/*
 * This file is part of Applied Energistics 2.
 * Copyright (c) 2013 - 2015, AlgorithmX2, All rights reserved.
 *
 * Applied Energistics 2 is free software: you can redistribute it and/or modify
 * it under the terms of the GNU Lesser General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * Applied Energistics 2 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 Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public License
 * along with Applied Energistics 2.  If not, see <http://www.gnu.org/licenses/lgpl>.
 */

package appeng.me;


import java.util.Collections;
import java.util.Comparator;
import java.util.Deque;
import java.util.EnumSet;
import java.util.LinkedList;
import java.util.List;

import net.minecraft.nbt.NBTTagCompound;
import net.minecraft.tileentity.TileEntity;
import net.minecraft.util.EnumFacing;
import net.minecraft.util.math.BlockPos;
import net.minecraft.world.World;

import appeng.api.exceptions.FailedConnection;
import appeng.api.networking.GridFlags;
import appeng.api.networking.GridNotification;
import appeng.api.networking.IGrid;
import appeng.api.networking.IGridBlock;
import appeng.api.networking.IGridCache;
import appeng.api.networking.IGridConnection;
import appeng.api.networking.IGridConnectionVisitor;
import appeng.api.networking.IGridHost;
import appeng.api.networking.IGridNode;
import appeng.api.networking.IGridVisitor;
import appeng.api.networking.energy.IEnergyGrid;
import appeng.api.networking.events.MENetworkChannelsChanged;
import appeng.api.networking.pathing.IPathingGrid;
import appeng.api.util.AEColor;
import appeng.api.util.AEPartLocation;
import appeng.api.util.DimensionalCoord;
import appeng.api.util.IReadOnlyCollection;
import appeng.core.worlddata.WorldData;
import appeng.hooks.TickHandler;
import appeng.me.pathfinding.IPathItem;
import appeng.util.IWorldCallable;
import appeng.util.ReadOnlyCollection;


public class GridNode implements IGridNode, IPathItem
{
	private static final MENetworkChannelsChanged EVENT = new MENetworkChannelsChanged();
	private static final int[] CHANNEL_COUNT = { 0, 8, 32 };

	private final List<IGridConnection> connections = new LinkedList<IGridConnection>();
	private final IGridBlock gridProxy;
	// old power draw, used to diff
	private double previousDraw = 0.0;
	private long lastSecurityKey = -1;
	private int playerID = -1;
	private GridStorage myStorage = null;
	private Grid myGrid;
	private Object visitorIterationNumber = null;
	// connection criteria
	private int compressedData = 0;
	private int usedChannels = 0;
	private int lastUsedChannels = 0;

	public GridNode( final IGridBlock what )
	{
		this.gridProxy = what;
	}

	IGridBlock getGridProxy()
	{
		return this.gridProxy;
	}

	Grid getMyGrid()
	{
		return this.myGrid;
	}

	public int usedChannels()
	{
		return this.lastUsedChannels;
	}

	Class<? extends IGridHost> getMachineClass()
	{
		return this.getMachine().getClass();
	}

	void addConnection( final IGridConnection gridConnection )
	{
		this.connections.add( gridConnection );
		if( gridConnection.hasDirection() )
		{
			this.gridProxy.onGridNotification( GridNotification.CONNECTIONS_CHANGED );
		}

		final IGridNode gn = this;

		Collections.sort( this.connections, new ConnectionComparator( gn ) );
	}

	void removeConnection( final IGridConnection gridConnection )
	{
		this.connections.remove( gridConnection );
		if( gridConnection.hasDirection() )
		{
			this.gridProxy.onGridNotification( GridNotification.CONNECTIONS_CHANGED );
		}
	}

	boolean hasConnection( final IGridNode otherSide )
	{
		for( final IGridConnection gc : this.connections )
		{
			if( gc.a() == otherSide || gc.b() == otherSide )
			{
				return true;
			}
		}
		return false;
	}

	void validateGrid()
	{
		final GridSplitDetector gsd = new GridSplitDetector( this.getInternalGrid().getPivot() );
		this.beginVisit( gsd );
		if( !gsd.isPivotFound() )
		{
			final IGridVisitor gp = new GridPropagator( new Grid( this ) );
			this.beginVisit( gp );
		}
	}

	public Grid getInternalGrid()
	{
		if( this.myGrid == null )
		{
			this.myGrid = new Grid( this );
		}

		return this.myGrid;
	}

	@Override
	public void beginVisit( final IGridVisitor g )
	{
		final Object tracker = new Object();

		LinkedList<GridNode> nextRun = new LinkedList<GridNode>();
		nextRun.add( this );

		this.visitorIterationNumber = tracker;

		if( g instanceof IGridConnectionVisitor )
		{
			final LinkedList<IGridConnection> nextConn = new LinkedList<IGridConnection>();
			final IGridConnectionVisitor gcv = (IGridConnectionVisitor) g;

			while( !nextRun.isEmpty() )
			{
				while( !nextConn.isEmpty() )
				{
					gcv.visitConnection( nextConn.poll() );
				}

				final Iterable<GridNode> thisRun = nextRun;
				nextRun = new LinkedList<GridNode>();

				for( final GridNode n : thisRun )
				{
					n.visitorConnection( tracker, g, nextRun, nextConn );
				}
			}
		}
		else
		{
			while( !nextRun.isEmpty() )
			{
				final Iterable<GridNode> thisRun = nextRun;
				nextRun = new LinkedList<GridNode>();

				for( final GridNode n : thisRun )
				{
					n.visitorNode( tracker, g, nextRun );
				}
			}
		}
	}

	@Override
	public void updateState()
	{
		final EnumSet<GridFlags> set = this.gridProxy.getFlags();

		this.compressedData = set.contains( GridFlags.CANNOT_CARRY ) ? 0 : ( set.contains( GridFlags.DENSE_CAPACITY ) ? 2 : 1 );

		this.compressedData |= ( this.gridProxy.getGridColor().ordinal() << 3 );

		for( final EnumFacing dir : this.gridProxy.getConnectableSides() )
		{
			this.compressedData |= ( 1 << ( dir.ordinal() + 8 ) );
		}

		this.FindConnections();
		this.getInternalGrid();
	}

	@Override
	public IGridHost getMachine()
	{
		return this.gridProxy.getMachine();
	}

	@Override
	public IGrid getGrid()
	{
		return this.myGrid;
	}

	void setGrid( final Grid grid )
	{
		if( this.myGrid == grid )
		{
			return;
		}

		if( this.myGrid != null )
		{
			this.myGrid.remove( this );

			if( this.myGrid.isEmpty() )
			{
				this.myGrid.saveState();

				for( final IGridCache c : grid.getCaches().values() )
				{
					c.onJoin( this.myGrid.getMyStorage() );
				}
			}
		}

		this.myGrid = grid;
		this.myGrid.add( this );
	}

	@Override
	public void destroy()
	{
		while( !this.connections.isEmpty() )
		{
			// not part of this network for real anymore.
			if( this.connections.size() == 1 )
			{
				this.setGridStorage( null );
			}

			final IGridConnection c = this.connections.listIterator().next();
			final GridNode otherSide = (GridNode) c.getOtherSide( this );
			otherSide.getInternalGrid().setPivot( otherSide );
			c.destroy();
		}

		if( this.myGrid != null )
		{
			this.myGrid.remove( this );
		}
	}

	@Override
	public World getWorld()
	{
		return this.gridProxy.getLocation().getWorld();
	}

	@Override
	public EnumSet<AEPartLocation> getConnectedSides()
	{
		final EnumSet<AEPartLocation> set = EnumSet.noneOf( AEPartLocation.class );
		for( final IGridConnection gc : this.connections )
		{
			set.add( gc.getDirection( this ) );
		}
		return set;
	}

	@Override
	public IReadOnlyCollection<IGridConnection> getConnections()
	{
		return new ReadOnlyCollection<IGridConnection>( this.connections );
	}

	@Override
	public IGridBlock getGridBlock()
	{
		return this.gridProxy;
	}

	@Override
	public boolean isActive()
	{
		final IGrid g = this.getGrid();
		if( g != null )
		{
			final IPathingGrid pg = g.getCache( IPathingGrid.class );
			final IEnergyGrid eg = g.getCache( IEnergyGrid.class );
			return this.meetsChannelRequirements() && eg.isNetworkPowered() && !pg.isNetworkBooting();
		}
		return false;
	}

	@Override
	public void loadFromNBT( final String name, final NBTTagCompound nodeData )
	{
		if( this.myGrid == null )
		{
			final NBTTagCompound node = nodeData.getCompoundTag( name );
			this.playerID = node.getInteger( "p" );
			this.setLastSecurityKey( node.getLong( "k" ) );

			final long storageID = node.getLong( "g" );
			final GridStorage gridStorage = WorldData.instance().storageData().getGridStorage( storageID );
			this.setGridStorage( gridStorage );
		}
		else
		{
			throw new IllegalStateException( "Loading data after part of a grid, this is invalid." );
		}
	}

	@Override
	public void saveToNBT( final String name, final NBTTagCompound nodeData )
	{
		if( this.myStorage != null )
		{
			final NBTTagCompound node = new NBTTagCompound();

			node.setInteger( "p", this.playerID );
			node.setLong( "k", this.getLastSecurityKey() );
			node.setLong( "g", this.myStorage.getID() );

			nodeData.setTag( name, node );
		}
		else
		{
			nodeData.removeTag( name );
		}
	}

	@Override
	public boolean meetsChannelRequirements()
	{
		return( !this.gridProxy.getFlags().contains( GridFlags.REQUIRE_CHANNEL ) || this.getUsedChannels() > 0 );
	}

	@Override
	public boolean hasFlag( final GridFlags flag )
	{
		return this.gridProxy.getFlags().contains( flag );
	}

	@Override
	public int getPlayerID()
	{
		return this.playerID;
	}

	@Override
	public void setPlayerID( final int playerID )
	{
		if( playerID >= 0 )
		{
			this.playerID = playerID;
		}
	}

	private int getUsedChannels()
	{
		return this.usedChannels;
	}

	private void FindConnections()
	{
		if( !this.gridProxy.isWorldAccessible() )
		{
			return;
		}

		final EnumSet<AEPartLocation> newSecurityConnections = EnumSet.noneOf( AEPartLocation.class );

		final DimensionalCoord dc = this.gridProxy.getLocation();
		for( final AEPartLocation f : AEPartLocation.SIDE_LOCATIONS )
		{
			final IGridHost te = this.findGridHost( dc.getWorld(), dc.x + f.xOffset, dc.y + f.yOffset, dc.z + f.zOffset );
			if( te != null )
			{
				final GridNode node = (GridNode) te.getGridNode( f.getOpposite() );
				if( node == null )
				{
					continue;
				}

				final boolean isValidConnection = this.canConnect( node, f ) && node.canConnect( this, f.getOpposite() );

				IGridConnection con = null; // find the connection for this
				// direction..
				for( final IGridConnection c : this.getConnections() )
				{
					if( c.getDirection( this ) == f )
					{
						con = c;
						break;
					}
				}

				if( con != null )
				{
					final IGridNode os = con.getOtherSide( this );
					if( os == node )
					{
						// if this connection is no longer valid, destroy it.
						if( !isValidConnection )
						{
							con.destroy();
						}
					}
					else
					{
						con.destroy();
						// throw new GridException( "invalid state found, encountered connection to phantom block." );
					}
				}
				else if( isValidConnection )
				{
					if( node.getLastSecurityKey() != -1 )
					{
						newSecurityConnections.add( f );
					}
					else
					{
						// construct a new connection between these two nodes.
						try
						{
							new GridConnection( node, this, f.getOpposite() );
						}
						catch( final FailedConnection e )
						{
							TickHandler.INSTANCE.addCallable( node.getWorld(), new MachineSecurityBreak( this ) );

							return;
						}
					}
				}
			}
		}

		for( final AEPartLocation f : newSecurityConnections )
		{
			final IGridHost te = this.findGridHost( dc.getWorld(), dc.x + f.xOffset, dc.y + f.yOffset, dc.z + f.zOffset );
			if( te != null )
			{
				final GridNode node = (GridNode) te.getGridNode( f.getOpposite() );
				if( node == null )
				{
					continue;
				}

				// construct a new connection between these two nodes.
				try
				{
					new GridConnection( node, this, f.getOpposite() );
				}
				catch( final FailedConnection e )
				{
					TickHandler.INSTANCE.addCallable( node.getWorld(), new MachineSecurityBreak( this ) );

					return;
				}
			}
		}
	}

	private IGridHost findGridHost( final World world, final int x, final int y, final int z )
	{
		final BlockPos pos = new BlockPos( x, y, z );
		if( world.isBlockLoaded( pos ) )
		{
			final TileEntity te = world.getTileEntity( pos );
			if( te instanceof IGridHost )
			{
				return (IGridHost) te;
			}
		}
		return null;
	}

	private boolean canConnect( final GridNode from, final AEPartLocation dir )
	{
		if( !this.isValidDirection( dir ) )
		{
			return false;
		}

		if( !from.getColor().matches( this.getColor() ) )
		{
			return false;
		}

		return true;
	}

	private boolean isValidDirection( final AEPartLocation dir )
	{
		return ( this.compressedData & ( 1 << ( 8 + dir.ordinal() ) ) ) > 0;
	}

	private AEColor getColor()
	{
		return AEColor.values()[( this.compressedData >> 3 ) & 0x1F];
	}

	private void visitorConnection( final Object tracker, final IGridVisitor g, final Deque<GridNode> nextRun, final Deque<IGridConnection> nextConnections )
	{
		if( g.visitNode( this ) )
		{
			for( final IGridConnection gc : this.getConnections() )
			{
				final GridNode gn = (GridNode) gc.getOtherSide( this );
				final GridConnection gcc = (GridConnection) gc;

				if( gcc.getVisitorIterationNumber() != tracker )
				{
					gcc.setVisitorIterationNumber( tracker );
					nextConnections.add( gc );
				}

				if( tracker == gn.visitorIterationNumber )
				{
					continue;
				}

				gn.visitorIterationNumber = tracker;

				nextRun.add( gn );
			}
		}
	}

	private void visitorNode( final Object tracker, final IGridVisitor g, final Deque<GridNode> nextRun )
	{
		if( g.visitNode( this ) )
		{
			for( final IGridConnection gc : this.getConnections() )
			{
				final GridNode gn = (GridNode) gc.getOtherSide( this );

				if( tracker == gn.visitorIterationNumber )
				{
					continue;
				}

				gn.visitorIterationNumber = tracker;

				nextRun.add( gn );
			}
		}
	}

	GridStorage getGridStorage()
	{
		return this.myStorage;
	}

	void setGridStorage( final GridStorage s )
	{
		this.myStorage = s;
		this.usedChannels = 0;
		this.lastUsedChannels = 0;
	}

	@Override
	public IPathItem getControllerRoute()
	{
		if( this.connections.isEmpty() || this.getFlags().contains( GridFlags.CANNOT_CARRY ) )
		{
			return null;
		}

		return (IPathItem) this.connections.get( 0 );
	}

	@Override
	public void setControllerRoute( final IPathItem fast, final boolean zeroOut )
	{
		if( zeroOut )
		{
			this.usedChannels = 0;
		}

		final int idx = this.connections.indexOf( fast );
		if( idx > 0 )
		{
			this.connections.remove( fast );
			this.connections.add( 0, (IGridConnection) fast );
		}
	}

	@Override
	public boolean canSupportMoreChannels()
	{
		return this.getUsedChannels() < this.getMaxChannels();
	}

	private int getMaxChannels()
	{
		return CHANNEL_COUNT[this.compressedData & 0x03];
	}

	@Override
	public IReadOnlyCollection<IPathItem> getPossibleOptions()
	{
		return (IReadOnlyCollection) this.getConnections();
	}

	@Override
	public void incrementChannelCount( final int usedChannels )
	{
		this.usedChannels += usedChannels;
	}

	@Override
	public EnumSet<GridFlags> getFlags()
	{
		return this.gridProxy.getFlags();
	}

	@Override
	public void finalizeChannels()
	{
		if( this.getFlags().contains( GridFlags.CANNOT_CARRY ) )
		{
			return;
		}

		if( this.getLastUsedChannels() != this.getUsedChannels() )
		{
			this.lastUsedChannels = this.usedChannels;

			if( this.getInternalGrid() != null )
			{
				this.getInternalGrid().postEventTo( this, EVENT );
			}
		}
	}

	private int getLastUsedChannels()
	{
		return this.lastUsedChannels;
	}

	public long getLastSecurityKey()
	{
		return this.lastSecurityKey;
	}

	public void setLastSecurityKey( final long lastSecurityKey )
	{
		this.lastSecurityKey = lastSecurityKey;
	}

	public double getPreviousDraw()
	{
		return this.previousDraw;
	}

	public void setPreviousDraw( final double previousDraw )
	{
		this.previousDraw = previousDraw;
	}

	private static class MachineSecurityBreak implements IWorldCallable<Void>
	{
		private final GridNode node;

		public MachineSecurityBreak( final GridNode node )
		{
			this.node = node;
		}

		@Override
		public Void call( final World world ) throws Exception
		{
			this.node.getMachine().securityBreak();

			return null;
		}
	}

	private static class ConnectionComparator implements Comparator<IGridConnection>
	{
		private final IGridNode gn;

		public ConnectionComparator( final IGridNode gn )
		{
			this.gn = gn;
		}

		@Override
		public int compare( final IGridConnection o1, final IGridConnection o2 )
		{
			final boolean preferredA = o1.getOtherSide( this.gn ).hasFlag( GridFlags.PREFERRED );
			final boolean preferredB = o2.getOtherSide( this.gn ).hasFlag( GridFlags.PREFERRED );

			return preferredA == preferredB ? 0 : ( preferredA ? -1 : 1 );
		}
	}
}