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/*
 *  eXist Image Module Extension GetHeightFunction
 *  Copyright (C) 2006-09 Adam Retter 
 *  www.adamretter.co.uk
 *  
 *  This program is free software; you can redistribute it and/or
 *  modify it under the terms of the GNU Lesser General Public License
 *  as published by the Free Software Foundation; either version 2
 *  of the License, or (at your option) any later version.
 *  
 *  This program is distributed in the hope that it will be useful,
 *  but WITHOUT ANY WARRANTY; without even the implied warranty of
 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *  GNU Lesser General Public License for more details.
 *  
 *  You should have received a copy of the GNU Lesser General Public License
 *  along with this program; if not, write to the Free Software
 *  Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
 *  
 *  $Id$
 */
package org.exist.xquery.modules.image;

import java.awt.Image;
import java.io.IOException;
import java.io.InputStream;
import javax.imageio.ImageIO;

import org.apache.logging.log4j.LogManager;
import org.apache.logging.log4j.Logger;
import org.exist.dom.QName;
import org.exist.xquery.BasicFunction;
import org.exist.xquery.Cardinality;
import org.exist.xquery.FunctionSignature;
import org.exist.xquery.XPathException;
import org.exist.xquery.XQueryContext;
import org.exist.xquery.value.BinaryValue;
import org.exist.xquery.value.FunctionParameterSequenceType;
import org.exist.xquery.value.FunctionReturnSequenceType;
import org.exist.xquery.value.IntegerValue;
import org.exist.xquery.value.Sequence;
import org.exist.xquery.value.SequenceType;
import org.exist.xquery.value.Type;

/**
 * eXist Image Module Extension GetHeightFunction 
 * 
 * Get's the height of an Image
 * 
 * @author Adam Retter
 * @version 1.2
 *
 * @see org.exist.xquery.BasicFunction#BasicFunction(org.exist.xquery.XQueryContext, org.exist.xquery.FunctionSignature)
 */
public class GetHeightFunction extends BasicFunction {

    private static final Logger logger = LogManager.getLogger(GetHeightFunction.class);
    public final static FunctionSignature signature =
            new FunctionSignature(
            new QName("get-height", ImageModule.NAMESPACE_URI, ImageModule.PREFIX),
            "Gets the Height of the image passed in, returning an integer of the images Height in pixels or an empty sequence if the image is invalid.",
            new SequenceType[]{
                new FunctionParameterSequenceType("image", Type.BASE64_BINARY, Cardinality.EXACTLY_ONE, "The image data")
            },
            new FunctionReturnSequenceType(Type.INTEGER, Cardinality.ZERO_OR_ONE, "the height in pixels"));

    /**
     * GetHeightFunction Constructor
     *
     * @param context	The Context of the calling XQuery
     */
    public GetHeightFunction(XQueryContext context) {
        super(context, signature);
    }

    /**
     * evaluate the call to the xquery get-height() function,
     * it is really the main entry point of this class
     *
     * @param args		arguments from the get-height() function call
     * @param contextSequence	the Context Sequence to operate on (not used here internally!)
     * @return		A sequence representing the result of the get-height() function call
     *
     * @see org.exist.xquery.BasicFunction#eval(org.exist.xquery.value.Sequence[], org.exist.xquery.value.Sequence)
     */
    @Override
    public Sequence eval(Sequence[] args, Sequence contextSequence) throws XPathException {
        //was an image speficifed
        if (args[0].isEmpty()) {
            return Sequence.EMPTY_SEQUENCE;
        }

        //get the image
        Image image = null;
        BinaryValue imageData = (BinaryValue) args[0].itemAt(0);
        try (InputStream inputStream = imageData.getInputStream()) {
            image = ImageIO.read(inputStream);

        } catch (IOException ioe) {
            logger.error("Unable to read image data!", ioe);
            return Sequence.EMPTY_SEQUENCE;
        }

        if (image == null) {
            logger.error("Unable to read image data!");
            return Sequence.EMPTY_SEQUENCE;
        }

        //Get the Height of the image
        int iHeight = image.getHeight(null);

        //did we get the Height of the image?
        if (iHeight == -1) {
            //no, log the error
            logger.error("Unable to read image data!");
            return Sequence.EMPTY_SEQUENCE;
        } else {
            //return the Height of the image
            return new IntegerValue(iHeight);
        }
    }
}