/*
 *  eXist Open Source Native XML Database
 *  Copyright (C) 2001-09 The eXist Project
 *  http://exist-db.org
 *
 *  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.functions.response;

import org.apache.logging.log4j.LogManager;
import org.apache.logging.log4j.Logger;

import org.exist.dom.QName;
import org.exist.http.servlets.ResponseWrapper;
import org.exist.xquery.*;
import org.exist.xquery.value.FunctionParameterSequenceType;
import org.exist.xquery.value.JavaObjectValue;
import org.exist.xquery.value.Sequence;
import org.exist.xquery.value.SequenceType;
import org.exist.xquery.value.Type;

import java.io.IOException;
import java.io.OutputStream;
import org.exist.xquery.value.BinaryValue;

public class StreamBinary extends BasicFunction {

    protected static final Logger logger = LogManager.getLogger(StreamBinary.class);
    protected static final FunctionParameterSequenceType BINARY_DATA_PARAM = new FunctionParameterSequenceType("binary-data", Type.BASE64_BINARY, Cardinality.EXACTLY_ONE, "The binary data to stream");
    protected static final FunctionParameterSequenceType CONTENT_TYPE_PARAM = new FunctionParameterSequenceType("content-type", Type.STRING, Cardinality.EXACTLY_ONE, "The ContentType HTTP header value");
    protected static final FunctionParameterSequenceType FILENAME_PARAM = new FunctionParameterSequenceType("filename", Type.STRING, Cardinality.ZERO_OR_ONE, "The filename.  If no filename is given, then the current request name is used");
    public final static FunctionSignature signature =
            new FunctionSignature(
            new QName("stream-binary", ResponseModule.NAMESPACE_URI, ResponseModule.PREFIX),
            "Streams the binary data to the current servlet response output stream. The ContentType "
            + "HTTP header is set to the value given in $content-type."
            + "Note: the servlet output stream will be closed afterwards and mime-type settings in the prolog "
            + "will not be passed.",
            new SequenceType[]{BINARY_DATA_PARAM, CONTENT_TYPE_PARAM, FILENAME_PARAM},
            new SequenceType(Type.EMPTY, Cardinality.EMPTY),
            true);

    public StreamBinary(XQueryContext context) {
        super(context, signature);
    }

    @Override
    public Sequence eval(Sequence[] args, Sequence contextSequence) throws XPathException {
        if(args[0].isEmpty() || args[1].isEmpty()) {
            return (Sequence.EMPTY_SEQUENCE);
        }

        final BinaryValue binary = (BinaryValue) args[0].itemAt(0);
        final String contentType = args[1].getStringValue();
        String filename = null;

        if((args.length > 2) && !args[2].isEmpty()) {
            filename = args[2].getStringValue();
        }

        final ResponseModule myModule = (ResponseModule) context.getModule(ResponseModule.NAMESPACE_URI);

        // response object is read from global variable $response
        final Variable respVar = myModule.resolveVariable(ResponseModule.RESPONSE_VAR);

        if((respVar == null) || (respVar.getValue() == null)) {
            throw (new XPathException(this, ErrorCodes.XPDY0002, "No response object found in the current XQuery context."));
        }

        if(respVar.getValue().getItemType() != Type.JAVA_OBJECT) {
            throw (new XPathException(this, ErrorCodes.XPDY0002, "Variable $response is not bound to an Java object."));
        }

        final JavaObjectValue respValue = (JavaObjectValue) respVar.getValue().itemAt(0);

        if(!"org.exist.http.servlets.HttpResponseWrapper".equals(respValue.getObject().getClass().getName())) {
            throw (new XPathException(this, ErrorCodes.XPDY0002, signature.toString() + " can only be used within the EXistServlet or XQueryServlet"));
        }

        final ResponseWrapper response = (ResponseWrapper) respValue.getObject();
        response.setHeader("Content-Type", contentType);

        if(filename != null) {
            response.setHeader("Content-Disposition", "inline; filename=\"" + filename + "\"");
        }

        try {
            final OutputStream os = response.getOutputStream();
            binary.streamBinaryTo(response.getOutputStream());
            os.close();

            //commit the response
            response.flushBuffer();
        } catch (final IOException e) {
            throw (new XPathException(this, "IO exception while streaming data: " + e.getMessage(), e));
        }

        return (Sequence.EMPTY_SEQUENCE);
    }
}