/*
 *  ============LICENSE_START=======================================================
 *  Copyright (C) 2021-2022 Nordix Foundation
 *  Modifications Copyright (C) 2021 Pantheon.tech
 *  Modifications Copyright (C) 2020-2022 Bell Canada.
 *  ================================================================================
 *  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.impl;

import static org.onap.cps.spi.FetchDescendantsOption.INCLUDE_ALL_DESCENDANTS;

import com.google.common.collect.ImmutableSet;
import com.google.common.collect.ImmutableSet.Builder;
import java.util.Collection;
import java.util.Collections;
import java.util.HashMap;
import java.util.HashSet;
import java.util.List;
import java.util.Map;
import java.util.Set;
import java.util.regex.Matcher;
import java.util.regex.Pattern;
import java.util.stream.Collectors;
import javax.transaction.Transactional;
import lombok.RequiredArgsConstructor;
import lombok.extern.slf4j.Slf4j;
import org.hibernate.StaleStateException;
import org.onap.cps.cpspath.parser.CpsPathQuery;
import org.onap.cps.spi.CpsDataPersistenceService;
import org.onap.cps.spi.FetchDescendantsOption;
import org.onap.cps.spi.entities.AnchorEntity;
import org.onap.cps.spi.entities.DataspaceEntity;
import org.onap.cps.spi.entities.FragmentEntity;
import org.onap.cps.spi.exceptions.AlreadyDefinedException;
import org.onap.cps.spi.exceptions.ConcurrencyException;
import org.onap.cps.spi.exceptions.CpsAdminException;
import org.onap.cps.spi.exceptions.CpsPathException;
import org.onap.cps.spi.exceptions.DataNodeNotFoundException;
import org.onap.cps.spi.model.DataNode;
import org.onap.cps.spi.model.DataNodeBuilder;
import org.onap.cps.spi.repository.AnchorRepository;
import org.onap.cps.spi.repository.DataspaceRepository;
import org.onap.cps.spi.repository.FragmentRepository;
import org.onap.cps.utils.JsonObjectMapper;
import org.springframework.dao.DataIntegrityViolationException;
import org.springframework.stereotype.Service;

@Service
@Slf4j
@RequiredArgsConstructor
public class CpsDataPersistenceServiceImpl implements CpsDataPersistenceService {

    private final DataspaceRepository dataspaceRepository;

    private final AnchorRepository anchorRepository;

    private final FragmentRepository fragmentRepository;

    private final JsonObjectMapper jsonObjectMapper;

    private static final String REG_EX_FOR_OPTIONAL_LIST_INDEX = "(\\[@[\\s\\S]+?]){0,1})";
    private static final Pattern REG_EX_PATTERN_FOR_LIST_ELEMENT_KEY_PREDICATE =
            Pattern.compile("\\[(\\@([^\\/]{0,9999}))\\]$");

    @Override
    @Transactional
    public void addChildDataNode(final String dataspaceName, final String anchorName, final String parentNodeXpath,
        final DataNode newChildDataNode) {
        addChildDataNodes(dataspaceName, anchorName, parentNodeXpath,  Collections.singleton(newChildDataNode));
    }

    @Override
    @Transactional
    public void addListElements(final String dataspaceName, final String anchorName, final String parentNodeXpath,
        final Collection<DataNode> newListElements) {
        addChildDataNodes(dataspaceName, anchorName, parentNodeXpath, newListElements);
    }

    private void addChildDataNodes(final String dataspaceName, final String anchorName, final String parentNodeXpath,
                                final Collection<DataNode> newChildren) {
        final FragmentEntity parentFragmentEntity = getFragmentByXpath(dataspaceName, anchorName, parentNodeXpath);
        try {
            for (final DataNode newChildAsDataNode : newChildren) {
                final FragmentEntity newChildAsFragmentEntity = convertToFragmentWithAllDescendants(
                    parentFragmentEntity.getDataspace(),
                    parentFragmentEntity.getAnchor(),
                    newChildAsDataNode);
                newChildAsFragmentEntity.setParentId(parentFragmentEntity.getId());
                fragmentRepository.save(newChildAsFragmentEntity);
            }
        } catch (final DataIntegrityViolationException exception) {
            final List<String> conflictXpaths = newChildren.stream()
                .map(DataNode::getXpath)
                .collect(Collectors.toList());
            throw AlreadyDefinedException.forDataNodes(conflictXpaths, anchorName, exception);
        }
    }

    @Override
    public void storeDataNode(final String dataspaceName, final String anchorName, final DataNode dataNode) {
        final DataspaceEntity dataspaceEntity = dataspaceRepository.getByName(dataspaceName);
        final AnchorEntity anchorEntity = anchorRepository.getByDataspaceAndName(dataspaceEntity, anchorName);
        final FragmentEntity fragmentEntity = convertToFragmentWithAllDescendants(dataspaceEntity, anchorEntity,
            dataNode);
        try {
            fragmentRepository.save(fragmentEntity);
        } catch (final DataIntegrityViolationException exception) {
            throw AlreadyDefinedException.forDataNode(dataNode.getXpath(), anchorName, exception);
        }
    }

    /**
     * Convert DataNode object into Fragment and places the result in the fragments placeholder. Performs same action
     * for all DataNode children recursively.
     *
     * @param dataspaceEntity       dataspace
     * @param anchorEntity          anchorEntity
     * @param dataNodeToBeConverted dataNode
     * @return a Fragment built from current DataNode
     */
    private FragmentEntity convertToFragmentWithAllDescendants(final DataspaceEntity dataspaceEntity,
        final AnchorEntity anchorEntity, final DataNode dataNodeToBeConverted) {
        final FragmentEntity parentFragment = toFragmentEntity(dataspaceEntity, anchorEntity, dataNodeToBeConverted);
        final Builder<FragmentEntity> childFragmentsImmutableSetBuilder = ImmutableSet.builder();
        for (final DataNode childDataNode : dataNodeToBeConverted.getChildDataNodes()) {
            final FragmentEntity childFragment =
                convertToFragmentWithAllDescendants(parentFragment.getDataspace(), parentFragment.getAnchor(),
                    childDataNode);
            childFragmentsImmutableSetBuilder.add(childFragment);
        }
        parentFragment.setChildFragments(childFragmentsImmutableSetBuilder.build());
        return parentFragment;
    }

    private FragmentEntity toFragmentEntity(final DataspaceEntity dataspaceEntity,
        final AnchorEntity anchorEntity, final DataNode dataNode) {
        return FragmentEntity.builder()
            .dataspace(dataspaceEntity)
            .anchor(anchorEntity)
            .xpath(dataNode.getXpath())
            .attributes(jsonObjectMapper.asJsonString(dataNode.getLeaves()))
            .build();
    }

    @Override
    public DataNode getDataNode(final String dataspaceName, final String anchorName, final String xpath,
        final FetchDescendantsOption fetchDescendantsOption) {
        final FragmentEntity fragmentEntity = getFragmentByXpath(dataspaceName, anchorName, xpath);
        return toDataNode(fragmentEntity, fetchDescendantsOption);
    }

    private FragmentEntity getFragmentByXpath(final String dataspaceName, final String anchorName,
        final String xpath) {
        final DataspaceEntity dataspaceEntity = dataspaceRepository.getByName(dataspaceName);
        final AnchorEntity anchorEntity = anchorRepository.getByDataspaceAndName(dataspaceEntity, anchorName);
        if (isRootXpath(xpath)) {
            return fragmentRepository.findFirstRootByDataspaceAndAnchor(dataspaceEntity, anchorEntity);
        } else {
            return fragmentRepository.getByDataspaceAndAnchorAndXpath(dataspaceEntity, anchorEntity,
                xpath);
        }
    }

    @Override
    public List<DataNode> queryDataNodes(final String dataspaceName, final String anchorName, final String cpsPath,
        final FetchDescendantsOption fetchDescendantsOption) {
        final DataspaceEntity dataspaceEntity = dataspaceRepository.getByName(dataspaceName);
        final AnchorEntity anchorEntity = anchorRepository.getByDataspaceAndName(dataspaceEntity, anchorName);
        final CpsPathQuery cpsPathQuery;
        try {
            cpsPathQuery = CpsPathQuery.createFrom(cpsPath);
        } catch (final IllegalStateException e) {
            throw new CpsPathException(e.getMessage());
        }
        List<FragmentEntity> fragmentEntities =
            fragmentRepository.findByAnchorAndCpsPath(anchorEntity.getId(), cpsPathQuery);
        if (cpsPathQuery.hasAncestorAxis()) {
            final Set<String> ancestorXpaths = processAncestorXpath(fragmentEntities, cpsPathQuery);
            fragmentEntities = ancestorXpaths.isEmpty()
                ? Collections.emptyList() : fragmentRepository.findAllByAnchorAndXpathIn(anchorEntity, ancestorXpaths);
        }
        return fragmentEntities.stream()
            .map(fragmentEntity -> toDataNode(fragmentEntity, fetchDescendantsOption))
            .collect(Collectors.toUnmodifiableList());
    }

    private static Set<String> processAncestorXpath(final List<FragmentEntity> fragmentEntities,
        final CpsPathQuery cpsPathQuery) {
        final Set<String> ancestorXpath = new HashSet<>();
        final Pattern pattern =
            Pattern.compile("([\\s\\S]*\\/" + Pattern.quote(cpsPathQuery.getAncestorSchemaNodeIdentifier())
                + REG_EX_FOR_OPTIONAL_LIST_INDEX + "\\/[\\s\\S]*");
        for (final FragmentEntity fragmentEntity : fragmentEntities) {
            final Matcher matcher = pattern.matcher(fragmentEntity.getXpath());
            if (matcher.matches()) {
                ancestorXpath.add(matcher.group(1));
            }
        }
        return ancestorXpath;
    }

    private DataNode toDataNode(final FragmentEntity fragmentEntity,
        final FetchDescendantsOption fetchDescendantsOption) {
        final List<DataNode> childDataNodes = getChildDataNodes(fragmentEntity, fetchDescendantsOption);
        Map<String, Object> leaves = new HashMap<>();
        if (fragmentEntity.getAttributes() != null) {
            leaves = jsonObjectMapper.convertJsonString(fragmentEntity.getAttributes(), Map.class);
        }
        return new DataNodeBuilder()
            .withXpath(fragmentEntity.getXpath())
            .withLeaves(leaves)
            .withChildDataNodes(childDataNodes).build();
    }

    private List<DataNode> getChildDataNodes(final FragmentEntity fragmentEntity,
        final FetchDescendantsOption fetchDescendantsOption) {
        if (fetchDescendantsOption == INCLUDE_ALL_DESCENDANTS) {
            return fragmentEntity.getChildFragments().stream()
                .map(childFragmentEntity -> toDataNode(childFragmentEntity, fetchDescendantsOption))
                .collect(Collectors.toUnmodifiableList());
        }
        return Collections.emptyList();
    }

    @Override
    public void updateDataLeaves(final String dataspaceName, final String anchorName, final String xpath,
        final Map<String, Object> leaves) {
        final FragmentEntity fragmentEntity = getFragmentByXpath(dataspaceName, anchorName, xpath);
        fragmentEntity.setAttributes(jsonObjectMapper.asJsonString(leaves));
        fragmentRepository.save(fragmentEntity);
    }

    @Override
    public void replaceDataNodeTree(final String dataspaceName, final String anchorName, final DataNode dataNode) {
        final FragmentEntity fragmentEntity = getFragmentByXpath(dataspaceName, anchorName, dataNode.getXpath());
        replaceDataNodeTree(fragmentEntity, dataNode);
        try {
            fragmentRepository.save(fragmentEntity);
        } catch (final StaleStateException staleStateException) {
            throw new ConcurrencyException("Concurrent Transactions",
                String.format("dataspace :'%s', Anchor : '%s' and xpath: '%s' is updated by another transaction.",
                    dataspaceName, anchorName, dataNode.getXpath()),
                staleStateException);
        }
    }

    private void replaceDataNodeTree(final FragmentEntity existingFragmentEntity,
                                            final DataNode newDataNode) {

        existingFragmentEntity.setAttributes(jsonObjectMapper.asJsonString(newDataNode.getLeaves()));

        final Map<String, FragmentEntity> existingChildrenByXpath = existingFragmentEntity.getChildFragments()
            .stream().collect(Collectors.toMap(FragmentEntity::getXpath, childFragmentEntity -> childFragmentEntity));

        final Collection<FragmentEntity> updatedChildFragments = new HashSet<>();

        for (final DataNode newDataNodeChild : newDataNode.getChildDataNodes()) {
            final FragmentEntity childFragment;
            if (isNewDataNode(newDataNodeChild, existingChildrenByXpath)) {
                childFragment = convertToFragmentWithAllDescendants(
                    existingFragmentEntity.getDataspace(), existingFragmentEntity.getAnchor(), newDataNodeChild);
            } else {
                childFragment = existingChildrenByXpath.get(newDataNodeChild.getXpath());
                replaceDataNodeTree(childFragment, newDataNodeChild);
            }
            updatedChildFragments.add(childFragment);
        }
        existingFragmentEntity.getChildFragments().clear();
        existingFragmentEntity.getChildFragments().addAll(updatedChildFragments);
    }

    @Override
    @Transactional
    public void replaceListContent(final String dataspaceName, final String anchorName, final String parentNodeXpath,
                                   final Collection<DataNode> newListElements) {
        final FragmentEntity parentEntity = getFragmentByXpath(dataspaceName, anchorName, parentNodeXpath);
        final String listElementXpathPrefix = getListElementXpathPrefix(newListElements);
        final Map<String, FragmentEntity> existingListElementFragmentEntitiesByXPath =
            extractListElementFragmentEntitiesByXPath(parentEntity.getChildFragments(), listElementXpathPrefix);
        deleteListElements(parentEntity.getChildFragments(), existingListElementFragmentEntitiesByXPath);
        final Set<FragmentEntity> updatedChildFragmentEntities = new HashSet<>();
        for (final DataNode newListElement : newListElements) {
            final FragmentEntity existingListElementEntity =
                existingListElementFragmentEntitiesByXPath.get(newListElement.getXpath());
            final FragmentEntity entityToBeAdded = getFragmentForReplacement(parentEntity, newListElement,
                existingListElementEntity);

            updatedChildFragmentEntities.add(entityToBeAdded);
        }
        parentEntity.getChildFragments().addAll(updatedChildFragmentEntities);
        fragmentRepository.save(parentEntity);
    }

    @Override
    @Transactional
    public void deleteDataNodes(final String dataspaceName, final String anchorName) {
        final DataspaceEntity dataspaceEntity = dataspaceRepository.getByName(dataspaceName);
        anchorRepository.findByDataspaceAndName(dataspaceEntity, anchorName)
            .ifPresent(
                anchorEntity -> fragmentRepository.deleteByAnchorIn(Set.of(anchorEntity)));
    }

    @Override
    @Transactional
    public void deleteListDataNode(final String dataspaceName, final String anchorName,
                                   final String targetXpath) {
        deleteDataNode(dataspaceName, anchorName, targetXpath, true);
    }

    @Override
    @Transactional
    public void deleteDataNode(final String dataspaceName, final String anchorName, final String targetXpath) {
        deleteDataNode(dataspaceName, anchorName, targetXpath, false);
    }

    private void deleteDataNode(final String dataspaceName, final String anchorName, final String targetXpath,
        final boolean onlySupportListNodeDeletion) {
        final String parentNodeXpath;
        FragmentEntity parentFragmentEntity = null;
        boolean targetDeleted = false;
        if (isRootXpath(targetXpath)) {
            deleteDataNodes(dataspaceName, anchorName);
            targetDeleted = true;
        } else {
            if (isContainerNodeXpath(targetXpath)) {
                parentNodeXpath = targetXpath;
            } else {
                parentNodeXpath = targetXpath.substring(0, targetXpath.lastIndexOf('/'));
            }
            parentFragmentEntity = getFragmentByXpath(dataspaceName, anchorName, parentNodeXpath);
            final String lastXpathElement = targetXpath.substring(targetXpath.lastIndexOf('/'));
            final boolean isListElement = REG_EX_PATTERN_FOR_LIST_ELEMENT_KEY_PREDICATE
                .matcher(lastXpathElement).find();
            if (isListElement) {
                targetDeleted = deleteDataNode(parentFragmentEntity, targetXpath);
            } else {
                targetDeleted = deleteAllListElements(parentFragmentEntity, targetXpath);
                final boolean tryToDeleteDataNode = !targetDeleted && !onlySupportListNodeDeletion;
                if (tryToDeleteDataNode) {
                    targetDeleted = deleteDataNode(parentFragmentEntity, targetXpath);
                }
            }
        }
        if (!targetDeleted) {
            final String additionalInformation = onlySupportListNodeDeletion
                ? "The target is probably not a List." : "";
            throw new DataNodeNotFoundException(parentFragmentEntity.getDataspace().getName(),
                parentFragmentEntity.getAnchor().getName(), targetXpath, additionalInformation);
        }
    }

    private boolean deleteDataNode(final FragmentEntity parentFragmentEntity, final String targetXpath) {
        if (parentFragmentEntity.getXpath().equals(targetXpath)) {
            fragmentRepository.delete(parentFragmentEntity);
            return true;
        }
        if (parentFragmentEntity.getChildFragments()
            .removeIf(fragment -> fragment.getXpath().equals(targetXpath))) {
            fragmentRepository.save(parentFragmentEntity);
            return true;
        }
        return false;
    }

    private boolean deleteAllListElements(final FragmentEntity parentFragmentEntity, final String listXpath) {
        final String deleteTargetXpathPrefix = listXpath + "[";
        if (parentFragmentEntity.getChildFragments()
            .removeIf(fragment -> fragment.getXpath().startsWith(deleteTargetXpathPrefix))) {
            fragmentRepository.save(parentFragmentEntity);
            return true;
        }
        return false;
    }

    private static void deleteListElements(
        final Collection<FragmentEntity> fragmentEntities,
        final Map<String, FragmentEntity> existingListElementFragmentEntitiesByXPath) {
        fragmentEntities.removeAll(existingListElementFragmentEntitiesByXPath.values());
    }

    private static String getListElementXpathPrefix(final Collection<DataNode> newListElements) {
        if (newListElements.isEmpty()) {
            throw new CpsAdminException("Invalid list replacement",
                "Cannot replace list elements with empty collection");
        }
        final String firstChildNodeXpath = newListElements.iterator().next().getXpath();
        return firstChildNodeXpath.substring(0, firstChildNodeXpath.lastIndexOf('[') + 1);
    }

    private FragmentEntity getFragmentForReplacement(final FragmentEntity parentEntity,
                                                            final DataNode newListElement,
                                                            final FragmentEntity existingListElementEntity) {
        if (existingListElementEntity == null) {
            return convertToFragmentWithAllDescendants(
                parentEntity.getDataspace(), parentEntity.getAnchor(), newListElement);
        }
        if (newListElement.getChildDataNodes().isEmpty()) {
            copyAttributesFromNewListElement(existingListElementEntity, newListElement);
            existingListElementEntity.getChildFragments().clear();
        } else {
            replaceDataNodeTree(existingListElementEntity, newListElement);
        }
        return existingListElementEntity;
    }

    private static boolean isNewDataNode(final DataNode replacementDataNode,
                                         final Map<String, FragmentEntity> existingListElementsByXpath) {
        return !existingListElementsByXpath.containsKey(replacementDataNode.getXpath());
    }

    private static boolean isContainerNodeXpath(final String xpath) {
        return 0 == xpath.lastIndexOf('/');
    }

    private void copyAttributesFromNewListElement(final FragmentEntity existingListElementEntity,
                                                         final DataNode newListElement) {
        final FragmentEntity replacementFragmentEntity =
                FragmentEntity.builder().attributes(jsonObjectMapper.asJsonString(
                        newListElement.getLeaves())).build();
        existingListElementEntity.setAttributes(replacementFragmentEntity.getAttributes());
    }

    private static Map<String, FragmentEntity> extractListElementFragmentEntitiesByXPath(
        final Set<FragmentEntity> childEntities, final String listElementXpathPrefix) {
        return childEntities.stream()
            .filter(fragmentEntity -> fragmentEntity.getXpath().startsWith(listElementXpathPrefix))
            .collect(Collectors.toMap(FragmentEntity::getXpath, fragmentEntity -> fragmentEntity));
    }

    private static boolean isRootXpath(final String xpath) {
        return "/".equals(xpath) || "".equals(xpath);
    }
}