/*
 * Copyright (C) 2008-2017, Juick
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU Affero General Public License as
 * published by the Free Software Foundation, either version 3 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 Affero General Public License for more details.
 *
 * You should have received a copy of the GNU Affero General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */

package com.juick.www;

import org.apache.commons.io.IOUtils;
import org.apache.commons.lang3.StringUtils;
import org.springframework.cache.annotation.Cacheable;

import java.io.IOException;
import java.io.InputStream;
import java.nio.charset.StandardCharsets;
import java.util.regex.Pattern;

/**
 * Created by aalexeev on 12/11/16.
 */
public class HelpService {
    private static final Pattern LANG_PATTERN = Pattern.compile("[a-z]{2}");

    private static final Pattern PAGE_PATTERN = Pattern.compile("[a-zA-Z0-9\\-_]+");

    private final String helpPath;


    public HelpService(String helpPath) {
        this.helpPath = helpPath;
    }

    @Cacheable("help")
    public String getHelp(final String page, final String lang) {
        if (canBePage(page) && canBeLang(lang)) {
            String path = StringUtils.joinWith("/", helpPath, lang, page + ".md");

            try (InputStream is = Thread.currentThread().getContextClassLoader().getResourceAsStream(path)) {
                if (is != null)
                    return IOUtils.toString(is, StandardCharsets.UTF_8);
            } catch (IOException e) {
            }
        }
        return null;
    }

    public boolean canBePage(final String anything) {
        return anything != null && PAGE_PATTERN.matcher(anything).matches();
    }

    public boolean canBeLang(final String anything) {
        return anything != null && LANG_PATTERN.matcher(anything).matches();
    }

    public String getHelpPath() {
        return helpPath;
    }
}