/*
 * This file is part of Applied Energistics 2.
 * Copyright (c) 2013 - 2014, 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.client.render.cablebus;


import java.util.ArrayList;
import java.util.List;

import javax.vecmath.Matrix4f;
import javax.vecmath.Point3f;
import javax.vecmath.Vector3f;

import net.minecraft.client.renderer.block.model.BakedQuad;
import net.minecraft.client.renderer.vertex.VertexFormat;
import net.minecraft.client.renderer.vertex.VertexFormatElement;
import net.minecraft.util.EnumFacing;

import appeng.client.render.FacingToRotation;
import appeng.core.AELog;


/**
 * Assuming a default-orientation of forward=NORTH and up=UP, this class rotates a given list of quads to the desired
 * facing
 */
public class QuadRotator
{

	public List<BakedQuad> rotateQuads( List<BakedQuad> quads, EnumFacing newForward, EnumFacing newUp )
	{
		if( newForward == EnumFacing.NORTH && newUp == EnumFacing.UP )
		{
			return quads; // This is the default orientation
		}

		List<BakedQuad> result = new ArrayList<>( quads.size() );

		for( BakedQuad quad : quads )
		{
			result.add( rotateQuad( quad, newForward, newUp ) );
		}

		return result;
	}

	private BakedQuad rotateQuad( BakedQuad quad, EnumFacing forward, EnumFacing up )
	{
		// Sanitize forward/up
		if( forward.getAxis() == up.getAxis() )
		{
			if( up.getAxis() == EnumFacing.Axis.Y )
			{
				up = EnumFacing.NORTH;
			}
			else
			{
				up = EnumFacing.UP;
			}
		}

		FacingToRotation rotation = FacingToRotation.get( forward, up );
		Matrix4f mat = rotation.getMat();

		// Clone the vertex data used by the quad
		int[] newData = quad.getVertexData().clone();

		// Figure out where the position is in the array
		VertexFormat format = quad.getFormat();
		int posIdx = findPositionOffset( format ) / 4;
		int stride = format.getNextOffset() / 4;
		int normalIdx = format.getNormalOffset();
		VertexFormatElement.EnumType normalType = null;
		// Figure out the type of the normals
		if( normalIdx != -1 )
		{
			for( int i = 0; i < format.getElements().size(); i++ )
			{
				VertexFormatElement element = format.getElement( i );
				if( element.getUsage() == VertexFormatElement.EnumUsage.NORMAL )
				{
					normalType = element.getType();
				}
			}
		}

		for( int i = 0; i < 4; i++ )
		{
			Point3f pos = new Point3f( Float.intBitsToFloat( newData[i * stride + posIdx] ) - 0.5f, Float.intBitsToFloat( newData[i * stride + posIdx + 1] ) - 0.5f, Float.intBitsToFloat( newData[i * stride + posIdx + 2] ) - 0.5f );

			// Rotate stuff around
			mat.transform( pos );

			// Write back
			newData[i * stride + posIdx] = Float.floatToIntBits( pos.getX() + 0.5f );
			newData[i * stride + posIdx + 1] = Float.floatToIntBits( pos.getY() + 0.5f );
			newData[i * stride + posIdx + 2] = Float.floatToIntBits( pos.getZ() + 0.5f );

			// Transform the normal if one is present
			if( normalIdx != -1 )
			{
				if( normalType == VertexFormatElement.EnumType.FLOAT )
				{
					Vector3f normal = new Vector3f( Float.intBitsToFloat( newData[i * stride + normalIdx] ), Float.intBitsToFloat( newData[i * stride + normalIdx + 1] ), Float.intBitsToFloat( newData[i * stride + normalIdx + 2] ) );

					// Rotate stuff around
					mat.transform( normal );

					// Write back
					newData[i * stride + normalIdx] = Float.floatToIntBits( normal.getX() );
					newData[i * stride + normalIdx + 1] = Float.floatToIntBits( normal.getY() );
					newData[i * stride + normalIdx + 2] = Float.floatToIntBits( normal.getZ() );
				}
				else if( normalType == VertexFormatElement.EnumType.BYTE )
				{
					int idx = i * stride * 4 + normalIdx;
					Vector3f normal = new Vector3f( getByte( newData, idx ) / 127.0f, getByte( newData, idx + 1 ) / 127.0f, getByte( newData, idx + 2 ) / 127.0f );

					// Rotate stuff around
					mat.transform( normal );

					// Write back
					setByte( newData, idx, (int) ( normal.getX() * 127 ) );
					setByte( newData, idx + 1, (int) ( normal.getY() * 127 ) );
					setByte( newData, idx + 2, (int) ( normal.getZ() * 127 ) );
				}
				else
				{
					AELog.warn( "Unsupported normal format: {}", normalType );
				}
			}
		}

		EnumFacing newFace = rotation.rotate( quad.getFace() );
		return new BakedQuad( newData, quad.getTintIndex(), newFace, quad.getSprite(), quad.shouldApplyDiffuseLighting(), quad.getFormat() );
	}

	private static int getByte( int[] data, int offset )
	{
		int idx = offset / 4;
		int subOffset = offset % 4;
		return (byte) ( data[idx] >> ( subOffset * 8 ) );
	}

	private static void setByte( int[] data, int offset, int value )
	{
		int idx = offset / 4;
		int subOffset = offset % 4;
		int mask = 0xFF << ( subOffset * 8 );
		data[idx] = data[idx] & ( ~mask ) | ( ( value & 0xFF ) << ( subOffset * 8 ) );
	}

	private int findPositionOffset( VertexFormat format )
	{
		List<VertexFormatElement> elements = format.getElements();
		for( int i = 0; i < elements.size(); i++ )
		{
			VertexFormatElement e = elements.get( i );
			if( e.isPositionElement() )
			{
				if( e.getType() != VertexFormatElement.EnumType.FLOAT )
				{
					throw new IllegalArgumentException( "Only floating point positions are supported" );
				}
				return i;
			}
		}

		throw new IllegalArgumentException( "Vertex format " + format + " has no position attribute!" );
	}
}