/*
 * 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.pdfbox.pdmodel.fdf;

import java.io.BufferedInputStream;
import java.io.BufferedWriter;
import java.io.Closeable;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.InputStream;
import java.io.IOException;
import java.io.OutputStream;
import java.io.OutputStreamWriter;
import java.io.Writer;

import org.apache.pdfbox.cos.COSDictionary;
import org.apache.pdfbox.cos.COSDocument;
import org.apache.pdfbox.cos.COSName;
import org.apache.pdfbox.exceptions.COSVisitorException;
import org.apache.pdfbox.pdfparser.NonSequentialPDFParser;
import org.apache.pdfbox.pdfwriter.COSWriter;
import org.apache.pdfbox.util.XMLUtil;
import org.w3c.dom.Document;
import org.w3c.dom.Element;

/**
 * This is the in-memory representation of the FDF document.  You need to call
 * close() on this object when you are done using it!!
 *
 * @author Ben Litchfield
 */
public class FDFDocument implements Closeable
{
    private COSDocument document;

    /**
     * Constructor, creates a new FDF document.
     *
     * @throws IOException If there is an error creating this document.
     */
    public FDFDocument() throws IOException
    {
        document = new COSDocument();
        document.setHeaderString( "%FDF-1.2" );

        //First we need a trailer
        document.setTrailer( new COSDictionary() );

        //Next we need the root dictionary.
        FDFCatalog catalog = new FDFCatalog();
        setCatalog( catalog );
    }

    /**
     * Constructor that uses an existing document.  The COSDocument that
     * is passed in must be valid.
     *
     * @param doc The COSDocument that this document wraps.
     */
    public FDFDocument( COSDocument doc )
    {
        document = doc;
    }

    /**
     * This will create an FDF document from an XFDF XML document.
     *
     * @param doc The XML document that contains the XFDF data.
     * @throws IOException If there is an error reading from the dom.
     */
    public FDFDocument( Document doc ) throws IOException
    {
        this();
        Element xfdf = doc.getDocumentElement();
        if( !xfdf.getNodeName().equals( "xfdf" ) )
        {
            throw new IOException( "Error while importing xfdf document, " +
                "root should be 'xfdf' and not '" + xfdf.getNodeName() + "'" );
        }
        FDFCatalog cat = new FDFCatalog( xfdf );
        setCatalog( cat );
    }

    /**
     * This will write this element as an XML document.
     *
     * @param output The stream to write the xml to.
     *
     * @throws IOException If there is an error writing the XML.
     */
    public void writeXML( Writer output ) throws IOException
    {
        output.write( "<?xml version=\"1.0\" encoding=\"UTF-8\"?>\n" );
        output.write( "<xfdf xmlns=\"http://ns.adobe.com/xfdf/\" xml:space=\"preserve\">\n" );

        getCatalog().writeXML( output );

        output.write( "</xfdf>\n" );
    }



    /**
     * This will get the low level document.
     *
     * @return The document that this layer sits on top of.
     */
    public COSDocument getDocument()
    {
        return document;
    }

    /**
     * This will get the FDF Catalog.  This is guaranteed to not return null.
     *
     * @return The documents /Root dictionary
     */
    public FDFCatalog getCatalog()
    {
        FDFCatalog retval = null;
        COSDictionary trailer = document.getTrailer();
        COSDictionary root = (COSDictionary)trailer.getDictionaryObject( COSName.ROOT );
        if( root == null )
        {
            retval = new FDFCatalog();
            setCatalog( retval );
        }
        else
        {
            retval = new FDFCatalog( root );
        }
        return retval;
    }

    /**
     * This will set the FDF catalog for this FDF document.
     *
     * @param cat The FDF catalog.
     */
    public void setCatalog( FDFCatalog cat )
    {
        COSDictionary trailer = document.getTrailer();
        trailer.setItem( COSName.ROOT, cat );
    }

    /**
     * This will load a document from a file.
     *
     * @param filename The name of the file to load.
     *
     * @return The document that was loaded.
     *
     * @throws IOException If there is an error reading from the stream.
     */
    public static FDFDocument load( String filename ) throws IOException
    {
        return load(new File(filename));
    }

    /**
     * This will load a document from a file.
     *
     * @param file The name of the file to load.
     *
     * @return The document that was loaded.
     *
     * @throws IOException If there is an error reading from the stream.
     */
    public static FDFDocument load( File file ) throws IOException
    {
        NonSequentialPDFParser parser = new NonSequentialPDFParser(file, null);
        parser.parse();
        return parser.getFDFDocument();
    }

    /**
     * This will load a document from an input stream.
     *
     * @param input The stream that contains the document.
     *
     * @return The document that was loaded.
     *
     * @throws IOException If there is an error reading from the stream.
     */
    public static FDFDocument load( InputStream input ) throws IOException
    {
        NonSequentialPDFParser parser = new NonSequentialPDFParser(input);
        parser.parse();
        return parser.getFDFDocument();
    }

    /**
     * This will load a document from a file.
     *
     * @param filename The name of the file to load.
     *
     * @return The document that was loaded.
     *
     * @throws IOException If there is an error reading from the stream.
     */
    public static FDFDocument loadXFDF( String filename ) throws IOException
    {
        return loadXFDF( new BufferedInputStream( new FileInputStream( filename ) ) );
    }

    /**
     * This will load a document from a file.
     *
     * @param file The name of the file to load.
     *
     * @return The document that was loaded.
     *
     * @throws IOException If there is an error reading from the stream.
     */
    public static FDFDocument loadXFDF( File file ) throws IOException
    {
        return loadXFDF( new BufferedInputStream( new FileInputStream( file ) ) );
    }

    /**
     * This will load a document from an input stream.
     *
     * @param input The stream that contains the document.
     *
     * @return The document that was loaded.
     *
     * @throws IOException If there is an error reading from the stream.
     */
    public static FDFDocument loadXFDF( InputStream input ) throws IOException
    {
        Document doc = XMLUtil.parse( input );
        return new FDFDocument( doc );
    }

    /**
     * This will save this document to the filesystem.
     *
     * @param fileName The file to save as.
     *
     * @throws IOException If there is an error saving the document.
     * @throws COSVisitorException If an error occurs while generating the data.
     */
    public void save( File fileName ) throws IOException, COSVisitorException
    {
        save( new FileOutputStream( fileName ) );
    }

    /**
     * This will save this document to the filesystem.
     *
     * @param fileName The file to save as.
     *
     * @throws IOException If there is an error saving the document.
     * @throws COSVisitorException If an error occurs while generating the data.
     */
    public void save( String fileName ) throws IOException, COSVisitorException
    {
        save( new FileOutputStream( fileName ) );
    }

    /**
     * This will save the document to an output stream.
     *
     * @param output The stream to write to.
     *
     * @throws IOException If there is an error writing the document.
     * @throws COSVisitorException If an error occurs while generating the data.
     */
    public void save( OutputStream output ) throws IOException, COSVisitorException
    {
        COSWriter writer = null;
        try
        {
            writer = new COSWriter( output );
            writer.write( document );
            writer.close();
        }
        finally
        {
            if( writer != null )
            {
                writer.close();
            }
        }
    }

    /**
     * This will save this document to the filesystem.
     *
     * @param fileName The file to save as.
     *
     * @throws IOException If there is an error saving the document.
     * @throws COSVisitorException If an error occurs while generating the data.
     */
    public void saveXFDF( File fileName ) throws IOException, COSVisitorException
    {
        saveXFDF(new BufferedWriter(new OutputStreamWriter(new FileOutputStream(fileName), "UTF-8")));
    }

    /**
     * This will save this document to the filesystem.
     *
     * @param fileName The file to save as.
     *
     * @throws IOException If there is an error saving the document.
     * @throws COSVisitorException If an error occurs while generating the data.
     */
    public void saveXFDF( String fileName ) throws IOException, COSVisitorException
    {
        saveXFDF(new BufferedWriter(new OutputStreamWriter(new FileOutputStream(fileName), "UTF-8")));
    }

    /**
     * This will save the document to an output stream and close the stream.
     *
     * @param output The stream to write to.
     *
     * @throws IOException If there is an error writing the document.
     * @throws COSVisitorException If an error occurs while generating the data.
     */
    public void saveXFDF( Writer output ) throws IOException, COSVisitorException
    {
        try
        {
            writeXML( output );
        }
        finally
        {
            if( output != null )
            {
                output.close();
            }
        }
    }

    /**
     * This will close the underlying COSDocument object.
     *
     * @throws IOException If there is an error releasing resources.
     */
    public void close() throws IOException
    {
        document.close();
    }
}
