SPIGOT-6705: Re-print tab completion "Display all" message in console, when another message is being logged

By: DerFrZocker <derrieple@gmail.com>

paper-server/src/main/java/org/bukkit/craftbukkit/util/TerminalCompletionHandler.java

@@ -0,0 +1,53 @@
+package org.bukkit.craftbukkit.util;
+
+import java.io.IOException;
+import java.util.HashSet;
+import java.util.List;
+import java.util.Set;
+import jline.console.ConsoleReader;
+import jline.console.completer.CompletionHandler;
+
+/**
+ * SPIGOT-6705: Make sure we print the display line again on tab completion, so that the user does not get stuck on it
+ * e.g. The user needs to press y / n to continue
+ */
+public class TerminalCompletionHandler implements CompletionHandler {
+
+    private final TerminalConsoleWriterThread writerThread;
+    private final CompletionHandler delegate;
+
+    public TerminalCompletionHandler(TerminalConsoleWriterThread writerThread, CompletionHandler delegate) {
+        this.writerThread = writerThread;
+        this.delegate = delegate;
+    }
+
+    @Override
+    public boolean complete(ConsoleReader reader, List<CharSequence> candidates, int position) throws IOException {
+        // First check normal list, so that we do not unnecessarily create a new HashSet if the not distinct list is already lower
+        if (candidates.size() <= reader.getAutoprintThreshold()) {
+            return delegate.complete(reader, candidates, position);
+        }
+
+        Set<CharSequence> distinct = new HashSet<>(candidates);
+        if (distinct.size() <= reader.getAutoprintThreshold()) {
+            return delegate.complete(reader, candidates, position);
+        }
+
+        writerThread.setCompletion(distinct.size());
+
+        // FIXME: Potential concurrency issue, when terminal writer prints the display message before the delegate does it
+        // resulting in two display message being present, until a new message gets logged or the user presses y / n
+        // But the probability of this happening are probably lower than the effort needed to fix this
+        // And seeing the display message at all should be a higher priority than seeing it two times in rare cases.
+        boolean result = delegate.complete(reader, candidates, position);
+
+        writerThread.setCompletion(-1);
+        // draw line to prevent concurrency issue,
+        // where terminal write would print the display message between delegate#complete finished and the completion set back to -1
+        // Resulting in the display message being present even after pressing y / n
+        reader.drawLine();
+        reader.flush();
+
+        return result;
+    }
+}

paper-server/src/main/java/org/bukkit/craftbukkit/util/TerminalConsoleWriterThread.java

@@ -3,16 +3,21 @@ package org.bukkit.craftbukkit.util;
 import com.mojang.logging.LogQueues;
 import java.io.IOException;
 import java.io.OutputStream;
+import java.util.Locale;
+import java.util.ResourceBundle;
 import java.util.logging.Level;
 import java.util.logging.Logger;
 import jline.console.ConsoleReader;
+import jline.console.completer.CandidateListCompletionHandler;
 import org.bukkit.craftbukkit.Main;
 import org.fusesource.jansi.Ansi;
 import org.fusesource.jansi.Ansi.Erase;
 
 public class TerminalConsoleWriterThread extends Thread {
+    private final ResourceBundle bundle = ResourceBundle.getBundle(CandidateListCompletionHandler.class.getName(), Locale.getDefault());
     private final ConsoleReader reader;
     private final OutputStream output;
+    private volatile int completion = -1;
 
     public TerminalConsoleWriterThread(OutputStream output, ConsoleReader reader) {
         super("TerminalConsoleWriter");
@@ -45,6 +50,12 @@ public class TerminalConsoleWriterThread extends Thread {
                     } catch (Throwable ex) {
                         reader.getCursorBuffer().clear();
                     }
+
+                    if (completion > -1) {
+                        // SPIGOT-6705: Make sure we print the display line again on tab completion, so that the user does not get stuck on it
+                        reader.print(String.format(bundle.getString("DISPLAY_CANDIDATES"), completion));
+                    }
+
                     reader.flush();
                 } else {
                     output.write(message.getBytes());
@@ -55,4 +66,8 @@ public class TerminalConsoleWriterThread extends Thread {
             }
         }
     }
+
+    void setCompletion(int completion) {
+        this.completion = completion;
+    }
 }