/* ###
 * IP: GHIDRA
 *
 * 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 ghidra.app.plugin.core.format;

import java.math.BigInteger;

import ghidra.util.HelpLocation;

/**
 * Converts byte values to binary representation.
 */
public class BinaryFormatModel implements UniversalDataFormatModel, MutableDataFormatModel {

	private int symbolSize;
	private static final String GOOD_CHARS = "01";

	public BinaryFormatModel() {

		symbolSize = 8;
	}

	/**
	 * Get the name of this formatter.
	 */
	@Override
	public String getName() {
		return "Binary";
	}

	/**
	 * Get the number of bytes to make a unit; in this case, 
	 * returns 1.
	 */
	@Override
	public int getUnitByteSize() {
		return 1;
	}

	/**
	 * Given a character position from 0 to data unit symbol size - 1
	 * it returns a number from 0 to unit byte size - 1 indicating which
	 * byte the character position was obtained from.
	 */
	@Override
	public int getByteOffset(ByteBlock block, int position) {
		return 0;
	}

	/**
	 * Given the byte offset into a unit, get the column position.
	 */
	@Override
	public int getColumnPosition(ByteBlock block, int byteOffset) {
		return 0;
	}

	/**
	 * Gets the number of characters required to display a
	 * unit. 
	 * @return 8 for number of characters in the binary representation.
	 */
	@Override
	public int getDataUnitSymbolSize() {
		return symbolSize;
	}

	/**
	 * Gets the string representation at the given index in the block.
	 * @param block block to change
	 * @param index byte index into the block
	 * @throws ByteBlockAccessException if the block cannot be read
	 * @throws IndexOutOfBoundsException if index is not valid for the
	 * block
	 */
	@Override
	public String getDataRepresentation(ByteBlock block, BigInteger index)
			throws ByteBlockAccessException {

		byte b = block.getByte(index);
		int i = b;
		i &= 0xff;

		String str = Integer.toBinaryString(i);

		if (str.length() > symbolSize) {
			str = str.substring(str.length() - symbolSize);
		}

		return DataFormatModel.pad(str, symbolSize);

	}

	/**
	 * Overwrite a value in a ByteBlock.
	 * @param block block to change
	 * @param index byte index into the block
	 * @param pos The position within the unit where c will be the
	 * new character.
	 * @param c new character to put at pos param
	 * @return true if the replacement is legal, false if the
	 * replacement value would not make sense for this format, e.g.
	 * attempt to put a 'z' in a hex unit.
	 * @throws ByteBlockAccessException if the block cannot be updated
	 * @throws IndexOutOfBoundsException if index is not valid for the
	 * block
	 */
	@Override
	public boolean replaceValue(ByteBlock block, BigInteger index, int charPosition, char c)
			throws ByteBlockAccessException {

		if (charPosition < 0 || charPosition > 7) {
			return false;
		}
		if (GOOD_CHARS.indexOf(c) == -1) {
			return false;
		}
		// make sure char is valid in the specified position
		if (charPosition == 0 && GOOD_CHARS.indexOf(c) > 1) {
			return false;
		}

		byte b = block.getByte(index);
		char[] charArray = { c };
		byte cb = Byte.parseByte(new String(charArray), 2);
		byte mask = (byte) ((byte) 1 << (7 - charPosition));

		b &= ~mask;
		if (cb == (byte) 1) {
			b |= mask;
		}

		block.setByte(index, b);
		return true;
	}

	/**
	 * Get the number of characters separating units.
	 */
	@Override
	public int getUnitDelimiterSize() {
		return 1;
	}

	@Override
	public HelpLocation getHelpLocation() {
		return new HelpLocation("ByteViewerPlugin", "Binary");
	}
}
