Added /kb delete <backup_name> for deleting an backup (with auto-complete supported).

Command /kb confirm now confirms both /kb restore and /kb delete.
Added /kb prev for easily check out the latest backup.

8 files changed, 120 insertions, 31 deletions

diff --git a/README.md b/README.md
index 9c498a4..006d014 100644
--- a/README.md
+++ b/README.md
@@ -14,10 +14,13 @@ commands:
 - **/kb restore \<backup_name\>**: restore to a certain backup. This command needs a confirm to execute.
 - **/kb confirm**: confirm executing restore operation. The operation is irreversible.
 - **/kb delete**: delete an existing backup.
+- **/kb prev**: Find and select the most recent backup file.
 
 
 To-Do List:
 
+- Add /kb prev command for easily select previous backup.
+- Use OCP to refactor pending task.
 - Optimize log output, normal output and op broadcast output.
 - More thorough test.
 - Enhance ZipUtil for hashing sub-files and generating incremental diff-table. (A:Add, M:Modification, D:Deletion)
diff --git a/src/main/java/com/keuin/kbackupfabric/KBCommandRegister.java b/src/main/java/com/keuin/kbackupfabric/KBCommandRegister.java
index 4b4dd59..79029bf 100644
--- a/src/main/java/com/keuin/kbackupfabric/KBCommandRegister.java
+++ b/src/main/java/com/keuin/kbackupfabric/KBCommandRegister.java
@@ -33,5 +33,7 @@ public final class KBCommandRegister {
         // register /kb cancel for cancelling the execution to be confirmed. OP is required.
         dispatcher.register(CommandManager.literal("kb").then(CommandManager.literal("cancel").requires(PermissionValidator::op).executes(KBCommands::cancel)));
 
+        // register /kb prev for showing the latest backup.
+        dispatcher.register(CommandManager.literal("kb").then(CommandManager.literal("prev").requires(PermissionValidator::op).executes(KBCommands::prev)));
     }
 }
diff --git a/src/main/java/com/keuin/kbackupfabric/KBCommands.java b/src/main/java/com/keuin/kbackupfabric/KBCommands.java
index be4d151..5302150 100644
--- a/src/main/java/com/keuin/kbackupfabric/KBCommands.java
+++ b/src/main/java/com/keuin/kbackupfabric/KBCommands.java
@@ -2,6 +2,8 @@ package com.keuin.kbackupfabric;
 
 import com.keuin.kbackupfabric.data.BackupMetadata;
 import com.keuin.kbackupfabric.data.PendingOperation;
+import com.keuin.kbackupfabric.util.BackupFilesystemUtil;
+import com.keuin.kbackupfabric.util.BackupNameTimeFormatter;
 import com.keuin.kbackupfabric.util.PrintUtil;
 import com.keuin.kbackupfabric.worker.BackupWorker;
 import com.keuin.kbackupfabric.worker.RestoreWorker;
@@ -14,9 +16,10 @@ import org.apache.logging.log4j.Logger;
 
 import java.io.File;
 import java.io.IOException;
-import java.time.LocalDateTime;
-import java.time.format.DateTimeFormatter;
-import java.util.HashMap;
+import java.util.ArrayList;
+import java.util.Arrays;
+import java.util.List;
+import java.util.Objects;
 
 import static com.keuin.kbackupfabric.util.BackupFilesystemUtil.*;
 import static com.keuin.kbackupfabric.util.PrintUtil.*;
@@ -30,7 +33,7 @@ public final class KBCommands {
 
     private static final Logger LOGGER = LogManager.getLogger();
 
-    private static final HashMap<Integer, String> backupIndexNameMapper = new HashMap<>(); // index -> backupName
+    private static final List<String> backupNameList = new ArrayList<>(); // index -> backupName
     private static PendingOperation pendingOperation = null;
 
     /**
@@ -56,13 +59,13 @@ public final class KBCommands {
         File[] files = getBackupSaveDirectory(server).listFiles(
                 (dir, name) -> dir.isDirectory() && name.toLowerCase().endsWith(".zip") && name.toLowerCase().startsWith(getBackupFileNamePrefix())
         );
-        backupIndexNameMapper.clear();
+        backupNameList.clear();
         if (files != null) {
             int i = 0;
             for (File file : files) {
                 ++i;
                 String backupName = getBackupName(file.getName());
-                backupIndexNameMapper.put(i, backupName);
+                backupNameList.add(backupName);
                 msgInfo(context, String.format("[%d] %s, size: %.1fMB", i, backupName, file.length() * 1.0 / 1024 / 1024));
             }
         }
@@ -160,9 +163,7 @@ public final class KBCommands {
     private static int doBackup(CommandContext<ServerCommandSource> context, String customName) {
         // Real backup name (compatible with legacy backup): date_name, such as 2020-04-23_21-03-00_test
         //KBMain.backup("name")
-        DateTimeFormatter formatter = DateTimeFormatter.ofPattern("yyyy-MM-dd_HH-mm-ss");
-        String timeString = LocalDateTime.now().format(formatter);
-        String backupName = timeString + "_" + customName;
+        String backupName = BackupNameTimeFormatter.getTimeString() + "_" + customName;
 
         // Validate file name
         final char[] ILLEGAL_CHARACTERS = {'/', '\n', '\r', '\t', '\0', '\f', '`', '?', '*', '\\', '<', '>', '|', '\"', ':'};
@@ -265,14 +266,51 @@ public final class KBCommands {
         }
     }
 
-    private static String parseBackupName(CommandContext<ServerCommandSource> context, String userInput) {
-        MinecraftServer server = context.getSource().getMinecraftServer();
-        String backupName = StringArgumentType.getString(context, "backupName");
+    /**
+     * Show the most recent backup.
+     * If there is no available backup, print specific info.
+     *
+     * @param context the context.
+     * @return stat code.
+     */
+    public static int prev(CommandContext<ServerCommandSource> context) {
+        try {
+            // List all backups
+            MinecraftServer server = context.getSource().getMinecraftServer();
+            List<File> files = Arrays.asList(Objects.requireNonNull(getBackupSaveDirectory(server).listFiles()));
+            files.removeIf(f -> !f.getName().startsWith(BackupFilesystemUtil.getBackupFileNamePrefix()));
+            files.sort((x, y) -> (int) (BackupFilesystemUtil.getBackupTimeFromBackupFileName(y.getName()) - BackupFilesystemUtil.getBackupTimeFromBackupFileName(x.getName())));
+            File prevBackupFile = files.get(0);
+            String backupName = getBackupName(prevBackupFile.getName());
+            int i = backupNameList.indexOf(backupName);
+            if (i == -1) {
+                backupNameList.add(backupName);
+                i = backupNameList.size();
+            } else {
+                ++i;
+            }
+            msgInfo(context, String.format("The most recent backup: [%d] %s , size: %s", i, backupName, humanFileSize(prevBackupFile.length())));
+        } catch (NullPointerException e) {
+            msgInfo(context, "There are no backups available.");
+        } catch (SecurityException ignored) {
+            msgErr(context, "Failed to read file.");
+            return FAILED;
+        }
+        return SUCCESS;
+    }
 
-        if (backupName.matches("[0-9]*")) {
-            // If numeric input
-            Integer index = Integer.parseInt(backupName);
-            return backupIndexNameMapper.get(index); // Replace input number with real backup name.
+
+    private static String parseBackupName(CommandContext<ServerCommandSource> context, String userInput) {
+        try {
+            MinecraftServer server = context.getSource().getMinecraftServer();
+            String backupName = StringArgumentType.getString(context, "backupName");
+
+            if (backupName.matches("[0-9]*")) {
+                // If numeric input
+                int index = Integer.parseInt(backupName) - 1;
+                return backupNameList.get(index); // Replace input number with real backup name.
+            }
+        } catch (NumberFormatException | IndexOutOfBoundsException ignored) {
         }
         return userInput;
     }
diff --git a/src/main/java/com/keuin/kbackupfabric/KBPluginEvents.java b/src/main/java/com/keuin/kbackupfabric/KBPluginEvents.java
index 3b1901e..47983b7 100644
--- a/src/main/java/com/keuin/kbackupfabric/KBPluginEvents.java
+++ b/src/main/java/com/keuin/kbackupfabric/KBPluginEvents.java
@@ -29,14 +29,14 @@ public final class KBPluginEvents implements ModInitializer, ServerStartCallback
 
     @Override
     public void onInitialize() {
-        System.out.println("KBackup: Binding events and commands ...");
+        System.out.println("[KBackup] Binding events and commands ...");
         CommandRegistry.INSTANCE.register(false, KBCommandRegister::registerCommands);
         ServerStartCallback.EVENT.register(this);
     }
 
     @Override
     public void onStartServer(MinecraftServer server) {
-        LOGGER.debug("KBackup: Initializing ...");
+        LOGGER.debug("[KBackup] Initializing ...");
 
         // Update backup suggestion list
         BackupNameSuggestionProvider.setBackupSaveDirectory(BackupFilesystemUtil.getBackupSaveDirectory(server).getPath());
@@ -55,7 +55,7 @@ public final class KBPluginEvents implements ModInitializer, ServerStartCallback
                 fileInputStream.close();
 
                 // Print metadata
-                LOGGER.info("Recovered from previous backup:");
+                LOGGER.info("[KBackup] Recovered from previous backup:");
                 LOGGER.info("Backup Name: " + metadata.getBackupName());
                 LOGGER.info("Create Time: " + (new SimpleDateFormat("yyyy-MM-dd HH:mm:ss")).format(new Date(metadata.getBackupTime())));
 
diff --git a/src/main/java/com/keuin/kbackupfabric/util/BackupFilesystemUtil.java b/src/main/java/com/keuin/kbackupfabric/util/BackupFilesystemUtil.java
index 5b8ba5a..ce39615 100644
--- a/src/main/java/com/keuin/kbackupfabric/util/BackupFilesystemUtil.java
+++ b/src/main/java/com/keuin/kbackupfabric/util/BackupFilesystemUtil.java
@@ -5,6 +5,8 @@ import net.minecraft.server.world.ThreadedAnvilChunkStorage;
 import net.minecraft.world.World;
 
 import java.io.File;
+import java.util.regex.Matcher;
+import java.util.regex.Pattern;
 
 /**
  * Functions deal with file name, directory name about Minecraft saves.
@@ -50,4 +52,27 @@ public final class BackupFilesystemUtil {
     public static String getBackupFileNamePrefix() {
         return backupFileNamePrefix;
     }
+
+    public static long getBackupTimeFromBackupFileName(String backupFileName) {
+        Matcher matcher = Pattern.compile("[0-9]{4}-[0-9]{2}-[0-9]{2}_[0-9]{2}-[0-9]{2}-[0-9]{2}").matcher(backupFileName);
+        if (matcher.find()) {
+            String timeString = matcher.group(0);
+            long timeStamp = BackupNameTimeFormatter.timeStringToEpochSeconds(timeString);
+            System.out.println(backupFileName + " -> " + timeStamp);
+            return timeStamp;
+        } else {
+            System.err.println("Failed to extract time from " + backupFileName);
+        }
+        return -1;
+    }
+
+    public static String humanFileSize(long size) {
+        double fileSize = size * 1.0 / 1024 / 1024; // Default unit is MB
+        if (fileSize > 1000)
+            //msgInfo(context, String.format("File size: %.2fGB", fileSize / 1024));
+            return String.format("%.2fGB", fileSize / 1024);
+        else
+            //msgInfo(context, String.format("File size: %.2fMB", fileSize));
+            return String.format("%.2fMB", fileSize);
+    }
 }
diff --git a/src/main/java/com/keuin/kbackupfabric/util/BackupNameTimeFormatter.java b/src/main/java/com/keuin/kbackupfabric/util/BackupNameTimeFormatter.java
new file mode 100644
index 0000000..5d00270
--- /dev/null
+++ b/src/main/java/com/keuin/kbackupfabric/util/BackupNameTimeFormatter.java
@@ -0,0 +1,22 @@
+package com.keuin.kbackupfabric.util;
+
+import java.time.LocalDateTime;
+import java.time.ZoneId;
+import java.time.ZoneOffset;
+import java.time.format.DateTimeFormatter;
+
+public class BackupNameTimeFormatter {
+    private static final DateTimeFormatter formatter = DateTimeFormatter.ofPattern("yyyy-MM-dd_HH-mm-ss");
+
+    public static String getTimeString() {
+        return LocalDateTime.now().format(formatter);
+    }
+
+    public static long timeStringToEpochSeconds(String timeString) {
+        ZoneId systemZone = ZoneId.systemDefault(); // my timezone
+        LocalDateTime localDateTime = LocalDateTime.parse(timeString, formatter);
+        ZoneOffset currentOffsetForMyZone = systemZone.getRules().getOffset(localDateTime);
+        return localDateTime.toEpochSecond(currentOffsetForMyZone);
+    }
+
+}
diff --git a/src/main/java/com/keuin/kbackupfabric/worker/BackupWorker.java b/src/main/java/com/keuin/kbackupfabric/worker/BackupWorker.java
index 57e59fb..3303f70 100644
--- a/src/main/java/com/keuin/kbackupfabric/worker/BackupWorker.java
+++ b/src/main/java/com/keuin/kbackupfabric/worker/BackupWorker.java
@@ -56,9 +56,9 @@ public final class BackupWorker implements Runnable {
         });
 
         // Force to save all player data and worlds
-        LOGGER.debug("Saving players ...");
+        LOGGER.info("Saving players ...");
         server.getPlayerManager().saveAllPlayerData();
-        LOGGER.debug("Saving worlds ...");
+        LOGGER.info("Saving worlds ...");
         server.save(true, true, true);
 
         // Start threaded worker
@@ -86,6 +86,7 @@ public final class BackupWorker implements Runnable {
             String levelPath = getLevelPath(server);
             String backupFileName = getBackupFileName(backupName);
             LOGGER.debug(String.format("zip(srcPath=%s, destPath=%s)", levelPath, backupSaveDirectoryFile.toString()));
+            LOGGER.info("Compressing level ...");
             ZipUtil.makeBackupZip(levelPath, backupSaveDirectoryFile.toString(), backupFileName, backupMetadata);
             File backupZipFile = new File(backupSaveDirectoryFile, backupFileName);
 
@@ -96,11 +97,7 @@ public final class BackupWorker implements Runnable {
             long timeEscapedMillis = System.currentTimeMillis() - startTime;
             msgInfo(context, String.format("Backup finished. (%.2fs)", timeEscapedMillis / 1000.0), true);
             try {
-                double fileSize = backupZipFile.length() * 1.0 / 1024 / 1024;
-                if (fileSize > 1000)
-                    msgInfo(context, String.format("File size: %.2fGB", fileSize / 1024));
-                else
-                    msgInfo(context, String.format("File size: %.2fMB", fileSize));
+                msgInfo(context, String.format("File size: %s", humanFileSize(backupZipFile.length())));
             } catch (SecurityException ignored) {
             }
 
diff --git a/src/main/java/com/keuin/kbackupfabric/worker/RestoreWorker.java b/src/main/java/com/keuin/kbackupfabric/worker/RestoreWorker.java
index 8d367d7..54e7beb 100644
--- a/src/main/java/com/keuin/kbackupfabric/worker/RestoreWorker.java
+++ b/src/main/java/com/keuin/kbackupfabric/worker/RestoreWorker.java
@@ -44,7 +44,7 @@ public final class RestoreWorker implements Runnable {
     public void run() {
         try {
             // Wait server thread die
-            LOGGER.debug("Waiting for the server thread to exit ...");
+            LOGGER.info("Waiting for the server thread to exit ...");
             while (serverThread.isAlive()) {
                 try {
                     serverThread.join();
@@ -52,15 +52,16 @@ public final class RestoreWorker implements Runnable {
                 }
             }
 
-            LOGGER.debug("Wait for 5 seconds ...");
+            LOGGER.info("Wait for 5 seconds ...");
             try {
                 Thread.sleep(5000);
             } catch (InterruptedException ignored) {
             }
 
             // Delete old level
-            LOGGER.debug("Server stopped. Deleting old level ...");
+            LOGGER.info("Server stopped. Deleting old level ...");
             File levelDirFile = new File(levelDirectory);
+            long startTime = System.currentTimeMillis();
 
             int failedCounter = 0;
             final int MAX_RETRY_TIMES = 20;
@@ -84,9 +85,10 @@ public final class RestoreWorker implements Runnable {
             }
 
             // Decompress archive
-            LOGGER.debug("Decompressing archived level");
+            LOGGER.info("Decompressing archived level");
             ZipUtil.unzip(backupFilePath, levelDirectory, false);
-            LOGGER.info("Restore complete! Please restart the server manually.");
+            long endTime = System.currentTimeMillis();
+            LOGGER.info(String.format("Restore complete! (%.2fs) Please restart the server manually.", (endTime - startTime) / 1000.0));
         } catch (SecurityException | IOException | ZipUtilException e) {
             LOGGER.error("An exception occurred while restoring: " + e.getMessage());
         }