/*
 * Copyright 2010 Red Hat, Inc. and/or its affiliates.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *       http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package org.jbpm.process.builder.dialect.mvel;

import java.util.HashMap;
import java.util.Map;
import java.util.Set;

import org.drools.compiler.compiler.DescrBuildError;
import org.drools.compiler.rule.builder.PackageBuildContext;
import org.drools.drl.ast.descr.ReturnValueDescr;
import org.drools.mvel.MVELDialectRuntimeData;
import org.drools.mvel.builder.MVELAnalysisResult;
import org.drools.mvel.builder.MVELDialect;
import org.drools.mvel.expr.MVELCompilationUnit;
import org.jbpm.process.builder.ProcessBuildContext;
import org.jbpm.process.builder.ReturnValueEvaluatorBuilder;
import org.jbpm.process.core.ContextResolver;
import org.jbpm.process.core.context.variable.VariableScope;
import org.jbpm.process.instance.impl.MVELReturnValueEvaluator;
import org.jbpm.process.instance.impl.ReturnValueConstraintEvaluator;

public class MVELReturnValueEvaluatorBuilder extends AbstractMVELBuilder
        implements
        ReturnValueEvaluatorBuilder {

    public MVELReturnValueEvaluatorBuilder() {

    }

    public void build(final PackageBuildContext context,
            final ReturnValueConstraintEvaluator constraintNode,
            final ReturnValueDescr descr,
            final ContextResolver contextResolver) {

        String text = descr.getText();
        Map<String, Class<?>> variables = new HashMap<>();

        try {
            MVELDialect dialect = (MVELDialect) context.getDialect("mvel");

            MVELAnalysisResult analysis = getAnalysis(context, descr, dialect, text, variables);

            if (analysis == null) {
                // not possible to get the analysis results
                return;
            }

            buildReturnValueEvaluator(context,
                    constraintNode,
                    descr,
                    contextResolver,
                    dialect,
                    analysis,
                    text,
                    variables);

        } catch (final Exception e) {
            context.getErrors().add(new DescrBuildError(context.getParentDescr(),
                    descr,
                    null,
                    "Unable to build expression for 'constraint' " + descr.getText() + "': " + e));
        }
    }

    public void buildReturnValueEvaluator(final PackageBuildContext context,
            final ReturnValueConstraintEvaluator constraintNode,
            final ReturnValueDescr descr,
            final ContextResolver contextResolver,
            final MVELDialect dialect,
            final MVELAnalysisResult analysis,
            final String text,
            Map<String, Class<?>> variables) throws Exception {

        Set<String> variableNames = analysis.getNotBoundedIdentifiers();
        if (contextResolver != null) {
            for (String variableName : variableNames) {
                if (analysis.getMvelVariables().keySet().contains(variableName) || variableName.equals("kcontext") || variableName.equals("context")) {
                    continue;
                }
                VariableScope variableScope = (VariableScope) contextResolver.resolveContext(VariableScope.VARIABLE_SCOPE, variableName);
                if (variableScope == null) {
                    context.getErrors().add(
                            new DescrBuildError(
                                    context.getParentDescr(),
                                    descr,
                                    null,
                                    "Could not find variable '" + variableName + "' for action '" + descr.getText() + "'"));
                } else {
                    variables.put(variableName,
                            context.getDialect().getTypeResolver().resolveType(variableScope.findVariable(variableName).getType().getStringType()));
                }
            }
        }

        MVELCompilationUnit unit = dialect.getMVELCompilationUnit(text,
                analysis,
                null,
                null,
                variables,
                context,
                "context",
                org.kie.api.runtime.process.ProcessContext.class,
                false,
                MVELCompilationUnit.Scope.EXPRESSION);

        MVELReturnValueEvaluator expr = new MVELReturnValueEvaluator(unit,
                dialect.getId());

        constraintNode.setEvaluator(expr);

        MVELDialectRuntimeData data = (MVELDialectRuntimeData) context.getPkg().getDialectRuntimeRegistry().getDialectData(dialect.getId());
        data.addCompileable(constraintNode,
                expr);

        expr.compile(data);

        collectTypes("MVELReturnValue", analysis, (ProcessBuildContext) context);
    }
}
