From 4ebf752522953da19f20f29b1511605ad425701b Mon Sep 17 00:00:00 2001
From: SamB440 <sam@islandearth.net>
Date: Sat, 20 Jul 2024 15:31:02 +0100
Subject: [PATCH] Add Java 17 warning

---
 .../ac/grim/grimac/manager/InitManager.java   |  1 +
 .../manager/init/start/JavaVersion.java       | 37 +++++++++++++++++++
 2 files changed, 38 insertions(+)
 create mode 100644 src/main/java/ac/grim/grimac/manager/init/start/JavaVersion.java

diff --git a/src/main/java/ac/grim/grimac/manager/InitManager.java b/src/main/java/ac/grim/grimac/manager/InitManager.java
index 77de7c771a..49216c58da 100644
--- a/src/main/java/ac/grim/grimac/manager/InitManager.java
+++ b/src/main/java/ac/grim/grimac/manager/InitManager.java
@@ -32,6 +32,7 @@ public InitManager() {
                 .put(DiscordManager.class, GrimAPI.INSTANCE.getDiscordManager())
                 .put(SpectateManager.class, GrimAPI.INSTANCE.getSpectateManager())
                 .put(GrimExternalAPI.class, GrimAPI.INSTANCE.getExternalAPI())
+                .put(JavaVersion.class, new JavaVersion())
                 .build();
 
         initializersOnStop = new ImmutableClassToInstanceMap.Builder<Initable>()
diff --git a/src/main/java/ac/grim/grimac/manager/init/start/JavaVersion.java b/src/main/java/ac/grim/grimac/manager/init/start/JavaVersion.java
new file mode 100644
index 0000000000..b26afeac12
--- /dev/null
+++ b/src/main/java/ac/grim/grimac/manager/init/start/JavaVersion.java
@@ -0,0 +1,37 @@
+package ac.grim.grimac.manager.init.start;
+
+import ac.grim.grimac.manager.init.Initable;
+import ac.grim.grimac.utils.anticheat.LogUtil;
+
+import java.util.regex.Matcher;
+import java.util.regex.Pattern;
+
+public class JavaVersion implements Initable {
+
+    @Override
+    public void start() {
+        // Stolen from Via, stolen from Paper
+        String javaVersion = System.getProperty("java.version");
+        Matcher matcher = Pattern.compile("(?:1\\.)?(\\d+)").matcher(javaVersion);
+        if (!matcher.find()) {
+            LogUtil.error("Failed to determine Java version; could not parse: " + javaVersion);
+            return;
+        }
+
+        String versionString = matcher.group(1);
+        int version;
+        try {
+            version = Integer.parseInt(versionString);
+        } catch (NumberFormatException e) {
+            LogUtil.error("Failed to determine Java version; could not parse: " + versionString);
+            e.printStackTrace();
+            return;
+        }
+
+        if (version < 17) {
+            LogUtil.warn("You are running an outdated Java version, please update it to at least Java 17 (your version is " + javaVersion + ").");
+            LogUtil.warn("GrimAC will no longer support this version of Java in a future release.");
+            LogUtil.warn("See https://github.com/GrimAnticheat/Grim/wiki/Updating-to-Java-17 for more information.");
+        }
+    }
+}