/*******************************************************************************
 * Copyright 2011 See AUTHORS file.
 * 
 * Licensed 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 com.google.gwt.corp.compatibility.Numbers;

class StringByteBuffer extends BaseByteBuffer {

	private String s;

	StringByteBuffer (String s) {
		super(s.length());
		this.s = s;
		order(ByteOrder.LITTLE_ENDIAN);
	}

	StringByteBuffer (String s, int position, int limit) {
		this(s);
		this.position = position;
		this.limit = limit;
	}

	public ByteBuffer asReadOnlyBuffer () {
		return this;
	}

	byte[] protectedArray () {
		throw new UnsupportedOperationException();
	}

	int protectedArrayOffset () {
		throw new UnsupportedOperationException();
	}

	boolean protectedHasArray () {
		throw new UnsupportedOperationException();
	}

	@Override
	public ByteBuffer compact () {
		return this;
	}

	@Override
	public ByteBuffer duplicate () {
		return this;
	}

	@Override
	public byte get () {
		return get(position++);
	}

	@Override
	public byte get (int index) {
		return get(s, 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;
		int result = loadInt(position);
		position = newPosition;
		return result;
	}

	public final int getInt (int index) {
		return loadInt(index);
	}

	public final long getLong () {
		throw new UnsupportedOperationException();
	}

	public final long getLong (int index) {
		throw new UnsupportedOperationException();
	}

	public final short getShort () {
		int newPosition = position + 2;
		short result = loadShort(position);
		position = newPosition;
		return result;
	}

	public final short getShort (int index) {
		return loadShort(index);
	}

	@Override
	public boolean isDirect () {
		return false;
	}

	@Override
	public ByteBuffer put (byte b) {
		throw new UnsupportedOperationException();
	}

	@Override
	public ByteBuffer put (int index, byte b) {
		throw new UnsupportedOperationException();
	}

	@Override
	public ByteBuffer putDouble (double value) {
		throw new UnsupportedOperationException();
	}

	@Override
	public ByteBuffer putDouble (int index, double value) {
		throw new UnsupportedOperationException();
	}

	@Override
	public ByteBuffer putFloat (float value) {
		throw new UnsupportedOperationException();
	}

	@Override
	public ByteBuffer putFloat (int index, float value) {
		throw new UnsupportedOperationException();
	}

	@Override
	public ByteBuffer putInt (int value) {
		throw new UnsupportedOperationException();
	}

	@Override
	public ByteBuffer putInt (int index, int value) {
		throw new UnsupportedOperationException();
	}

	@Override
	public ByteBuffer putLong (long value) {
		throw new UnsupportedOperationException();
	}

	@Override
	public ByteBuffer putLong (int index, long value) {
		throw new UnsupportedOperationException();
	}

	@Override
	public ByteBuffer putShort (short value) {
		throw new UnsupportedOperationException();
	}

	@Override
	public ByteBuffer putShort (int index, short value) {
		throw new UnsupportedOperationException();
	}

	@Override
	public ByteBuffer slice () {
		// TODO(jgw): I don't think this is right, but might work for our purposes.
		StringByteBuffer slice = new StringByteBuffer(s, position, limit);
		slice.order = order;
		return slice;
	}

	@Override
	public boolean isReadOnly () {
		return true;
	}

	private native byte get (String s, int i) /*-{
															var x = s.charCodeAt(i) & 0xff;
															if (x > 127) x -= 256;
															return x;
															}-*/;

	protected final int loadInt (int baseOffset) {
		int bytes = 0;
		for (int i = 3; i >= 0; i--) {
			bytes = bytes << 8;
			bytes = bytes | (get(baseOffset + i) & 0xFF);
		}
		return bytes;
	}

	protected final short loadShort (int baseOffset) {
		short bytes = 0;
		bytes = (short)(get(baseOffset + 1) << 8);
		bytes |= (get(baseOffset) & 0xFF);
		return bytes;
	}
}