script: replace method call with calculated result (#1251)

jadx-plugins/jadx-script/examples/scripts/replace_method_call.jadx.kts

@@ -0,0 +1,60 @@
+/**
+ * Replace method call with calculated result.
+ * Useful for custom string deobfuscation.
+ *
+ * Example for sample from issue https://github.com/skylot/jadx/issues/1251
+ */
+
+import jadx.core.dex.instructions.ConstStringNode
+import jadx.core.dex.instructions.InvokeNode
+import jadx.core.dex.instructions.args.InsnArg
+import jadx.core.dex.instructions.args.InsnWrapArg
+import jadx.core.dex.instructions.args.RegisterArg
+
+
+val jadx = getJadxInstance()
+
+jadx.replace.insns { mth, insn ->
+	if (insn is InvokeNode
+		&& insn.callMth.rawFullId == "com.xshield.aa.iIiIiiiiII(Ljava/lang/String;)Ljava/lang/String;"
+	) {
+		val str = getConstStr(insn.getArg(0))
+		if (str != null) {
+			val resultStr = decode(str)
+			log.info { "Decode '$str' to '$resultStr' in $mth" }
+			return@insns ConstStringNode(resultStr)
+		}
+	}
+	null
+}
+
+fun getConstStr(arg: InsnArg): String? {
+	val insn = when (arg) {
+		is InsnWrapArg -> arg.wrapInsn
+		is RegisterArg -> arg.assignInsn
+		else -> null
+	}
+	if (insn is ConstStringNode) {
+		return insn.string
+	}
+	return null
+}
+
+/**
+ * Decompiled method, automatically converted to Kotlin by IntelliJ Idea
+ */
+fun decode(str: String): String {
+	val length = str.length
+	val cArr = CharArray(length)
+	var i = length - 1
+	while (i >= 0) {
+		val i2 = i - 1
+		cArr[i] = (str[i].code xor 'z'.code).toChar()
+		if (i2 < 0) {
+			break
+		}
+		i = i2 - 1
+		cArr[i2] = (str[i2].code xor '\u000c'.code).toChar()
+	}
+	return String(cArr)
+}