[GitHub] [james-project] ottoka commented on a diff in pull request #1004: James 3758 Endpoint to delete old emails from INBOXes

[GitBox <gi...@apache.org>]

ottoka commented on code in PR #1004:
URL: https://github.com/apache/james-project/pull/1004#discussion_r875572072


##########
mailet/standard/src/main/java/org/apache/james/transport/mailets/Expires.java:
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@@ -0,0 +1,144 @@
+/****************************************************************
+ * 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.james.transport.mailets;
+
+import java.io.StringReader;
+import java.time.Duration;
+import java.time.ZoneOffset;
+import java.time.ZonedDateTime;
+import java.time.temporal.ChronoUnit;
+import java.util.Optional;
+import java.util.function.Supplier;
+
+import javax.mail.MessagingException;
+import javax.mail.internet.MimeMessage;
+
+import org.apache.james.mime4j.dom.datetime.DateTime;
+import org.apache.james.mime4j.field.datetime.parser.DateTimeParser;
+import org.apache.james.mime4j.field.datetime.parser.ParseException;
+import org.apache.james.util.DurationParser;
+import org.apache.mailet.Mail;
+import org.apache.mailet.base.DateFormats;
+import org.apache.mailet.base.GenericMailet;
+
+
+/**
+ * <p>Adds an Expires header to the message, or enforces the period of an existing one.</p>
+ *
+ * <p>Sample configuration:</p>
+ *
+ * <pre><code>
+ * &lt;mailet match="All" class="Expires"&gt;
+ *   &lt;minAge&gt;1d&lt;/minAge&gt;
+ *   &lt;maxAge&gt;1w&lt;/maxAge&gt;
+ *   &lt;defaultAge&gt;4w&lt;/defaultAge&gt;
+ * &lt;/mailet&gt;
+ * </code></pre>
+ *
+ * @version 1.0.0, 2021-12-14
+ */
+public class Expires extends GenericMailet {
+    
+    public static final String EXPIRES = "Expires";
+    
+    Supplier<ZonedDateTime> timeSource = ZonedDateTime::now; 
+
+    private Optional<Duration> minAge = Optional.empty();
+    private Optional<Duration> maxAge = Optional.empty();
+    private Optional<Duration> defaultAge = Optional.empty();
+    
+    @Override
+    public void init() throws MessagingException {
+        minAge = parseDuration("minAge");
+        maxAge = parseDuration("maxAge");
+        defaultAge = parseDuration("defaultAge");
+
+        if (minAge.isEmpty() && maxAge.isEmpty() && defaultAge.isEmpty()) {
+            throw new MessagingException("Please configure at least one of minAge, maxAge, defaultAge");
+        }
+
+        if (isAfter(minAge, maxAge)) {
+            throw new MessagingException("minAge must be before maxAge");
+        }
+        if (isAfter(defaultAge, maxAge)) {
+            throw new MessagingException("defaultAge must be before maxAge");
+        }
+        if (isAfter(minAge, defaultAge)) {
+            throw new MessagingException("minAge must be before defaultAge");
+        }
+    }
+
+    @Override
+    public void service(Mail mail) throws MessagingException {
+        ZonedDateTime now = timeSource.get();
+        MimeMessage message = mail.getMessage();
+        Optional<ZonedDateTime> expires = parseExpiresHeader(message);
+        if (expires.isPresent()) {
+            if (minAge.isPresent() && expires.get().isBefore(now.plus(minAge.get()))) {
+                setExpiresAfter(message, now, minAge.get());
+            } else
+            if (maxAge.isPresent() && expires.get().isAfter(now.plus(maxAge.get()))) {
+                setExpiresAfter(message, now, maxAge.get());
+            }
+        } else if (defaultAge.isPresent()) {
+            setExpiresAfter(message, now, defaultAge.get());
+        }
+    }
+
+    @Override
+    public String getMailetInfo() {
+        return "Expire Mailet";
+    }
+
+    private Optional<Duration> parseDuration(String param) {
+        String duration = getInitParameter(param);
+        if (duration == null) {
+            return Optional.empty();
+        } else {
+            return Optional.of(DurationParser.parse(duration, ChronoUnit.DAYS));
+        }
+    }
+    
+    private boolean isAfter(Optional<Duration> a, Optional<Duration> b) {
+        return a.isPresent() && b.isPresent() && a.get().compareTo(b.get()) > 0;
+    }
+    
+    private Optional<ZonedDateTime> parseExpiresHeader(MimeMessage message) {
+        try {
+            String[] expires = message.getHeader(EXPIRES);
+            if (expires == null || expires.length == 0) {
+                return Optional.empty();
+            } else {
+                DateTime dt = new DateTimeParser(new StringReader(expires[0])).parseAll();
+                return Optional.of(ZonedDateTime.of(
+                    dt.getYear(), dt.getMonth(), dt.getDay(),
+                    dt.getHour(), dt.getMinute(), dt.getSecond(), 0,
+                    ZoneOffset.ofHoursMinutes(dt.getTimeZone() / 100, dt.getTimeZone() % 100)));

Review Comment:
   I assumed this was the right way of doing it, since MessageSearches uses DateTimeParser as well. In its defense, it nicely ignores any extra zone info some mail programs like to add, like (CEST) or [Berlin]. Plus it actually preserves the zone offset, giving us a proper DateTime. 
   Of course, I can change it over to another parser. DateTimeFieldLenientImpl.PARSER seems to be somewhat strict for this purpose, would require additional input string sanitation before use. What about javax.mail.internet.MailDateFormat ?



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