/**************************************************************************
 OmegaT - Computer Assisted Translation (CAT) tool
          with fuzzy matching, translation memory, keyword search,
          glossaries, and translation leveraging into updated projects.

 Copyright (C) 2010 Alex Buloichik, Ibai Lakunza Velasco, Didier Briel
               2013 Martin Wunderlich, Didier Briel
               2015 Didier Briel
               Home page: http://www.omegat.org/
               Support center: http://groups.yahoo.com/group/OmegaT/

 This file is part of OmegaT.

 OmegaT is free software: you can redistribute it and/or modify
 it under the terms of the GNU General Public License as published by
 the Free Software Foundation, either version 3 of the License, or
 (at your option) any later version.

 OmegaT 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 General Public License for more details.

 You should have received a copy of the GNU General Public License
 along with this program.  If not, see <http://www.gnu.org/licenses/>.
 **************************************************************************/

package org.omegat.core.machinetranslators;

import java.io.StringReader;
import java.io.UnsupportedEncodingException;
import java.net.URLEncoder;

import javax.xml.xpath.XPath;
import javax.xml.xpath.XPathConstants;
import javax.xml.xpath.XPathExpression;

import org.omegat.util.Language;
import org.omegat.util.OStrings;
import org.omegat.util.Preferences;
import org.w3c.dom.Document;
import org.w3c.dom.Node;
import org.xml.sax.InputSource;

/**
 * @author Ibai Lakunza Velasco
 * @author Didier Briel
 * @author Martin Wunderlich
 */
public final class MyMemoryMachineTranslate extends AbstractMyMemoryTranslate {
    // Note: Add parameter &mt=0 to suppress MT results from being included in the TMX response; omit this
    // parameter to include MT results
    protected static final String GT_URL2 = "&langpair=#sourceLang#|#targetLang#&of=#format#&mt=1";

    @Override
    protected String getPreferenceName() {
        return Preferences.ALLOW_MYMEMORY_MACHINE_TRANSLATE;
    }

    @Override
    public String getName() {
        return OStrings.getString("MT_ENGINE_MYMEMORY_MACHINE");
    }

    @Override
    protected String translate(Language sLang, Language tLang, String text) throws Exception {
        String prev = getFromCache(sLang, tLang, text);
        if (prev != null) {
            return prev;
        }

        String tmxResponse = "";
        String machineTranslationMatch = "";

        // Get MyMemory response in TMX format
        try {
            tmxResponse = getMyMemoryResponse(sLang, tLang, text, "tmx");
        } catch (Exception e) {
            return e.getLocalizedMessage();
        }

        // Adjust DTD location and bug in entity encoding; the second line should be removed as soon as the bug is
        // fixed by MyMemory; TODO: Use local DTD
        tmxResponse = tmxResponse.replace("<!DOCTYPE tmx SYSTEM \"tmx11.dtd\">", "");
        tmxResponse = tmxResponse.replace("&", "&");

        // We must remove anything before the XML declaration, otherwise we get an exception when creating the
        // DOM object. Currently, MyMemory returns \r\n<?xml
        tmxResponse = getXMLString(tmxResponse);

        // Build DOM object from the returned XML string
        InputSource source = new InputSource(new StringReader(tmxResponse));
        Document document = factory.newDocumentBuilder().parse(source);

        // Extract MT response and remove MT TU from XML
        // MyMemory is using hyphens instead of underscores and uppercase codes in 4-letter locale-codes
        String targetLangCode =  tLang.getLocaleCode().replace('_', '-').toUpperCase();
        machineTranslationMatch = extractMTresponse(document, targetLangCode);

        machineTranslationMatch = cleanSpacesAroundTags(machineTranslationMatch, text);

        putToCache(sLang, tLang, text, machineTranslationMatch);
        return machineTranslationMatch;
    }

    private String extractMTresponse(Document document, String targetLang) {
        String mtResponse = "";
        String mtQuery = String.format("/tmx/body/tu[@creationid='MT!']/tuv[starts-with(@lang, '%s')]/seg/text()",
                targetLang);
        Object result = null;

        XPath xpath = xPathFactory.newXPath();

        try {
            XPathExpression expr = xpath.compile(mtQuery);
            result = expr.evaluate(document, XPathConstants.NODE);

            Node node = (Node) result;
            mtResponse = node.getTextContent();
        } catch (Exception ex) {
            // silently catch the exception and provide details to user
            mtResponse = OStrings.getString("MT_ENGINE_MYMEMORY_MACHINE_ERROR") + ex.getMessage();
        }

        mtResponse = cleanUpText(mtResponse);

        return mtResponse;
    }

    /**
     * Builds the URL for the XML query
     */
    @Override
    protected String buildMyMemoryUrl(Language sLang, Language tLang, String text, String format)
            throws UnsupportedEncodingException {
        String sourceLang = mymemoryCode(sLang);
        String targetLang = mymemoryCode(tLang);
        String url2 = GT_URL2.replace("#sourceLang#", sourceLang).replace("#targetLang#", targetLang)
                .replace("#format#", format);
        String url = GT_URL + URLEncoder.encode(text, "UTF-8") + url2;

        return url;
    }

}