/*
 * 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 3 of the License, or (at your option) any later
 * version.
 *
 * This program is distributed in the hope that it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
 * FOR A PARTICULAR PURPOSE. See the GNU General Public License for more
 * details.
 *
 * You should have received a copy of the GNU General Public License along with
 * this program. If not, see <http://www.gnu.org/licenses/>.
 */
package net.sf.l2j.gameserver.pathfinding.geonodes;

import java.io.BufferedReader;
import java.io.File;
import java.io.FileReader;
import java.io.LineNumberReader;
import java.io.RandomAccessFile;
import java.nio.ByteBuffer;
import java.nio.IntBuffer;
import java.nio.MappedByteBuffer;
import java.nio.channels.FileChannel;
import java.util.List;
import java.util.Map;
import java.util.StringTokenizer;
import java.util.logging.Logger;

import javolution.util.FastList;
import javolution.util.FastMap;
import net.sf.l2j.Config;
import net.sf.l2j.gameserver.pathfinding.AbstractNodeLoc;
import net.sf.l2j.gameserver.pathfinding.Node;
import net.sf.l2j.gameserver.pathfinding.PathFinding;

/**
 * @author -Nemesiss-
 */
public class GeoPathFinding extends PathFinding
{
	private static Logger _log = Logger.getLogger(GeoPathFinding.class.getName());
	private static GeoPathFinding _instance;
	private static Map<Short, ByteBuffer> _pathNodes = new FastMap<Short, ByteBuffer>();
	private static Map<Short, IntBuffer> _pathNodesIndex = new FastMap<Short, IntBuffer>();

	public static GeoPathFinding getInstance()
	{
		if (_instance == null)
			_instance = new GeoPathFinding();
		return _instance;
	}

	/**
	 * @see net.sf.l2j.gameserver.pathfinding.PathFinding#PathNodesExist(short)
	 */
	@Override
	public boolean pathNodesExist(short regionoffset)
	{
		return _pathNodesIndex.containsKey(regionoffset);
	}

	/**
	 * @see net.sf.l2j.gameserver.pathfinding.PathFinding#FindPath(int, int, short, int, int, short)
	 */
	@Override
	public List<AbstractNodeLoc> findPath(int gx, int gy, short z, int gtx, int gty, short tz)
	{
		Node start = readNode(gx, gy, z);
		Node end = readNode(gtx, gty, tz);
		if (start == null || end == null)
			return null;
		if (start == end)
			return null;
		// return searchAStar(start, end);
		return searchByClosest(start, end);
	}

	/**
	 * @see net.sf.l2j.gameserver.pathfinding.PathFinding#ReadNeighbors(short, short)
	 */
	@Override
	public Node[] readNeighbors(short node_x, short node_y, int idx)
	{
		short regoffset = getRegionOffset(getRegionX(node_x), getRegionY(node_y));
		ByteBuffer pn = _pathNodes.get(regoffset);
		List<Node> Neighbors = new FastList<Node>(8);
		Node newNode;
		short new_node_x, new_node_y;
		// Region for sure will change, we must read from correct file
		byte neighbor = pn.get(idx); // N
		idx++;
		if (neighbor > 0)
		{
			neighbor--;
			new_node_x = node_x;
			new_node_y = (short) (node_y - 1);
			newNode = readNode(new_node_x, new_node_y, neighbor);
			if (newNode != null)
				Neighbors.add(newNode);
		}
		neighbor = pn.get(idx); // NE
		idx++;
		if (neighbor > 0)
		{
			neighbor--;
			new_node_x = (short) (node_x + 1);
			new_node_y = (short) (node_y - 1);
			newNode = readNode(new_node_x, new_node_y, neighbor);
			if (newNode != null)
				Neighbors.add(newNode);
		}
		neighbor = pn.get(idx); // E
		idx++;
		if (neighbor > 0)
		{
			neighbor--;
			new_node_x = (short) (node_x + 1);
			new_node_y = node_y;
			newNode = readNode(new_node_x, new_node_y, neighbor);
			if (newNode != null)
				Neighbors.add(newNode);
		}
		neighbor = pn.get(idx); // SE
		idx++;
		if (neighbor > 0)
		{
			neighbor--;
			new_node_x = (short) (node_x + 1);
			new_node_y = (short) (node_y + 1);
			newNode = readNode(new_node_x, new_node_y, neighbor);
			if (newNode != null)
				Neighbors.add(newNode);
		}
		neighbor = pn.get(idx); // S
		idx++;
		if (neighbor > 0)
		{
			neighbor--;
			new_node_x = node_x;
			new_node_y = (short) (node_y + 1);
			newNode = readNode(new_node_x, new_node_y, neighbor);
			if (newNode != null)
				Neighbors.add(newNode);
		}
		neighbor = pn.get(idx); // SW
		idx++;
		if (neighbor > 0)
		{
			neighbor--;
			new_node_x = (short) (node_x - 1);
			new_node_y = (short) (node_y + 1);
			newNode = readNode(new_node_x, new_node_y, neighbor);
			if (newNode != null)
				Neighbors.add(newNode);
		}
		neighbor = pn.get(idx); // W
		idx++;
		if (neighbor > 0)
		{
			neighbor--;
			new_node_x = (short) (node_x - 1);
			new_node_y = node_y;
			newNode = readNode(new_node_x, new_node_y, neighbor);
			if (newNode != null)
				Neighbors.add(newNode);
		}
		neighbor = pn.get(idx); // NW
		idx++;
		if (neighbor > 0)
		{
			neighbor--;
			new_node_x = (short) (node_x - 1);
			new_node_y = (short) (node_y - 1);
			newNode = readNode(new_node_x, new_node_y, neighbor);
			if (newNode != null)
				Neighbors.add(newNode);
		}
		Node[] result = new Node[Neighbors.size()];
		return Neighbors.toArray(result);
	}

	// Private
	private Node readNode(short node_x, short node_y, byte layer)
	{
		short regoffset = getRegionOffset(getRegionX(node_x), getRegionY(node_y));
		if (!pathNodesExist(regoffset))
			return null;
		short nbx = getNodeBlock(node_x);
		short nby = getNodeBlock(node_y);
		int idx = _pathNodesIndex.get(regoffset).get((nby << 8) + nbx);
		ByteBuffer pn = _pathNodes.get(regoffset);
		// reading
		byte nodes = pn.get(idx);
		idx += layer * 10 + 1;// byte + layer*10byte
		if (nodes < layer)
		{
			_log.warning("SmthWrong!");
		}
		short node_z = pn.getShort(idx);
		idx += 2;
		return new Node(new GeoNodeLoc(node_x, node_y, node_z), idx);
	}

	private Node readNode(int gx, int gy, short z)
	{
		short node_x = getNodePos(gx);
		short node_y = getNodePos(gy);
		short regoffset = getRegionOffset(getRegionX(node_x), getRegionY(node_y));
		if (!pathNodesExist(regoffset))
			return null;
		short nbx = getNodeBlock(node_x);
		short nby = getNodeBlock(node_y);
		int idx = _pathNodesIndex.get(regoffset).get((nby << 8) + nbx);
		ByteBuffer pn = _pathNodes.get(regoffset);
		// reading
		byte nodes = pn.get(idx);
		idx++;// byte
		int idx2 = 0; // create index to nearlest node by z
		short last_z = Short.MIN_VALUE;
		while (nodes > 0)
		{
			short node_z = pn.getShort(idx);
			if (Math.abs(last_z - z) > Math.abs(node_z - z))
			{
				last_z = node_z;
				idx2 = idx + 2;
			}
			idx += 10; // short + 8 byte
			nodes--;
		}
		return new Node(new GeoNodeLoc(node_x, node_y, last_z), idx2);
	}

	private GeoPathFinding()
	{
		LineNumberReader lnr = null;
		try
		{
			_log.info("PathFinding Engine: - Loading Path Nodes...");
			File Data = new File("./data/pathnode/pn_index.txt");
			if (!Data.exists())
				return;
			lnr = new LineNumberReader(new BufferedReader(new FileReader(Data)));
		}
		catch (Exception e)
		{
			e.printStackTrace();
			throw new Error("Failed to Load pn_index File.");
		}
		String line;
		try
		{
			while ((line = lnr.readLine()) != null)
			{
				if (line.trim().length() == 0)
					continue;
				StringTokenizer st = new StringTokenizer(line, "_");
				byte rx = Byte.parseByte(st.nextToken());
				byte ry = Byte.parseByte(st.nextToken());
				LoadPathNodeFile(rx, ry);
			}
		}
		catch (Exception e)
		{
			e.printStackTrace();
			throw new Error("Failed to Read pn_index File.");
		}
	}

	private void LoadPathNodeFile(byte rx, byte ry)
	{
		String fname = "./data/pathnode/" + rx + "_" + ry + ".pn";
		short regionoffset = getRegionOffset(rx, ry);
		_log.info("PathFinding Engine: - Loading: " + fname + " -> region offset: " + regionoffset + "X: " + rx + " Y: " + ry);
		File Pn = new File(fname);
		int node = 0, size, index = 0;
		try
		{
			// Create a read-only memory-mapped file
			FileChannel roChannel = new RandomAccessFile(Pn, "r").getChannel();
			size = (int) roChannel.size();
			MappedByteBuffer nodes;
			if (Config.FORCE_GEODATA) // Force O/S to Loads this buffer's
				// content into physical memory.
				// it is not guarantee, because the underlying operating system
				// may have paged out some of the buffer's data
				nodes = roChannel.map(FileChannel.MapMode.READ_ONLY, 0, size).load();
			else
				nodes = roChannel.map(FileChannel.MapMode.READ_ONLY, 0, size);
			// Indexing pathnode files, so we will know where each block
			// starts
			IntBuffer indexs = IntBuffer.allocate(65536);
			while (node < 65536)
			{
				byte layer = nodes.get(index);
				indexs.put(node, index);
				node++;
				index += layer * 10 + 1;
			}
			_pathNodesIndex.put(regionoffset, indexs);
			_pathNodes.put(regionoffset, nodes);
		}
		catch (Exception e)
		{
			e.printStackTrace();
			_log.warning("Failed to Load PathNode File: " + fname + "\n");
		}
	}
}
