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

import org.cojen.classfile.TypeDesc;
import org.objectweb.asm.Label;
import org.simantics.scl.compiler.constants.FunctionValue;
import org.simantics.scl.compiler.constants.LocalVariableConstant;
import org.simantics.scl.compiler.internal.codegen.continuations.Cont;
import org.simantics.scl.compiler.internal.codegen.references.IVal;
import org.simantics.scl.compiler.internal.codegen.references.Val;
import org.simantics.scl.compiler.internal.codegen.utils.LocalVariable;
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;

/**
 * Dynamic :: a -> Dynamic
 */
public class DynamicConstructor extends FunctionValue {
    private static final TVar A = Types.var(Kinds.STAR);
    public static final DynamicConstructor INSTANCE = new DynamicConstructor();
    
    private DynamicConstructor() {
        super(new TVar[] {A}, Types.NO_EFFECTS, Types.DYNAMIC, A);
    }

    @Override
    public Type applyExact(MethodBuilder mb, Val[] parameters) {
        mb.pushBoxed(parameters[0]);
        return Types.DYNAMIC;
    }

    @Override
    public void deconstruct(MethodBuilder mb, IVal parameter, Cont success, Label failure) {
        Type expectedType = success.getParameterType(0);
        TypeDesc expectedTypeDesc = mb.getJavaTypeTranslator().toTypeDesc(expectedType);
        TypeDesc expectedObjectTypeDesc = expectedTypeDesc.toObjectType();
        LocalVariable cachedParameter = mb.cacheValue(parameter, Types.DYNAMIC);
        mb.loadLocal(cachedParameter);
        mb.instanceOf(expectedObjectTypeDesc);
        mb.ifZeroComparisonBranch(failure, "==");
        
        mb.loadLocal(cachedParameter);
        mb.checkCast(expectedObjectTypeDesc);
        mb.unbox(expectedType);
        LocalVariable casted = mb.createLocalVariable("dynamicContent", expectedTypeDesc); 
        mb.storeLocal(casted);
        mb.jump(success, new LocalVariableConstant(expectedType, casted));
    }
}