SemVer compatibility, also change up the messages a bit.

src/main/java/us/myles/ViaVersion/update/UpdateUtil.java

@@ -23,7 +23,7 @@ public class UpdateUtil {
     public final static String PREFIX = ChatColor.GREEN + "" + ChatColor.BOLD + "[ViaVersion] " + ChatColor.GREEN;
     private final static String URL = "http://api.spiget.org/v2/resources/";
     private final static int PLUGIN = 19254;
-	private final static String LATEST_VERSION = "/versions/latest";
+    private final static String LATEST_VERSION = "/versions/latest";
 
     public static void sendUpdateMessage(final UUID uuid, final Plugin plugin) {
         new BukkitRunnable() {
@@ -82,13 +82,17 @@ public class UpdateUtil {
         try {
             current = new Version(ViaVersion.getInstance().getVersion());
         } catch (IllegalArgumentException e) {
-            return "You are using a debug/custom version, consider updating.";
+            return "You are using a custom version, consider updating.";
         }
         Version newest = new Version(newestString);
         if (current.compareTo(newest) < 0)
-            return "There is a newer version available: " + newest.toString();
+            return "There is a newer version available: " + newest.toString() + ", you're on: " + current.toString();
         else if (console && current.compareTo(newest) != 0) {
-            return "You are running a newer version than is released!";
+            if (current.getTag().toLowerCase().startsWith("dev") || current.getTag().toLowerCase().startsWith("snapshot")) {
+                return "You are running a development version, please report any bugs to GitHub.";
+            } else {
+                return "You are running a newer version than is released!";
+            }
         }
         return null;
     }

src/main/java/us/myles/ViaVersion/update/Version.java

@@ -2,21 +2,26 @@ package us.myles.ViaVersion.update;
 
 import org.apache.commons.lang.StringUtils;
 
+import java.util.regex.Matcher;
+import java.util.regex.Pattern;
+
 public class Version implements Comparable<Version> {
-    private int[] parts;
+    private static Pattern semVer = Pattern.compile("(?<a>0|[1-9]\\d*)\\.(?<b>0|[1-9]\\d*)(?:\\.(?<c>0|[1-9]\\d*))?(?:-(?<tag>[A-z0-9.-]*))?");
+    private int[] parts = new int[3];
+    private String tag;
 
     public Version(String value) {
         if (value == null)
             throw new IllegalArgumentException("Version can not be null");
 
-        if (!value.matches("^[0-9]+(\\.[0-9]+)*$"))
+        Matcher matcher = semVer.matcher(value);
+        if (!matcher.matches())
             throw new IllegalArgumentException("Invalid version format");
+        parts[0] = Integer.parseInt(matcher.group("a"));
+        parts[1] = Integer.parseInt(matcher.group("b"));
+        parts[2] = matcher.group("c") == null ? 0 : Integer.parseInt(matcher.group("c"));
 
-        String[] split = value.split("\\.");
+        tag = matcher.group("tag") == null ? "" : matcher.group("tag");
-        parts = new int[split.length];
-
-        for (int i = 0; i < split.length; i += 1)
-            parts[i] = Integer.parseInt(split[i]);
     }
 
     public static int compare(Version verA, Version verB) {
@@ -33,6 +38,12 @@ public class Version implements Comparable<Version> {
             if (partA > partB) return 1;
         }
 
+        // Simple tag check
+        if (verA.tag.length() == 0 && verB.tag.length() > 0)
+            return 1;
+        if (verA.tag.length() > 0 && verB.tag.length() == 0)
+            return -1;
+
         return 0;
     }
 
@@ -47,7 +58,7 @@ public class Version implements Comparable<Version> {
         for (int i = 0; i < parts.length; i += 1)
             split[i] = String.valueOf(parts[i]);
 
-        return StringUtils.join(split, ".");
+        return StringUtils.join(split, ".") + (tag.length() != 0 ? "-" + tag : "");
     }
 
     @Override
@@ -59,4 +70,8 @@ public class Version implements Comparable<Version> {
     public boolean equals(Object that) {
         return that instanceof Version && equals(this, (Version) that);
     }
+
+    public String getTag() {
+        return tag;
+    }
 }