5 files changed, 146 insertions, 0 deletions
diff --git a/src/main/java/io/github/moulberry/notenoughupdates/envcheck/EnvironmentScan.java b/src/main/java/io/github/moulberry/notenoughupdates/envcheck/EnvironmentScan.java
new file mode 100644
index 00000000..a42b4cb6
--- /dev/null
+++ b/src/main/java/io/github/moulberry/notenoughupdates/envcheck/EnvironmentScan.java
@@ -0,0 +1,85 @@
+package io.github.moulberry.notenoughupdates.envcheck;
+
+import javax.swing.*;
+import java.lang.reflect.Field;
+import java.util.Objects;
+
+public class EnvironmentScan {
+
+		static Class<?> tryGetClass(String name) {
+				try {
+						return Class.forName(name);
+				} catch (ClassNotFoundException e) {
+						return null;
+				}
+		}
+
+		static Object tryGetField(Class<?> clazz, Object inst, String name) {
+				if (clazz == null) return null;
+				try {
+						Field declaredField = clazz.getDeclaredField(name);
+						return declaredField.get(inst);
+				} catch (NoSuchFieldException | IllegalAccessException ignored) {
+				}
+				return null;
+		}
+
+
+		static boolean isAtLeast(Object left, int right) {
+				if (left instanceof Integer) {
+						return (Integer) left >= right;
+				}
+				return false;
+		}
+
+		static boolean shouldCheckOnce = true;
+
+		static void checkEnvironmentOnce() {
+				if (shouldCheckOnce) checkEnvironment();
+		}
+
+
+		static void checkEnvironment() {
+				shouldCheckOnce = false;
+				checkForgeEnvironment();
+		}
+
+		static void checkForgeEnvironment() {
+				Class<?> forgeVersion = tryGetClass("net.minecraftforge.common.ForgeVersion");
+				if (forgeVersion == null
+								|| !Objects.equals(tryGetField(forgeVersion, null, "majorVersion"), 11)
+								|| !Objects.equals(tryGetField(forgeVersion, null, "minorVersion"), 15)
+								|| !isAtLeast(tryGetField(forgeVersion, null, "revisionVersion"), 1)
+								|| !Objects.equals(tryGetField(forgeVersion, null, "mcVersion"), "1.8.9")
+				) {
+
+						System.out.printf("Forge Version : %s%nMajor : %s%nMinor : %s%nRevision : %s%nMinecraft : %s%n",
+										forgeVersion,
+										tryGetField(forgeVersion, null, "majorVersion"),
+										tryGetField(forgeVersion, null, "minorVersion"),
+										tryGetField(forgeVersion, null, "revisionVersion"),
+										tryGetField(forgeVersion, null, "mcVersion")
+						);
+						missingOrOutdatedForgeError();
+				}
+		}
+
+		static void missingOrOutdatedForgeError() {
+				showErrorMessage(
+								"You just launched NotEnoughUpdates with the wrong (or no) modloader installed.",
+								"",
+								"NotEnoughUpdates only works in Minecraft 1.8.9, with Forge 11.15.1+",
+								"Please relaunch NotEnoughUpdates in the correct environment.",
+								"If you are in using Minecraft 1.8.9 with Forge 11.15.1+ installed, please contact support.",
+								"Click OK to launch anyways."
+				);
+		}
+
+
+		public static void showErrorMessage(String... messages) {
+				String message = String.join("\n", messages);
+				JOptionPane.showMessageDialog(
+								null, message, "NotEnoughUpdates - Problematic System Configuration", JOptionPane.ERROR_MESSAGE
+				);
+		}
+}
diff --git a/src/main/java/io/github/moulberry/notenoughupdates/envcheck/NEUMixinConfigPlugin.java b/src/main/java/io/github/moulberry/notenoughupdates/envcheck/NEUMixinConfigPlugin.java
new file mode 100644
index 00000000..44e24ff4
--- /dev/null
+++ b/src/main/java/io/github/moulberry/notenoughupdates/envcheck/NEUMixinConfigPlugin.java
@@ -0,0 +1,46 @@
+package io.github.moulberry.notenoughupdates.envcheck;
+
+import org.spongepowered.asm.lib.tree.ClassNode;
+import org.spongepowered.asm.mixin.extensibility.IMixinConfigPlugin;
+import org.spongepowered.asm.mixin.extensibility.IMixinInfo;
+
+import java.util.List;
+import java.util.Set;
+
+public class NEUMixinConfigPlugin implements IMixinConfigPlugin {
+
+		static {
+				EnvironmentScan.checkEnvironmentOnce();
+		}
+
+		@Override
+		public void onLoad(String mixinPackage) {
+		}
+
+		@Override
+		public String getRefMapperConfig() {
+				return null;
+		}
+
+		@Override
+		public boolean shouldApplyMixin(String targetClassName, String mixinClassName) {
+				return true;
+		}
+
+		@Override
+		public void acceptTargets(Set<String> myTargets, Set<String> otherTargets) {
+		}
+
+		@Override
+		public List<String> getMixins() {
+				return null;
+		}
+
+		@Override
+		public void preApply(String targetClassName, ClassNode targetClass, String mixinClassName, IMixinInfo mixinInfo) {
+		}
+
+		@Override
+		public void postApply(String targetClassName, ClassNode targetClass, String mixinClassName, IMixinInfo mixinInfo) {
+		}
+}
diff --git a/src/main/resources/META-INF/mods.toml b/src/main/resources/META-INF/mods.toml
new file mode 100644
index 00000000..281faf65
--- /dev/null
+++ b/src/main/resources/META-INF/mods.toml
@@ -0,0 +1,14 @@
+# This mods.toml is loaded by forge 1.13-1.19 and is only here to make forge display an error message
+modLoader = "javafml"
+loaderVersion = "[12,)"
+license = "LGPL"
+
+[[mods]]
+modId="notenoughupdateserrordisplay"
+version="99.99"
+displayName="NotEnoughUpdates (1.8.9)"
+description='''
+This mod description is only here to warn you about using the wrong version of Minecraft and Forge.
+'''
+
+
diff --git a/src/main/resources/META-INF/versions/9/module-info.class b/src/main/resources/META-INF/versions/9/module-info.class
new file mode 100644
index 00000000..6438019f
--- /dev/null
+++ b/src/main/resources/META-INF/versions/9/module-info.class
diff --git a/src/main/resources/mixins.notenoughupdates.json b/src/main/resources/mixins.notenoughupdates.json
index 8b1d4559..ed1ba55a 100644
--- a/src/main/resources/mixins.notenoughupdates.json
+++ b/src/main/resources/mixins.notenoughupdates.json
@@ -2,6 +2,7 @@
   "package": "io.github.moulberry.notenoughupdates.mixins",
   "refmap": "mixins.notenoughupdates.refmap.json",
   "minVersion": "0.7",
+  "plugin": "io.github.moulberry.notenoughupdates.envcheck.NEUMixinConfigPlugin",
   "compatibilityLevel": "JAVA_8",
   "mixins": [
     "AccessorEntityAgeable",