/*
 * Copyright (C) 2008-2020, 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 ru.sape;

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import com.juick.www.ad.models.Site;

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.Reader;
import java.io.StringWriter;
import java.net.HttpURLConnection;
import java.net.URL;
import java.nio.charset.StandardCharsets;
import java.util.*;

public class SapeConnection {
    private static final Logger logger = LoggerFactory.getLogger(SapeConnection.class);
    private final String version = "1.0.3";
    private final List<String> serverList = Arrays.asList("dispenser-01.sape.ru", "dispenser-02.sape.ru");
    private final String dispenserPath;
    private final String userAgent;
    private final int socketTimeout;
    private final int cacheLifeTime;

    public SapeConnection(String dispenserPath, String userAgent, int socketTimeout, int cacheLifeTime) {
        this.dispenserPath = dispenserPath;
        this.userAgent = userAgent;
        this.socketTimeout = socketTimeout;
        this.cacheLifeTime = cacheLifeTime;
    }

    protected String fetchRemoteFile(String host, String path) throws IOException {
        Reader r = null;

        try {
            HttpURLConnection connection = (HttpURLConnection) ((new URL(("http://" + host + path)).openConnection()));

            if (socketTimeout > 0) {
                connection.setConnectTimeout(socketTimeout);
                connection.setReadTimeout(socketTimeout);
            }

            connection.addRequestProperty("User-Agent", userAgent + ' ' + version);

            connection.setDoOutput(true);
            connection.setDoInput(true);
            connection.setUseCaches(false);
            connection.setRequestMethod("GET");
            connection.connect();

            r = new BufferedReader(new InputStreamReader(connection.getInputStream(), StandardCharsets.UTF_8));

            StringWriter sw = new StringWriter();

            int b;

            while ((b = r.read()) != -1) {
                sw.write(b);
            }

            return sw.toString();
        } finally {
            if (r != null) {
                r.close();
            }
        }
    }
    Site cachedSite;
    long cacheUpdated;

    public Optional<Site> getData() {
        if (cacheLifeTime <= (System.currentTimeMillis() - cacheUpdated) / 1000) {
            for (String server : serverList) {
                String data;

                try {
                    data = fetchRemoteFile(server, dispenserPath + "&charset=UTF-8&as_xml=true");
                } catch (IOException e1) {
                    continue;
                }

                if (data.startsWith("FATAL ERROR:")) {
                    logger.error("Sape responded with error: {}", data);

                    continue;
                }

                try {
                    cachedSite = Site.fromXMLData(data);
                } catch (Exception e) {
                    logger.error("Can't parse Sape data", e);
                    continue;
                }

                cacheUpdated = System.currentTimeMillis();

                return Optional.of(cachedSite);
            }

            logger.error("Unable to fetch Sape data");

            return Optional.empty();
        }

        return Optional.of(cachedSite);
    }
}