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/*
 *  Licensed to the Apache Software Foundation (ASF) under one or more
 *  contributor license agreements.  See the NOTICE file distributed with
 *  this work for additional information regarding copyright ownership.
 *  The ASF licenses this file to You under the Apache License, Version 2.0
 *  (the "License"); you may not use this file except in compliance with
 *  the License.  You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 *  Unless required by applicable law or agreed to in writing, software
 *  distributed under the License is distributed on an "AS IS" BASIS,
 *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 *  See the License for the specific language governing permissions and
 *  limitations under the License.
 */

package java.nio;

import java.io.Numbers;

import org.w3c.dom.typedarray.ArrayBuffer;
import org.w3c.dom.typedarray.ArrayBufferView;
import org.w3c.dom.typedarray.Int8Array;

import com.dragome.utils.Endianness;
import com.dragome.web.html.dom.w3c.ArrayBufferFactory;
import com.dragome.web.html.dom.w3c.TypedArraysFactory;

/** DirectByteBuffer, DirectReadWriteByteBuffer and DirectReadOnlyHeapByteBuffer compose the implementation of direct byte buffers.
 * 
 * DirectByteBuffer implements all the shared readonly methods and is extended by the other two classes.
 * 
 * 
 * All methods are marked final for runtime performance.
 *  */
abstract class DirectByteBuffer extends BaseByteBuffer implements HasArrayBufferView
{

	Int8Array byteArray;

	DirectByteBuffer(int capacity)
	{
		this(ArrayBufferFactory.createArrayBuffer(capacity), capacity, 0);
	}

	DirectByteBuffer(ArrayBuffer buf)
	{
		this(buf, buf.getByteLength(), 0);
	}

	DirectByteBuffer(ArrayBuffer buffer, int capacity, int offset)
	{
		super(capacity);
		byteArray= TypedArraysFactory.createInstanceOf(Int8Array.class, buffer, offset, capacity);
	}

	public ArrayBufferView getTypedArray()
	{
		return byteArray;
	}

	public int getElementSize()
	{
		return 1;
	}

	/*
	 * Override ByteBuffer.get(byte[], int, int) to improve performance.
	 *
	 * (non-Javadoc)
	 *
	 * @see java.nio.ByteBuffer#get(byte[], int, int)
	 */
	public final ByteBuffer get(byte[] dest, int off, int len)
	{
		int length= dest.length;
		if (off < 0 || len < 0 || (long) off + (long) len > length)
		{
			throw new IndexOutOfBoundsException();
		}
		if (len > remaining())
		{
			throw new BufferUnderflowException();
		}

		for (int i= 0; i < len; i++)
		{
			dest[i + off]= get(position + i);
		}

		position+= len;
		return this;
	}

	public final byte get()
	{
		// if (position == limit) {
		// throw new BufferUnderflowException();
		// }
		return (byte) byteArray.get(position++);
	}

	public final byte get(int index)
	{
		// if (index < 0 || index >= limit) {
		// throw new IndexOutOfBoundsException();
		// }
		return (byte) byteArray.get(index);
	}

	public final double getDouble()
	{
		return Numbers.longBitsToDouble(getLong());
	}

	public final double getDouble(int index)
	{
		return Numbers.longBitsToDouble(getLong(index));
	}

	public final float getFloat()
	{
		return Numbers.intBitsToFloat(getInt());
	}

	public final float getFloat(int index)
	{
		return Numbers.intBitsToFloat(getInt(index));
	}

	public final int getInt()
	{
		int newPosition= position + 4;
		// if (newPosition > limit) {
		// throw new BufferUnderflowException();
		// }
		int result= loadInt(position);
		position= newPosition;
		return result;
	}

	public final int getInt(int index)
	{
		// if (index < 0 || index + 4 > limit) {
		// throw new IndexOutOfBoundsException();
		// }
		return loadInt(index);
	}

	public final long getLong()
	{
		int newPosition= position + 8;
		// if (newPosition > limit) {
		// throw new BufferUnderflowException();
		// }
		long result= loadLong(position);
		position= newPosition;
		return result;
	}

	public final long getLong(int index)
	{
		// if (index < 0 || index + 8 > limit) {
		// throw new IndexOutOfBoundsException();
		// }
		return loadLong(index);
	}

	public final short getShort()
	{
		int newPosition= position + 2;
		// if (newPosition > limit) {
		// throw new BufferUnderflowException();
		// }
		short result= loadShort(position);
		position= newPosition;
		return result;
	}

	public final short getShort(int index)
	{
		// if (index < 0 || index + 2 > limit) {
		// throw new IndexOutOfBoundsException();
		// }
		return loadShort(index);
	}

	public final boolean isDirect()
	{
		return false;
	}

	protected final int loadInt(int baseOffset)
	{
		int bytes= 0;
		if (order == Endianness.BIG_ENDIAN)
		{
			for (int i= 0; i < 4; i++)
			{
				bytes= bytes << 8;
				bytes= bytes | (byteArray.get(baseOffset + i) & 0xFF);
			}
		}
		else
		{
			for (int i= 3; i >= 0; i--)
			{
				bytes= bytes << 8;
				bytes= bytes | (byteArray.get(baseOffset + i) & 0xFF);
			}
		}
		return bytes;
	}

	protected final long loadLong(int baseOffset)
	{
		long bytes= 0;
		if (order == Endianness.BIG_ENDIAN)
		{
			for (int i= 0; i < 8; i++)
			{
				bytes= bytes << 8;
				bytes= bytes | (byteArray.get(baseOffset + i) & 0xFF);
			}
		}
		else
		{
			for (int i= 7; i >= 0; i--)
			{
				bytes= bytes << 8;
				bytes= bytes | (byteArray.get(baseOffset + i) & 0xFF);
			}
		}
		return bytes;
	}

	protected final short loadShort(int baseOffset)
	{
		short bytes= 0;
		if (order == Endianness.BIG_ENDIAN)
		{
			bytes= (short) (byteArray.get(baseOffset) << 8);
			bytes|= (byteArray.get(baseOffset + 1) & 0xFF);
		}
		else
		{
			bytes= (short) (byteArray.get(baseOffset + 1) << 8);
			bytes|= (byteArray.get(baseOffset) & 0xFF);
		}
		return bytes;
	}

	protected final void store(int baseOffset, int value)
	{
		if (order == Endianness.BIG_ENDIAN)
		{
			for (int i= 3; i >= 0; i--)
			{
				byteArray.set(baseOffset + i, (byte) (value & 0xFF));
				value= value >> 8;
			}
		}
		else
		{
			for (int i= 0; i <= 3; i++)
			{
				byteArray.set(baseOffset + i, (byte) (value & 0xFF));
				value= value >> 8;
			}
		}
	}

	protected final void store(int baseOffset, long value)
	{
		if (order == Endianness.BIG_ENDIAN)
		{
			for (int i= 7; i >= 0; i--)
			{
				byteArray.set(baseOffset + i, (byte) (value & 0xFF));
				value= value >> 8;
			}
		}
		else
		{
			for (int i= 0; i <= 7; i++)
			{
				byteArray.set(baseOffset + i, (byte) (value & 0xFF));
				value= value >> 8;
			}
		}
	}

	protected final void store(int baseOffset, short value)
	{
		if (order == Endianness.BIG_ENDIAN)
		{
			byteArray.set(baseOffset, (byte) ((value >> 8) & 0xFF));
			byteArray.set(baseOffset + 1, (byte) (value & 0xFF));
		}
		else
		{
			byteArray.set(baseOffset + 1, (byte) ((value >> 8) & 0xFF));
			byteArray.set(baseOffset, (byte) (value & 0xFF));
		}
	}
}