/* ====================================================================
   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.hdgf;

import java.io.IOException;
import java.io.InputStream;

import org.apache.poi.POIReadOnlyDocument;
import org.apache.poi.hdgf.chunks.ChunkFactory;
import org.apache.poi.hdgf.pointers.Pointer;
import org.apache.poi.hdgf.pointers.PointerFactory;
import org.apache.poi.hdgf.streams.PointerContainingStream;
import org.apache.poi.hdgf.streams.Stream;
import org.apache.poi.hdgf.streams.StringsStream;
import org.apache.poi.hdgf.streams.TrailerStream;
import org.apache.poi.poifs.filesystem.DirectoryNode;
import org.apache.poi.poifs.filesystem.POIFSFileSystem;
import org.apache.poi.util.IOUtils;
import org.apache.poi.util.LittleEndian;
import org.apache.poi.util.LocaleUtil;

/**
 * See
 *  http://www.redferni.uklinux.net/visio/
 *  http://www.gnome.ru/projects/docs/vsdocs.html
 *  http://www.gnome.ru/projects/docs/slide1.png
 *  http://www.gnome.ru/projects/docs/slide2.png
 */
public final class HDGFDiagram extends POIReadOnlyDocument {
    private static final String VISIO_HEADER = "Visio (TM) Drawing\r\n";

    private long docSize;

    private Pointer trailerPointer;
    private TrailerStream trailer;

    public HDGFDiagram(POIFSFileSystem fs) throws IOException {
        this(fs.getRoot());
    }

    public HDGFDiagram(DirectoryNode dir) throws IOException {
        super(dir);

        // Grab the document stream
        final byte[] _docstream;
        try (InputStream is = dir.createDocumentInputStream("VisioDocument")) {
            _docstream = IOUtils.toByteArray(is);
        }

        // Check it's really visio
        String typeString = new String(_docstream, 0, 20, LocaleUtil.CHARSET_1252 );
        if(! typeString.equals(VISIO_HEADER)) {
            throw new IllegalArgumentException("Wasn't a valid visio document, started with " + typeString);
        }

        // Grab the version number, 0x1a -> 0x1b
        short version = LittleEndian.getShort(_docstream, 0x1a);
        // Grab the document size, 0x1c -> 0x1f
        docSize = LittleEndian.getUInt(_docstream, 0x1c);
        // ??? 0x20 -> 0x23

        // Create the Chunk+Pointer Factories for the document version
        PointerFactory ptrFactory = new PointerFactory(version);
        ChunkFactory chunkFactory = new ChunkFactory(version);

        // Grab the pointer to the trailer
        trailerPointer = ptrFactory.createPointer(_docstream, 0x24);

        // Now grab the trailer
        Stream stream = Stream.createStream(trailerPointer, _docstream, chunkFactory, ptrFactory);
        if (!(stream instanceof TrailerStream)) {
            throw new IllegalStateException("Stream is not a TrailerStream: " + stream);
        }
        trailer = (TrailerStream)stream;

        // Finally, find all our streams
        trailer.findChildren(_docstream);
    }

    /**
     * Returns the TrailerStream, which is at the root of the
     *  tree of Streams.
     *
     * @return the TrailerStream
     */
    public TrailerStream getTrailerStream() { return trailer; }

    /**
     * Returns all the top level streams, which are the streams
     *  pointed to by the TrailerStream.
     *
     * @return the top level streams
     */
    public Stream[] getTopLevelStreams() { return trailer.getPointedToStreams(); }

    public long getDocumentSize() { return docSize; }

    /**
     * Prints out some simple debug on the base contents of the file.
     * @see org.apache.poi.hdgf.dev.VSDDumper
     */
    public void debug() {
        System.err.println("Trailer is at " + trailerPointer.getOffset());
        System.err.println("Trailer has type " + trailerPointer.getType());
        System.err.println("Trailer has length " + trailerPointer.getLength());
        System.err.println("Trailer has format " + trailerPointer.getFormat());

        for(int i=0; i<trailer.getPointedToStreams().length; i++) {
            Stream stream = trailer.getPointedToStreams()[i];
            Pointer ptr = stream.getPointer();

            System.err.println("Looking at pointer " + i);
            System.err.println("\tType is " + ptr.getType() + "\t\t" + Integer.toHexString(ptr.getType()));
            System.err.println("\tOffset is " + ptr.getOffset() + "\t\t" + Long.toHexString(ptr.getOffset()));
            System.err.println("\tAddress is " + ptr.getAddress() + "\t" + Long.toHexString(ptr.getAddress()));
            System.err.println("\tLength is " + ptr.getLength() + "\t\t" + Long.toHexString(ptr.getLength()));
            System.err.println("\tFormat is " + ptr.getFormat() + "\t\t" + Long.toHexString(ptr.getFormat()));
            System.err.println("\tCompressed is " + ptr.destinationCompressed());
            System.err.println("\tStream is " + stream.getClass());

            if(stream instanceof PointerContainingStream) {
                PointerContainingStream pcs = (PointerContainingStream)stream;

                if(pcs.getPointedToStreams() != null && pcs.getPointedToStreams().length > 0) {
                    System.err.println("\tContains " + pcs.getPointedToStreams().length + " other pointers/streams");
                    for(int j=0; j<pcs.getPointedToStreams().length; j++) {
                        Stream ss = pcs.getPointedToStreams()[j];
                        Pointer sptr = ss.getPointer();
                        System.err.println("\t\t" + j + " - Type is " + sptr.getType() + "\t\t" + Integer.toHexString(sptr.getType()));
                        System.err.println("\t\t" + j + " - Length is " + sptr.getLength() + "\t\t" + Long.toHexString(sptr.getLength()));
                    }
                }
            }

            if(stream instanceof StringsStream) {
                System.err.println("\t\t**strings**");
                StringsStream ss = (StringsStream)stream;
                System.err.println("\t\t" + ss._getContentsLength());
            }
        }
    }
}