/*
 * 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.iotdb.commons.pipe.event;

import org.apache.iotdb.commons.consensus.index.ProgressIndex;
import org.apache.iotdb.commons.pipe.agent.task.meta.PipeTaskMeta;
import org.apache.iotdb.commons.pipe.agent.task.progress.CommitterKey;
import org.apache.iotdb.commons.pipe.agent.task.progress.PipeEventCommitManager;
import org.apache.iotdb.commons.pipe.config.PipeConfig;
import org.apache.iotdb.commons.pipe.datastructure.pattern.PipePattern;
import org.apache.iotdb.commons.utils.TestOnly;
import org.apache.iotdb.pipe.api.event.Event;

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import java.util.ArrayList;
import java.util.Collections;
import java.util.List;
import java.util.Objects;
import java.util.concurrent.atomic.AtomicBoolean;
import java.util.concurrent.atomic.AtomicInteger;

/**
 * {@link EnrichedEvent} is an {@link Event} that can be enriched with additional runtime
 * information. The additional information mainly includes the {@link EnrichedEvent#referenceCount}
 * of the {@link Event}.
 */
public abstract class EnrichedEvent implements Event {

  private static final Logger LOGGER = LoggerFactory.getLogger(EnrichedEvent.class);

  protected final AtomicInteger referenceCount;
  // This variable is used to indicate whether the event's reference count has ever been decreased
  // to zero.
  protected final AtomicBoolean isReleased;

  protected final String pipeName;
  protected final long creationTime;

  protected final PipeTaskMeta pipeTaskMeta;

  protected CommitterKey committerKey;
  public static final long NO_COMMIT_ID = -1;
  protected long commitId = NO_COMMIT_ID;
  protected int rebootTimes = 0;

  protected final PipePattern pipePattern;

  protected final long startTime;
  protected final long endTime;

  protected boolean isPatternParsed;
  protected boolean isTimeParsed;

  protected volatile boolean shouldReportOnCommit = true;
  protected List<Runnable> onCommittedHooks = new ArrayList<>();

  protected EnrichedEvent(
      final String pipeName,
      final long creationTime,
      final PipeTaskMeta pipeTaskMeta,
      final PipePattern pipePattern,
      final long startTime,
      final long endTime) {
    referenceCount = new AtomicInteger(0);
    isReleased = new AtomicBoolean(false);
    this.pipeName = pipeName;
    this.creationTime = creationTime;
    this.pipeTaskMeta = pipeTaskMeta;
    this.pipePattern = pipePattern;
    this.startTime = startTime;
    this.endTime = endTime;
    isPatternParsed = this.pipePattern == null || this.pipePattern.isRoot();
    isTimeParsed = Long.MIN_VALUE == startTime && Long.MAX_VALUE == endTime;
  }

  protected void trackResource() {
    // do nothing by default
  }

  /**
   * Increase the {@link EnrichedEvent#referenceCount} of this event. When the {@link
   * EnrichedEvent#referenceCount} is positive, the data in the resource of this {@link
   * EnrichedEvent} should be safe to use.
   *
   * @param holderMessage the message of the invoker
   * @return {@code true} if the {@link EnrichedEvent#referenceCount} is increased successfully,
   *     {@code false} otherwise
   */
  public synchronized boolean increaseReferenceCount(final String holderMessage) {
    boolean isSuccessful = true;

    if (isReleased.get()) {
      LOGGER.warn(
          "re-increase reference count to event that has already been released: {}, stack trace: {}",
          coreReportMessage(),
          Thread.currentThread().getStackTrace());
      isSuccessful = false;
      return isSuccessful;
    }

    if (referenceCount.get() == 0) {
      // We assume that this function will not throw any exceptions.
      isSuccessful = internallyIncreaseResourceReferenceCount(holderMessage);
    }

    if (isSuccessful) {
      if (referenceCount.incrementAndGet() == 1
          && PipeConfig.getInstance().getPipeEventReferenceTrackingEnabled()) {
        trackResource();
      }
    } else {
      LOGGER.warn(
          "increase reference count failed, EnrichedEvent: {}, stack trace: {}",
          coreReportMessage(),
          Thread.currentThread().getStackTrace());
    }

    return isSuccessful;
  }

  /**
   * Increase the {@link EnrichedEvent#referenceCount} of the resource of this {@link
   * EnrichedEvent}.
   *
   * <p>We assume that this function will not throw any exceptions.
   *
   * @param holderMessage the message of the invoker
   * @return {@code true} if the {@link EnrichedEvent#referenceCount} is increased successfully,
   *     {@code false} if the {@link EnrichedEvent} is not controlled by the invoker, which means
   *     the data stored in the event is not safe to use
   */
  public abstract boolean internallyIncreaseResourceReferenceCount(final String holderMessage);

  /**
   * Decrease the {@link EnrichedEvent#referenceCount} of this {@link EnrichedEvent} by 1. If the
   * {@link EnrichedEvent#referenceCount} is decreased to 0, the {@link EnrichedEvent} can be
   * recycled and the data stored in the {@link EnrichedEvent} is not safe to use, the processing
   * {@link ProgressIndex} of the event should be reported to the {@link PipeTaskMeta}.
   *
   * @param holderMessage the message of the invoker
   * @return {@code true} if the {@link EnrichedEvent#referenceCount} is decreased successfully,
   *     {@code false} otherwise
   */
  public synchronized boolean decreaseReferenceCount(
      final String holderMessage, final boolean shouldReport) {
    boolean isSuccessful = true;

    if (isReleased.get()) {
      LOGGER.warn(
          "decrease reference count to event that has already been released: {}, stack trace: {}",
          coreReportMessage(),
          Thread.currentThread().getStackTrace());
      isSuccessful = false;
      return isSuccessful;
    }

    if (referenceCount.get() == 1) {
      if (!shouldReport) {
        shouldReportOnCommit = false;
      }
      // We assume that this function will not throw any exceptions.
      if (!internallyDecreaseResourceReferenceCount(holderMessage)) {
        LOGGER.warn(
            "resource reference count is decreased to 0, but failed to release the resource, EnrichedEvent: {}, stack trace: {}",
            coreReportMessage(),
            Thread.currentThread().getStackTrace());
      }
      PipeEventCommitManager.getInstance().commit(this, committerKey);
    }

    // No matter whether the resource is released, we should decrease the reference count.
    final int newReferenceCount = referenceCount.decrementAndGet();
    if (newReferenceCount <= 0) {
      isReleased.set(true);
      isSuccessful = newReferenceCount == 0;
      if (newReferenceCount < 0) {
        LOGGER.warn(
            "reference count is decreased to {}, event: {}, stack trace: {}",
            newReferenceCount,
            coreReportMessage(),
            Thread.currentThread().getStackTrace());
        referenceCount.set(0);
      }
    }

    if (!isSuccessful) {
      LOGGER.warn(
          "decrease reference count failed, EnrichedEvent: {}, stack trace: {}",
          coreReportMessage(),
          Thread.currentThread().getStackTrace());
    }
    return isSuccessful;
  }

  /**
   * Decrease the {@link EnrichedEvent#referenceCount} of this {@link EnrichedEvent} to 0, to
   * release the {@link EnrichedEvent} directly. The {@link EnrichedEvent} can be recycled and the
   * data stored in the {@link EnrichedEvent} may not be safe to use.
   *
   * @param holderMessage the message of the invoker
   * @return {@code true} if the {@link EnrichedEvent#referenceCount} is cleared successfully,
   *     {@code false} otherwise; {@link EnrichedEvent#referenceCount} will be reset to zero
   *     regardless of the circumstances
   */
  public synchronized boolean clearReferenceCount(final String holderMessage) {
    if (isReleased.get()) {
      return false;
    }

    if (referenceCount.get() >= 1) {
      shouldReportOnCommit = false;
      // We assume that this function will not throw any exceptions.
      if (!internallyDecreaseResourceReferenceCount(holderMessage)) {
        LOGGER.warn(
            "resource reference count is decreased to 0, but failed to release the resource, EnrichedEvent: {}, stack trace: {}",
            coreReportMessage(),
            Thread.currentThread().getStackTrace());
      }
    }

    referenceCount.set(0);
    isReleased.set(true);
    return true;
  }

  /**
   * Decrease the {@link EnrichedEvent#referenceCount} of this {@link EnrichedEvent}. If the {@link
   * EnrichedEvent#referenceCount} is decreased to 0, the {@link EnrichedEvent} can be recycled and
   * the data stored in the {@link EnrichedEvent} may not be safe to use.
   *
   * <p>We assume that this function will not throw any exceptions.
   *
   * @param holderMessage the message of the invoker
   * @return {@code true} if the {@link EnrichedEvent#referenceCount} is decreased successfully,
   *     {@code true} otherwise
   */
  public abstract boolean internallyDecreaseResourceReferenceCount(final String holderMessage);

  /**
   * Externally skip the report of the processing {@link ProgressIndex} of this {@link
   * EnrichedEvent} when committed. Report by generated events are still allowed.
   */
  public void skipReportOnCommit() {
    shouldReportOnCommit = false;
  }

  public void bindProgressIndex(final ProgressIndex progressIndex) {
    throw new UnsupportedOperationException("This event does not support binding progressIndex.");
  }

  public abstract ProgressIndex getProgressIndex();

  /**
   * Get the {@link EnrichedEvent#referenceCount} of this {@link EnrichedEvent}.
   *
   * @return the {@link EnrichedEvent#referenceCount}
   */
  public int getReferenceCount() {
    return referenceCount.get();
  }

  public final String getPipeName() {
    return pipeName;
  }

  public final long getCreationTime() {
    return creationTime;
  }

  public final int getRegionId() {
    // TODO: persist regionId in EnrichedEvent
    return committerKey == null ? -1 : committerKey.getRegionId();
  }

  public final boolean isDataRegionEvent() {
    return !(this instanceof PipeWritePlanEvent) && !(this instanceof PipeSnapshotEvent);
  }

  /**
   * Get the pattern string of this {@link EnrichedEvent}.
   *
   * @return the pattern string
   */
  public final String getPatternString() {
    return pipePattern != null ? pipePattern.getPattern() : null;
  }

  public final PipePattern getPipePattern() {
    return pipePattern;
  }

  public final long getStartTime() {
    return startTime;
  }

  public final long getEndTime() {
    return endTime;
  }

  /**
   * If pipe's pattern is database-level, then no need to parse {@link EnrichedEvent} by pattern
   * cause pipes are data-region-level.
   */
  public void skipParsingPattern() {
    isPatternParsed = true;
  }

  public void skipParsingTime() {
    isTimeParsed = true;
  }

  public boolean shouldParseTimeOrPattern() {
    return shouldParseTime() || shouldParsePattern();
  }

  public boolean shouldParsePattern() {
    return !isPatternParsed;
  }

  public boolean shouldParseTime() {
    return !isTimeParsed;
  }

  public abstract EnrichedEvent shallowCopySelfAndBindPipeTaskMetaForProgressReport(
      final String pipeName,
      final long creationTime,
      final PipeTaskMeta pipeTaskMeta,
      final PipePattern pattern,
      final long startTime,
      final long endTime);

  @TestOnly
  public void setShouldReportOnCommit(final boolean shouldReportOnCommit) {
    this.shouldReportOnCommit = shouldReportOnCommit;
  }

  public boolean isShouldReportOnCommit() {
    return shouldReportOnCommit;
  }

  public List<Runnable> getOnCommittedHooks() {
    return onCommittedHooks;
  }

  public PipeTaskMeta getPipeTaskMeta() {
    return pipeTaskMeta;
  }

  public abstract boolean isGeneratedByPipe();

  /** Whether the {@link EnrichedEvent} need to be committed in order. */
  public boolean needToCommit() {
    return true;
  }

  public abstract boolean mayEventTimeOverlappedWithTimeRange();

  public abstract boolean mayEventPathsOverlappedWithPattern();

  public void setCommitterKeyAndCommitId(final CommitterKey committerKey, final long commitId) {
    this.committerKey = committerKey;
    this.commitId = commitId;
  }

  public void setRebootTimes(final int rebootTimes) {
    this.rebootTimes = rebootTimes;
  }

  public int getRebootTimes() {
    return rebootTimes;
  }

  public CommitterKey getCommitterKey() {
    return committerKey;
  }

  public boolean hasMultipleCommitIds() {
    return false;
  }

  public long getCommitId() {
    return commitId;
  }

  public List<EnrichedEvent> getDummyEventsForCommitIds() {
    return Collections.emptyList();
  }

  public List<Long> getCommitIds() {
    return Collections.singletonList(commitId);
  }

  public void addOnCommittedHook(final Runnable hook) {
    onCommittedHooks.add(hook);
  }

  public boolean isReleased() {
    return isReleased.get();
  }

  /**
   * Used for pipeConsensus. In PipeConsensus, we only need committerKey, commitId and rebootTimes
   * to uniquely identify an event
   */
  public boolean equalsInPipeConsensus(final Object o) {
    if (this == o) {
      return true;
    }
    if (o == null || getClass() != o.getClass()) {
      return false;
    }
    final EnrichedEvent otherEvent = (EnrichedEvent) o;
    return Objects.equals(committerKey, otherEvent.committerKey)
        && commitId == otherEvent.commitId
        && rebootTimes == otherEvent.rebootTimes;
  }

  @Override
  public String toString() {
    return "EnrichedEvent{"
        + "referenceCount="
        + referenceCount.get()
        + ", isReleased="
        + isReleased.get()
        + ", pipeName='"
        + pipeName
        + "', pipeTaskMeta="
        + pipeTaskMeta
        + ", committerKey='"
        + committerKey
        + "', commitId="
        + commitId
        + ", pattern='"
        + pipePattern
        + "', startTime="
        + startTime
        + ", endTime="
        + endTime
        + ", isPatternParsed="
        + isPatternParsed
        + ", isTimeParsed="
        + isTimeParsed
        + ", shouldReportOnCommit="
        + shouldReportOnCommit
        + '}';
  }

  public String coreReportMessage() {
    return "EnrichedEvent{"
        + "referenceCount="
        + referenceCount.get()
        + ", isReleased="
        + isReleased.get()
        + ", pipeName='"
        + pipeName
        + "', committerKey='"
        + committerKey
        + "', commitId="
        + commitId
        + ", pattern='"
        + pipePattern
        + "', startTime="
        + startTime
        + ", endTime="
        + endTime
        + ", isPatternParsed="
        + isPatternParsed
        + ", isTimeParsed="
        + isTimeParsed
        + ", shouldReportOnCommit="
        + shouldReportOnCommit
        + '}';
  }
}
