src/main/java/de/uapcore/lightpit/modules/LanguageModule.java

/*
 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS HEADER.
 *
 * Copyright 2021 Mike Becker. All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are met:
 *
 *   1. Redistributions of source code must retain the above copyright
 *      notice, this list of conditions and the following disclaimer.
 *
 *   2. Redistributions in binary form must reproduce the above copyright
 *      notice, this list of conditions and the following disclaimer in the
 *      documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
 * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
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package de.uapcore.lightpit.modules;

import de.uapcore.lightpit.AbstractServlet;
import de.uapcore.lightpit.Constants;
import de.uapcore.lightpit.HttpMethod;
import de.uapcore.lightpit.RequestMapping;
import de.uapcore.lightpit.viewmodel.LanguageView;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;
import java.util.*;

@WebServlet(
        name = "LanguageModule",
        urlPatterns = "/language/*"
)
public final class LanguageModule extends AbstractServlet {

    private static final Logger LOG = LoggerFactory.getLogger(LanguageModule.class);

    private final List<Locale> languages = new ArrayList<>();

    @Override
    public void init() throws ServletException {
        super.init();

        Optional<String[]> langs = availableLanguages();
        if (langs.isPresent()) {
            for (String lang : langs.get()) {
                try {
                    Locale locale = Locale.forLanguageTag(lang);
                    if (locale.getLanguage().isEmpty()) {
                        throw new IllformedLocaleException();
                    }
                    languages.add(locale);
                } catch (IllformedLocaleException ex) {
                    LOG.warn("Specified language {} in context parameter cannot be mapped to an existing locale - skipping.", lang);
                }
            }

        } else {
            languages.add(Locale.ENGLISH);
            LOG.warn("Context parameter 'available-languages' not found. Only english will be available.");
        }
    }

    @Override
    public void destroy() {
        super.destroy();
        languages.clear();
    }

    @RequestMapping(method = HttpMethod.GET)
    public void handle(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {

        final var viewModel = new LanguageView();
        viewModel.setLanguages(languages);
        viewModel.setBrowserLanguage(req.getLocale());
        viewModel.setCurrentLanguage((Locale)req.getSession().getAttribute(Constants.SESSION_ATTR_LANGUAGE));

        setViewModel(req, viewModel);
        setStylesheet(req, "language");
        setContentPage(req, "language");

        renderSite(req, resp);
    }

    @RequestMapping(method = HttpMethod.POST)
    public void switchLanguage(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {

        Optional<Locale> chosenLanguage = Optional.ofNullable(req.getParameter("language"))
                .map(Locale::forLanguageTag)
                .filter((l) -> !l.getLanguage().isEmpty());

        chosenLanguage.ifPresent((l) -> req.getSession().setAttribute(Constants.SESSION_ATTR_LANGUAGE, l));
        chosenLanguage.ifPresent(resp::setLocale);

        handle(req, resp);
    }
}