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

import java.util.ArrayList;

import org.cojen.classfile.TypeDesc;
import org.objectweb.asm.Opcodes;
import org.simantics.scl.compiler.elaboration.chr.CHRRule;
import org.simantics.scl.compiler.elaboration.chr.CHRRuleset;
import org.simantics.scl.compiler.elaboration.chr.relations.CHRConstraint;
import org.simantics.scl.compiler.internal.codegen.references.BoundVar;
import org.simantics.scl.compiler.internal.codegen.utils.ClassBuilder;
import org.simantics.scl.compiler.internal.codegen.utils.Constants;
import org.simantics.scl.compiler.internal.codegen.utils.MethodBuilderBase;
import org.simantics.scl.compiler.internal.codegen.utils.ModuleBuilder;

public class CHRRuntimeRulesetCodeGenerator implements CHRCodeGenerationConstants {

    public static void generateRuntimeRuleset(ModuleBuilder moduleBuilder, CHRRuleset ruleset) {
        ClassBuilder storeClassBuilder = new ClassBuilder(moduleBuilder, Opcodes.ACC_PUBLIC, ruleset.runtimeRulesetName, CHRRuntimeRuleset_name);
        if(ruleset.parameters == null)
            ruleset.parameters = new BoundVar[0];
        ruleset.parameterTypeDescs = moduleBuilder.getJavaTypeTranslator().getTypeDescs(ruleset.parameters); 

        ArrayList<StoreInitialization> hashIndexInitializations = new ArrayList<StoreInitialization>();
        for(CHRConstraint constraint : ruleset.constraints)
            generateFact(storeClassBuilder, constraint, hashIndexInitializations);
        
        for(int i=ruleset.rules.size()-1;i>=0;--i)
            generateFactContainer(storeClassBuilder, ruleset, ruleset.rules.get(i));

        // Fields
        for(int i=0;i<ruleset.parameterTypeDescs.length;++i) {
            TypeDesc typeDesc = ruleset.parameterTypeDescs[i];
            if(typeDesc.equals(TypeDesc.VOID))
                continue;
            storeClassBuilder.addField(Opcodes.ACC_PUBLIC | Opcodes.ACC_FINAL, CHRCodeGenerationConstants.parameterName(i), typeDesc);
        }
        for(StoreInitialization ini : hashIndexInitializations)
            storeClassBuilder.addField(ini.access, ini.fieldName, ini.fieldType);
        for(CHRRule rule : ruleset.rules)
            storeClassBuilder.addField(Opcodes.ACC_PUBLIC | Opcodes.ACC_FINAL, CHRCodeGenerationConstants.priorityName(rule.priority), CHRPriorityFactContainer);

        // Constructors

        {
            MethodBuilderBase mb = storeClassBuilder.addConstructor(Opcodes.ACC_PUBLIC, ruleset.parameterTypeDescs);
            mb.loadThis();
            mb.invokeConstructor(storeClassBuilder.getSuperClassName(), Constants.EMPTY_TYPEDESC_ARRAY);
            for(int i=0;i<ruleset.parameterTypeDescs.length;++i) {
                TypeDesc typeDesc = ruleset.parameterTypeDescs[i];
                if(typeDesc.equals(TypeDesc.VOID))
                    continue;
                mb.loadThis();
                mb.loadLocal(mb.getParameter(i));
                mb.storeField(ruleset.runtimeRulesetName, CHRCodeGenerationConstants.parameterName(i), ruleset.parameterTypeDescs[i]);
            }
            for(StoreInitialization ini : hashIndexInitializations) {
                mb.loadThis();
                mb.newObject(ini.className);
                mb.dup();
                mb.invokeConstructor(ini.className, Constants.EMPTY_TYPEDESC_ARRAY);
                mb.storeField(ruleset.runtimeRulesetName, ini.fieldName, ini.fieldType);
            }
            TypeDesc[] runtimeRulesetTypeDescArray = new TypeDesc[] {TypeDesc.forClass(storeClassBuilder.getClassName())};
            for(CHRRule rule : ruleset.rules) {
                mb.loadThis();
                mb.newObject(rule.containerClassName);
                mb.dup();
                mb.loadThis();
                mb.invokeConstructor(rule.containerClassName, runtimeRulesetTypeDescArray);
                mb.storeField(ruleset.runtimeRulesetName, CHRCodeGenerationConstants.priorityName(rule.priority), CHRPriorityFactContainer);
            }
            mb.returnVoid();
            mb.finish();
        }

        moduleBuilder.addClass(storeClassBuilder);
    }

    private static void generateFact(ClassBuilder storeClassBuilder, CHRConstraint constraint, ArrayList<StoreInitialization> hashIndexInitializations) {
        CHRFactCodeGenerator generator = new CHRFactCodeGenerator(storeClassBuilder, constraint);
        generator.generate(hashIndexInitializations);
    }

    private static void generateFactContainer(ClassBuilder storeClassBuilder, CHRRuleset ruleset, CHRRule rule) {
        CHRPriorityFactContainerCodeGenerator generator = new CHRPriorityFactContainerCodeGenerator(storeClassBuilder, ruleset, rule); 
        generator.generate();
        rule.containerClassName = generator.containerClassName;
    }
}