From b96066e41b3d03c005b1e571dd042769b787725c Mon Sep 17 00:00:00 2001
From: Zach Brown <zach@zachbr.io>
Date: Mon, 27 May 2019 01:10:06 -0500
Subject: [PATCH] Version Command 2.0


diff --git a/src/main/java/com/destroystokyo/paper/util/VersionFetcher.java b/src/main/java/com/destroystokyo/paper/util/VersionFetcher.java
new file mode 100644
index 00000000..2a265129
--- /dev/null
+++ b/src/main/java/com/destroystokyo/paper/util/VersionFetcher.java
@@ -0,0 +1,44 @@
+package com.destroystokyo.paper.util;
+
+import org.bukkit.Bukkit;
+import org.jetbrains.annotations.NotNull;
+
+public interface VersionFetcher {
+    /**
+     * Amount of time to cache results for in milliseconds
+     * <p>
+     * Negative values will never cache.
+     *
+     * @return cache time
+     */
+    long getCacheTime();
+
+    /**
+     * Gets the version message to cache and show to command senders. Multiple messages can be sent using newlines (\n)
+     * in the string. The string will be split on these newlines and sent as individual messages.
+     * <p>
+     * NOTE: This is run in a new thread separate from that of the command processing thread
+     *
+     * @param serverVersion the current version of the server (will match {@link Bukkit#getVersion()})
+     * @return the message to show when requesting a version
+     */
+    @NotNull
+    String getVersionMessage(@NotNull String serverVersion);
+
+    class DummyVersionFetcher implements VersionFetcher {
+
+        @Override
+        public long getCacheTime() {
+            return -1;
+        }
+
+        @NotNull
+        @Override
+        public String getVersionMessage(@NotNull String serverVersion) {
+            Bukkit.getLogger().warning("Version provider has not been set, cannot check for updates!");
+            Bukkit.getLogger().info("Override the default implementation of org.bukkit.UnsafeValues#getVersionFetcher()");
+            new Throwable().printStackTrace();
+            return "Unable to check for updates. No version provider set.";
+        }
+    }
+}
diff --git a/src/main/java/org/bukkit/UnsafeValues.java b/src/main/java/org/bukkit/UnsafeValues.java
index 72c5501e..c0ff133d 100644
--- a/src/main/java/org/bukkit/UnsafeValues.java
+++ b/src/main/java/org/bukkit/UnsafeValues.java
@@ -76,5 +76,12 @@ public interface UnsafeValues {
      * @return name
      */
     String getTimingsServerName();
+
+    /**
+     * Called once by the version command on first use, then cached.
+     */
+    default com.destroystokyo.paper.util.VersionFetcher getVersionFetcher() {
+        return new com.destroystokyo.paper.util.VersionFetcher.DummyVersionFetcher();
+    }
     // Paper end
 }
diff --git a/src/main/java/org/bukkit/command/defaults/VersionCommand.java b/src/main/java/org/bukkit/command/defaults/VersionCommand.java
index cbce5244..0486abd1 100644
--- a/src/main/java/org/bukkit/command/defaults/VersionCommand.java
+++ b/src/main/java/org/bukkit/command/defaults/VersionCommand.java
@@ -1,5 +1,6 @@
 package org.bukkit.command.defaults;
 
+import com.destroystokyo.paper.util.VersionFetcher; // Paper - version supplier
 import com.google.common.base.Charsets;
 import com.google.common.collect.ImmutableList;
 import com.google.common.io.Resources;
@@ -26,6 +27,15 @@ import org.bukkit.util.StringUtil;
 import org.jetbrains.annotations.NotNull;
 
 public class VersionCommand extends BukkitCommand {
+    private VersionFetcher versionFetcher;
+    private VersionFetcher getVersionFetcher() { // lazy load because unsafe isn't available at command registration
+        if (versionFetcher == null) {
+            versionFetcher = Bukkit.getUnsafe().getVersionFetcher();
+        }
+
+        return versionFetcher;
+    }
+
     public VersionCommand(@NotNull String name) {
         super(name);
 
@@ -150,18 +160,18 @@ public class VersionCommand extends BukkitCommand {
 
     private void sendVersion(@NotNull CommandSender sender) {
         if (hasVersion) {
-            if (System.currentTimeMillis() - lastCheck > 21600000) {
+            if (System.currentTimeMillis() - lastCheck > getVersionFetcher().getCacheTime()) { // Paper - use version supplier
                 lastCheck = System.currentTimeMillis();
                 hasVersion = false;
             } else {
-                sender.sendMessage(versionMessage);
+                sendMessages(versionMessage, sender); // Paper - allow \n for multiple messages
                 return;
             }
         }
         versionLock.lock();
         try {
             if (hasVersion) {
-                sender.sendMessage(versionMessage);
+                sendMessages(versionMessage, sender); // Paper - allow \n for multiple messages
                 return;
             }
             versionWaiters.add(sender);
@@ -183,7 +193,12 @@ public class VersionCommand extends BukkitCommand {
 
     private void obtainVersion() {
         String version = Bukkit.getVersion();
-        if (version == null) version = "Custom";
+        // Paper start
+        if (version.startsWith("null")) { // running from ide?
+            setVersionMessage("Unknown version, custom build?");
+            return;
+        }
+        /*
         if (version.startsWith("git-Spigot-")) {
             String[] parts = version.substring("git-Spigot-".length()).split("-");
             int cbVersions = getDistance("craftbukkit", parts[1].substring(0, parts[1].indexOf(' ')));
@@ -213,6 +228,9 @@ public class VersionCommand extends BukkitCommand {
         } else {
             setVersionMessage("Unknown version, custom build?");
         }
+         */
+        setVersionMessage(getVersionFetcher().getVersionMessage(version));
+        // Paper end
     }
 
     private void setVersionMessage(@NotNull String msg) {
@@ -222,8 +240,13 @@ public class VersionCommand extends BukkitCommand {
         try {
             hasVersion = true;
             versionTaskStarted = false;
+            // Paper - allow \n for multiple messages
+            String[] messages = versionMessage.split("\n");
             for (CommandSender sender : versionWaiters) {
-                sender.sendMessage(versionMessage);
+                for (String message : messages) {
+                    sender.sendMessage(message);
+                }
+                // Paper end
             }
             versionWaiters.clear();
         } finally {
@@ -231,6 +254,15 @@ public class VersionCommand extends BukkitCommand {
         }
     }
 
+    // Paper start
+    private void sendMessages(String toSplit, CommandSender target) {
+        String[] messages = toSplit.split("\n");
+        for (String message : messages) {
+            target.sendMessage(message);
+        }
+    }
+    // Paper end
+
     private static int getDistance(@NotNull String repo, @NotNull String hash) {
         try {
             BufferedReader reader = Resources.asCharSource(
-- 
2.21.0