/**
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you 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
 * <p>
 * http://www.apache.org/licenses/LICENSE-2.0
 * <p>
 * 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.apache.atlas.discovery;


import org.apache.atlas.AtlasClient;
import org.apache.atlas.AtlasErrorCode;
import org.apache.atlas.annotation.GraphTransaction;
import org.apache.atlas.authorize.AtlasAuthorizationUtils;
import org.apache.atlas.authorize.AtlasEntityAccessRequest;
import org.apache.atlas.authorize.AtlasPrivilege;
import org.apache.atlas.exception.AtlasBaseException;
import org.apache.atlas.model.instance.AtlasEntity;
import org.apache.atlas.model.instance.AtlasEntity.AtlasEntityWithExtInfo;
import org.apache.atlas.model.instance.AtlasEntityHeader;
import org.apache.atlas.model.instance.AtlasObjectId;
import org.apache.atlas.model.lineage.AtlasLineageInfo;
import org.apache.atlas.model.lineage.AtlasLineageInfo.LineageDirection;
import org.apache.atlas.model.lineage.AtlasLineageInfo.LineageRelation;
import org.apache.atlas.repository.graphdb.AtlasGraph;
import org.apache.atlas.repository.graphdb.AtlasVertex;
import org.apache.atlas.repository.store.graph.v1.AtlasGraphUtilsV1;
import org.apache.atlas.repository.store.graph.v1.EntityGraphRetriever;
import org.apache.atlas.type.AtlasEntityType;
import org.apache.atlas.type.AtlasTypeRegistry;
import org.apache.atlas.type.AtlasTypeUtil;
import org.apache.atlas.util.AtlasGremlinQueryProvider;
import org.apache.atlas.util.AtlasGremlinQueryProvider.AtlasGremlinQuery;
import org.apache.atlas.v1.model.lineage.SchemaResponse.SchemaDetails;
import org.apache.commons.collections.CollectionUtils;
import org.apache.commons.collections.MapUtils;
import org.apache.commons.lang.StringUtils;
import org.springframework.stereotype.Service;

import javax.inject.Inject;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.HashSet;
import java.util.Iterator;
import java.util.List;
import java.util.Map;
import java.util.Set;
import java.util.stream.Collectors;

@Service
public class EntityLineageService implements AtlasLineageService {
    private static final String INPUT_PROCESS_EDGE  = "__Process.inputs";
    private static final String OUTPUT_PROCESS_EDGE = "__Process.outputs";
    private static final String COLUMNS             = "columns";

    private final AtlasGraph                graph;
    private final AtlasGremlinQueryProvider gremlinQueryProvider;
    private final EntityGraphRetriever      entityRetriever;
    private final AtlasTypeRegistry         atlasTypeRegistry;

    @Inject
    EntityLineageService(AtlasTypeRegistry typeRegistry, AtlasGraph atlasGraph) {
        this.graph = atlasGraph;
        this.gremlinQueryProvider = AtlasGremlinQueryProvider.INSTANCE;
        this.entityRetriever = new EntityGraphRetriever(typeRegistry);
        this.atlasTypeRegistry = typeRegistry;
    }

    @Override
    @GraphTransaction
    public AtlasLineageInfo getAtlasLineageInfo(String guid, LineageDirection direction, int depth) throws AtlasBaseException {
        AtlasLineageInfo lineageInfo;

        AtlasEntityHeader entity = entityRetriever.toAtlasEntityHeaderWithClassifications(guid);

        AtlasAuthorizationUtils.verifyAccess(new AtlasEntityAccessRequest(atlasTypeRegistry, AtlasPrivilege.ENTITY_READ, entity), "read entity lineage: guid=", guid);

        AtlasEntityType entityType = atlasTypeRegistry.getEntityTypeByName(entity.getTypeName());

        if (entityType == null || !entityType.getTypeAndAllSuperTypes().contains(AtlasClient.DATA_SET_SUPER_TYPE)) {
            throw new AtlasBaseException(AtlasErrorCode.INSTANCE_GUID_NOT_DATASET, guid);
        }

        if (direction != null) {
            if (direction.equals(LineageDirection.INPUT)) {
                lineageInfo = getLineageInfo(guid, LineageDirection.INPUT, depth);
            } else if (direction.equals(LineageDirection.OUTPUT)) {
                lineageInfo = getLineageInfo(guid, LineageDirection.OUTPUT, depth);
            } else if (direction.equals(LineageDirection.BOTH)) {
                lineageInfo = getBothLineageInfo(guid, depth);
            } else {
                throw new AtlasBaseException(AtlasErrorCode.INSTANCE_LINEAGE_INVALID_PARAMS, "direction", direction.toString());
            }
        } else {
            throw new AtlasBaseException(AtlasErrorCode.INSTANCE_LINEAGE_INVALID_PARAMS, "direction", null);
        }

        return lineageInfo;
    }

    @Override
    @GraphTransaction
    public SchemaDetails getSchemaForHiveTableByName(final String datasetName) throws AtlasBaseException {
        if (StringUtils.isEmpty(datasetName)) {
            // TODO: Complete error handling here
            throw new AtlasBaseException(AtlasErrorCode.BAD_REQUEST);
        }

        AtlasEntityType hive_table = atlasTypeRegistry.getEntityTypeByName("hive_table");

        Map<String, Object> lookupAttributes = new HashMap<>();
        lookupAttributes.put("qualifiedName", datasetName);
        String guid = AtlasGraphUtilsV1.getGuidByUniqueAttributes(hive_table, lookupAttributes);

        return getSchemaForHiveTableByGuid(guid);
    }

    @Override
    @GraphTransaction
    public SchemaDetails getSchemaForHiveTableByGuid(final String guid) throws AtlasBaseException {
        if (StringUtils.isEmpty(guid)) {
            throw new AtlasBaseException(AtlasErrorCode.BAD_REQUEST);
        }
        SchemaDetails ret = new SchemaDetails();
        AtlasEntityType hive_column = atlasTypeRegistry.getEntityTypeByName("hive_column");

        ret.setDataType(AtlasTypeUtil.toClassTypeDefinition(hive_column));

        AtlasEntityWithExtInfo entityWithExtInfo = entityRetriever.toAtlasEntityWithExtInfo(guid);
        AtlasEntity            entity            = entityWithExtInfo.getEntity();

        AtlasAuthorizationUtils.verifyAccess(new AtlasEntityAccessRequest(atlasTypeRegistry, AtlasPrivilege.ENTITY_READ, new AtlasEntityHeader(entity)),
                                             "read entity schema: guid=", guid);

        Map<String, AtlasEntity> referredEntities = entityWithExtInfo.getReferredEntities();
        List<String>             columnIds        = getColumnIds(entity);

        if (MapUtils.isNotEmpty(referredEntities)) {
            List<Map<String, Object>> rows = referredEntities.entrySet()
                                                             .stream()
                                                             .filter(e -> isColumn(columnIds, e))
                                                             .map(e -> AtlasTypeUtil.toMap(e.getValue()))
                                                             .collect(Collectors.toList());
            ret.setRows(rows);
        }

        return ret;
    }

    private List<String> getColumnIds(AtlasEntity entity) {
        List<String> ret        = new ArrayList<>();
        Object       columnObjs = entity.getAttribute(COLUMNS);

        if (columnObjs != null && columnObjs instanceof List) {
            for (Object pkObj : (List) columnObjs) {
                if (pkObj instanceof AtlasObjectId) {
                    ret.add(((AtlasObjectId) pkObj).getGuid());
                }
            }
        }

        return ret;
    }

    private boolean isColumn(List<String> columnIds, Map.Entry<String, AtlasEntity> e) {
        return columnIds.contains(e.getValue().getGuid());
    }

    private AtlasLineageInfo getLineageInfo(String guid, LineageDirection direction, int depth) throws AtlasBaseException {
        Map<String, AtlasEntityHeader> entities     = new HashMap<>();
        Set<LineageRelation>           relations    = new HashSet<>();
        String                         lineageQuery = getLineageQuery(guid, direction, depth);

        List paths = (List) graph.executeGremlinScript(lineageQuery, true);

        if (CollectionUtils.isNotEmpty(paths)) {
            for (Object path : paths) {
                if (path instanceof List) {
                    List vertices = (List) path;

                    if (CollectionUtils.isNotEmpty(vertices)) {
                        AtlasEntityHeader prev = null;

                        for (Object vertex : vertices) {
                            if (!(vertex instanceof AtlasVertex)) {
                                continue;
                            }

                            AtlasEntityHeader entity = entityRetriever.toAtlasEntityHeader((AtlasVertex) vertex);

                            if (!entities.containsKey(entity.getGuid())) {
                                entities.put(entity.getGuid(), entity);
                            }

                            if (prev != null) {
                                if (direction.equals(LineageDirection.INPUT)) {
                                    relations.add(new LineageRelation(entity.getGuid(), prev.getGuid()));
                                } else if (direction.equals(LineageDirection.OUTPUT)) {
                                    relations.add(new LineageRelation(prev.getGuid(), entity.getGuid()));
                                }
                            }
                            prev = entity;
                        }
                    }
                }
            }
        }

        return new AtlasLineageInfo(guid, entities, relations, direction, depth);
    }

    private AtlasLineageInfo getBothLineageInfo(String guid, int depth) throws AtlasBaseException {
        AtlasLineageInfo inputLineage  = getLineageInfo(guid, LineageDirection.INPUT, depth);
        AtlasLineageInfo outputLineage = getLineageInfo(guid, LineageDirection.OUTPUT, depth);
        AtlasLineageInfo ret           = inputLineage;

        ret.getRelations().addAll(outputLineage.getRelations());
        ret.getGuidEntityMap().putAll(outputLineage.getGuidEntityMap());
        ret.setLineageDirection(LineageDirection.BOTH);

        return ret;
    }

    private String getLineageQuery(String entityGuid, LineageDirection direction, int depth) {
        String lineageQuery = null;

        if (direction.equals(LineageDirection.INPUT)) {
            lineageQuery = generateLineageQuery(entityGuid, depth, OUTPUT_PROCESS_EDGE, INPUT_PROCESS_EDGE);

        } else if (direction.equals(LineageDirection.OUTPUT)) {
            lineageQuery = generateLineageQuery(entityGuid, depth, INPUT_PROCESS_EDGE, OUTPUT_PROCESS_EDGE);
        }

        return lineageQuery;
    }

    private String generateLineageQuery(String entityGuid, int depth, String incomingFrom, String outgoingTo) {
        String lineageQuery;
        if (depth < 1) {
            String query = gremlinQueryProvider.getQuery(AtlasGremlinQuery.FULL_LINEAGE);
            lineageQuery = String.format(query, entityGuid, incomingFrom, outgoingTo);
        } else {
            String query = gremlinQueryProvider.getQuery(AtlasGremlinQuery.PARTIAL_LINEAGE);
            lineageQuery = String.format(query, entityGuid, incomingFrom, outgoingTo, depth);
        }
        return lineageQuery;
    }
}