/*
 * Licensed to CRATE Technology GmbH ("Crate") under one or more contributor
 * license agreements.  See the NOTICE file distributed with this work for
 * additional information regarding copyright ownership.  Crate 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.
 *
 * However, if you have executed another commercial license agreement
 * with Crate these terms will supersede the license and you may use the
 * software solely pursuant to the terms of the relevant commercial agreement.
 */

package io.crate.metadata.blob;

import com.google.common.cache.CacheBuilder;
import com.google.common.cache.CacheLoader;
import com.google.common.cache.LoadingCache;
import com.google.common.util.concurrent.UncheckedExecutionException;
import io.crate.blob.v2.BlobIndex;
import io.crate.exceptions.ResourceUnknownException;
import io.crate.exceptions.UnhandledServerException;
import io.crate.metadata.TableIdent;
import io.crate.metadata.table.SchemaInfo;
import io.crate.metadata.table.TableInfo;
import org.elasticsearch.cluster.ClusterChangedEvent;
import org.elasticsearch.cluster.service.ClusterService;
import org.elasticsearch.common.inject.Inject;

import javax.annotation.Nonnull;
import javax.annotation.Nullable;
import java.util.Iterator;
import java.util.concurrent.ExecutionException;
import java.util.function.Function;
import java.util.stream.Stream;

public class BlobSchemaInfo implements SchemaInfo {

    public static final String NAME = "blob";

    private final ClusterService clusterService;
    private final BlobTableInfoFactory blobTableInfoFactory;

    private final LoadingCache<String, BlobTableInfo> cache = CacheBuilder.newBuilder()
        .maximumSize(10000)
        .build(
            new CacheLoader<String, BlobTableInfo>() {
                @Override
                public BlobTableInfo load(@Nonnull String key) throws Exception {
                    return innerGetTableInfo(key);
                }
            }
        );

    private final Function<String, TableInfo> tableInfoFunction;

    @Inject
    public BlobSchemaInfo(ClusterService clusterService,
                          BlobTableInfoFactory blobTableInfoFactory) {
        this.clusterService = clusterService;
        this.blobTableInfoFactory = blobTableInfoFactory;
        tableInfoFunction = new Function<String, TableInfo>() {
            @Nullable
            @Override
            public TableInfo apply(@Nullable String input) {
                return getTableInfo(input);
            }
        };
    }

    private BlobTableInfo innerGetTableInfo(String name) {
        return blobTableInfoFactory.create(new TableIdent(NAME, name), clusterService);
    }

    @Override
    public BlobTableInfo getTableInfo(String name) {
        try {
            return cache.get(name);
        } catch (ExecutionException e) {
            throw new UnhandledServerException("Failed to get TableInfo", e.getCause());
        } catch (UncheckedExecutionException e) {
            if (e.getCause() instanceof ResourceUnknownException) {
                return null;
            }
            throw e;
        }
    }

    @Override
    public String name() {
        return NAME;
    }

    @Override
    public void invalidateTableCache(String tableName) {
        cache.invalidate(tableName);
    }

    @Override
    public void update(ClusterChangedEvent event) {
        if (event.metaDataChanged()) {
            cache.invalidateAll();
        }
    }

    @Override
    public Iterator<TableInfo> iterator() {
        return Stream.of(clusterService.state().metaData().getConcreteAllOpenIndices())
            .filter(BlobIndex::isBlobIndex)
            .map(BlobIndex::stripPrefix)
            .map(tableInfoFunction)
            .iterator();
    }

    @Override
    public void close() throws Exception {
    }
}