/*
 * ============LICENSE_START=======================================================
 *  Copyright (C) 2021 Bell Canada. 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.
 *
 *  SPDX-License-Identifier: Apache-2.0
 *  ============LICENSE_END=========================================================
 */

package org.onap.cps.spi.model;

import com.google.common.collect.ImmutableMap;
import com.google.common.collect.ImmutableSet;
import java.util.Collection;
import java.util.Collections;
import java.util.LinkedList;
import java.util.List;
import java.util.Map;
import java.util.Optional;
import java.util.Set;
import lombok.extern.slf4j.Slf4j;
import org.onap.cps.utils.YangUtils;
import org.opendaylight.yangtools.yang.data.api.schema.DataContainerNode;
import org.opendaylight.yangtools.yang.data.api.schema.LeafSetNode;
import org.opendaylight.yangtools.yang.data.api.schema.MapEntryNode;
import org.opendaylight.yangtools.yang.data.api.schema.MapNode;
import org.opendaylight.yangtools.yang.data.api.schema.NormalizedNode;
import org.opendaylight.yangtools.yang.data.api.schema.ValueNode;

@Slf4j
public class DataNodeBuilder {

    private NormalizedNode normalizedNodeTree;
    private String xpath;
    private Collection<DataNode> childDataNodes = Collections.emptySet();


    /** To use {@link NormalizedNode} for creating {@link DataNode}.
     *
     * @param normalizedNodeTree used for creating the Data Node
     *
     * @return this {@link DataNodeBuilder} object
     */
    public DataNodeBuilder withNormalizedNodeTree(final NormalizedNode normalizedNodeTree) {
        this.normalizedNodeTree = normalizedNodeTree;
        return this;
    }

    /**
     * To use xpath for creating {@link DataNode}.
     * @param xpath for the data node
     * @return DataNodeBuilder
     */
    public DataNodeBuilder withXpath(final String xpath) {
        this.xpath = xpath;
        return this;
    }

    /**
     * To specify child nodes needs to be used while creating {@link DataNode}.
     * @param childDataNodes to be added to the dataNode
     * @return DataNodeBuilder
     */
    public DataNodeBuilder withChildDataNodes(final Collection<DataNode> childDataNodes) {
        // Added as this is being set from test cases .
        // Open for suggestions
        this.childDataNodes = childDataNodes;
        return this;
    }

    /**
     * To create the {@link DataNode}.
     *
     * @return {@link DataNode}
     */
    public DataNode build() {
        if (normalizedNodeTree != null) {
            return buildFromNormalizedNodeTree();
        } else {
            return buildFromAttributes();
        }
    }

    private DataNode buildFromAttributes() {
        final DataNode dataNode = new DataNode();
        dataNode.setXpath(xpath);
        dataNode.setChildDataNodes(childDataNodes);
        return dataNode;
    }

    private DataNode buildFromNormalizedNodeTree() {
        xpath = YangUtils.buildXpath(normalizedNodeTree.getIdentifier());
        final DataNode dataNode = new DataNodeBuilder().withXpath(xpath).build();
        addDataNodeFromNormalizedNode(dataNode, normalizedNodeTree);
        return dataNode;
    }

    private void addDataNodeFromNormalizedNode(final DataNode currentDataNode,
        final NormalizedNode normalizedNode) {
        if (normalizedNode instanceof DataContainerNode) {
            addYangContainer(currentDataNode, (DataContainerNode) normalizedNode);
        } else if (normalizedNode instanceof MapNode) {
            addDataNodeForEachListElement(currentDataNode, (MapNode) normalizedNode);
        } else if (normalizedNode instanceof ValueNode) {
            final ValueNode valuesNode = (ValueNode) normalizedNode;
            addYangLeaf(currentDataNode, valuesNode.getNodeType().getLocalName(), valuesNode.getValue());
        } else if (normalizedNode instanceof LeafSetNode) {
            addYangLeafList(currentDataNode, (LeafSetNode) normalizedNode);
        } else {
            log.warn("Cannot normalize {}", normalizedNode.getClass());
        }
    }

    private void addYangContainer(final DataNode currentDataNode, final DataContainerNode dataContainerNode) {
        final Collection<NormalizedNode> normalizedChildNodes = dataContainerNode.getValue();
        for (final NormalizedNode normalizedNode : normalizedChildNodes) {
            addDataNodeFromNormalizedNode(currentDataNode, normalizedNode);
        }
    }

    private void addYangLeaf(final DataNode currentDataNode, final String leafName, final Object leafValue) {
        final Map leaves = new ImmutableMap.Builder<String, Object>()
            .putAll(currentDataNode.getLeaves())
            .put(leafName, leafValue)
            .build();
        currentDataNode.setLeaves(leaves);
    }

    private void addYangLeafList(final DataNode currentDataNode, final LeafSetNode leafSetNode) {
        final ImmutableSet.Builder builder = new ImmutableSet.Builder<String>();
        final String leafListName = leafSetNode.getNodeType().getLocalName();
        final Optional<Set<String>> optionalLeafListNames = currentDataNode.getOptionalLeafListNames();
        if (optionalLeafListNames.isPresent()) {
            builder.addAll(optionalLeafListNames.get());
        }
        builder.add(leafListName);
        final ImmutableSet leafListNames = builder.build();
        currentDataNode.setOptionalLeafListNames(Optional.of(leafListNames));
        final List leafListValues = new LinkedList();
        for (final NormalizedNode normalizedNode : (Collection<NormalizedNode>) leafSetNode.getValue()) {
            leafListValues.add(((ValueNode) normalizedNode).getValue());
        }
        addYangLeaf(currentDataNode, leafListName, leafListValues);
    }

    private void addDataNodeForEachListElement(final DataNode currentDataNode, final MapNode mapNode) {
        final Collection<MapEntryNode> mapEntryNodes = mapNode.getValue();
        for (final MapEntryNode mapEntryNode : mapEntryNodes) {
            final String xpathChild = YangUtils.buildXpath(mapEntryNode.getIdentifier());
            final DataNode childDataNode = createAndAddChildDataNode(currentDataNode, xpathChild);
            addDataNodeFromNormalizedNode(childDataNode, mapEntryNode);
        }
    }

    private DataNode createAndAddChildDataNode(final DataNode parentDataNode, final String childXpath) {
        final DataNode newChildDataNode = new DataNodeBuilder().withXpath(xpath + childXpath)
            .build();
        final Set<DataNode> allChildDataNodes = new ImmutableSet.Builder<DataNode>()
            .addAll(parentDataNode.getChildDataNodes())
            .add(newChildDataNode)
            .build();
        parentDataNode.setChildDataNodes(allChildDataNodes);
        return newChildDataNode;
    }

}