[server] Handle image version deletion, interface for sending mails (no SMTP yet)

10 files changed, 502 insertions, 143 deletions

diff --git a/dozentenmodulserver/src/main/java/org/openslx/bwlp/sat/database/mappers/DbImage.java b/dozentenmodulserver/src/main/java/org/openslx/bwlp/sat/database/mappers/DbImage.java
index 0f925371..9aee00b8 100644
--- a/dozentenmodulserver/src/main/java/org/openslx/bwlp/sat/database/mappers/DbImage.java
+++ b/dozentenmodulserver/src/main/java/org/openslx/bwlp/sat/database/mappers/DbImage.java
@@ -14,8 +14,9 @@ import org.openslx.bwlp.sat.database.MysqlConnection;
 import org.openslx.bwlp.sat.database.MysqlStatement;
 import org.openslx.bwlp.sat.database.Paginator;
 import org.openslx.bwlp.sat.database.models.LocalImageVersion;
-import org.openslx.bwlp.sat.fileserv.FileServer;
+import org.openslx.bwlp.sat.maintenance.Mailer;
 import org.openslx.bwlp.sat.permissions.User;
+import org.openslx.bwlp.sat.util.FileSystem;
 import org.openslx.bwlp.sat.util.Util;
 import org.openslx.bwlp.thrift.iface.ImageBaseWrite;
 import org.openslx.bwlp.thrift.iface.ImageDetailsRead;
@@ -86,7 +87,7 @@ public class DbImage {
 					+ " FROM imagebase i"
 					+ " LEFT JOIN imagepermission perm ON (i.imagebaseid = perm.imagebaseid AND perm.userid = :userid)"
 					+ " WHERE i.imagebaseid = :imagebaseid");
-			stmt.setString("userid", user.userId);
+			stmt.setString("userid", user == null ? "-" : user.userId);
 			stmt.setString("imagebaseid", imageBaseId);
 			ResultSet rs = stmt.executeQuery();
 			if (!rs.next())
@@ -120,8 +121,8 @@ public class DbImage {
 			if (!rs.next())
 				throw new TNotFoundException();
 			return new LocalImageVersion(rs.getString("imageversionid"), rs.getString("imagebaseid"),
-					rs.getString("filepath"), rs.getLong("filesize"), rs.getLong("createtime"), rs.getLong("expiretime"),
-					rs.getBoolean("isvalid"));
+					rs.getString("filepath"), rs.getLong("filesize"), rs.getLong("createtime"),
+					rs.getLong("expiretime"), rs.getBoolean("isvalid"));
 		} catch (SQLException e) {
 			LOGGER.error("Query failed in DbImage.getLocalImageData()", e);
 			throw e;
@@ -138,13 +139,14 @@ public class DbImage {
 		List<LocalImageVersion> list = new ArrayList<>();
 		while (rs.next()) {
 			list.add(new LocalImageVersion(rs.getString("imageversionid"), rs.getString("imagebaseid"),
-					rs.getString("filepath"), rs.getLong("filesize"), rs.getLong("createtime"), rs.getLong("expiretime"),
-					rs.getBoolean("isvalid")));
+					rs.getString("filepath"), rs.getLong("filesize"), rs.getLong("createtime"),
+					rs.getLong("expiretime"), rs.getBoolean("isvalid")));
 		}
 		return list;
 	}
 
-	public static List<LocalImageVersion> getExpiringLocalImageVersions(int maxRemainingDays) throws SQLException {
+	public static List<LocalImageVersion> getExpiringLocalImageVersions(int maxRemainingDays)
+			throws SQLException {
 		try (MysqlConnection connection = Database.getConnection()) {
 			MysqlStatement stmt = connection.prepareStatement("SELECT"
 					+ " imageversionid, imagebaseid, filepath, filesize, createtime, expiretime, isvalid"
@@ -154,8 +156,8 @@ public class DbImage {
 			List<LocalImageVersion> list = new ArrayList<>();
 			while (rs.next()) {
 				list.add(new LocalImageVersion(rs.getString("imageversionid"), rs.getString("imagebaseid"),
-						rs.getString("filepath"), rs.getLong("filesize"), rs.getLong("createtime"), rs.getLong("expiretime"),
-						rs.getBoolean("isvalid")));
+						rs.getString("filepath"), rs.getLong("filesize"), rs.getLong("createtime"),
+						rs.getLong("expiretime"), rs.getBoolean("isvalid")));
 			}
 			return list;
 		} catch (SQLException e) {
@@ -492,7 +494,8 @@ public class DbImage {
 			baseStmt.setString("imageversionid", imageVersionId);
 			baseStmt.setString("imagebaseid", imageBaseId);
 			baseStmt.executeUpdate();
-			LocalImageVersion liv = new LocalImageVersion(imageVersionId, imageBaseId, filePath, fileSize, nowSecs, expireTime, true);
+			LocalImageVersion liv = new LocalImageVersion(imageVersionId, imageBaseId, filePath, fileSize,
+					nowSecs, expireTime, true);
 			DbLecture.autoUpdateUsedImage(connection, imageBaseId, liv);
 			setLatestVersion(connection, imageBaseId, liv);
 			connection.commit();
@@ -502,8 +505,8 @@ public class DbImage {
 		}
 	}
 
-	protected static void markValid(MysqlConnection connection, boolean valid, LocalImageVersion... imageVersion)
-			throws SQLException {
+	protected static void markValid(MysqlConnection connection, boolean valid,
+			LocalImageVersion... imageVersion) throws SQLException {
 		if (imageVersion == null || imageVersion.length == 0)
 			return;
 		MysqlStatement stmt = connection.prepareStatement("UPDATE imageversion SET isvalid = :valid"
@@ -515,7 +518,8 @@ public class DbImage {
 		}
 	}
 
-	public static void markValid(boolean valid, boolean async, LocalImageVersion... imageVersion) throws SQLException {
+	public static void markValid(boolean valid, boolean async, LocalImageVersion... imageVersion)
+			throws SQLException {
 		if (imageVersion == null || imageVersion.length == 0)
 			return;
 		try (MysqlConnection connection = Database.getConnection()) {
@@ -532,7 +536,7 @@ public class DbImage {
 			updateLatestVersionAsync(imageVersion);
 		}
 	}
-	
+
 	public static void deletePermanently(LocalImageVersion image) throws SQLException {
 		try (MysqlConnection connection = Database.getConnection()) {
 			MysqlStatement stmt = connection.prepareStatement("DELETE FROM imageversion"
@@ -545,7 +549,7 @@ public class DbImage {
 			throw e;
 		}
 	}
-	
+
 	private static void updateLatestVersionAsync(final LocalImageVersion... changingVersion) {
 		if (changingVersion == null || changingVersion.length == 0)
 			return;
@@ -575,16 +579,14 @@ public class DbImage {
 			}
 		});
 	}
-	
-	private static void updateLatestVersion(MysqlConnection connection,
-			LocalImageVersion... versions) throws
-			SQLException {
+
+	private static void updateLatestVersion(MysqlConnection connection, LocalImageVersion... versions)
+			throws SQLException {
 		if (versions == null || versions.length == 0)
 			return;
 		for (LocalImageVersion version : versions) {
 			try {
-				versionValidityChanged(connection, version.imageVersionId,
-						version.imageBaseId);
+				versionValidityChanged(connection, version.imageVersionId, version.imageBaseId);
 			} catch (TNotFoundException e) {
 				// Swallow - logging happens in called method
 			}
@@ -612,59 +614,69 @@ public class DbImage {
 		}
 		// Determine new latest version, as we might have to update the imagebase and lecture tables
 		List<LocalImageVersion> versions = DbImage.getLocalImageVersions(connection, imageBaseId);
-		LocalImageVersion newVersion = null;
-		LocalImageVersion oldVersion = null;
+		LocalImageVersion latestVersion = null;
+		LocalImageVersion changingVersion = null;
 		for (LocalImageVersion version : versions) {
 			if (version.imageVersionId.equals(changingImageVersionId)) {
-				oldVersion = version;
+				changingVersion = version;
 			}
-			if (version.isValid && (newVersion == null || version.createTime > newVersion.createTime)) {
-				File versionFile = FileServer.composeAbsolutePath(version);
-				if (versionFile.canRead() && versionFile.length() == version.fileSize) {
-					newVersion = version;
-				} else {
-					markValid(connection, false, version);
+			if (version.isValid && (latestVersion == null || version.createTime > latestVersion.createTime)) {
+				File versionFile = FileSystem.composeAbsoluteImagePath(version);
+				if (versionFile != null) {
+					if (versionFile.canRead() && versionFile.length() == version.fileSize) {
+						latestVersion = version;
+					} else {
+						markValid(connection, false, version);
+					}
 				}
 			}
 		}
-		if (oldVersion == null) {
+		if (changingVersion == null) {
 			LOGGER.warn("BUG: oldVersion ninjad away on updateLatestVersion (" + changingImageVersionId + ")");
 		} else {
 			// Switch any lectures linking to this version if applicable
-			if (oldVersion.isValid) {
-				DbLecture.autoUpdateUsedImage(connection, imageBaseId, newVersion);
+			if (changingVersion.isValid) {
+				// The version that changed became valid. In case it was the latest version (by date), this is now
+				// the version to be used by auto-updating lectures. If it wasn't the latest version, the following call will
+				// do nothing
+				DbLecture.autoUpdateUsedImage(connection, imageBaseId, latestVersion);
 			} else {
-				DbLecture.forcefullySwitchUsedImage(connection, oldVersion, newVersion);
+				// The version that changed is now invalid. Switch any lecture using it to the latest
+				// available version, ignoring the "auto update" flag of the lecture
+				DbLecture.forcefullySwitchUsedImage(connection, changingVersion, latestVersion);
 			}
 		}
 		// Now update the latestversionid of the baseimage if applicable
-		if (setLatestVersion(connection, imageBaseId, newVersion)) {
-			// TODO: Latest version changed -> mail
-			//Something.versionDeleted(imageBaseId, oldVersion, newVersion);
+		if (setLatestVersion(connection, imageBaseId, latestVersion)) {
+			Mailer.versionDeleted(imageBaseId, changingVersion, latestVersion);
 		}
 	}
-	
+
 	/**
 	 * Set the latest version id of the given base image. Returns true if and
-	 * only if the latest version id of the base image did actually change through
-	 * this call <b>and</b> the new latest version is <b>not null</b>.
-	 *
+	 * only if the latest version id of the base image did actually change
+	 * through this call.
+	 * 
 	 * @param connection mysql connection to use
 	 * @param imageBaseId base id of image in question
 	 * @param latest image version that is to become the latest version, or
-	 * 		<code>null</code> if there is no valid version
+	 *            <code>null</code> if there is no valid version
 	 * @return true if changed to a different, non-null image
 	 * @throws SQLException
 	 */
-	private static boolean setLatestVersion(MysqlConnection connection, String imageBaseId, LocalImageVersion latest) throws SQLException {
+	private static boolean setLatestVersion(MysqlConnection connection, String imageBaseId,
+			LocalImageVersion latest) throws SQLException {
 		// Update latestversionid reference in imagebase table
 		MysqlStatement latestStmt = connection.prepareStatement("UPDATE imagebase SET latestversionid = :newversionid"
 				+ " WHERE imagebaseid = :imagebaseid");
 		latestStmt.setString("newversionid", latest == null ? null : latest.imageVersionId);
 		latestStmt.setString("imagebaseid", imageBaseId);
 		// If nothing changed, or the latest version was set to NULL, bail out
-		if (latestStmt.executeUpdate() == 0 || latest == null)
+		if (latestStmt.executeUpdate() == 0)
 			return false;
+		// It there is no valid version, bail out as a shortcut - queries below wouldn't do anything
+		if (latest == null)
+			return true;
 		// Latest version changed - update expire dates of related versions
 		// Set short expire date for versions that are NOT the latest version but are still marked valid
 		long shortExpire = Util.unixTime() + RuntimeConfig.getOldVersionExpireSeconds();
diff --git a/dozentenmodulserver/src/main/java/org/openslx/bwlp/sat/database/mappers/DbLecture.java b/dozentenmodulserver/src/main/java/org/openslx/bwlp/sat/database/mappers/DbLecture.java
index 2623a9b6..f6431b46 100644
--- a/dozentenmodulserver/src/main/java/org/openslx/bwlp/sat/database/mappers/DbLecture.java
+++ b/dozentenmodulserver/src/main/java/org/openslx/bwlp/sat/database/mappers/DbLecture.java
@@ -4,6 +4,7 @@ import java.sql.ResultSet;
 import java.sql.SQLException;
 import java.util.ArrayList;
 import java.util.Arrays;
+import java.util.Iterator;
 import java.util.List;
 import java.util.UUID;
 
@@ -12,6 +13,7 @@ import org.openslx.bwlp.sat.database.Database;
 import org.openslx.bwlp.sat.database.MysqlConnection;
 import org.openslx.bwlp.sat.database.MysqlStatement;
 import org.openslx.bwlp.sat.database.models.LocalImageVersion;
+import org.openslx.bwlp.sat.maintenance.Mailer;
 import org.openslx.bwlp.sat.permissions.User;
 import org.openslx.bwlp.sat.util.Json;
 import org.openslx.bwlp.thrift.iface.LectureRead;
@@ -129,38 +131,50 @@ public class DbLecture {
 		}
 	}
 
+	private static LectureSummary fillSummary(UserInfo user, ResultSet rs) throws SQLException {
+		LectureSummary lecture = new LectureSummary();
+		lecture.setLectureId(rs.getString("lectureid"));
+		lecture.setLectureName(rs.getString("lecturename"));
+		lecture.setImageVersionId(rs.getString("imageversionid"));
+		lecture.setImageBaseId(rs.getString("imagebaseid"));
+		lecture.setIsEnabled(rs.getBoolean("isenabled"));
+		lecture.setStartTime(rs.getLong("starttime"));
+		lecture.setEndTime(rs.getLong("endtime"));
+		lecture.setLastUsed(rs.getLong("lastused"));
+		lecture.setUseCount(rs.getInt("usecount"));
+		lecture.setOwnerId(rs.getString("ownerid"));
+		lecture.setUpdaterId(rs.getString("updaterid"));
+		lecture.setIsExam(rs.getBoolean("isexam"));
+		lecture.setHasInternetAccess(rs.getBoolean("hasinternetaccess"));
+		lecture.setDefaultPermissions(DbLecturePermissions.fromResultSetDefault(rs));
+		lecture.setUserPermissions(DbLecturePermissions.fromResultSetUser(rs));
+		lecture.setIsImageVersionUsable(rs.getBoolean("imgvalid"));
+		if (user != null) {
+			User.setCombinedUserPermissions(lecture, user);
+		}
+		return lecture;
+	}
+
+	private static final String summaryBaseSql = "SELECT"
+			+ " l.lectureid, l.displayname AS lecturename, l.imageversionid, i.imagebaseid,"
+			+ " l.isenabled, l.starttime, l.endtime, l.lastused, l.usecount, l.ownerid, l.updaterid,"
+			+ " l.isexam, l.hasinternetaccess, l.caneditdefault, l.canadmindefault,"
+			+ " i.isvalid AS imgvalid, perm.canedit, perm.canadmin"
+			+ "                      FROM lecture l                 "
+			+ " INNER JOIN imageversion i USING (imageversionid)"
+			+ " LEFT JOIN lecturepermission perm ON (perm.lectureid = l.lectureid AND perm.userid = :userid)";
+
 	public static LectureSummary getLectureSummary(UserInfo user, String lectureId) throws SQLException,
 			TNotFoundException {
 		try (MysqlConnection connection = Database.getConnection()) {
-			MysqlStatement stmt = connection.prepareStatement("SELECT"
-					+ " l.lectureid, l.displayname AS lecturename, l.imageversionid, l.isenabled,"
-					+ " l.starttime, l.endtime, l.lastused, l.usecount, l.ownerid, l.updaterid,"
-					+ " l.isexam, l.hasinternetaccess, l.caneditdefault, l.canadmindefault,"
-					+ " perm.canedit, perm.canadmin FROM lecture l"
-					+ " LEFT JOIN lecturepermission perm ON (perm.lectureid = l.lectureid AND perm.userid = :userid)"
+			MysqlStatement stmt = connection.prepareStatement(summaryBaseSql
 					+ " WHERE l.lectureid = :lectureid");
 			stmt.setString("lectureid", lectureId);
-			stmt.setString("userid", user.userId);
+			stmt.setString("userid", user == null ? "-" : user.userId);
 			ResultSet rs = stmt.executeQuery();
 			if (!rs.next())
 				throw new TNotFoundException();
-			LectureSummary lecture = new LectureSummary();
-			lecture.setLectureId(rs.getString("lectureid"));
-			lecture.setLectureName(rs.getString("lecturename"));
-			lecture.setImageVersionId(rs.getString("imageversionid"));
-			lecture.setIsEnabled(rs.getBoolean("isenabled"));
-			lecture.setStartTime(rs.getLong("starttime"));
-			lecture.setEndTime(rs.getLong("endtime"));
-			lecture.setLastUsed(rs.getLong("lastused"));
-			lecture.setUseCount(rs.getInt("usecount"));
-			lecture.setOwnerId(rs.getString("ownerid"));
-			lecture.setUpdaterId(rs.getString("updaterid"));
-			lecture.setIsExam(rs.getBoolean("isexam"));
-			lecture.setHasInternetAccess(rs.getBoolean("hasinternetaccess"));
-			lecture.setDefaultPermissions(DbLecturePermissions.fromResultSetDefault(rs));
-			lecture.setUserPermissions(DbLecturePermissions.fromResultSetUser(rs));
-			User.setCombinedUserPermissions(lecture, user);
-			return lecture;
+			return fillSummary(user, rs);
 		} catch (SQLException e) {
 			LOGGER.error("Query failed in DbLecture.getLectureSummary()", e);
 			throw e;
@@ -169,42 +183,13 @@ public class DbLecture {
 
 	public static List<LectureSummary> getAll(UserInfo user, int page) throws SQLException {
 		try (MysqlConnection connection = Database.getConnection()) {
-			MysqlStatement stmt = connection.prepareStatement("SELECT"
-					+ " l.lectureid, l.displayname AS lecturename, l.imageversionid, i.imagebaseid,"
-					+ " l.isenabled, l.starttime, l.endtime, l.lastused, l.usecount, l.ownerid, l.updaterid,"
-					+ " l.isexam, l.hasinternetaccess, l.caneditdefault, l.canadmindefault,"
-					+ " i.isvalid AS imgvalid, p.canedit, p.canadmin"
-					+ "               FROM lecture l                      "
-					+ " INNER JOIN imageversion i USING (imageversionid)"
-					+ " LEFT JOIN lecturepermission p ON (p.lectureid = l.lectureid AND p.userid = :userid)"
+			MysqlStatement stmt = connection.prepareStatement(summaryBaseSql
 					+ (User.isStudent(user) ? " WHERE i.isrestricted = 0" : ""));
-			if (user == null) {
-				stmt.setString("userid", "-");
-			} else {
-				stmt.setString("userid", user.userId);
-			}
+			stmt.setString("userid", user == null ? "-" : user.userId);
 			ResultSet rs = stmt.executeQuery();
 			List<LectureSummary> list = new ArrayList<>(100);
 			while (rs.next()) {
-				LectureSummary lecture = new LectureSummary();
-				lecture.setLectureId(rs.getString("lectureid"));
-				lecture.setLectureName(rs.getString("lecturename"));
-				lecture.setImageVersionId(rs.getString("imageversionid"));
-				lecture.setImageBaseId(rs.getString("imagebaseid"));
-				lecture.setIsEnabled(rs.getBoolean("isenabled"));
-				lecture.setStartTime(rs.getLong("starttime"));
-				lecture.setEndTime(rs.getLong("endtime"));
-				lecture.setLastUsed(rs.getLong("lastused"));
-				lecture.setUseCount(rs.getInt("usecount"));
-				lecture.setOwnerId(rs.getString("ownerid"));
-				lecture.setUpdaterId(rs.getString("updaterid"));
-				lecture.setIsExam(rs.getBoolean("isexam"));
-				lecture.setHasInternetAccess(rs.getBoolean("hasinternetaccess"));
-				lecture.setDefaultPermissions(DbLecturePermissions.fromResultSetDefault(rs));
-				lecture.setUserPermissions(DbLecturePermissions.fromResultSetUser(rs));
-				lecture.setIsImageVersionUsable(rs.getBoolean("imgvalid"));
-				User.setCombinedUserPermissions(lecture, user);
-				list.add(lecture);
+				list.add(fillSummary(user, rs));
 			}
 			return list;
 		} catch (SQLException e) {
@@ -213,14 +198,30 @@ public class DbLecture {
 		}
 	}
 
-	protected static List<String> getAllUsingImageVersion(MysqlConnection connection, String imageVersionId)
+	protected static List<LectureSummary> getAllUsingImageBase(MysqlConnection connection, String imageBaseId, boolean autoUpdateOnly)
 			throws SQLException {
-		MysqlStatement stmt = connection.prepareStatement("SELECT lectureid FROM lecture WHERE imageversionid = :imageversionid");
+		MysqlStatement stmt = connection.prepareStatement(summaryBaseSql
+				+ " WHERE imagebaseid = :imagebaseid" + (autoUpdateOnly ? " AND autoupdate = 1" : ""));
+		stmt.setString("imagebaseid", imageBaseId);
+		stmt.setString("userid", "-");
+		ResultSet rs = stmt.executeQuery();
+		List<LectureSummary> list = new ArrayList<>();
+		while (rs.next()) {
+			list.add(fillSummary(null, rs));
+		}
+		return list;
+	}
+
+	protected static List<LectureSummary> getAllUsingImageVersion(MysqlConnection connection,
+			String imageVersionId) throws SQLException {
+		MysqlStatement stmt = connection.prepareStatement(summaryBaseSql
+				+ " WHERE imageversionid = :imageversionid");
 		stmt.setString("imageversionid", imageVersionId);
+		stmt.setString("userid", "-");
 		ResultSet rs = stmt.executeQuery();
-		List<String> list = new ArrayList<>();
+		List<LectureSummary> list = new ArrayList<>();
 		while (rs.next()) {
-			list.add(rs.getString("lectureid"));
+			list.add(fillSummary(null, rs));
 		}
 		return list;
 	}
@@ -322,8 +323,18 @@ public class DbLecture {
 	 */
 	protected static void autoUpdateUsedImage(MysqlConnection connection, String imageBaseId,
 			LocalImageVersion newVersion) throws SQLException {
-		// TODO: select first so we can email
-		// TODO: If new version is null, do not change, but send warning mail
+		if (newVersion == null)
+			return;
+		List<LectureSummary> lectures = getAllUsingImageBase(connection, imageBaseId, true);
+		if (lectures.isEmpty())
+			return;
+		// Remove lectures that are already on the given latest version from the list...
+		for (Iterator<LectureSummary> it = lectures.iterator(); it.hasNext();) {
+			LectureSummary lecture = it.next();
+			if (lecture.imageVersionId.equals(newVersion.imageVersionId))
+				it.remove();
+		}
+		// Update lectures in DB
 		MysqlStatement stmt = connection.prepareStatement("UPDATE lecture l, imageversion v SET"
 				+ " l.imageversionid = :imageversionid"
 				+ " WHERE v.imageversionid = l.imageversionid AND v.imagebaseid = :imagebaseid"
@@ -331,6 +342,8 @@ public class DbLecture {
 		stmt.setString("imageversionid", newVersion.imageVersionId);
 		stmt.setString("imagebaseid", imageBaseId);
 		stmt.executeUpdate();
+		// Send informative mail to lecture admins
+		Mailer.lectureAutoUpdate(lectures, newVersion);
 	}
 
 	/**
@@ -343,21 +356,24 @@ public class DbLecture {
 				|| (newVersion != null && newVersion.imageVersionId.equals(oldVersion.imageVersionId)))
 			return;
 		// First, get list of lectures using the image version to switch away from
-		List<String> lectures = getAllUsingImageVersion(connection, oldVersion.imageVersionId);
+		List<LectureSummary> lectures = getAllUsingImageVersion(connection, oldVersion.imageVersionId);
 		if (lectures.isEmpty())
 			return;
-		// TODO: If there is no new candidate to switch to, send a warning via mail
+		// TODO: If there is no new candidate to switch to, send a warning via mail, otherwise, inform about switch
+		MysqlStatement stmt;
 		if (newVersion == null) {
-			// ... email stuff
-			return;
+			stmt = connection.prepareStatement("UPDATE lecture SET isenabled = 0 WHERE imageversionid = :oldversionid");
+			stmt.setString("oldversionid", oldVersion.imageVersionId);
+			Mailer.lectureDeactivated(lectures);
+		} else {
+			// Update and send info mail
+			stmt = connection.prepareStatement("UPDATE lecture SET imageversionid = :newversionid"
+					+ " WHERE imageversionid = :oldversionid");
+			stmt.setString("oldversionid", oldVersion.imageVersionId);
+			stmt.setString("newversionid", newVersion.imageVersionId);
+			Mailer.lectureForcedUpdate(lectures, newVersion);
 		}
-		// Update and send info mail
-		MysqlStatement stmt = connection.prepareStatement("UPDATE lecture SET imageversionid = :newversionid"
-				+ " WHERE imageversionid = :oldversionid");
-		stmt.setString("oldversionid", oldVersion.imageVersionId);
-		stmt.setString("newversionid", newVersion.imageVersionId);
 		stmt.executeUpdate();
-		// TODO: Send mails .. Something.sendLectureChangeNotify(lectures, oldVersion, newVersion);
 	}
 
 }
diff --git a/dozentenmodulserver/src/main/java/org/openslx/bwlp/sat/database/mappers/DbUser.java b/dozentenmodulserver/src/main/java/org/openslx/bwlp/sat/database/mappers/DbUser.java
index 9c80caf4..4552a1d7 100644
--- a/dozentenmodulserver/src/main/java/org/openslx/bwlp/sat/database/mappers/DbUser.java
+++ b/dozentenmodulserver/src/main/java/org/openslx/bwlp/sat/database/mappers/DbUser.java
@@ -4,6 +4,8 @@ import java.sql.ResultSet;
 import java.sql.SQLException;
 import java.util.ArrayList;
 import java.util.List;
+import java.util.Map;
+import java.util.concurrent.TimeUnit;
 
 import org.apache.log4j.Logger;
 import org.openslx.bwlp.sat.database.Database;
@@ -11,12 +13,40 @@ import org.openslx.bwlp.sat.database.MysqlConnection;
 import org.openslx.bwlp.sat.database.MysqlStatement;
 import org.openslx.bwlp.sat.database.Paginator;
 import org.openslx.bwlp.sat.database.models.LocalUser;
+import org.openslx.bwlp.thrift.iface.TNotFoundException;
 import org.openslx.bwlp.thrift.iface.UserInfo;
+import org.openslx.util.TimeoutHashMap;
 
 public class DbUser {
 
 	private static final Logger LOGGER = Logger.getLogger(DbUser.class);
 
+	private static Map<String, UserInfo> userCache;
+
+	private static void initCache() throws SQLException {
+		if (userCache != null)
+			return;
+		synchronized (DbUser.class) {
+			if (userCache == null) {
+				try (MysqlConnection connection = Database.getConnection()) {
+					userCache = new TimeoutHashMap<>(TimeUnit.DAYS.toMillis(2));
+					MysqlStatement stmt = connection.prepareStatement("SELECT userid, firstname, lastname, email, organizationid"
+							+ " FROM user ORDER BY lastlogin DESC LIMIT 30");
+					ResultSet rs = stmt.executeQuery();
+					while (rs.next()) {
+						UserInfo user = new UserInfo(rs.getString("userid"), rs.getString("firstname"),
+								rs.getString("lastname"), rs.getString("email"),
+								rs.getString("organizationid"));
+						userCache.put(user.userId, user);
+					}
+				} catch (SQLException e) {
+					LOGGER.error("Query failed in DbUser.initCache()", e);
+					throw e;
+				}
+			}
+		}
+	}
+
 	/**
 	 * Get all users, starting at page <code>page</code>.
 	 * This function will return a maximum of {@link #PER_PAGE} results, so
@@ -105,6 +135,36 @@ public class DbUser {
 			LOGGER.error("Query failed in DbUser.writeUserOnLogin()", e);
 			throw e;
 		}
+		synchronized (DbUser.class) {
+			initCache();
+			userCache.put(ui.userId, ui);
+		}
+	}
+
+	public static UserInfo getCached(String userId) throws SQLException, TNotFoundException {
+		synchronized (DbUser.class) {
+			initCache();
+			UserInfo user = userCache.get(userId);
+			if (user != null)
+				return user;
+		}
+		try (MysqlConnection connection = Database.getConnection()) {
+			MysqlStatement stmt = connection.prepareStatement("SELECT userid, firstname, lastname, email, organizationid"
+					+ " FROM user WHERE userid = :userid");
+			stmt.setString("userid", userId);
+			ResultSet rs = stmt.executeQuery();
+			if (!rs.next())
+				throw new TNotFoundException();
+			UserInfo user = new UserInfo(rs.getString("userid"), rs.getString("firstname"),
+					rs.getString("lastname"), rs.getString("email"), rs.getString("organizationid"));
+			synchronized (DbUser.class) {
+				userCache.put(user.userId, user);
+			}
+			return user;
+		} catch (SQLException e) {
+			LOGGER.error("Query failed in DbUser.getCached()", e);
+			throw e;
+		}
 	}
 
 }
diff --git a/dozentenmodulserver/src/main/java/org/openslx/bwlp/sat/database/models/LocalImageVersion.java b/dozentenmodulserver/src/main/java/org/openslx/bwlp/sat/database/models/LocalImageVersion.java
index 238633fd..fea36200 100644
--- a/dozentenmodulserver/src/main/java/org/openslx/bwlp/sat/database/models/LocalImageVersion.java
+++ b/dozentenmodulserver/src/main/java/org/openslx/bwlp/sat/database/models/LocalImageVersion.java
@@ -13,7 +13,7 @@ public class LocalImageVersion {
 	public final boolean isValid;
 
 	public final long createTime;
-	
+
 	public final long expireTime;
 
 	public LocalImageVersion(String imageVersionId, String imageBaseId, String filePath, long fileSize,
@@ -27,4 +27,10 @@ public class LocalImageVersion {
 		this.isValid = isValid;
 	}
 
+	@Override
+	public boolean equals(Object that) {
+		return this.imageVersionId != null && that != null && (that instanceof LocalImageVersion)
+				&& this.imageVersionId.equals(((LocalImageVersion) that).imageVersionId);
+	}
+
 }
diff --git a/dozentenmodulserver/src/main/java/org/openslx/bwlp/sat/fileserv/FileServer.java b/dozentenmodulserver/src/main/java/org/openslx/bwlp/sat/fileserv/FileServer.java
index 7d158459..6e8bcf1c 100644
--- a/dozentenmodulserver/src/main/java/org/openslx/bwlp/sat/fileserv/FileServer.java
+++ b/dozentenmodulserver/src/main/java/org/openslx/bwlp/sat/fileserv/FileServer.java
@@ -18,8 +18,8 @@ import javax.net.ssl.SSLContext;
 import org.apache.log4j.Logger;
 import org.openslx.bwlp.sat.database.mappers.DbImage;
 import org.openslx.bwlp.sat.database.models.LocalImageVersion;
-import org.openslx.bwlp.sat.util.Configuration;
 import org.openslx.bwlp.sat.util.Constants;
+import org.openslx.bwlp.sat.util.FileSystem;
 import org.openslx.bwlp.sat.util.Formatter;
 import org.openslx.bwlp.sat.util.Identity;
 import org.openslx.bwlp.thrift.iface.ImageDetailsRead;
@@ -190,25 +190,29 @@ public class FileServer implements IncomingEvent {
 					+ "/" + Constants.MAX_UPLOADS + ").");
 		}
 		// Determine src file and go
-		File srcFile = composeAbsolutePath(localImageData);
-		if (!srcFile.canRead()) {
+		File srcFile = FileSystem.composeAbsoluteImagePath(localImageData);
+		String errorMessage = null;
+		if (srcFile == null) {
+			LOGGER.warn("Rejecting download of VID " + localImageData.imageVersionId
+					+ ": Invalid local relative path");
+			errorMessage = "File has invalid path on server";
+		} else if (!srcFile.canRead()) {
 			LOGGER.warn("Rejecting download of VID " + localImageData.imageVersionId + ": Missing "
 					+ srcFile.getPath());
-			try {
-				DbImage.markValid(false, true, localImageData);
-			} catch (SQLException e) {
-			}
-			throw new TTransferRejectedException("File missing on server");
+			errorMessage = "File missing on server";
 		}
 		if (srcFile.length() != localImageData.fileSize) {
 			LOGGER.warn("Rejecting download of VID " + localImageData.imageVersionId + ": Size mismatch for "
 					+ srcFile.getPath() + " (expected " + localImageData.fileSize + ", is "
 					+ srcFile.length() + ")");
+			errorMessage = "File corrupted on server";
+		}
+		if (errorMessage != null) {
 			try {
 				DbImage.markValid(false, true, localImageData);
 			} catch (SQLException e) {
 			}
-			throw new TTransferRejectedException("File corrupted on server");
+			throw new TTransferRejectedException(errorMessage);
 		}
 		String key = UUID.randomUUID().toString();
 		ActiveDownload transfer = new ActiveDownload(key, srcFile);
@@ -216,8 +220,4 @@ public class FileServer implements IncomingEvent {
 		return transfer;
 	}
 
-	public static File composeAbsolutePath(LocalImageVersion localImageData) {
-		return new File(Configuration.getVmStoreBasePath(), localImageData.filePath);
-	}
-
 }
diff --git a/dozentenmodulserver/src/main/java/org/openslx/bwlp/sat/maintenance/DeleteOldImages.java b/dozentenmodulserver/src/main/java/org/openslx/bwlp/sat/maintenance/DeleteOldImages.java
index 9a308dcd..c3168253 100644
--- a/dozentenmodulserver/src/main/java/org/openslx/bwlp/sat/maintenance/DeleteOldImages.java
+++ b/dozentenmodulserver/src/main/java/org/openslx/bwlp/sat/maintenance/DeleteOldImages.java
@@ -8,7 +8,7 @@ import org.apache.log4j.Logger;
 import org.joda.time.DateTime;
 import org.openslx.bwlp.sat.database.mappers.DbImage;
 import org.openslx.bwlp.sat.database.models.LocalImageVersion;
-import org.openslx.bwlp.sat.fileserv.FileServer;
+import org.openslx.bwlp.sat.util.FileSystem;
 import org.openslx.util.QuickTimer;
 import org.openslx.util.QuickTimer.Task;
 
@@ -73,7 +73,7 @@ public class DeleteOldImages implements Runnable {
 		for (LocalImageVersion version : versions) {
 			if (version.expireTime < hardDelete) {
 				hardDeleteCount++;
-				FileServer.composeAbsolutePath(version).delete();
+				FileSystem.deleteImageRelatedFiles(version);
 				try {
 					DbImage.deletePermanently(version);
 				} catch (SQLException e) {
diff --git a/dozentenmodulserver/src/main/java/org/openslx/bwlp/sat/maintenance/Mailer.java b/dozentenmodulserver/src/main/java/org/openslx/bwlp/sat/maintenance/Mailer.java
new file mode 100644
index 00000000..d2241e37
--- /dev/null
+++ b/dozentenmodulserver/src/main/java/org/openslx/bwlp/sat/maintenance/Mailer.java
@@ -0,0 +1,161 @@
+package org.openslx.bwlp.sat.maintenance;
+
+import java.sql.SQLException;
+import java.util.ArrayList;
+import java.util.HashMap;
+import java.util.List;
+import java.util.Map;
+import java.util.Map.Entry;
+
+import org.apache.log4j.Logger;
+import org.openslx.bwlp.sat.database.mappers.DbImage;
+import org.openslx.bwlp.sat.database.mappers.DbImagePermissions;
+import org.openslx.bwlp.sat.database.mappers.DbLecturePermissions;
+import org.openslx.bwlp.sat.database.mappers.DbUser;
+import org.openslx.bwlp.sat.database.models.LocalImageVersion;
+import org.openslx.bwlp.sat.util.Formatter;
+import org.openslx.bwlp.thrift.iface.ImageDetailsRead;
+import org.openslx.bwlp.thrift.iface.ImagePermissions;
+import org.openslx.bwlp.thrift.iface.ImageVersionDetails;
+import org.openslx.bwlp.thrift.iface.LecturePermissions;
+import org.openslx.bwlp.thrift.iface.LectureSummary;
+import org.openslx.bwlp.thrift.iface.TNotFoundException;
+import org.openslx.bwlp.thrift.iface.UserInfo;
+
+public class Mailer {
+
+	private static final Logger LOGGER = Logger.getLogger(Mailer.class);
+
+	public static void lectureAutoUpdate(List<LectureSummary> lectures, LocalImageVersion newVersion) {
+		for (LectureSummary lecture : lectures) {
+			LOGGER.debug("Auto-Update mail for " + lecture.lectureId + " " + lecture.lectureName);
+			List<UserInfo> relevantUsers = getUserToMail(lecture);
+			for (UserInfo user : relevantUsers) {
+				LOGGER.debug("Sending auto-update info to " + Formatter.userFullName(user));
+			}
+		}
+	}
+
+	public static void lectureForcedUpdate(List<LectureSummary> lectures, LocalImageVersion newVersion) {
+		for (LectureSummary lecture : lectures) {
+			LOGGER.debug("Forced-Update mail for " + lecture.lectureId + " " + lecture.lectureName);
+			List<UserInfo> relevantUsers = getUserToMail(lecture);
+			for (UserInfo user : relevantUsers) {
+				LOGGER.debug("Sending forced-update info to " + Formatter.userFullName(user));
+			}
+		}
+	}
+
+	public static void lectureDeactivated(List<LectureSummary> lectures) {
+		for (LectureSummary lecture : lectures) {
+			LOGGER.debug("Deactivated mail for " + lecture.lectureId + " " + lecture.lectureName);
+			List<UserInfo> relevantUsers = getUserToMail(lecture);
+			for (UserInfo user : relevantUsers) {
+				LOGGER.debug("Sending deactivated info to " + Formatter.userFullName(user));
+			}
+		}
+	}
+
+	private static List<UserInfo> getUserToMail(LectureSummary lecture) {
+		Map<String, LecturePermissions> users;
+		try {
+			users = DbLecturePermissions.getForLecture(lecture.lectureId, false);
+		} catch (SQLException e) {
+			users = new HashMap<>();
+		}
+		users.put(lecture.ownerId, new LecturePermissions(true, true));
+		List<UserInfo> list = new ArrayList<>(users.size());
+		for (Entry<String, LecturePermissions> entry : users.entrySet()) {
+			LecturePermissions perms = entry.getValue();
+			if (!perms.admin && !perms.edit)
+				continue;
+			UserInfo user;
+			try {
+				user = DbUser.getCached(entry.getKey());
+			} catch (TNotFoundException e) {
+				LOGGER.warn("UserID " + entry.getKey() + " unknown");
+				continue;
+			} catch (SQLException e) {
+				continue; // Logging happened in DbUser
+			}
+			list.add(user);
+		}
+		return list;
+	}
+
+	private static List<UserInfo> getUserToMail(ImageDetailsRead image) {
+		Map<String, ImagePermissions> users;
+		try {
+			users = DbImagePermissions.getForImageBase(image.imageBaseId, false);
+		} catch (SQLException e) {
+			users = new HashMap<>();
+		}
+		users.put(image.ownerId, new ImagePermissions(true, true, true, true));
+		List<UserInfo> list = new ArrayList<>(users.size());
+		for (Entry<String, ImagePermissions> entry : users.entrySet()) {
+			ImagePermissions perms = entry.getValue();
+			if (!perms.admin && !perms.edit)
+				continue;
+			UserInfo user;
+			try {
+				user = DbUser.getCached(entry.getKey());
+			} catch (TNotFoundException e) {
+				LOGGER.warn("UserID " + entry.getKey() + " unknown");
+				continue;
+			} catch (SQLException e) {
+				continue; // Logging happened in DbUser
+			}
+			list.add(user);
+		}
+		return list;
+	}
+
+	public static void versionDeleted(String imageBaseId, LocalImageVersion oldLocal,
+			LocalImageVersion newLocal) {
+		ImageDetailsRead image;
+		try {
+			image = DbImage.getImageDetails(null, imageBaseId);
+		} catch (TNotFoundException | SQLException e) {
+			LOGGER.warn("Version Deleted for image=" + imageBaseId + " failed", e);
+			return;
+		}
+		LOGGER.debug("Sending info mail about deleted image version "
+				+ (oldLocal == null ? "-" : oldLocal.imageVersionId) + " (" + image.imageName + ")");
+		ImageVersionDetails oldVersion = null;
+		ImageVersionDetails newVersion = null;
+		for (ImageVersionDetails version : image.versions) {
+			if (oldLocal != null && version.versionId.equals(oldLocal.imageVersionId)) {
+				oldVersion = version;
+			}
+			if (newLocal != null && version.versionId.equals(newLocal.imageVersionId)) {
+				newVersion = version;
+			}
+		}
+		String message;
+		if (newVersion == null) {
+			message = "Last version deleted; WARNING: No more valid image versions";
+		} else {
+			String uploaderName;
+			try {
+				UserInfo uploader = DbUser.getCached(newVersion.uploaderId);
+				uploaderName = uploader.firstName + " " + uploader.lastName + " <" + uploader.eMail + ">";
+			} catch (TNotFoundException | SQLException e) {
+				uploaderName = "an unknown person";
+				;
+			}
+			if (oldVersion == null) {
+				message = "Old version deleted;";
+			} else {
+				message = "Old version (created " + Formatter.date(oldVersion.createTime) + ") deleted;";
+			}
+			message += " new version now in use was uploaded on "
+						+ Formatter.date(newVersion.createTime) + " by " + uploaderName;
+		}
+		LOGGER.debug("Mail: " + message);
+		List<UserInfo> relevantUsers = getUserToMail(image);
+		for (UserInfo user : relevantUsers) {
+			LOGGER.debug("Sending mail to " + Formatter.userFullName(user));
+		}
+	}
+
+}
diff --git a/dozentenmodulserver/src/main/java/org/openslx/bwlp/sat/util/Configuration.java b/dozentenmodulserver/src/main/java/org/openslx/bwlp/sat/util/Configuration.java
index 07cd3a8d..b02d73d0 100644
--- a/dozentenmodulserver/src/main/java/org/openslx/bwlp/sat/util/Configuration.java
+++ b/dozentenmodulserver/src/main/java/org/openslx/bwlp/sat/util/Configuration.java
@@ -32,7 +32,7 @@ public class Configuration {
 		}
 
 		vmStoreBasePath = new File(prop.getProperty("vmstore.path"));
-		vmStoreProdPath = new File(vmStoreBasePath, "prod");
+		vmStoreProdPath = new File(vmStoreBasePath, "bwlehrpool_store");
 		dbUri = prop.getProperty("db.uri");
 		dbUsername = prop.getProperty("db.username");
 		dbPassword = prop.getProperty("db.password");
@@ -43,6 +43,12 @@ public class Configuration {
 
 	// Static ("real") fields
 
+	/**
+	 * Get the path of the VM storage space. Traditionally, this is
+	 * '/srv/openslx/nfs'.
+	 * 
+	 * @return path of the VM storage
+	 */
 	public static File getVmStoreBasePath() {
 		return vmStoreBasePath;
 	}
diff --git a/dozentenmodulserver/src/main/java/org/openslx/bwlp/sat/util/FileSystem.java b/dozentenmodulserver/src/main/java/org/openslx/bwlp/sat/util/FileSystem.java
index c8f24e3f..a8a7151b 100644
--- a/dozentenmodulserver/src/main/java/org/openslx/bwlp/sat/util/FileSystem.java
+++ b/dozentenmodulserver/src/main/java/org/openslx/bwlp/sat/util/FileSystem.java
@@ -2,7 +2,9 @@ package org.openslx.bwlp.sat.util;
 
 import java.io.File;
 
+import org.apache.commons.io.FilenameUtils;
 import org.apache.log4j.Logger;
+import org.openslx.bwlp.sat.database.models.LocalImageVersion;
 import org.openslx.util.QuickTimer;
 import org.openslx.util.QuickTimer.Task;
 
@@ -26,24 +28,106 @@ public class FileSystem {
 	}
 
 	/**
-	 * Delete given file on the quicktimer thread, preventing the calling thread
-	 * from freezing/hanging on I/O problems.
+	 * Delete given file on the {@link QuickTimer} thread, preventing the
+	 * calling thread from freezing/hanging on I/O problems.
 	 * 
 	 * @param file the file to delete
 	 */
-	public static void deleteAsync(final File file) {
+	public static void deleteAsync(final File... files) {
+		if (files == null || files.length == 0)
+			return;
 		QuickTimer.scheduleOnce(new Task() {
 			@Override
 			public void fire() {
-				if (!file.exists()) {
-					LOGGER.info("deleteAsync called for nonexistent file " + file.getAbsolutePath());
-					return;
-				}
-				if (!file.delete()) {
-					LOGGER.warn("Could not delete file " + file.getAbsolutePath());
+				for (File file : files) {
+					if (!file.exists()) {
+						LOGGER.info("deleteAsync called for nonexistent file " + file.getAbsolutePath());
+						return;
+					}
+					if (!file.delete()) {
+						LOGGER.warn("Could not delete file " + file.getAbsolutePath());
+					}
 				}
 			}
 		});
 	}
 
+	/**
+	 * Checks if the VM store is mounted.
+	 * 
+	 * @return true if mounted, false otherwise.
+	 */
+	public static boolean isStorageMounted() {
+		File flagFile = new File(Configuration.getVmStoreBasePath(), ".notmounted");
+		if (flagFile.exists())
+			return false;
+		File prodPath = Configuration.getVmStoreProdPath();
+		if (prodPath.isDirectory())
+			return true;
+		return prodPath.mkdir();
+	}
+
+	private static Object storageMutex = new Object();
+
+	public static boolean waitForStorage() {
+		if (isStorageMounted())
+			return true;
+		synchronized (storageMutex) {
+			if (isStorageMounted())
+				return true;
+			LOGGER.warn("VM storage gone, waiting for it to reappear...");
+			int intrCount = 0;
+			do {
+				try {
+					Thread.sleep(10000);
+					intrCount = 0;
+				} catch (InterruptedException e) {
+					intrCount++;
+					if (intrCount > 2) {
+						LOGGER.warn("Lost patience while waiting");
+						return false;
+					}
+				}
+			} while (!isStorageMounted());
+		}
+		LOGGER.info("VM storage back online");
+		return true;
+	}
+
+	/**
+	 * Delete the given image file (and all related files) from the storage.
+	 * 
+	 * @param image The image to be deleted
+	 */
+	public static void deleteImageRelatedFiles(LocalImageVersion image) {
+		File imageFile = composeAbsoluteImagePath(image);
+		if (imageFile == null)
+			return;
+		File metaFile = new File(imageFile.getPath() + ".meta");
+		File crcFile = new File(imageFile.getPath() + ".crc");
+		File mapFile = new File(imageFile.getPath() + ".map");
+		if (!waitForStorage())
+			return;
+		deleteAsync(imageFile, metaFile, crcFile, mapFile);
+	}
+
+	/**
+	 * Given a local image version, return a {@link File} object that holds the
+	 * full path to the image file in the file system.
+	 * 
+	 * @param localImageData
+	 * @return {@link File} representing the physical image file, or
+	 *         <code>null</code> if the path would not be valid
+	 */
+	public static File composeAbsoluteImagePath(LocalImageVersion localImageData) {
+		String rel = localImageData.filePath == null ? null
+				: FilenameUtils.normalize(localImageData.filePath);
+		if (rel == null || rel.startsWith("/")) {
+			LOGGER.warn("Invalid path for local image " + localImageData.imageVersionId + ": "
+					+ localImageData.filePath);
+			return null;
+		}
+		return new File(Configuration.getVmStoreBasePath(), rel);
+	}
+
 }
diff --git a/dozentenmodulserver/src/main/java/org/openslx/bwlp/sat/util/Formatter.java b/dozentenmodulserver/src/main/java/org/openslx/bwlp/sat/util/Formatter.java
index bc64c8fe..adfeaac3 100644
--- a/dozentenmodulserver/src/main/java/org/openslx/bwlp/sat/util/Formatter.java
+++ b/dozentenmodulserver/src/main/java/org/openslx/bwlp/sat/util/Formatter.java
@@ -10,7 +10,9 @@ import org.openslx.bwlp.thrift.iface.UserInfo;
 public class Formatter {
 
 	private static final DateTimeFormatter vmNameDateFormat = DateTimeFormat.forPattern("dd_HH-mm-ss");
-	
+
+	private static final DateTimeFormatter displayDateFormat = DateTimeFormat.forPattern("dd.MM.yy HH:mm");
+
 	/**
 	 * Generate a unique file name used for a virtual machine
 	 * image that is currently uploading.
@@ -54,4 +56,16 @@ public class Formatter {
 	public static String userFullName(UserInfo ui) {
 		return ui.firstName + " " + ui.lastName;
 	}
+
+	/**
+	 * Format a unix time stamp as dd.MM.yy HH:mm
+	 * 
+	 * @param unixTime seconds since 01.01.1970 UTC
+	 * @return dd.MM.yy HH:mm
+	 */
+	public static String date(long unixTime) {
+		if (unixTime == 0)
+			return "???";
+		return displayDateFormat.print(unixTime * 1000);
+	}
 }