/*

 *   SONEWS News Server

 *   see AUTHORS for the list of contributors

 *

 *   This program 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.

 *

 *   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 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.sonews.storage.impl;

import java.io.UnsupportedEncodingException;

import java.sql.Connection;

import java.sql.DriverManager;

import java.sql.PreparedStatement;

import java.sql.ResultSet;

import java.sql.SQLException;

import java.sql.Statement;

import java.util.ArrayList;

import java.util.Collections;

import java.util.List;

import java.util.logging.Level;

import java.util.logging.Logger;

import javax.mail.internet.MimeUtility;

import org.sonews.config.Config;

import org.sonews.feed.Subscription;

import org.sonews.storage.Article;

import org.sonews.storage.ArticleHead;

import org.sonews.storage.Group;

import org.sonews.storage.Storage;

import org.sonews.storage.StorageBackendException;

import org.sonews.util.Pair;

/**

 *

 * @author František Kučera (frantovo.cz)

 */

public class DrupalDatabase implements Storage {

	private static final Logger log = Logger.getLogger(DrupalDatabase.class.getName());

	public static final String CRLF = "\r\n";

	public static final int MAX_RESTARTS = 2;

	/** How many times the database connection was reinitialized */

	protected int restarts = 0;

	protected Connection conn = null;

	public DrupalDatabase() throws StorageBackendException {

		connectDatabase();

	}

	private void connectDatabase() throws StorageBackendException {

		try {

			// Load database driver

			String driverClass = Config.inst().get(Config.LEVEL_FILE, Config.STORAGE_DBMSDRIVER, "java.lang.Object");

			Class.forName(driverClass);

			// Establish database connection

			String url = Config.inst().get(Config.LEVEL_FILE, Config.STORAGE_DATABASE, "<not specified>");

			String username = Config.inst().get(Config.LEVEL_FILE, Config.STORAGE_USER, "root");

			String password = Config.inst().get(Config.LEVEL_FILE, Config.STORAGE_PASSWORD, "");

			conn = DriverManager.getConnection(url, username, password);

			conn.setTransactionIsolation(Connection.TRANSACTION_SERIALIZABLE);

			if (conn.getTransactionIsolation() != Connection.TRANSACTION_SERIALIZABLE) {

				log.warning("Database is NOT fully serializable!");

			}

		} catch (Exception e) {

			throw new StorageBackendException(e);

		}

	}

	protected static void close(Connection connection, Statement statement, ResultSet resultSet) {

		if (resultSet != null) {

			try {

				resultSet.close();

			} catch (Exception e) {

			}

		}

		if (statement != null) {

			try {

				statement.close();

			} catch (Exception e) {

			}

		}

		if (connection != null) {

			try {

				connection.close();

			} catch (Exception e) {

			}

		}

	}

	/**

	 * 

	 * @param messageID {0}-{1}-{2}@domain.tld where {0} is nntp_id and {1} is group_id and {2} is group_name

	 * @return array where [0] = nntp_id and [1] = group_id and [2] = group_name or returns null if messageID is invalid

	 */

	private static String[] parseMessageID(String messageID) {

		if (messageID.matches("[0-9]+\\-[0-9]+\\-[a-z0-9\\.]+@.+")) {

			return messageID.split("@")[0].split("\\-");

		} else {

			return null;

		}

	}

	private static Long parseArticleID(String messageID) {

		String[] localPart = parseMessageID(messageID);

		if (localPart == null) {

			return null;

		} else {

			return Long.parseLong(localPart[0]);

		}

	}

	private static Long parseGroupID(String messageID) {

		String[] localPart = parseMessageID(messageID);

		if (localPart == null) {

			return null;

		} else {

			return Long.parseLong(localPart[1]);

		}

	}

	private static String parseGroupName(String messageID) {

		String[] localPart = parseMessageID(messageID);

		if (localPart == null) {

			return null;

		} else {

			return localPart[2];

		}

	}

	private static String constructHeaders(ResultSet rs) throws SQLException, UnsupportedEncodingException {

		StringBuilder sb = new StringBuilder();

		sb.append("Message-id: ");

		sb.append(rs.getInt("id"));

		sb.append("-");

		sb.append(rs.getInt("group_id"));

		sb.append("-");

		sb.append(rs.getString("group_name"));

		sb.append("@");

		sb.append("nntp.kinderporno.cz");

		sb.append(CRLF);

		sb.append("From: ");

		sb.append(MimeUtility.encodeWord(rs.getString("sender_name")));

		sb.append(" <>");

		sb.append(CRLF);

		sb.append("Subject: ");

		sb.append(MimeUtility.encodeWord(rs.getString("subject")));

		sb.append(CRLF);

		return sb.toString();

	}

	@Override

	public List<Group> getGroups() throws StorageBackendException {

		PreparedStatement ps = null;

		ResultSet rs = null;

		try {

			ps = conn.prepareStatement("SELECT * FROM nntp_group");

			rs = ps.executeQuery();

			List<Group> skupiny = new ArrayList<Group>();

			while (rs.next()) {

				skupiny.add(new Group(rs.getString("name"), rs.getInt("id"), Group.READONLY));

			}

			return skupiny;

		} catch (Exception e) {

			throw new StorageBackendException(e);

		} finally {

			close(null, ps, rs);

		}

	}

	@Override

	public Group getGroup(String name) throws StorageBackendException {

		PreparedStatement ps = null;

		ResultSet rs = null;

		try {

			ps = conn.prepareStatement("SELECT * FROM nntp_group WHERE name = ?");

			ps.setString(1, name);

			rs = ps.executeQuery();

			while (rs.next()) {

				return new Group(rs.getString("name"), rs.getInt("id"), Group.READONLY);

			}

			return null;

		} catch (Exception e) {

			throw new StorageBackendException(e);

		} finally {

			close(null, ps, rs);

		}

	}

	@Override

	public boolean isGroupExisting(String groupname) throws StorageBackendException {

		return getGroup(groupname) != null;

	}

	@Override

	public Article getArticle(String messageID) throws StorageBackendException {

		Long articleID = parseArticleID(messageID);

		Long groupID = parseGroupID(messageID);

		if (articleID == null || groupID == null) {

			log.log(Level.SEVERE, "Invalid messageID: {0}", new Object[]{messageID});

			return null;

		} else {

			return getArticle(articleID, groupID);

		}

	}

	@Override

	public Article getArticle(long articleID, long groupID) throws StorageBackendException {

		PreparedStatement ps = null;

		ResultSet rs = null;

		try {

			ps = conn.prepareStatement("SELECT * FROM nntp_article WHERE id = ? AND group_id = ?");

			ps.setLong(1, articleID);

			ps.setLong(2, groupID);

			rs = ps.executeQuery();

			if (rs.next()) {

				String headers = constructHeaders(rs);

				byte[] body = rs.getString("text").getBytes();

				return new Article(headers, body);

			} else {

				return null;

			}

		} catch (Exception e) {

			throw new StorageBackendException(e);

		} finally {

			close(null, ps, rs);

		}

	}

	@Override

	public List<Pair<Long, ArticleHead>> getArticleHeads(Group group, long first, long last) throws StorageBackendException {

		PreparedStatement ps = null;

		ResultSet rs = null;

		try {

			ps = conn.prepareStatement("SELECT * FROM nntp_article WHERE group_id = ? AND id >= ? AND id <= ?");

			ps.setLong(1, group.getInternalID());

			ps.setLong(2, first);

			ps.setLong(3, last);

			rs = ps.executeQuery();

			List<Pair<Long, ArticleHead>> heads = new ArrayList<Pair<Long, ArticleHead>>();

			while (rs.next()) {

				String headers = constructHeaders(rs);

				heads.add(new Pair<Long, ArticleHead>(rs.getLong("id"), new ArticleHead(headers)));

			}

			return heads;

		} catch (Exception e) {

			throw new StorageBackendException(e);

		} finally {

			close(null, ps, rs);

		}

	}

	@Override

	public List<Pair<Long, String>> getArticleHeaders(Group group, long start, long end, String header, String pattern) throws StorageBackendException {

		log.log(Level.SEVERE, "TODO: getArticleHeaders {0} / {1} / {2} / {3} / {4}", new Object[]{group, start, end, header, pattern});

		/** TODO: */

		return Collections.emptyList();

	}

	@Override

	public long getArticleIndex(Article article, Group group) throws StorageBackendException {

		Long id = parseArticleID(article.getMessageID());

		if (id == null) {

			throw new StorageBackendException("Invalid messageID: " + article.getMessageID());

		} else {

			return id;

		}

	}

	@Override

	public List<Long> getArticleNumbers(long groupID) throws StorageBackendException {

		PreparedStatement ps = null;

		ResultSet rs = null;

		try {

			ps = conn.prepareStatement("SELECT id FROM nntp_article WHERE group_id = ?");

			ps.setLong(1, groupID);

			rs = ps.executeQuery();

			List<Long> articleNumbers = new ArrayList<Long>();

			while (rs.next()) {

				articleNumbers.add(rs.getLong(1));

			}

			return articleNumbers;

		} catch (Exception e) {

			throw new StorageBackendException(e);

		} finally {

			close(null, ps, rs);

		}

	}

	@Override

	public int getFirstArticleNumber(Group group) throws StorageBackendException {

		PreparedStatement ps = null;

		ResultSet rs = null;

		try {

			ps = conn.prepareStatement("SELECT min(id) FROM nntp_article WHERE group_id = ?");

			ps.setLong(1, group.getInternalID());

			rs = ps.executeQuery();

			rs.next();

			return rs.getInt(1);

		} catch (Exception e) {

			throw new StorageBackendException(e);

		} finally {

			close(null, ps, rs);

		}

	}

	@Override

	public int getLastArticleNumber(Group group) throws StorageBackendException {

		PreparedStatement ps = null;

		ResultSet rs = null;

		try {

			ps = conn.prepareStatement("SELECT max(id) FROM nntp_article WHERE group_id = ?");

			ps.setLong(1, group.getInternalID());

			rs = ps.executeQuery();

			rs.next();

			return rs.getInt(1);

		} catch (Exception e) {

			throw new StorageBackendException(e);

		} finally {

			close(null, ps, rs);

		}

	}

	@Override

	public boolean isArticleExisting(String messageID) throws StorageBackendException {

		Long articleID = parseArticleID(messageID);

		Long groupID = parseGroupID(messageID);

		if (articleID == null || groupID == null) {

			return false;

		} else {

			PreparedStatement ps = null;

			ResultSet rs = null;

			try {

				ps = conn.prepareStatement("SELECT count(*) FROM nntp_article WHERE id = ? AND group_id = ?");

				ps.setLong(1, articleID);

				ps.setLong(2, groupID);

				rs = ps.executeQuery();

				rs.next();

				return rs.getInt(1) == 1;

			} catch (Exception e) {

				throw new StorageBackendException(e);

			} finally {

				close(null, ps, rs);

			}

		}

	}

	//

	// --- zatím neimplementovat ---

	//

	@Override

	public void addArticle(Article art) throws StorageBackendException {

		log.log(Level.SEVERE, "TODO: addArticle {0}", new Object[]{art});

	}

	@Override

	public void addEvent(long timestamp, int type, long groupID) throws StorageBackendException {

		log.log(Level.SEVERE, "TODO: addEvent {0} / {1} / {2}", new Object[]{timestamp, type, groupID});

	}

	@Override

	public void addGroup(String groupname, int flags) throws StorageBackendException {

		log.log(Level.SEVERE, "TODO: addGroup {0} / {1}", new Object[]{groupname, flags});

	}

	@Override

	public int countArticles() throws StorageBackendException {

		log.log(Level.SEVERE, "TODO: countArticles");

		return 0;

	}

	@Override

	public int countGroups() throws StorageBackendException {

		log.log(Level.SEVERE, "TODO: countGroups");

		return 0;

	}

	@Override

	public void delete(String messageID) throws StorageBackendException {

		log.log(Level.SEVERE, "TODO: delete {0}", new Object[]{messageID});

	}

	@Override

	public String getConfigValue(String key) throws StorageBackendException {

		log.log(Level.SEVERE, "TODO: getConfigValue {0}", new Object[]{key});

		return null;

	}

	@Override

	public int getEventsCount(int eventType, long startTimestamp, long endTimestamp, Group group) throws StorageBackendException {

		log.log(Level.SEVERE, "TODO: getEventsCount {0} / {1} / {2} / {3}", new Object[]{eventType, startTimestamp, endTimestamp, group});

		return 0;

	}

	@Override

	public double getEventsPerHour(int key, long gid) throws StorageBackendException {

		log.log(Level.SEVERE, "TODO: getEventsPerHour {0} / {1}", new Object[]{key, gid});

		return 0;

	}

	@Override

	public List<String> getGroupsForList(String listAddress) throws StorageBackendException {

		log.log(Level.SEVERE, "TODO: getGroupsForList {0}", new Object[]{listAddress});

		return Collections.emptyList();

	}

	@Override

	public List<String> getListsForGroup(String groupname) throws StorageBackendException {

		log.log(Level.SEVERE, "TODO: getListsForGroup {0}", new Object[]{groupname});

		return Collections.emptyList();

	}

	@Override

	public String getOldestArticle() throws StorageBackendException {

		log.log(Level.SEVERE, "TODO: getOldestArticle");

		return null;

	}

	@Override

	public int getPostingsCount(String groupname) throws StorageBackendException {

		log.log(Level.SEVERE, "TODO: getPostingsCount {0}", new Object[]{groupname});

		return 0;

	}

	@Override

	public List<Subscription> getSubscriptions(int type) throws StorageBackendException {

		log.log(Level.SEVERE, "TODO: getSubscriptions {0}", new Object[]{type});

		return Collections.emptyList();

	}

	@Override

	public void purgeGroup(Group group) throws StorageBackendException {

		log.log(Level.SEVERE, "TODO: purgeGroup {0}", new Object[]{group});

	}

	@Override

	public void setConfigValue(String key, String value) throws StorageBackendException {

		log.log(Level.SEVERE, "TODO: setConfigValue {0} = {1}", new Object[]{key, value});

	}

	@Override

	public boolean update(Article article) throws StorageBackendException {

		log.log(Level.SEVERE, "TODO: update {0}", new Object[]{article});

		throw new StorageBackendException("Not implemented yet.");

	}

	@Override

	public boolean update(Group group) throws StorageBackendException {

		log.log(Level.SEVERE, "TODO: update {0}", new Object[]{group});

		throw new StorageBackendException("Not implemented yet.");

	}

}