package org.simantics.scl.compiler.internal.codegen.chr;

import org.cojen.classfile.TypeDesc;
import org.objectweb.asm.Label;
import org.objectweb.asm.Opcodes;
import org.simantics.scl.compiler.elaboration.chr.relations.CHRConstraint;
import org.simantics.scl.compiler.elaboration.chr.relations.CHRConstraint.IndexInfo;
import org.simantics.scl.compiler.internal.codegen.types.JavaTypeTranslator;
import org.simantics.scl.compiler.internal.codegen.utils.ClassBuilder;
import org.simantics.scl.compiler.internal.codegen.utils.CodeBuilderUtils;
import org.simantics.scl.compiler.internal.codegen.utils.Constants;
import org.simantics.scl.compiler.internal.codegen.utils.LocalVariable;
import org.simantics.scl.compiler.internal.codegen.utils.MethodBuilderBase;
import org.simantics.scl.compiler.internal.codegen.utils.ModuleBuilder;

public class CHRHashIndexCodeGenerator implements CHRCodeGenerationConstants {
    
    public static ClassBuilder generateHashIndex(ClassBuilder storeClassBuilder, CHRConstraint constraint, IndexInfo indexInfo, TypeDesc factClassTypeDesc, String factClassName) {
        // new CHRHashIndex() {
        //     @Override
        //     protected boolean keyEquals(Object a, Object b) {
        //         return ((ExampleFact)a).c0 == ((ExampleFact)b).c0;
        //     }
        //     @Override
        //     protected int keyHashCode(Object key) {
        //         return ((ExampleFact)key).c0;
        //     }
        // }

        ModuleBuilder moduleBuilder = storeClassBuilder.getModuleBuilder();
        JavaTypeTranslator jtt = moduleBuilder.getJavaTypeTranslator();

        String hashIndexClassName = factClassName + "$" + indexInfo.indexName; 
        ClassBuilder hashIndexClassBuilder = new ClassBuilder(moduleBuilder, Opcodes.ACC_PUBLIC, hashIndexClassName, "org/simantics/scl/runtime/chr/CHRHashIndex");

        // Method: keyEquals

        {

            // @Override
            // protected boolean keyEquals(Object a, Object b) {
            //     return ((ExampleFact)a).c0 == ((ExampleFact)b).c0;
            // }

            MethodBuilderBase mb = hashIndexClassBuilder.addMethodBase(Opcodes.ACC_PROTECTED, "keyEquals", TypeDesc.BOOLEAN, Constants.OBJECTS[2]);
            mb.loadLocal(mb.getParameter(0));
            mb.checkCast(factClassTypeDesc);
            LocalVariable aVar = mb.createLocalVariable("a", factClassTypeDesc);
            mb.storeLocal(aVar);

            mb.loadLocal(mb.getParameter(1));
            mb.checkCast(factClassTypeDesc);
            LocalVariable bVar = mb.createLocalVariable("b", factClassTypeDesc);
            mb.storeLocal(bVar);

            Label failure = mb.createLabel();

            int curMask = indexInfo.indexMask;
            for(int i=0;i<constraint.parameterTypes.length;++i,curMask>>=1)
                if((curMask&1) == 1) {
                    TypeDesc fieldTypeDesc = jtt.toTypeDesc(constraint.parameterTypes[i]);
                    if(fieldTypeDesc.equals(TypeDesc.VOID))
                        continue;
                    mb.loadLocal(aVar);
                    mb.loadField(factClassName, CHRCodeGenerationConstants.fieldName(i), fieldTypeDesc);

                    mb.loadLocal(bVar);
                    mb.loadField(factClassName, CHRCodeGenerationConstants.fieldName(i), fieldTypeDesc);

                    CodeBuilderUtils.equals(mb, fieldTypeDesc, failure);
                }
            mb.loadConstant(true);
            mb.returnValue(TypeDesc.BOOLEAN);

            mb.setLocation(failure);
            mb.loadConstant(false);
            mb.returnValue(TypeDesc.BOOLEAN);
            mb.finish();
        }

        // Method: keyHashCode

        {
            // @Override
            // protected int keyHashCode(Object key) {
            //     return (0x811C9DC5^((ExampleFact)key).c0)*16777619;
            // }

            MethodBuilderBase mb = hashIndexClassBuilder.addMethodBase(Opcodes.ACC_PROTECTED, "keyHashCode", TypeDesc.INT, Constants.OBJECTS[1]);
            mb.loadLocal(mb.getParameter(0));
            mb.checkCast(factClassTypeDesc);
            LocalVariable factVar = mb.createLocalVariable("fact", factClassTypeDesc);
            mb.storeLocal(factVar);

            mb.loadConstant(0x811C9DC5);

            int curMask = indexInfo.indexMask;
            for(int i=0;i<constraint.parameterTypes.length;++i,curMask>>=1)
                if((curMask&1) == 1) {
                    TypeDesc fieldTypeDesc = jtt.toTypeDesc(constraint.parameterTypes[i]);
                    if(fieldTypeDesc.equals(TypeDesc.VOID))
                        continue;
                    mb.loadLocal(factVar);
                    mb.loadField(factClassName, CHRCodeGenerationConstants.fieldName(i), fieldTypeDesc);
                    CodeBuilderUtils.hashCode(mb, fieldTypeDesc);
                    mb.math(Opcodes.IXOR);
                    mb.loadConstant(16777619);
                    mb.math(Opcodes.IMUL);

                }
            mb.returnValue(TypeDesc.INT);
            mb.finish();
        }

        hashIndexClassBuilder.addDefaultConstructor();

        return hashIndexClassBuilder;
    }

}