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/*
 * Copyright (c) 2018-present PowerFlows.org - all rights reserved.
 *
 * 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.powerflows.dmn.io.yaml;

import org.powerflows.dmn.io.yaml.model.YamlDecision;
import org.powerflows.dmn.io.yaml.model.rule.entry.YamlInputEntry;
import org.powerflows.dmn.io.yaml.model.rule.entry.YamlOutputEntry;
import org.yaml.snakeyaml.introspector.Property;
import org.yaml.snakeyaml.nodes.Node;
import org.yaml.snakeyaml.nodes.NodeTuple;
import org.yaml.snakeyaml.nodes.Tag;
import org.yaml.snakeyaml.representer.Represent;
import org.yaml.snakeyaml.representer.Representer;

import java.util.Collection;
import java.util.Map;

public class CustomRepresenter extends Representer {
    CustomRepresenter() {
        this.setPropertyUtils(new CustomPropertyUtils());
        this.addClassTag(YamlDecision.class, Tag.MAP);
        this.representers.put(YamlInputEntry.class, new RepresentYamlInputEntry());
        this.representers.put(YamlOutputEntry.class, new RepresentYamlOutputEntry());
    }

    class RepresentYamlInputEntry implements Represent {

        @Override
        public Node representData(Object data) {
            if (data instanceof YamlInputEntry) {
                final YamlInputEntry yie = (YamlInputEntry) data;

                if (yie.getEvaluationMode() == null && yie.getExpressionType() == null && yie.getNameAlias() == null) {
                    return represent(yie.getExpression());
                }
            }

            return representJavaBean(getProperties(data.getClass()), data);
        }
    }

    class RepresentYamlOutputEntry implements Represent {
        @Override
        public Node representData(Object data) {
            if (data instanceof YamlOutputEntry) {
                final YamlOutputEntry yoe = (YamlOutputEntry) data;

                if (yoe.getExpressionType() == null) {
                    return represent(yoe.getExpression());
                }
            }

            return representJavaBean(getProperties(data.getClass()), data);
        }
    }

    @Override
    protected NodeTuple representJavaBeanProperty(final Object javaBean, final Property property, final Object propertyValue, final Tag customTag) {
        if (propertyValue == null || isEmpty(propertyValue)) {
            return null;
        } else {
            return super.representJavaBeanProperty(javaBean, property, propertyValue, customTag);
        }
    }

    private boolean isEmpty(final Object propertyValue) {
        final boolean empty;

        if (propertyValue instanceof Collection) {
            empty = ((Collection) propertyValue).isEmpty();
        } else if (propertyValue instanceof Map) {
            empty = ((Map) propertyValue).isEmpty();
        } else if (propertyValue instanceof String) {
            empty = ((String) propertyValue).isEmpty();
        } else {
            empty = false;
        }

        return empty;
    }
}