/*
 * Licensed to Elasticsearch under one or more contributor
 * license agreements. See the NOTICE file distributed with
 * this work for additional information regarding copyright
 * ownership. Elasticsearch 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.elasticsearch.index.engine;

import org.apache.lucene.analysis.Analyzer;
import org.apache.lucene.codecs.Codec;
import org.apache.lucene.index.IndexWriterConfig;
import org.apache.lucene.search.similarities.Similarity;
import org.elasticsearch.common.Nullable;
import org.elasticsearch.common.logging.ESLogger;
import org.elasticsearch.common.settings.Settings;
import org.elasticsearch.common.unit.ByteSizeUnit;
import org.elasticsearch.common.unit.ByteSizeValue;
import org.elasticsearch.common.unit.TimeValue;
import org.elasticsearch.common.util.concurrent.EsExecutors;
import org.elasticsearch.index.codec.CodecService;
import org.elasticsearch.index.deletionpolicy.SnapshotDeletionPolicy;
import org.elasticsearch.index.indexing.ShardIndexingService;
import org.elasticsearch.index.merge.policy.MergePolicyProvider;
import org.elasticsearch.index.merge.scheduler.MergeSchedulerProvider;
import org.elasticsearch.index.settings.IndexSettingsService;
import org.elasticsearch.index.shard.ShardId;
import org.elasticsearch.index.store.Store;
import org.elasticsearch.index.translog.Translog;
import org.elasticsearch.indices.IndicesWarmer;
import org.elasticsearch.threadpool.ThreadPool;

import java.util.concurrent.TimeUnit;

/*
 * Holds all the configuration that is used to create an {@link Engine}.
 * Once {@link Engine} has been created with this object, changes to this
 * object will affect the {@link Engine} instance.
 */
public final class EngineConfig {
    private final ShardId shardId;
    private volatile boolean failOnMergeFailure = true;
    private volatile boolean failEngineOnCorruption = true;
    private volatile ByteSizeValue indexingBufferSize;
    private final int indexConcurrency;
    private volatile boolean compoundOnFlush = true;
    private long gcDeletesInMillis = DEFAULT_GC_DELETES.millis();
    private volatile boolean enableGcDeletes = true;
    private final String codecName;
    private final boolean optimizeAutoGenerateId;
    private final ThreadPool threadPool;
    private final ShardIndexingService indexingService;
    private final IndexSettingsService indexSettingsService;
    @Nullable
    private final IndicesWarmer warmer;
    private final Store store;
    private final SnapshotDeletionPolicy deletionPolicy;
    private final Translog translog;
    private final MergePolicyProvider mergePolicyProvider;
    private final MergeSchedulerProvider mergeScheduler;
    private final Analyzer analyzer;
    private final Similarity similarity;
    private final CodecService codecService;
    private final Engine.FailedEngineListener failedEngineListener;

    /**
     * Index setting for index concurrency / number of threadstates in the indexwriter.
     * The default is depending on the number of CPUs in the system. We use a 0.65 the number of CPUs or at least {@value org.apache.lucene.index.IndexWriterConfig#DEFAULT_MAX_THREAD_STATES}
     * This setting is <b>not</b> realtime updateable
     */
    public static final String INDEX_CONCURRENCY_SETTING = "index.index_concurrency";

    /**
     * Index setting for compound file on flush. This setting is realtime updateable.
     */
    public static final String INDEX_COMPOUND_ON_FLUSH = "index.compound_on_flush";

    /**
     * Setting to control auto generated ID optimizations. Default is <code>true</code> if not present.
     * This setting is <b>not</b> realtime updateable.
     */
    public static final String INDEX_OPTIMIZE_AUTOGENERATED_ID_SETTING = "index.optimize_auto_generated_id";

    /**
     * Index setting to enable / disable deletes garbage collection.
     * This setting is realtime updateable
     */
    public static final String INDEX_GC_DELETES_SETTING = "index.gc_deletes";

    /**
     * Index setting to enable / disable engine failures on merge exceptions. Default is <code>true</code> / <tt>enabled</tt>.
     * This setting is realtime updateable.
     */
    public static final String INDEX_FAIL_ON_MERGE_FAILURE_SETTING = "index.fail_on_merge_failure";

    /**
     * Index setting to enable / disable engine failures on detected index corruptions. Default is <code>true</code> / <tt>enabled</tt>.
     * This setting is realtime updateable.
     */
    public static final String INDEX_FAIL_ON_CORRUPTION_SETTING = "index.fail_on_corruption";

    /**
     * Index setting to control the initial index buffer size.
     * This setting is <b>not</b> realtime updateable.
     */
    public static final String INDEX_BUFFER_SIZE_SETTING = "index.buffer_size";

    /**
     * Index setting to change the low level lucene codec used for writing new segments.
     * This setting is <b>not</b> realtime updateable.
     */
    public static final String INDEX_CODEC_SETTING = "index.codec";

    public static final TimeValue DEFAULT_REFRESH_INTERVAL = new TimeValue(1, TimeUnit.SECONDS);
    public static final TimeValue DEFAULT_GC_DELETES = TimeValue.timeValueSeconds(60);
    public static final ByteSizeValue DEFAUTL_INDEX_BUFFER_SIZE = new ByteSizeValue(64, ByteSizeUnit.MB);
    public static final ByteSizeValue INACTIVE_SHARD_INDEXING_BUFFER = ByteSizeValue.parseBytesSizeValue("500kb");

    private static final String DEFAULT_CODEC_NAME = "default";


    /**
     * Creates a new {@link org.elasticsearch.index.engine.EngineConfig}
     */
    public EngineConfig(ShardId shardId, boolean optimizeAutoGenerateId, ThreadPool threadPool, ShardIndexingService indexingService, IndexSettingsService indexSettingsService, IndicesWarmer warmer, Store store, SnapshotDeletionPolicy deletionPolicy, Translog translog, MergePolicyProvider mergePolicyProvider, MergeSchedulerProvider mergeScheduler, Analyzer analyzer, Similarity similarity, CodecService codecService, Engine.FailedEngineListener failedEngineListener) {
        this.shardId = shardId;
        this.optimizeAutoGenerateId = optimizeAutoGenerateId;
        this.threadPool = threadPool;
        this.indexingService = indexingService;
        this.indexSettingsService = indexSettingsService;
        this.warmer = warmer;
        this.store = store;
        this.deletionPolicy = deletionPolicy;
        this.translog = translog;
        this.mergePolicyProvider = mergePolicyProvider;
        this.mergeScheduler = mergeScheduler;
        this.analyzer = analyzer;
        this.similarity = similarity;
        this.codecService = codecService;
        this.failedEngineListener = failedEngineListener;
        Settings indexSettings = indexSettingsService.getSettings();
        this.compoundOnFlush = indexSettings.getAsBoolean(EngineConfig.INDEX_COMPOUND_ON_FLUSH, compoundOnFlush);
        this.indexConcurrency = indexSettings.getAsInt(EngineConfig.INDEX_CONCURRENCY_SETTING, Math.max(IndexWriterConfig.DEFAULT_MAX_THREAD_STATES, (int) (EsExecutors.boundedNumberOfProcessors(indexSettings) * 0.65)));
        codecName = indexSettings.get(EngineConfig.INDEX_CODEC_SETTING, EngineConfig.DEFAULT_CODEC_NAME);
        indexingBufferSize = indexSettings.getAsBytesSize(INDEX_BUFFER_SIZE_SETTING, DEFAUTL_INDEX_BUFFER_SIZE);
        failEngineOnCorruption = indexSettings.getAsBoolean(INDEX_FAIL_ON_CORRUPTION_SETTING, true);
        failOnMergeFailure = indexSettings.getAsBoolean(INDEX_FAIL_ON_MERGE_FAILURE_SETTING, true);
        gcDeletesInMillis = indexSettings.getAsTime(INDEX_GC_DELETES_SETTING, EngineConfig.DEFAULT_GC_DELETES).millis();
    }

    /**
     * Sets the indexing buffer
     */
    public void setIndexingBufferSize(ByteSizeValue indexingBufferSize) {
        this.indexingBufferSize = indexingBufferSize;
    }

    /**
     * Enables / disables gc deletes
     *
     * @see #isEnableGcDeletes()
     */
    public void setEnableGcDeletes(boolean enableGcDeletes) {
        this.enableGcDeletes = enableGcDeletes;
    }

    /**
     * Returns <code>true</code> iff the engine should be failed if a merge error is hit. Defaults to <code>true</code>
     */
    public boolean isFailOnMergeFailure() {
        return failOnMergeFailure;
    }

    /**
     * Returns <code>true</code> if the engine should be failed in the case of a corrupted index. Defaults to <code>true</code>
     */
    public boolean isFailEngineOnCorruption() {
        return failEngineOnCorruption;
    }

    /**
     * Returns the initial index buffer size. This setting is only read on startup and otherwise controlled by {@link org.elasticsearch.indices.memory.IndexingMemoryController}
     */
    public ByteSizeValue getIndexingBufferSize() {
        return indexingBufferSize;
    }

    /**
     * Returns the index concurrency that directly translates into the number of thread states used in the engines
     * {@code IndexWriter}.
     *
     * @see org.apache.lucene.index.IndexWriterConfig#getMaxThreadStates()
     */
    public int getIndexConcurrency() {
        return indexConcurrency;
    }

    /**
     * Returns <code>true</code> iff flushed segments should be written as compound file system. Defaults to <code>true</code>
     */
    public boolean isCompoundOnFlush() {
        return compoundOnFlush;
    }

    /**
     * Returns the GC deletes cycle in milliseconds.
     */
    public long getGcDeletesInMillis() {
        return gcDeletesInMillis;
    }

    /**
     * Returns <code>true</code> iff delete garbage collection in the engine should be enabled. This setting is updateable
     * in realtime and forces a volatile read. Consumers can safely read this value directly go fetch it's latest value. The default is <code>true</code>
     * <p>
     *     Engine GC deletion if enabled collects deleted documents from in-memory realtime data structures after a certain amount of
     *     time ({@link #getGcDeletesInMillis()} if enabled. Before deletes are GCed they will cause re-adding the document that was deleted
     *     to fail.
     * </p>
     */
    public boolean isEnableGcDeletes() {
        return enableGcDeletes;
    }

    /**
     * Returns the {@link Codec} used in the engines {@link org.apache.lucene.index.IndexWriter}
     * <p>
     *     Note: this settings is only read on startup.
     * </p>
     */
    public Codec getCodec() {
        return codecService.codec(codecName);
    }

    /**
     * Returns <code>true</code> iff documents with auto-generated IDs are optimized if possible. This mainly means that
     * they are simply appended to the index if no update call is necessary.
     */
    public boolean isOptimizeAutoGenerateId() {
        return optimizeAutoGenerateId;
    }

    /**
     * Returns a thread-pool mainly used to get estimated time stamps from {@link org.elasticsearch.threadpool.ThreadPool#estimatedTimeInMillis()} and to schedule
     * async force merge calls on the {@link org.elasticsearch.threadpool.ThreadPool.Names#OPTIMIZE} thread-pool
     */
    public ThreadPool getThreadPool() {
        return threadPool;
    }

    /**
     * Returns a {@link org.elasticsearch.index.indexing.ShardIndexingService} used inside the engine to inform about
     * pre and post index and create operations. The operations are used for statistic purposes etc.
     *
     * @see org.elasticsearch.index.indexing.ShardIndexingService#postCreate(org.elasticsearch.index.engine.Engine.Create)
     * @see org.elasticsearch.index.indexing.ShardIndexingService#preCreate(org.elasticsearch.index.engine.Engine.Create)
     *
     */
    public ShardIndexingService getIndexingService() {
        return indexingService;
    }

    /**
     * Returns an {@link org.elasticsearch.indices.IndicesWarmer} used to warm new searchers before they are used for searching.
     * Note: This method might retrun <code>null</code>
     */
    @Nullable
    public IndicesWarmer getWarmer() {
        return warmer;
    }

    /**
     * Returns the {@link org.elasticsearch.index.store.Store} instance that provides access to the {@link org.apache.lucene.store.Directory}
     * used for the engines {@link org.apache.lucene.index.IndexWriter} to write it's index files to.
     * <p>
     * Note: In order to use this instance the consumer needs to increment the stores reference before it's used the first time and hold
     * it's reference until it's not needed anymore.
     * </p>
     */
    public Store getStore() {
        return store;
    }

    /**
     * Returns a {@link org.elasticsearch.index.deletionpolicy.SnapshotDeletionPolicy} used in the engines
     * {@link org.apache.lucene.index.IndexWriter}.
     */
    public SnapshotDeletionPolicy getDeletionPolicy() {
        return deletionPolicy;
    }

    /**
     * Returns a {@link Translog instance}
     */
    public Translog getTranslog() {
        return translog;
    }

    /**
     * Returns the {@link org.elasticsearch.index.merge.policy.MergePolicyProvider} used to obtain
     * a {@link org.apache.lucene.index.MergePolicy} for the engines {@link org.apache.lucene.index.IndexWriter}
     */
    public MergePolicyProvider getMergePolicyProvider() {
        return mergePolicyProvider;
    }

    /**
     * Returns the {@link org.elasticsearch.index.merge.scheduler.MergeSchedulerProvider} used to obtain
     * a {@link org.apache.lucene.index.MergeScheduler} for the engines {@link org.apache.lucene.index.IndexWriter}
     */
    public MergeSchedulerProvider getMergeScheduler() {
        return mergeScheduler;
    }

    /**
     * Returns a listener that should be called on engine failure
     */
    public Engine.FailedEngineListener getFailedEngineListener() {
        return failedEngineListener;
    }

    /**
     * Returns the latest index settings directly from the index settings service.
     */
    public Settings getIndexSettings() {
        return indexSettingsService.getSettings();
    }

    /**
     * Returns the engines shard ID
     */
    public ShardId getShardId() { return shardId; }

    /**
     * Returns the analyzer as the default analyzer in the engines {@link org.apache.lucene.index.IndexWriter}
     */
    public Analyzer getAnalyzer() {
        return analyzer;
    }

    /**
     * Returns the {@link org.apache.lucene.search.similarities.Similarity} used for indexing and searching.
     */
    public Similarity getSimilarity() {
        return similarity;
    }

    /**
     * Sets the GC deletes cycle in milliseconds.
     */
    public void setGcDeletesInMillis(long gcDeletesInMillis) {
        this.gcDeletesInMillis = gcDeletesInMillis;
    }

    /**
     * Sets if flushed segments should be written as compound file system. Defaults to <code>true</code>
     */
    public void setCompoundOnFlush(boolean compoundOnFlush) {
        this.compoundOnFlush = compoundOnFlush;
    }

    /**
     * Sets if the engine should be failed in the case of a corrupted index. Defaults to <code>true</code>
     */
    public void setFailEngineOnCorruption(boolean failEngineOnCorruption) {
        this.failEngineOnCorruption = failEngineOnCorruption;
    }

    /**
     * Sets if the engine should be failed if a merge error is hit. Defaults to <code>true</code>
     */
    public void setFailOnMergeFailure(boolean failOnMergeFailure) {
        this.failOnMergeFailure = failOnMergeFailure;
    }
}
