From e9b2ad6d628b866b2cb825687dd069904894bafc Mon Sep 17 00:00:00 2001
From: Graham <gpe@openrs2.dev>
Date: Sun, 11 Aug 2019 21:02:44 +0100
Subject: [PATCH] Add initial BinaryExprOrderTransformer

---
 .../dev/openrs2/deob/ast/AstDeobfuscator.java |  4 +-
 .../transform/BinaryExprOrderTransformer.java | 48 +++++++++++++++++++
 2 files changed, 51 insertions(+), 1 deletion(-)
 create mode 100644 deob-ast/src/main/java/dev/openrs2/deob/ast/transform/BinaryExprOrderTransformer.java

diff --git a/deob-ast/src/main/java/dev/openrs2/deob/ast/AstDeobfuscator.java b/deob-ast/src/main/java/dev/openrs2/deob/ast/AstDeobfuscator.java
index 36bd452e..0c9c38a9 100644
--- a/deob-ast/src/main/java/dev/openrs2/deob/ast/AstDeobfuscator.java
+++ b/deob-ast/src/main/java/dev/openrs2/deob/ast/AstDeobfuscator.java
@@ -13,6 +13,7 @@ import com.github.javaparser.symbolsolver.resolution.typesolvers.ReflectionTypeS
 import com.github.javaparser.utils.SourceRoot;
 import com.google.common.collect.ImmutableList;
 import dev.openrs2.deob.ast.transform.AddSubTransformer;
+import dev.openrs2.deob.ast.transform.BinaryExprOrderTransformer;
 import dev.openrs2.deob.ast.transform.ComplementTransformer;
 import dev.openrs2.deob.ast.transform.IfElseTransformer;
 import dev.openrs2.deob.ast.transform.Transformer;
@@ -21,7 +22,8 @@ public final class AstDeobfuscator {
 	private static final ImmutableList<Transformer> TRANSFORMERS = ImmutableList.of(
 		new AddSubTransformer(),
 		new ComplementTransformer(),
-		new IfElseTransformer()
+		new IfElseTransformer(),
+		new BinaryExprOrderTransformer()
 	);
 
 	public static void main(String[] args) {
diff --git a/deob-ast/src/main/java/dev/openrs2/deob/ast/transform/BinaryExprOrderTransformer.java b/deob-ast/src/main/java/dev/openrs2/deob/ast/transform/BinaryExprOrderTransformer.java
new file mode 100644
index 00000000..dc5c4618
--- /dev/null
+++ b/deob-ast/src/main/java/dev/openrs2/deob/ast/transform/BinaryExprOrderTransformer.java
@@ -0,0 +1,48 @@
+package dev.openrs2.deob.ast.transform;
+
+import java.util.Optional;
+
+import com.github.javaparser.ast.CompilationUnit;
+import com.github.javaparser.ast.expr.BinaryExpr;
+
+public final class BinaryExprOrderTransformer extends Transformer {
+	private static Optional<BinaryExpr.Operator> flip(BinaryExpr.Operator op) {
+		// TODO(gpe): handle the PLUS operator (we can't flip it if the type of the expression is String)
+		switch (op) {
+		case MULTIPLY:
+		case EQUALS:
+		case NOT_EQUALS:
+		case BINARY_AND:
+		case BINARY_OR:
+		case XOR:
+		case OR:
+		case AND:
+			return Optional.of(op);
+		case GREATER:
+			return Optional.of(BinaryExpr.Operator.LESS);
+		case GREATER_EQUALS:
+			return Optional.of(BinaryExpr.Operator.LESS_EQUALS);
+		case LESS:
+			return Optional.of(BinaryExpr.Operator.GREATER);
+		case LESS_EQUALS:
+			return Optional.of(BinaryExpr.Operator.GREATER_EQUALS);
+		default:
+			return Optional.empty();
+		}
+	}
+
+	@Override
+	public void transform(CompilationUnit unit) {
+		unit.findAll(BinaryExpr.class).forEach(expr -> {
+			flip(expr.getOperator()).ifPresent(op -> {
+				var left = expr.getLeft();
+				var right = expr.getRight();
+				if (left.isLiteralExpr() && !right.isLiteralExpr()) {
+					expr.setOperator(op);
+					expr.setLeft(right);
+					expr.setRight(left);
+				}
+			});
+		});
+	}
+}