/* ====================================================================
   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 org.apache.poi.hslf.record;

import org.apache.poi.util.LittleEndian;
import org.apache.poi.util.StringUtil;
import java.io.IOException;
import java.io.OutputStream;
import java.io.UnsupportedEncodingException;

/**
 * This atom corresponds exactly to a Windows Logical Font (LOGFONT) structure.
 * It keeps all the information needed to define the attributes of a font,
 * such as height, width, etc. For more information, consult the
 * Windows API Programmer's reference.
 *
 * @author Yegor Kozlov
 */

public class FontEntityAtom extends RecordAtom {
	/**
     * record header
     */
    private byte[] _header;

	/**
     * record data
     */
	private byte[] _recdata;

    /**
     * Build an instance of <code>FontEntityAtom</code> from on-disk data
     */
	protected FontEntityAtom(byte[] source, int start, int len) {
		// Get the header
		_header = new byte[8];
		System.arraycopy(source,start,_header,0,8);

		// Grab the record data
		_recdata = new byte[len-8];
		System.arraycopy(source,start+8,_recdata,0,len-8);
	}

    /**
     * Create a new instance of <code>FontEntityAtom</code>
     */
    protected FontEntityAtom() {
        _recdata = new byte[68];

        _header = new byte[8];
        LittleEndian.putShort(_header, 2, (short)getRecordType());
        LittleEndian.putInt(_header, 4, _recdata.length);
    }

    public long getRecordType() {
        return RecordTypes.FontEntityAtom.typeID;
    }

    /**
     * A null-terminated string that specifies the typeface name of the font.
     * The length of this string must not exceed 32 characters 
	 *  including the null terminator.
     * @return font name
     */
    public String getFontName(){
        String name = null;
        try {
            int i = 0;
            while(i < 64){
                //loop until find null-terminated end of the font name
                if(_recdata[i] == 0 && _recdata[i + 1] == 0) {
                    name = new String(_recdata, 0, i, "UTF-16LE");
                    break;
                }
                i += 2;
            }
        } catch (UnsupportedEncodingException e){
            throw new RuntimeException(e.getMessage(), e);
        }
        return name;
    }

    /**
     * Set the name of the font.
     * The length of this string must not exceed 32 characters 
	 *  including the null terminator.
	 * Will be converted to null-terminated if not already
     * @param name of the font
     */
    public void setFontName(String name){
		// Add a null termination if required
		if(! name.endsWith("\000")) {
			name = name + "\000";
		}

		// Ensure it's not now too long
		if(name.length() > 32) {
			throw new RuntimeException("The length of the font name, including null termination, must not exceed 32 characters");
		}

		// Everything's happy, so save the name
        try {
            byte[] bytes = name.getBytes("UTF-16LE");
            System.arraycopy(bytes, 0, _recdata, 0, bytes.length);
        } catch (UnsupportedEncodingException e){
            throw new RuntimeException(e.getMessage(), e);
        }
    }

    protected void setFontIndex(int idx){
        LittleEndian.putShort(_header, 0, (short)idx);
    }

    protected int getFontIndex(){
        return LittleEndian.getShort(_header, 0);
    }

	/**
	 * Write the contents of the record back, so it can be written to disk
	 */
	public void writeOut(OutputStream out) throws IOException {
		out.write(_header);
		out.write(_recdata);
	}
}