working on dropping old mails

src/main/java/de/srsoftware/widerhall/data/Database.java

@@ -11,6 +11,7 @@ import java.sql.SQLException;
 import java.util.*;
 
 import static de.srsoftware.widerhall.Util.t;
+import static de.srsoftware.widerhall.data.MailingList.HOLD_TIME;
 
 /**
  * @author Stephan Richter, 2022
@@ -280,9 +281,30 @@ public class Database {
         if (!tableExists(MailingList.TABLE_NAME)) MailingList.createTable();
         if (!tableExists(ListMember.TABLE_NAME)) ListMember.createTable();
         if (!tableExists(Post.TABLE_NAME)) Post.createTable();
+        if (!columnExists(MailingList.TABLE_NAME,HOLD_TIME)) MailingList.createHoldTimeColumn();
         return this;
     }
 
+    private boolean columnExists(String tableName, String columnName) throws SQLException {
+        var rs = Database.open().select("pragma_table_info('"+tableName+"')","COUNT(*) AS num").where("name",columnName).compile().exec();
+        try {
+            if (rs.next()) return rs.getInt("num") > 0;
+        } finally {
+            rs.close();
+        }
+        return false;
+    }
+
+    public void createColumn(String tableName, String colName, String...typeArgs) throws SQLException {
+        var sql = new StringBuilder("ALTER TABLE ")
+                .append(tableName)
+                .append(" ADD COLUMN ")
+                .append(colName)
+                .append(" ")
+                .append(String.join(" ",typeArgs));
+        new Request(sql).compile().run();
+    }
+
     /**
      * prepare a deletion statement
      * @param tableName

src/main/java/de/srsoftware/widerhall/data/MailingList.java

@@ -12,6 +12,7 @@ import org.stringtemplate.v4.ST;
 import javax.mail.*;
 import javax.mail.internet.AddressException;
 import javax.mail.internet.InternetAddress;
+import javax.xml.crypto.Data;
 import java.io.*;
 import java.sql.ResultSet;
 import java.sql.SQLException;
@@ -27,14 +28,16 @@ import static de.srsoftware.widerhall.data.User.PERMISSION_ADMIN;
  * this class encapsulates a MailingList db object
  */
 public class MailingList implements MessageHandler, ProblemListener {
-    public static final String KEY_FORWARD_FROM = "forward_from";
+    public static final String KEY_ARCHIVE = "archive";
+    public static final String KEY_DELETE_MESSAGES = "delete_messages";
     public static final String KEY_FORWARD_ATTACHED = "forward_attached";
+    public static final String KEY_FORWARD_FROM = "forward_from";
     public static final String KEY_HIDE_RECEIVERS = "hide_receivers";
-    public static final String KEY_REPLY_TO_LIST = "reply_to_list";
+    public static final String KEY_MODS_CAN_EDIT_MODS = "edit_mods";
     public static final String KEY_OPEN_FOR_GUESTS = "open_for_guests";
     public static final String KEY_OPEN_FOR_SUBSCRIBERS = "open_for_subscribers";
-    public static final String KEY_ARCHIVE = "archive";
-    public static final String KEY_MODS_CAN_EDIT_MODS = "edit_mods";
+    public static final String KEY_REPLY_TO_LIST = "reply_to_list";
+    public static final String HOLD_TIME = "hold_time";
     private static final Logger LOG = LoggerFactory.getLogger(MailingList.class);
     private static final String IMAP_HOST = "imap_host";
     private static final String IMAP_PORT = "imap_port";
@@ -68,6 +71,7 @@ public class MailingList implements MessageHandler, ProblemListener {
     private ImapClient imap;
 
     private static final HashMap<String,MailingList> cache = new HashMap<>();
+    private Integer holdTime = null;
 
     /**
      * create a new ML object
@@ -123,6 +127,10 @@ public class MailingList implements MessageHandler, ProblemListener {
         return new MailingList(email, name, imapHost, imapPort, imapUser, imapPass, inbox, smtpHost, smtpPort, smtpUser, smtpPass, DEFAULT_STATE).save();
     }
 
+    public static void createHoldTimeColumn() throws SQLException {
+        Database.open().createColumn(TABLE_NAME,HOLD_TIME,INT);
+    }
+
     /**
      * create underlying db table
      * @throws SQLException
@@ -148,6 +156,20 @@ public class MailingList implements MessageHandler, ProblemListener {
         Database.open().query(sql).compile().run();
     }
 
+    public void deleteMessages(boolean enable, String daysString) {
+        try {
+            holdTime = enable ? Integer.parseInt(daysString) : null;
+            Database.open().update(TABLE_NAME).set(HOLD_TIME, holdTime).run();
+        } catch (SQLException throwables) {
+            LOG.warn("Failed to update {} setting!",HOLD_TIME);
+        }
+    }
+
+    private void dropOldMails() throws MessagingException {
+        if (holdTime == null) return;
+        imap.dropMailsOlderThan(holdTime);
+    }
+
     public String email() {
         return email;
     }
@@ -226,6 +248,10 @@ public class MailingList implements MessageHandler, ProblemListener {
         return setFlag(STATE_HIDE_RECEIVERS,hide);
     }
 
+    public Integer holdTime() {
+        return holdTime;
+    }
+
     /**
      * test, whether the current ML is subscribable by a given user
      * @param user
@@ -435,7 +461,7 @@ public class MailingList implements MessageHandler, ProblemListener {
         } catch (SQLException e){
             LOG.warn("Failed to process message '{}'",subject,e);
         }
-
+        dropOldMails();
     }
 
     public MailingList openForGuests(boolean open) throws SQLException {