package org.simantics.scl.compiler.elaboration.java;

import org.cojen.classfile.TypeDesc;
import org.objectweb.asm.Label;
import org.simantics.scl.compiler.constants.ComparisonFunction;
import org.simantics.scl.compiler.constants.FunctionValue;
import org.simantics.scl.compiler.internal.codegen.continuations.Cont;
import org.simantics.scl.compiler.internal.codegen.references.Val;
import org.simantics.scl.compiler.internal.codegen.utils.Constants;
import org.simantics.scl.compiler.internal.codegen.utils.MethodBuilder;
import org.simantics.scl.compiler.types.TVar;
import org.simantics.scl.compiler.types.Type;
import org.simantics.scl.compiler.types.Types;
import org.simantics.scl.compiler.types.kinds.Kinds;

public class EqualsFunction extends FunctionValue implements ComparisonFunction {
    private static final TVar A = Types.var(Kinds.STAR);
    public static final EqualsFunction INSTANCE = new EqualsFunction();
    
    private EqualsFunction() {
        super(new TVar[] {A}, Types.NO_EFFECTS, Types.BOOLEAN, A, A);
    }

    @Override
    public Type applyExact(MethodBuilder mb, Val[] parameters) {
        parameters[0].push(mb);
        parameters[1].push(mb);
        TypeDesc parameterType = mb.getJavaTypeTranslator().getTypeDesc(parameters[0]);
        if(parameterType.isPrimitive()) {
            if(parameterType.equals(TypeDesc.VOID)) {
                mb.loadConstant(true);
            }
            else {
                Label end = mb.createLabel();
                Label isEqual = mb.createLabel();
                mb.ifComparisonBranch(isEqual, "==", parameterType);
                mb.loadConstant(false);
                mb.branch(end);
                mb.setLocation(isEqual);
                mb.loadConstant(true);
                mb.setLocation(end);
            }
        }
        else
            mb.invokeStatic("java/util/Objects", "equals", TypeDesc.BOOLEAN, Constants.OBJECTS[2]);
        return Types.BOOLEAN;
    }
    
    @Override
    public String toString() {
        return "==";
    }

    @Override
    public void generateCondition(MethodBuilder mb, Val[] parameters, Cont then_, Cont else_) {
        parameters[0].push(mb);
        parameters[1].push(mb);
        TypeDesc parameterType = mb.getJavaTypeTranslator().getTypeDesc(parameters[0]);
        if(parameterType.isPrimitive()) {
            if(parameterType.equals(TypeDesc.VOID)) {
                mb.jump(then_);
            }
            else {
                mb.ifComparisonBranch(mb.getLabel(then_), "==", parameterType);
                mb.jump(else_);
                mb.ensureExists(then_);
            }
        }
        else {
            mb.invokeStatic("java/util/Objects", "equals", TypeDesc.BOOLEAN, Constants.OBJECTS[2]);
            mb.ifZeroComparisonBranch(mb.getLabel(else_), "==");
            mb.jump(then_);
            mb.ensureExists(else_);
        }
    }
}