/*

 *   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;

import java.io.BufferedReader;

import java.io.ByteArrayOutputStream;

import java.io.IOException;

import java.io.InputStream;

import java.io.InputStreamReader;

import java.io.PrintStream;

import java.io.StringReader;

import java.io.StringWriter;

import java.io.UnsupportedEncodingException;

import java.sql.ResultSet;

import java.sql.SQLException;

import java.util.ArrayList;

import java.util.Date;

import java.util.Enumeration;

import java.util.logging.Level;

import java.util.logging.Logger;

import javax.mail.Header;

import javax.mail.MessagingException;

import javax.mail.Multipart;

import javax.mail.Session;

import javax.mail.internet.InternetAddress;

import javax.mail.internet.MimeBodyPart;

import javax.mail.internet.MimeMessage;

import javax.mail.internet.MimeMultipart;

import javax.xml.transform.Transformer;

import javax.xml.transform.TransformerFactory;

import javax.xml.transform.stream.StreamResult;

import javax.xml.transform.stream.StreamSource;

import org.sonews.util.io.Resource;

/**

 * This is MimeMessage which enables custom Message-ID header

 * (this header will not be overwritten by the default one like in MimeMessage).

 * 

 * Also add header and body separate serialization.

 * 

 * And can be deserialized from SQL ResultSet

 * 

 * @author František Kučera (frantovo.cz)

 */

public class DrupalMessage extends MimeMessage {

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

	private static final String MESSAGE_ID_HEADER = "Message-ID";

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

	public static final String CHARSET = "UTF-8";

	private static final String XHTML_CONTENT_TYPE = "text/html; charset=" + CHARSET;

	private String messageID;

	/**

	 * Constructs MIME message from SQL result.

	 * @param rs ResultSet containing message data. No {@link ResultSet#next()} will be called, just values from current row will be read.

	 * @param constructBody true if whole message should be constructed | false if we need only message headers (body will be dummy).

	 */

	public DrupalMessage(ResultSet rs, String myDomain, boolean constructBody) throws SQLException, UnsupportedEncodingException, MessagingException {

		super(Session.getDefaultInstance(System.getProperties()));

		addHeader("Message-id", constructMessageId(rs.getInt("id"), rs.getInt("group_id"), rs.getString("group_name"), myDomain));

		addHeader("Newsgroups", rs.getString("group_name"));

		setFrom(new InternetAddress(rs.getString("sender_email"), rs.getString("sender_name")));

		setSubject(rs.getString("subject"));

		setSentDate(new Date(rs.getLong("created")));

		int parentID = rs.getInt("parent_id");

		if (parentID > 0) {

			String parentMessageID = constructMessageId(parentID, rs.getInt("group_id"), rs.getString("group_name"), myDomain);

			addHeader("In-Reply-To", parentMessageID);

			addHeader("References", parentMessageID);

		}

		if (constructBody) {

			Multipart multipart = new MimeMultipart("alternative");

			setContent(multipart);

			/** XHTML part */

			MimeBodyPart htmlPart = new MimeBodyPart();

			String xhtmlText = readXhtmlText(rs);

			htmlPart.setContent(xhtmlText, XHTML_CONTENT_TYPE);

			/** Plain text part */

			MimeBodyPart textPart = new MimeBodyPart();

			textPart.setText(readPlainText(rs, xhtmlText));

			/**

			 * Thunderbirdu záleží, v jakém pořadí části jsou 

			 * (když je prostý text druhý, html se nezobrazí),

			 * KNode zobrazuje HTML správně, i když je na prvním místě.

			 */

			multipart.addBodyPart(textPart);

			multipart.addBodyPart(htmlPart);

		} else {

			/** empty body, just headers */

			setText("");

		}

	}

	private String readPlainText(ResultSet rs, String xhtmlText) {

		/**

		 * TODO: převést na prostý text

		 */

		return "TODO: obyčejný text\n(zatím čtěte XHTML verzi)";

	}

	private String readXhtmlText(ResultSet rs) {

		/**

		 * TODO: 

		 *		- znovupoužívat XSL transformér

		 *		- používat cache, ukládat si vygenerované články

		 */

		try {

			String inputText = makeSimpleXHTML(rs.getString("text"));

			TransformerFactory tf = TransformerFactory.newInstance();

			Transformer paragraphTransformer = tf.newTransformer(new StreamSource(Resource.getAsStream("helpers/mimeXhtmlPart-make-paragraphs.xsl")));

			String paragraphedText;

			boolean tidyWasUsed = false;

			try {

				StringReader input = new StringReader(inputText);

				StringWriter output = new StringWriter(2 * inputText.length());

				paragraphTransformer.transform(new StreamSource(input), new StreamResult(output));

				paragraphedText = output.toString();

			} catch (Exception e) {

				log.log(Level.FINER, "HTML input was shitty – Tidy had to be called.", e);

				StringReader input = new StringReader(tidyXhtml(inputText));

				StringWriter output = new StringWriter(2 * inputText.length());

				paragraphTransformer.transform(new StreamSource(input), new StreamResult(output));

				paragraphedText = output.toString();

				tidyWasUsed = true;

			}

			Transformer xhtmlTransformer = tf.newTransformer(new StreamSource(Resource.getAsStream("helpers/mimeXhtmlPart.xsl")));

			xhtmlTransformer.setParameter("isRoot", (rs.getInt("parent_id") == 0));

			xhtmlTransformer.setParameter("title", rs.getString("subject"));

			xhtmlTransformer.setParameter("urlBase", rs.getString("urlBase"));

			xhtmlTransformer.setParameter("wwwRead", rs.getString("wwwRead"));

			xhtmlTransformer.setParameter("wwwPost", rs.getString("wwwPost"));

			xhtmlTransformer.setParameter("headComment", String.format("Drupal-NNTP bridge. Transformed: %1$tc. Tidy had to be used: %2$b", new Date(), tidyWasUsed));

			StringReader input = new StringReader(paragraphedText);

			StringWriter output = new StringWriter(2 * paragraphedText.length());

			xhtmlTransformer.transform(new StreamSource(input), new StreamResult(output));

			return output.toString();

		} catch (Exception e) {

			/**

			 * TODO: lepší ošetření chyby

			 */

			log.log(Level.WARNING, "Error while transforming article to XHTML", e);

			return makeSimpleXHTML("<p>Při transformaci příspěvku bohužel došlo k chybě.</p>");

		}

	}

	private static String makeSimpleXHTML(String body) {

		return "<html xmlns=\"http://www.w3.org/1999/xhtml\"><body>" + body + "</body></html>";

	}

	/**

	 * TODO: refaktorovat, přesunout

	 */

	private static String tidyXhtml(String inputText) throws IOException {

		// https://sourceforge.net/tracker/index.php?func=detail&aid=3424437&group_id=27659&atid=390966

		inputText = inputText.replaceAll("\\n", "◆\n");

		Runtime r = Runtime.getRuntime();

		Process p = r.exec(new String[]{"tidy", // http://tidy.sourceforge.net

					"-asxml", // well formed XHTML

					"-numeric", // číselné entity

					"-utf8", // kódování

					"--show-warnings", "false", // žádná varování nás nezajímají

					"--show-errors", "0", // ani chyby

					"--doctype", "omit", // doctype nepotřebujeme (doplníme si případně vlastní v XSLT)

					"--logical-emphasis", "true", // em a strong místo i a b

					"--literal-attributes", "true", // zachovat mezery a konce řádků v atributech

					"--force-output", "true" // neznámé značky zahodíme, vložíme jen jejich obsah

				});

		PrintStream vstupProcesu = new PrintStream(p.getOutputStream());

		vstupProcesu.print(inputText);

		vstupProcesu.close();

		String outputText = streamToString(p.getInputStream());

		outputText = outputText.replaceAll("◆\\n", "\n");

		outputText = outputText.replaceAll("◆", "\n");

		return outputText;

	}

	/**

	 * TODO: refaktorovat, přesunout

	 */

	private static String streamToString(InputStream proud) throws IOException {

		StringBuilder výsledek = new StringBuilder();

		BufferedReader buf = new BufferedReader(new InputStreamReader(proud));

		while (true) {

			String radek = buf.readLine();

			if (radek == null) {

				break;

			} else {

				výsledek.append(radek);

				výsledek.append("\n");

			}

		}

		return výsledek.toString();

	}

	private static String constructMessageId(int articleID, int groupID, String groupName, String domainName) {

		StringBuilder sb = new StringBuilder();

		sb.append("<");

		sb.append(articleID);

		sb.append("-");

		sb.append(groupID);

		sb.append("-");

		sb.append(groupName);

		sb.append("@");

		sb.append(domainName);

		sb.append(">");

		return sb.toString();

	}

	@Override

	public void setHeader(String name, String value) throws MessagingException {

		super.setHeader(name, value);

		if (MESSAGE_ID_HEADER.equalsIgnoreCase(name)) {

			messageID = value;

		}

	}

	@Override

	public final void addHeader(String name, String value) throws MessagingException {

		super.addHeader(name, value);

		if (MESSAGE_ID_HEADER.equalsIgnoreCase(name)) {

			messageID = value;

		}

	}

	@Override

	public void removeHeader(String name) throws MessagingException {

		super.removeHeader(name);

		if (MESSAGE_ID_HEADER.equalsIgnoreCase(name)) {

			messageID = null;

		}

	}

	public void setMessageID(String messageID) {

		this.messageID = messageID;

	}

	@Override

	protected void updateMessageID() throws MessagingException {

		if (messageID == null) {

			super.updateMessageID();

		} else {

			setHeader(MESSAGE_ID_HEADER, messageID);

		}

	}

	/**

	 * Call {@link #saveChanges()} before this method, if you want all headers including such ones like:

	 * 

	 * <pre>MIME-Version: 1.0

	 *Content-Type: multipart/alternative;</pre>

	 * 

	 * @return serialized headers

	 * @throws MessagingException if getAllHeaders() fails

	 */

	public String getHeaders() throws MessagingException {

		StringBuilder sb = new StringBuilder();

		for (Enumeration eh = getAllHeaderLines(); eh.hasMoreElements();) {

			sb.append(eh.nextElement());

			sb.append(CRLF);

		}

		return sb.toString();

	}

	public byte[] getBody() throws IOException, MessagingException {

		saveChanges();

		ArrayList<String> skipHeaders = new ArrayList<String>();

		for (Enumeration eh = getAllHeaders(); eh.hasMoreElements();) {

			Header h = (Header) eh.nextElement();

			skipHeaders.add(h.getName());

		}

		ByteArrayOutputStream baos = new ByteArrayOutputStream(1024);

		writeTo(baos, skipHeaders.toArray(new String[skipHeaders.size()]));

		return baos.toByteArray();

	}

}