/*
 * 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
 *
 *      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.apache.ignite.internal.processors.query;

import java.io.Serializable;
import java.util.ArrayList;
import java.util.Collection;
import java.util.Collections;
import java.util.HashMap;
import java.util.HashSet;
import java.util.LinkedList;
import java.util.List;
import java.util.Map;
import java.util.Set;
import java.util.UUID;
import org.apache.ignite.cache.QueryEntity;
import org.apache.ignite.cache.QueryEntityPatch;
import org.apache.ignite.cache.QueryIndex;
import org.apache.ignite.configuration.CacheConfiguration;
import org.apache.ignite.internal.processors.query.schema.message.SchemaFinishDiscoveryMessage;
import org.apache.ignite.internal.processors.query.schema.operation.SchemaAbstractOperation;
import org.apache.ignite.internal.processors.query.schema.operation.SchemaAddQueryEntityOperation;
import org.apache.ignite.internal.processors.query.schema.operation.SchemaAlterTableAddColumnOperation;
import org.apache.ignite.internal.processors.query.schema.operation.SchemaAlterTableDropColumnOperation;
import org.apache.ignite.internal.processors.query.schema.operation.SchemaIndexCreateOperation;
import org.apache.ignite.internal.processors.query.schema.operation.SchemaIndexDropOperation;
import org.apache.ignite.internal.util.typedef.F;
import org.apache.ignite.internal.util.typedef.internal.S;

/**
 * Dynamic cache schema.
 */
public class QuerySchema implements Serializable {
    /** */
    private static final long serialVersionUID = 0L;

    /** Query entities. */
    private final Collection<QueryEntity> entities = new LinkedList<>();

    /** Mutex for state synchronization. */
    private final Object mux = new Object();

    /**
     * Default constructor.
     */
    public QuerySchema() {
        // No-op.
    }

    /**
     * Constructor.
     *
     * @param entities Query entities.
     */
    public QuerySchema(Collection<QueryEntity> entities) {
        assert entities != null;

        for (QueryEntity qryEntity : entities)
            this.entities.add(QueryUtils.copy(qryEntity));
    }

    /**
     * Copy object.
     *
     * @return Copy.
     */
    public QuerySchema copy() {
        synchronized (mux) {
            QuerySchema res = new QuerySchema();

            for (QueryEntity qryEntity : entities)
                res.entities.add(QueryUtils.copy(qryEntity));

            return res;
        }
    }

    /**
     * Make query schema patch.
     *
     * @param target Query entity list to which current schema should be expanded.
     * @return Patch to achieve entity which is a result of merging current one and target.
     * @see QuerySchemaPatch
     */
    public QuerySchemaPatch makePatch(Collection<QueryEntity> target) {
        return makePatch(null, target);
    }

    /**
     * Make query schema patch.
     *
     * @param targetCfg Cache configuration when it should be changed (enabling indexing dynamically).
     * @param target Query entity list to which current schema should be expanded.
     * @return Patch to achieve entity which is a result of merging current one and target.
     * @see QuerySchemaPatch
     */
    public QuerySchemaPatch makePatch(CacheConfiguration<?, ?> targetCfg, Collection<QueryEntity> target) {
        synchronized (mux) {
            if (entities.isEmpty() && targetCfg != null) {
                SchemaAddQueryEntityOperation op = new SchemaAddQueryEntityOperation(
                    UUID.randomUUID(),
                    targetCfg.getName(),
                    targetCfg.getSqlSchema(),
                    target,
                    targetCfg.getQueryParallelism(),
                    targetCfg.isSqlEscapeAll()
                );

                return new QuerySchemaPatch(Collections.singletonList(op), Collections.emptyList(), "");
            }

            Map<String, QueryEntity> locEntities = new HashMap<>();

            for (QueryEntity entity : entities) {
                if (locEntities.put(entity.getTableName(), entity) != null)
                    throw new IllegalStateException("Duplicate key");
            }

            Collection<SchemaAbstractOperation> patchOperations = new ArrayList<>();
            Collection<QueryEntity> entityToAdd = new ArrayList<>();

            StringBuilder conflicts = new StringBuilder();

            for (QueryEntity qryEntity : target) {
                if (locEntities.containsKey(qryEntity.getTableName())) {
                    QueryEntity locEntity = locEntities.get(qryEntity.getTableName());

                    QueryEntityPatch entityPatch = locEntity.makePatch(qryEntity);

                    if (entityPatch.hasConflict()) {
                        if (conflicts.length() > 0)
                            conflicts.append("\n");

                        conflicts.append(entityPatch.getConflictsMessage());
                    }

                    if (!entityPatch.isEmpty())
                        patchOperations.addAll(entityPatch.getPatchOperations());
                }
                else
                    entityToAdd.add(QueryUtils.copy(qryEntity));
            }

            return new QuerySchemaPatch(patchOperations, entityToAdd, conflicts.toString());
        }
    }

    /**
     * Apply query schema patch for changing this schema.
     *
     * @param patch Patch to apply.
     * @return {@code true} if applying was success and {@code false} otherwise.
     */
    public boolean applyPatch(QuerySchemaPatch patch) {
        synchronized (mux) {
            if (patch.hasConflicts())
                return false;

            if (patch.isEmpty())
                return true;

            for (SchemaAbstractOperation operation : patch.getPatchOperations()) {
                finish(operation);
            }

            entities.addAll(patch.getEntityToAdd());

            return true;
        }
    }

    /**
     * Process finish message.
     *
     * @param msg Message.
     */
    public void finish(SchemaFinishDiscoveryMessage msg) {
        finish(msg.operation());
    }

    /**
     * Process operation.
     *
     * @param op Operation for handle.
     */
    public void finish(SchemaAbstractOperation op) {
        synchronized (mux) {
            if (op instanceof SchemaIndexCreateOperation) {
                SchemaIndexCreateOperation op0 = (SchemaIndexCreateOperation)op;

                for (QueryEntity entity : entities) {
                    String tblName = entity.getTableName();

                    if (F.eq(tblName, op0.tableName())) {
                        boolean exists = false;

                        for (QueryIndex idx : entity.getIndexes()) {
                            if (F.eq(idx.getName(), op0.indexName())) {
                                exists = true;

                                break;
                            }
                        }

                        if (!exists) {
                            List<QueryIndex> idxs = new ArrayList<>(entity.getIndexes());

                            idxs.add(op0.index());

                            entity.setIndexes(idxs);
                        }

                        break;
                    }
                }
            }
            else if (op instanceof SchemaIndexDropOperation) {
                SchemaIndexDropOperation op0 = (SchemaIndexDropOperation)op;

                for (QueryEntity entity : entities) {
                    Collection<QueryIndex> idxs = entity.getIndexes();

                    QueryIndex victim = null;

                    for (QueryIndex idx : idxs) {
                        if (F.eq(idx.getName(), op0.indexName())) {
                            victim = idx;

                            break;
                        }
                    }

                    if (victim != null) {
                        List<QueryIndex> newIdxs = new ArrayList<>(entity.getIndexes());

                        newIdxs.remove(victim);

                        entity.setIndexes(newIdxs);

                        break;
                    }
                }
            }
            else if (op instanceof SchemaAlterTableAddColumnOperation) {
                SchemaAlterTableAddColumnOperation op0 = (SchemaAlterTableAddColumnOperation)op;

                int targetIdx = -1;

                for (int i = 0; i < entities.size(); i++) {
                    QueryEntity entity = ((List<QueryEntity>)entities).get(i);

                    if (F.eq(entity.getTableName(), op0.tableName())) {
                        targetIdx = i;

                        break;
                    }
                }

                if (targetIdx == -1)
                    return;

                boolean replaceTarget = false;

                QueryEntity target = ((List<QueryEntity>)entities).get(targetIdx);

                for (QueryField field : op0.columns()) {
                    target.addQueryField(field.name(), field.typeName(), field.alias());

                    if (!field.isNullable()) {
                        if (!(target instanceof QueryEntityEx)) {
                            target = new QueryEntityEx(target);

                            replaceTarget = true;
                        }

                        QueryEntityEx target0 = (QueryEntityEx)target;

                        Set<String> notNullFields = target0.getNotNullFields();

                        if (notNullFields == null) {
                            notNullFields = new HashSet<>();

                            target0.setNotNullFields(notNullFields);
                        }

                        notNullFields.add(field.name());
                    }
                }

                if (replaceTarget)
                    ((List<QueryEntity>)entities).set(targetIdx, target);
            }
            else if (op instanceof SchemaAlterTableDropColumnOperation) {
                SchemaAlterTableDropColumnOperation op0 = (SchemaAlterTableDropColumnOperation)op;

                int targetIdx = -1;

                for (int i = 0; i < entities.size(); i++) {
                    QueryEntity entity = ((List<QueryEntity>)entities).get(i);

                    if (F.eq(entity.getTableName(), op0.tableName())) {
                        targetIdx = i;

                        break;
                    }
                }

                if (targetIdx == -1)
                    return;

                QueryEntity entity = ((List<QueryEntity>)entities).get(targetIdx);

                for (String field : op0.columns()) {
                    boolean rmv = QueryUtils.removeFieldAndAlias(entity, field);

                    assert rmv || op0.ifExists() : "Invalid operation state [removed=" + rmv
                        + ", ifExists=" + op0.ifExists() + ']';
                }
            }
            else {
                assert op instanceof SchemaAddQueryEntityOperation : "Unsupported schema operation [" + op.toString() + "]";

                assert entities.isEmpty();

                for (QueryEntity opEntity: ((SchemaAddQueryEntityOperation)op).entities())
                    entities.add(QueryUtils.copy(opEntity));
            }
        }
    }

    /**
     * @return Query entities.
     */
    public Collection<QueryEntity> entities() {
        synchronized (mux) {
            return new ArrayList<>(entities);
        }
    }

    /**
     * @return {@code True} if entities is not empty.
     */
    public boolean isEmpty() {
        synchronized (mux) {
            return entities.isEmpty();
        }
    }

    /** {@inheritDoc} */
    @Override public String toString() {
        return S.toString(QuerySchema.class, this);
    }
}