/**
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
 * with the License.  You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package org.apache.oozie.action.email;

import java.util.ArrayList;
import java.util.List;
import java.util.Properties;

import javax.mail.Authenticator;
import javax.mail.Message;
import javax.mail.Message.RecipientType;
import javax.mail.MessagingException;
import javax.mail.NoSuchProviderException;
import javax.mail.PasswordAuthentication;
import javax.mail.Session;
import javax.mail.Transport;
import javax.mail.internet.AddressException;
import javax.mail.internet.InternetAddress;
import javax.mail.internet.MimeMessage;

import org.apache.oozie.action.ActionExecutor;
import org.apache.oozie.action.ActionExecutorException;
import org.apache.oozie.action.ActionExecutorException.ErrorType;
import org.apache.oozie.client.WorkflowAction;
import org.apache.oozie.util.XmlUtils;
import org.jdom.Element;
import org.jdom.Namespace;

/**
 * Email action executor. It takes to, cc addresses along with a subject and body and sends
 * out an email.
 */
public class EmailActionExecutor extends ActionExecutor {

    public static final String CONF_PREFIX = "oozie.email.";
    public static final String EMAIL_SMTP_HOST = CONF_PREFIX + "smtp.host";
    public static final String EMAIL_SMTP_PORT = CONF_PREFIX + "smtp.port";
    public static final String EMAIL_SMTP_AUTH = CONF_PREFIX + "smtp.auth";
    public static final String EMAIL_SMTP_USER = CONF_PREFIX + "smtp.username";
    public static final String EMAIL_SMTP_PASS = CONF_PREFIX + "smtp.password";
    public static final String EMAIL_SMTP_FROM = CONF_PREFIX + "from.address";

    private final static String TO = "to";
    private final static String CC = "cc";
    private final static String SUB = "subject";
    private final static String BOD = "body";
    private final static String COMMA = ",";
    private final static String CONTENT_TYPE = "content_type";

    private final static String DEFAULT_CONTENT_TYPE = "text/plain";
    public EmailActionExecutor() {
        super("email");
    }

    @Override
    public void initActionType() {
        super.initActionType();
    }

    @Override
    public void start(Context context, WorkflowAction action) throws ActionExecutorException {
        try {
            context.setStartData("-", "-", "-");
            Element actionXml = XmlUtils.parseXml(action.getConf());
            validateAndMail(context, actionXml);
            context.setExecutionData("OK", null);
        }
        catch (Exception ex) {
            throw convertException(ex);
        }
    }

    @SuppressWarnings("unchecked")
    protected void validateAndMail(Context context, Element element) throws ActionExecutorException {
        // The XSD does the min/max occurrence validation for us.
        Namespace ns = element.getNamespace();
        String tos[] = new String[0];
        String ccs[] = new String[0];
        String subject = "";
        String body = "";
        String contentType;
        Element child = null;

        // <to> - One ought to exist.
        String text = element.getChildTextTrim(TO, ns);
        if (text.isEmpty()) {
            throw new ActionExecutorException(ErrorType.ERROR, "EM001", "No receipents were specified in the to-address field.");
        }
        tos = text.split(COMMA);

        // <cc> - Optional, but only one ought to exist.
        try {
            ccs = element.getChildTextTrim(CC, ns).split(COMMA);
        } catch (Exception e) {
            // It is alright for cc to be given empty or not be present.
            ccs = new String[0];
        }

        // <subject> - One ought to exist.
        subject = element.getChildTextTrim(SUB, ns);

        // <body> - One ought to exist.
        body = element.getChildTextTrim(BOD, ns);

        contentType = element.getChildTextTrim(CONTENT_TYPE, ns);
        if (contentType == null || contentType.isEmpty()) {
            contentType = DEFAULT_CONTENT_TYPE;
        }


        // All good - lets try to mail!
        email(context, tos, ccs, subject, body, contentType);
    }

    protected void email(Context context, String[] to, String[] cc, String subject, String body, String contentType)
            throws ActionExecutorException {
        // Get mailing server details.
        String smtpHost = getOozieConf().get(EMAIL_SMTP_HOST, "localhost");
        String smtpPort = getOozieConf().get(EMAIL_SMTP_PORT, "25");
        Boolean smtpAuth = getOozieConf().getBoolean(EMAIL_SMTP_AUTH, false);
        String smtpUser = getOozieConf().get(EMAIL_SMTP_USER, "");
        String smtpPassword = getOozieConf().get(EMAIL_SMTP_PASS, "");
        String fromAddr = getOozieConf().get(EMAIL_SMTP_FROM, "oozie@localhost");

        Properties properties = new Properties();
        properties.setProperty("mail.smtp.host", smtpHost);
        properties.setProperty("mail.smtp.port", smtpPort);
        properties.setProperty("mail.smtp.auth", smtpAuth.toString());

        Session session;
        // Do not use default instance (i.e. Session.getDefaultInstance)
        // (cause it may lead to issues when used second time).
        if (!smtpAuth) {
            session = Session.getInstance(properties);
        } else {
            session = Session.getInstance(properties, new JavaMailAuthenticator(smtpUser, smtpPassword));
        }

        Message message = new MimeMessage(session);
        InternetAddress from;
        List<InternetAddress> toAddrs = new ArrayList<InternetAddress>(to.length);
        List<InternetAddress> ccAddrs = new ArrayList<InternetAddress>(cc.length);

        try {
            from = new InternetAddress(fromAddr);
            message.setFrom(from);
        } catch (AddressException e) {
            throw new ActionExecutorException(ErrorType.ERROR, "EM002", "Bad from address specified in ${oozie.email.from.address}.", e);
        } catch (MessagingException e) {
            throw new ActionExecutorException(ErrorType.ERROR, "EM003", "Error setting a from address in the message.", e);
        }

        try {
            // Add all <to>
            for (String toStr : to) {
                toAddrs.add(new InternetAddress(toStr.trim()));
            }
            message.addRecipients(RecipientType.TO, toAddrs.toArray(new InternetAddress[0]));

            // Add all <cc>
            for (String ccStr : cc) {
                ccAddrs.add(new InternetAddress(ccStr.trim()));
            }
            message.addRecipients(RecipientType.CC, ccAddrs.toArray(new InternetAddress[0]));

            // Set subject
            message.setSubject(subject);
            message.setContent(body, contentType);
        } catch (AddressException e) {
            throw new ActionExecutorException(ErrorType.ERROR, "EM004", "Bad address format in <to> or <cc>.", e);
        } catch (MessagingException e) {
            throw new ActionExecutorException(ErrorType.ERROR, "EM005", "An error occured while adding recipients.", e);
        }

        try {
            // Send over SMTP Transport
            // (Session+Message has adequate details.)
            Transport.send(message);
        } catch (NoSuchProviderException e) {
            throw new ActionExecutorException(ErrorType.ERROR, "EM006", "Could not find an SMTP transport provider to email.", e);
        } catch (MessagingException e) {
            throw new ActionExecutorException(ErrorType.ERROR, "EM007", "Encountered an error while sending the email message over SMTP.", e);
        }
    }

    @Override
    public void end(Context context, WorkflowAction action) throws ActionExecutorException {
        String externalStatus = action.getExternalStatus();
        WorkflowAction.Status status = externalStatus.equals("OK") ? WorkflowAction.Status.OK :
                                       WorkflowAction.Status.ERROR;
        context.setEndData(status, getActionSignal(status));
    }

    @Override
    public void check(Context context, WorkflowAction action)
            throws ActionExecutorException {

    }

    @Override
    public void kill(Context context, WorkflowAction action)
            throws ActionExecutorException {

    }

    @Override
    public boolean isCompleted(String externalStatus) {
        return true;
    }

    public static class JavaMailAuthenticator extends Authenticator {

        String user;
        String password;

        public JavaMailAuthenticator(String user, String password) {
            this.user = user;
            this.password = password;
        }

        @Override
        protected PasswordAuthentication getPasswordAuthentication() {
           return new PasswordAuthentication(user, password);
        }
    }
}