openrs2/deob-ast/src/main/java/dev/openrs2/deob/ast/transform/IncrementTransformer.kt

package dev.openrs2.deob.ast.transform

import com.github.javaparser.ast.CompilationUnit
import com.github.javaparser.ast.Node
import com.github.javaparser.ast.expr.UnaryExpr
import com.github.javaparser.ast.stmt.ExpressionStmt
import com.github.javaparser.ast.stmt.ForStmt
import dev.openrs2.deob.ast.util.walk

class IncrementTransformer : Transformer() {
    override fun transform(unit: CompilationUnit) {
        unit.walk(Node.TreeTraversal.POSTORDER) { stmt: ExpressionStmt ->
            if (!stmt.expression.isUnaryExpr) {
                return@walk
            }

            val unaryExpr = stmt.expression.asUnaryExpr()
            unaryExpr.operator = prefixToPostfix(unaryExpr.operator)
        }

        unit.walk(Node.TreeTraversal.POSTORDER) { stmt: ForStmt ->
            stmt.update.forEach {
                if (!it.isUnaryExpr) {
                    return@forEach
                }

                val unaryExpr = it.asUnaryExpr()
                unaryExpr.operator = prefixToPostfix(unaryExpr.operator)
            }
        }
    }

    companion object {
        private fun prefixToPostfix(operator: UnaryExpr.Operator) = when (operator) {
            UnaryExpr.Operator.PREFIX_INCREMENT -> UnaryExpr.Operator.POSTFIX_INCREMENT
            UnaryExpr.Operator.PREFIX_DECREMENT -> UnaryExpr.Operator.POSTFIX_DECREMENT
            else -> operator
        }
    }
}