package nabble.model;

import fschmidt.util.mail.Content;
import fschmidt.util.mail.Mail;
import fschmidt.util.mail.MailAddress;
import fschmidt.util.mail.MailHome;
import fschmidt.util.mail.MailParseException;
import fschmidt.util.mail.MixedMultipartContent;
import fschmidt.util.mail.PlainTextContent;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import java.util.ArrayList;
import java.util.Date;
import java.util.List;


final class MailSubsystem {
	private static final Logger logger = LoggerFactory.getLogger(MailSubsystem.class);

	private MailSubsystem() {}  // never

	/**
	 * Send an error message.
	 *
	 * @param mail      a mail caused a message, may be null
	 * @param mailTo    sent error message to
	 * @param subject   message subject
	 * @param errorText error text
	 */
	static void sendErrorMail(Mail mail, MailAddress mailTo, String subject, String errorText) {
		Mail errMail = MailHome.newMail();
		errMail.setFrom(new MailAddress(ModelHome.noReply));
		errMail.setTo(mailTo);
		errMail.setSubject(subject);
		errMail.setSentDate(new Date());
		Content content = (mail != null) ?
				new MixedMultipartContent(new Content[]{
						new PlainTextContent(errorText),
						mail,
				}) :
				new MixedMultipartContent(new Content[]{
						new PlainTextContent(errorText)
				});
		errMail.setContent(content);
		ModelHome.send(errMail);
	}

/*
	static String stripBrackets(String s) {
		if (s == null) return null;
		int start = s.lastIndexOf('<');
		int end = s.lastIndexOf('>');
		if (start >= 0 && end > start)
			s = s.substring(start + 1, end);
		return s.trim();
	}
*/
	static String stripBrackets(String s) {
		int start = s.lastIndexOf('<');
		int end = s.indexOf('>');
		if( start == -1 && end == -1 )
			return s;
		if( start == -1 || end < start )
			throw new MailParseException("no brackets found in '"+s+"'");
		return s.substring(start + 1, end);
	}

	static List<String> stripMultiBrackets(final String s) {
		List<String> list = new ArrayList<String>();
		for( int i=0; i<s.length(); ) {
			int start = s.indexOf('<',i);
			int end = s.indexOf('>',i);
			if( start == -1 && end == -1 )
				break;
			if( start == -1 || end < start )
				throw new MailParseException("malformed brackets found in '"+s+"'");
			list.add( s.substring(start + 1, end) );
			i = end + 1;
		}
		return list;
	}




	/**
	 * Prepare message headers for sending
	 *
	 * @param mail	   to prepare
	 * @param node	   node to be sent
	 */
	static void setHeaders(Mail mail, NodeImpl node) {
		mail.setSentDate(new Date());
		mail.setMessageID("<" + node.getOrGenerateMessageID() + ">");
		NodeImpl parent = node.getParentImpl();
		if (parent != null && parent.getKind() != Node.Kind.APP) {
			mail.setHeader("In-Reply-To", "<" + parent.getOrGenerateMessageID() + ">");
			mail.setHeader("References", getReferences(parent, 0).trim());
		}
	}

	private static final int MAX_REFERENCES = 10;

	private static String getReferences(NodeImpl node, int count) {
		return (node == null || node.getKind() == Node.Kind.APP || count==MAX_REFERENCES) ?
				"" :
				getReferences(node.getParentImpl(), count+1) + " <" + node.getOrGenerateMessageID() + ">";
	}


	static String getReturnPath(Mail mail) {
		String[] a = mail.getHeader("Return-path");
		return a==null ? null : MailSubsystem.stripBrackets(a[0]);
	}

	static void bounce(Mail mail,String msg) {
		Mail bounce = MailHome.newMail();
		bounce.setFrom( new MailAddress(ModelHome.noReply,"Nabble") );
		bounce.setTo( new MailAddress(getReturnPath(mail)) );
		bounce.setSubject( "Delivery Status Notification (Failure)" );
		bounce.setHeader( "X-Failed-Recipients", mail.getHeader("Envelope-To") );
		StringBuilder content = new StringBuilder();
		content
			.append( msg )
			.append( "\n----- Original message -----\n\n" )
			.append( mail.getRawInput() )
		;
		bounce.setContent(new PlainTextContent(content.toString()));
		ModelHome.send(bounce);
	}
}