Add update checker

Author: Cosmiiko

src/main/java/com/cosmiiko/bsodod/UpdateChecker.java

@@ -0,0 +1,41 @@
+package com.cosmiiko.bsodod;
+
+import org.apache.commons.io.IOUtils;
+import java.io.IOException;
+import java.net.URL;
+import java.nio.charset.Charset;
+import java.util.regex.Matcher;
+import java.util.regex.Pattern;
+
+public class UpdateChecker {
+    static String GetLatestVersion() {
+        String gradleFile = null;
+        try {
+            gradleFile = IOUtils.toString(
+                    new URL("https://raw.githubusercontent.com/Cosmiiko/MC-BSODOnDeath/main/build.gradle"),
+                    Charset.defaultCharset()
+            );
+        } catch (IOException e) {
+            return null;
+        }
+
+        if (gradleFile == null) return null;
+
+        Pattern pattern = Pattern.compile("version = '(.*)'");
+        Matcher matcher = pattern.matcher(gradleFile);
+
+        if (matcher.find())
+        {
+            return matcher.group(1);
+        }
+        else
+        {
+            return null;
+        }
+    }
+
+    static String GetCurrentVersion()
+    {
+        return UpdateChecker.class.getPackage().getImplementationVersion();
+    }
+}

src/main/java/com/cosmiiko/bsodod/WarningScreen.java

@@ -31,6 +31,25 @@ public void init()
         textLines.add("By clicking 'I understand', you acknowledge the risks involved in");
         textLines.add("playing with such a mod.");
 
+        String latestVersion = UpdateChecker.GetLatestVersion();
+        String currentVersion = UpdateChecker.GetCurrentVersion();
+
+        if (latestVersion != null && currentVersion != null)
+        {
+            if (!latestVersion.equals(currentVersion))
+            {
+                textLines.add(TextFormatting.RED + "Your mod version is outdated (v" + currentVersion + ", latest is v" + latestVersion + ").");
+                textLines.add(TextFormatting.RED + "This version may contain bugs or accidental blue screens.");
+            }
+            else
+            {
+                textLines.add(TextFormatting.GREEN + "Your mod version is up-to-date.");
+            }
+        }
+        else
+        {
+            textLines.add(TextFormatting.GOLD + "Could not check for updates. Proceed with caution.");
+        }
 
         textVOffset = this.height/2 - (textLines.size()*LINESIZE + WARNINGSIZE)/2;