************************************************************************/

#include "astar.h"
#include <iostream.h>
#include <fstream.h>
#include <stdlib.h>

aStar::aStar(unsigned tmpmapWidth, unsigned tmpmapHeight , unsigned tmptileSize, unsigned tmpnumberPeople){
  unsigned i;
	mapWidth = tmpmapWidth; mapHeight = tmpmapHeight; tileSize = tmptileSize; numberPeople = tmpnumberPeople;
	onClosedList = 10;
	notfinished = 0; notStarted = 0;// path-related constants
	found = 1; nonexistent = 2;
	walkable = 0; unwalkable = 1;// walkability array constants

  //Create needed arrays
	walkability = new char*[mapWidth]; //[(const int)mapHeight];
  for (i = 0; i < mapWidth; ++i)
        walkability[i] = new char[mapHeight];
	map = new char*[mapWidth]; //[(const int)mapHeight];
  for (i = 0; i < mapWidth; ++i)
        map[i] = new char[mapHeight];
  
	openList = new int[mapWidth*mapHeight+2]; //1 dimensional array holding ID# of open list items

  whichList= new int*[mapWidth+1]; //[mapHeight+1];  //2 dimensional array used to record
  for (i = 0; i < mapWidth+1; ++i)
        whichList[i] = new int[mapHeight+1];

  // 		whether a cell is on the open list or on the closed list.
	openX = new int[mapWidth*mapHeight+2]; //1d array stores the x location of an item on the open list
	openY = new int[mapWidth*mapHeight+2]; //1d array stores the y location of an item on the open list

  parentX = new int*[mapWidth+1]; //[mapHeight+1]; //2d array to store parent of each cell (x)
  for (i = 0; i < mapWidth+1; ++i)
        parentX[i] = new int[mapHeight+1];

  parentY = new int*[mapWidth+1]; //[mapHeight+1]; //2d array to store parent of each cell (y)
  for (i = 0; i < mapWidth+1; ++i)
        parentY[i] = new int[mapHeight+1];

  Fcost = new int[mapWidth*mapHeight+2];	//1d array to store F cost of a cell on the open list

  Gcost = new int*[mapWidth+1]; //[mapHeight+1]; 	//2d array to store G cost for each cell.
  for (i = 0; i < mapWidth+1; ++i)
        Gcost[i] = new int[mapHeight+1];

  Hcost = new int[mapWidth*mapHeight+2];	//1d array to store H cost of a cell on the open list
	pathLength = new int[numberPeople+1];     //stores length of the found path for critter
	pathLocation = new int[numberPeople+1];   //stores current position along the chosen path for critter
	pathBank = new int*[numberPeople+1];
	for (i = 0; i < numberPeople+1; i++)
		pathBank [i] = new int[4];
  
	//Path reading variables
	pathStatus = new int[numberPeople+1];
	xPath = new int[numberPeople+1];
	yPath = new int[numberPeople+1];

  for (unsigned x = 0; x < mapWidth; x++){
    for (unsigned y = 0; y < mapHeight; y++){
	    walkability [x][y] = walkable;
	    map [x][y] = walkable;
	  }
  }

}

//-----------------------------------------------------------------------------
// Name: FindPath
// Desc: Finds a path using A*
//-----------------------------------------------------------------------------
int aStar::FindPath (int pathfinderID,int startingX, int startingY,
			  int targetX, int targetY)
{
  int onOpenList=0, parentXval=0, parentYval=0,
	a=0, b=0, m=0, u=0, v=0, temp=0, corner=0, numberOfOpenListItems=0,
	addedGCost=0, tempGcost = 0, path = 0,
	tempx, pathX, pathY, cellPosition,
	newOpenListItemID=0;

//1. Convert location data (in pixels) to coordinates in the walkability array.
	int startX = startingX/tileSize;
	int startY = startingY/tileSize;
	targetX = targetX/tileSize;
	targetY = targetY/tileSize;

//1.1 Check Values
  if( startX < 0 || startY < 0 || startX >= mapWidth || startY >= mapHeight)
		return nonexistent;
  if( targetX < 0 || targetY < 0 || targetX >= mapWidth || targetY >= mapHeight)
		return nonexistent;
  
//2.Quick Path Checks: Under the some circumstances no path needs to
//	be generated ...

//	If starting location and target are in the same location...
	if (startX == targetX && startY == targetY && pathLocation[pathfinderID] > 0)
		return found;
	if (startX == targetX && startY == targetY && pathLocation[pathfinderID] == 0)
		return nonexistent;

//	If target square is unwalkable, return that it's a nonexistent path.
	if (walkability[targetX][targetY] == unwalkable)
		goto noPath;

//3.Reset some variables that need to be cleared
	if (onClosedList > 1000000) //reset whichList occasionally
	{
		for (unsigned x = 0; x < mapWidth;x++) {
			for (unsigned y = 0; y < mapHeight;y++)
				whichList [x][y] = 0;
		}
		onClosedList = 10;
	}
	onClosedList = onClosedList+2; //changing the values of onOpenList and onClosed list is faster than redimming whichList() array
	onOpenList = onClosedList-1;
	pathLength [pathfinderID] = notStarted;//i.e, = 0
	pathLocation [pathfinderID] = notStarted;//i.e, = 0
	Gcost[startX][startY] = 0; //reset starting square's G value to 0

//4.Add the starting location to the open list of squares to be checked.
	numberOfOpenListItems = 1;
	openList[1] = 1;//assign it as the top (and currently only) item in the open list, which is maintained as a binary heap (explained below)
	openX[1] = startX ; openY[1] = startY;


//5.Do the following until a path is found or deemed nonexistent.
	do
	{

//6.If the open list is not empty, take the first cell off of the list.
//	This is the lowest F cost cell on the open list.
	if (numberOfOpenListItems != 0)
	{

//7. Pop the first item off the open list.
	parentXval = openX[openList[1]];
	parentYval = openY[openList[1]]; //record cell coordinates of the item
	whichList[parentXval][parentYval] = onClosedList;//add the item to the closed list

//	Open List = Binary Heap: Delete this item from the open list, which
//  is maintained as a binary heap. For more information on binary heaps, see:
//	http://www.policyalmanac.org/games/binaryHeaps.htm
	numberOfOpenListItems = numberOfOpenListItems - 1;//reduce number of open list items by 1

//	Delete the top item in binary heap and reorder the heap, with the lowest F cost item rising to the top.
	openList[1] = openList[numberOfOpenListItems+1];//move the last item in the heap up to slot #1
	v = 1;

//	Repeat the following until the new item in slot #1 sinks to its proper spot in the heap.
	do
	{
	u = v;
	if (2*u+1 <= numberOfOpenListItems) //if both children exist
	{
	 	//Check if the F cost of the parent is greater than each child.
		//Select the lowest of the two children.
		if (Fcost[openList[u]] >= Fcost[openList[2*u]])
			v = 2*u;
		if (Fcost[openList[v]] >= Fcost[openList[2*u+1]])
			v = 2*u+1;
	}
	else
	{
		if (2*u <= numberOfOpenListItems) //if only child #1 exists
		{
	 	//Check if the F cost of the parent is greater than child #1
			if (Fcost[openList[u]] >= Fcost[openList[2*u]])
				v = 2*u;
		}
	}

	if (u != v) //if parent's F is > one of its children, swap them
	{
		temp = openList[u];
		openList[u] = openList[v];
		openList[v] = temp;
	}
	else
		break; //otherwise, exit loop

	}
	while (1);//reorder the binary heap

//7.Check the adjacent squares. (Its "children" -- these path children
//	are similar, conceptually, to the binary heap children mentioned
//	above, but don't confuse them. They are different. Path children
//	are portrayed in Demo 1 with grey pointers pointing toward
//	their parents.) Add these adjacent child squares to the open list
//	for later consideration if appropriate (see various if statements
//	below).
	for (b = parentYval-1; b <= parentYval+1; b++){
	for (a = parentXval-1; a <= parentXval+1; a++){

//	If not off the map (do this first to avoid array out-of-bounds errors)
	if (a != -1 && b != -1 && a != mapWidth && b != mapHeight){

//	If not already on the closed list (items on the closed list have
//	already been considered and can now be ignored).
	if (whichList[a][b] != onClosedList) {

//	If not a wall/obstacle square.
	if (walkability [a][b] != unwalkable) {

//	Don't cut across corners
	corner = walkable;
	if (a == parentXval-1)
	{
		if (b == parentYval-1)
		{
			if (walkability[parentXval-1][parentYval] == unwalkable
				|| walkability[parentXval][parentYval-1] == unwalkable) \
				corner = unwalkable;
		}
		else if (b == parentYval+1)
		{
			if (walkability[parentXval][parentYval+1] == unwalkable
				|| walkability[parentXval-1][parentYval] == unwalkable)
				corner = unwalkable;
		}
	}
	else if (a == parentXval+1)
	{
		if (b == parentYval-1)
		{
			if (walkability[parentXval][parentYval-1] == unwalkable
				|| walkability[parentXval+1][parentYval] == unwalkable)
				corner = unwalkable;
		}
		else if (b == parentYval+1)
		{
			if (walkability[parentXval+1][parentYval] == unwalkable
				|| walkability[parentXval][parentYval+1] == unwalkable)
				corner = unwalkable;
		}
	}
	if (corner == walkable) {

//	If not already on the open list, add it to the open list.
	if (whichList[a][b] != onOpenList)
	{

		//Create a new open list item in the binary heap.
		newOpenListItemID = newOpenListItemID + 1; //each new item has a unique ID #
		m = numberOfOpenListItems+1;
		openList[m] = newOpenListItemID;//place the new open list item (actually, its ID#) at the bottom of the heap
		openX[newOpenListItemID] = a;
		openY[newOpenListItemID] = b;//record the x and y coordinates of the new item

		//Figure out its G cost
		if (abs(a-parentXval) == 1 && abs(b-parentYval) == 1)
			addedGCost = 14;//cost of going to diagonal squares
		else
			addedGCost = 10;//cost of going to non-diagonal squares
		Gcost[a][b] = Gcost[parentXval][parentYval] + addedGCost;

		//Figure out its H and F costs and parent
		Hcost[openList[m]] = 10*(abs(a - targetX) + abs(b - targetY));
		Fcost[openList[m]] = Gcost[a][b] + Hcost[openList[m]];
		parentX[a][b] = parentXval ; parentY[a][b] = parentYval;

		//Move the new open list item to the proper place in the binary heap.
		//Starting at the bottom, successively compare to parent items,
		//swapping as needed until the item finds its place in the heap
		//or bubbles all the way to the top (if it has the lowest F cost).
		while (m != 1) //While item hasn't bubbled to the top (m=1)
		{
			//Check if child's F cost is < parent's F cost. If so, swap them.
			if (Fcost[openList[m]] <= Fcost[openList[m/2]])
			{
				temp = openList[m/2];
				openList[m/2] = openList[m];
				openList[m] = temp;
				m = m/2;
			}
			else
				break;
		}
		numberOfOpenListItems = numberOfOpenListItems+1;//add one to the number of items in the heap

		//Change whichList to show that the new item is on the open list.
		whichList[a][b] = onOpenList;
	}

//8.If adjacent cell is already on the open list, check to see if this
//	path to that cell from the starting location is a better one.
//	If so, change the parent of the cell and its G and F costs.
	else //If whichList(a,b) = onOpenList
	{

		//Figure out the G cost of this possible new path
		if (abs(a-parentXval) == 1 && abs(b-parentYval) == 1)
			addedGCost = 14;//cost of going to diagonal tiles
		else
			addedGCost = 10;//cost of going to non-diagonal tiles
		tempGcost = Gcost[parentXval][parentYval] + addedGCost;

		//If this path is shorter (G cost is lower) then change
		//the parent cell, G cost and F cost.
		if (tempGcost < Gcost[a][b]) //if G cost is less,
		{
			parentX[a][b] = parentXval; //change the square's parent
			parentY[a][b] = parentYval;
			Gcost[a][b] = tempGcost;//change the G cost

			//Because changing the G cost also changes the F cost, if
			//the item is on the open list we need to change the item's
			//recorded F cost and its position on the open list to make
			//sure that we maintain a properly ordered open list.
			for (int x = 1; x <= numberOfOpenListItems; x++) //look for the item in the heap
			{
			if (openX[openList[x]] == a && openY[openList[x]] == b) //item found
			{
				Fcost[openList[x]] = Gcost[a][b] + Hcost[openList[x]];//change the F cost

				//See if changing the F score bubbles the item up from it's current location in the heap
				m = x;
				while (m != 1) //While item hasn't bubbled to the top (m=1)
				{
					//Check if child is < parent. If so, swap them.
					if (Fcost[openList[m]] < Fcost[openList[m/2]])
					{
						temp = openList[m/2];
						openList[m/2] = openList[m];
						openList[m] = temp;
						m = m/2;
					}
					else
						break;
				}
				break; //exit for x = loop
			} //If openX(openList(x)) = a
			} //For x = 1 To numberOfOpenListItems
		}//If tempGcost < Gcost(a,b)

	}//else If whichList(a,b) = onOpenList
	}//If not cutting a corner
	}//If not a wall/obstacle square.
	}//If not already on the closed list
	}//If not off the map
	}//for (a = parentXval-1; a <= parentXval+1; a++){
	}//for (b = parentYval-1; b <= parentYval+1; b++){

	}//if (numberOfOpenListItems != 0)

//9.If open list is empty then there is no path.
	else
	{
		path = nonexistent; break;
	}

	//If target is added to open list then path has been found.
	if (whichList[targetX][targetY] == onOpenList)
	{
		path = found; break;
	}

	}
	while (1);//Do until path is found or deemed nonexistent

//10.Save the path if it exists.
	if (path == found)
	{

//a.Working backwards from the target to the starting location by checking
//	each cell's parent, figure out the length of the path.
	pathX = targetX; pathY = targetY;
	do
	{
		//Look up the parent of the current cell.
		tempx = parentX[pathX][pathY];
		pathY = parentY[pathX][pathY];
		pathX = tempx;

		//Figure out the path length
		pathLength[pathfinderID] = pathLength[pathfinderID] + 1;
	}
	while (pathX != startX || pathY != startY);

//b.Resize the data bank to the right size in bytes
	pathBank[pathfinderID] = (int*) realloc (pathBank[pathfinderID],
		pathLength[pathfinderID]*8);

//c. Now copy the path information over to the databank. Since we are
//	working backwards from the target to the start location, we copy
//	the information to the data bank in reverse order. The result is
//	a properly ordered set of path data, from the first step to the
//	last.
	pathX = targetX ; pathY = targetY;
	cellPosition = pathLength[pathfinderID]*2;//start at the end
	do
	{
	cellPosition = cellPosition - 2;//work backwards 2 integers
	pathBank[pathfinderID] [cellPosition] = pathX;
	pathBank[pathfinderID] [cellPosition+1] = pathY;

//d.Look up the parent of the current cell.
	tempx = parentX[pathX][pathY];
	pathY = parentY[pathX][pathY];
	pathX = tempx;

//e.If we have reached the starting square, exit the loop.
	}
	while (pathX != startX || pathY != startY);

//11.Read the first path step into xPath/yPath arrays
	ReadPath(pathfinderID,startingX,startingY,1);

	}
	return path;
    
//13.If there is no path to the selected target, set the pathfinder's
//	xPath and yPath equal to its current location and return that the
//	path is nonexistent.
noPath:
	xPath[pathfinderID] = startingX;
	yPath[pathfinderID] = startingY;
	return nonexistent;

}

void aStar::ReadPath(int pathfinderID,int currentX,int currentY, int pixelsPerFrame)
{
/*
;	Note on PixelsPerFrame: The need for this parameter probably isn't
;	that obvious, so a little explanation is in order. This
;	parameter is used to determine if the pathfinder has gotten close
;	enough to the center of a given path square to warrant looking up
;	the next step on the path.
;
;	This is needed because the speed of certain sprites can
;	make reaching the exact center of a path square impossible.
;	In Demo #2, the chaser has a velocity of 3 pixels per frame. Our
;	tile size is 50 pixels, so the center of a tile will be at location
;	25, 75, 125, etc. Some of these are not evenly divisible by 3, so
;	our pathfinder has to know how close is close enough to the center.
;	It calculates this by seeing if the pathfinder is less than
;	pixelsPerFrame # of pixels from the center of the square.

;	This could conceivably cause problems if you have a *really* fast
;	sprite and/or really small tiles, in which case you may need to
;	adjust the formula a bit. But this should almost never be a problem
;	for games with standard sized tiles and normal speeds. Our smiley
;	in Demo #4 moves at a pretty fast clip and it isn't even close
;	to being a problem.
*/

	int ID = pathfinderID; //redundant, but makes the following easier to read

	//If a path has been found for the pathfinder	...
	if (pathStatus[ID] == found)
	{

		//If path finder is just starting a new path or has reached the
		//center of the current path square (and the end of the path
		//hasn't been reached), look up the next path square.
		if (pathLocation[ID] < pathLength[ID])
		{
			//if just starting or if close enough to center of square
			if (pathLocation[ID] == 0 ||
				(abs(currentX - xPath[ID]) < pixelsPerFrame && abs(currentY - yPath[ID]) < pixelsPerFrame))
					pathLocation[ID] = pathLocation[ID] + 1;
		}

		//Read the path data.
		xPath[ID] = ReadPathX(ID,pathLocation[ID]);
		yPath[ID] = ReadPathY(ID,pathLocation[ID]);

		//If the center of the last path square on the path has been
		//reached then reset.
		if (pathLocation[ID] == pathLength[ID])
		{
			if (abs(currentX - xPath[ID]) < pixelsPerFrame
				&& abs(currentY - yPath[ID]) < pixelsPerFrame) //if close enough to center of square
					pathStatus[ID] = notStarted;
		}
	}

	//If there is no path for this pathfinder, simply stay in the current
 	//location.
	else
	{
		xPath[ID] = currentX;
		yPath[ID] = currentY;
	}
}

int aStar::ReadPathX(int pathfinderID,int pathLocation)
{
	int x=-1;
	if (pathLocation <= pathLength[pathfinderID])
	{

	//Read coordinate from bank
	x = pathBank[pathfinderID] [pathLocation*2-2];

	//Adjust the coordinates so they align with the center
	//of the path square (optional). This assumes that you are using
	//sprites that are centered -- i.e., with the midHandle command.
	//Otherwise you will want to adjust this.
	x = tileSize*x + .5*tileSize;

	}
	return x;
}

int aStar::ReadPathY(int pathfinderID,int pathLocation)
{
	int y=-1;
	if (pathLocation <= pathLength[pathfinderID])
	{

	//Read coordinate from bank
	y = pathBank[pathfinderID] [pathLocation*2-1];

	//Adjust the coordinates so they align with the center
	//of the path square (optional). This assumes that you are using
	//sprites that are centered -- i.e., with the midHandle command.
	//Otherwise you will want to adjust this.
	y = tileSize*y + .5*tileSize;

	}
	return y;
}

int aStar::ReadMap(const char *filename)
{
	ifstream filein;
	filein.open(filename,ios::in);
	if (filein)
	{
	  for (unsigned y = 0; y < mapHeight; y++){
		  for (unsigned x = 0; x < mapWidth; x++){
			filein >> walkability [x][y];//or filein.read(buffer,length)
      map[x][y]= walkability [x][y];
      if (walkability [x][y] == '.') walkability [x][y] = walkable;
      else  walkability [x][y] = unwalkable;
		}}
		filein.close();
    return 0;
	}
  else
  {
    return 1;
  }
}

int aStar::ReadMapValue(int x ,int y)
{
  if(x >= 0 && x < mapWidth && y >= 0 && y < mapHeight )
  {
     return(map[x][y]);
  }
  return(0);
}

aStar::~aStar(){
  unsigned i;
  
  for (i = 0; i < mapWidth; ++i)
        delete[] walkability[i];
  delete[] walkability;
  for (i = 0; i < mapWidth; ++i)
        delete[] map[i];
  delete[] map;
  delete[] openList;
  for (i = 0; i < mapWidth+1; ++i)
        delete[] whichList[i];
  delete[] whichList;
  delete[] openX;
  delete[] openY;
  for (i = 0; i < mapWidth+1; ++i)
        delete[] parentX[i];
  delete[] parentX;
  for (i = 0; i < mapWidth+1; ++i)
        delete[] parentY[i];
  delete[] parentY;
  delete[] Fcost;
  for (i = 0; i < mapWidth+1; ++i)
        delete[] Gcost[i];
  delete[] Gcost;
  delete[] Hcost;
  delete[] pathLength;
  delete[] pathLocation;
	for (i = 0; i < numberPeople+1; i++)
		  delete[] pathBank [i];
  delete[] pathBank;
  delete[] pathStatus;
  delete[] xPath;
  delete[] yPath;
}


