/* ====================================================================
   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 java.io.*;
import org.apache.poi.poifs.filesystem.*;
import org.apache.poi.util.LittleEndian;
import org.apache.poi.util.StringUtil;
import org.apache.poi.hslf.exceptions.CorruptPowerPointFileException;


/**
 * This is a special kind of Atom, becauase it doesn't live inside the
 *  PowerPoint document. Instead, it lives in a seperate stream in the
 *  document. As such, it has to be treaded specially
 *
 * @author Nick Burch
 */

public class CurrentUserAtom
{
	/** Standard Atom header */
	public static final byte[] atomHeader = new byte[] { 0, 0, -10, 15 };
	/** The Powerpoint magic numer */
	public static final byte[] magicNumber = new byte[] { 95, -64, -111, -29 };
	/** The Powerpoint 97 version, major and minor numbers */
	public static final byte[] ppt97FileVer = new byte[] { 8, 00, -13, 03, 03, 00 };

	/** The version, major and minor numbers */
	private int docFinalVersionA;
	private int docFinalVersionB;
	private byte docMajorNo;
	private byte docMinorNo;

	/** The Offset into the file for the current edit */
    private long currentEditOffset;
	/** The Username of the last person to edit the file */
	private String lastEditUser;
	/** The document release version */
	private long releaseVersion;

	/** Only correct after reading in or writing out */
	private byte[] _contents;


	/* ********************* getter/setter follows *********************** */

	public int  getDocFinalVersionA() { return docFinalVersionA; }
	public int  getDocFinalVersionB() { return docFinalVersionB; }
	public byte getDocMajorNo()       { return docMajorNo; }
	public byte getDocMinorNo()       { return docMinorNo; }

	public long getReleaseVersion()  { return releaseVersion; }
	public void setReleaseVersion(long rv) { releaseVersion = rv; }

	/** Points to the UserEditAtom */
	public long getCurrentEditOffset() { return currentEditOffset; }
	public void setCurrentEditOffset(long id ) { currentEditOffset = id; }

	public String getLastEditUsername() { return lastEditUser; }
	public void setLastEditUsername(String u) { lastEditUser = u; }


	/* ********************* real code follows *************************** */

	/**
	 * Create a new Current User Atom
	 */
	public CurrentUserAtom() {
		_contents = new byte[0];
		throw new RuntimeException("Creation support for Current User Atom not complete");
	}

	/** 
	 * Find the Current User in the filesystem, and create from that
	 */
	public CurrentUserAtom(POIFSFileSystem fs) throws IOException {
		// Decide how big it is
		DocumentEntry docProps =
			(DocumentEntry)fs.getRoot().getEntry("Current User");
		_contents = new byte[docProps.getSize()];

		// Check it's big enough - if it's not at least 28 bytes long, then
		//  the record is corrupt
		if(_contents.length < 28) {
			throw new CorruptPowerPointFileException("The Current User stream must be at least 28 bytes long, but was only " + _contents.length);
		}

		// Grab the contents
		InputStream in = fs.createDocumentInputStream("Current User");
		in.read(_contents);

		// Set everything up
		init();
	}

	/** 
	 * Create things from the bytes
	 */
	public CurrentUserAtom(byte[] b) {
		_contents = b;
		init();
	}

	/**
	 * Actually do the creation from a block of bytes
	 */
	private void init() {
		// Grab the edit offset
		currentEditOffset = LittleEndian.getUInt(_contents,16);

		// Grab the versions
		docFinalVersionA = LittleEndian.getUShort(_contents,20);
		docFinalVersionB = LittleEndian.getUShort(_contents,22);
		docMajorNo = _contents[24];
		docMinorNo = _contents[25];

		// Get the username length
		long usernameLen = LittleEndian.getUShort(_contents,20);
		if(usernameLen > 512) {
			// Handle the case of it being garbage
			System.err.println("Warning - invalid username length " + usernameLen + " found, treating as if there was no username set");
			usernameLen = 0;
		}

		// Now we know the length of the username, 
		//  use this to grab the revision
		if(_contents.length >= 28+(int)usernameLen + 4) {
			releaseVersion = LittleEndian.getUInt(_contents,28+(int)usernameLen);
		} else {
			// No revision given, as not enough data. Odd
			releaseVersion = 0;
		}

		// Grab the unicode username, if stored
		int start = 28+(int)usernameLen+4;
		int len = 2*(int)usernameLen;

		if(_contents.length >= start+len) {
			byte[] textBytes = new byte[len];
			System.arraycopy(_contents,start,textBytes,0,len);
			lastEditUser = StringUtil.getFromUnicodeLE(textBytes);
		} else {
			// Fake from the 8 bit version
			byte[] textBytes = new byte[(int)usernameLen];
			System.arraycopy(_contents,28,textBytes,0,(int)usernameLen);
			lastEditUser = StringUtil.getFromCompressedUnicode(textBytes,0,(int)usernameLen);
		}
	}


	/**
	 * Writes ourselves back out
	 */
	public void writeOut(OutputStream out) throws IOException {
		// Decide on the size
		//  8 = atom header
		//  20 = up to name
		//  4 = revision
		//  3 * len = ascii + unicode
		int size = 8 + 20 + 4 + (3 * lastEditUser.length());
		_contents = new byte[size];

		// First we have a 8 byte atom header
		System.arraycopy(atomHeader,0,_contents,0,4);	
		// Size is 20+user len + revision len(4)
		int atomSize = 20+4+lastEditUser.length();
		LittleEndian.putInt(_contents,4,atomSize);

		// Now we have the size of the details, which is 20
		LittleEndian.putInt(_contents,8,20);

		// Now the ppt magic number (4 bytes)
		System.arraycopy(magicNumber,0,_contents,12,4);

		// Now the current edit offset
		LittleEndian.putInt(_contents,16,(int)currentEditOffset);

		// Now the file versions, 2+2+1+1
		LittleEndian.putShort(_contents,20,(short)docFinalVersionA);
		LittleEndian.putShort(_contents,22,(short)docFinalVersionB);
		_contents[24] = docMajorNo;
		_contents[25] = docMinorNo;

		// 2 bytes blank
		_contents[26] = 0;
		_contents[27] = 0;

		// username in bytes in us ascii
		byte[] asciiUN = new byte[lastEditUser.length()];
		StringUtil.putCompressedUnicode(lastEditUser,asciiUN,0);
		System.arraycopy(asciiUN,0,_contents,28,asciiUN.length);

		// 4 byte release version
		LittleEndian.putInt(_contents,28+asciiUN.length,(int)releaseVersion);

		// username in unicode
		byte [] ucUN = new byte[lastEditUser.length()*2];
		StringUtil.putUnicodeLE(lastEditUser,ucUN,0);
		System.arraycopy(ucUN,0,_contents,28+asciiUN.length+4,ucUN.length);

		// Write out
		out.write(_contents);
	}

	/**
	 * Writes ourselves back out to a filesystem
	 */
	public void writeToFS(POIFSFileSystem fs) throws IOException {
		// Grab contents
		ByteArrayOutputStream baos = new ByteArrayOutputStream();
		writeOut(baos);
		ByteArrayInputStream bais = 
			new ByteArrayInputStream(baos.toByteArray());

		// Write out
		fs.createDocument(bais,"Current User");
	}
}