/*
 * 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.logging.log4j.core.appender.rolling;

import java.io.File;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.OutputStream;
import java.io.Serializable;
import java.nio.ByteBuffer;
import java.util.concurrent.Semaphore;
import java.util.concurrent.atomic.AtomicReferenceFieldUpdater;

import org.apache.logging.log4j.core.Layout;
import org.apache.logging.log4j.core.LogEvent;
import org.apache.logging.log4j.core.appender.FileManager;
import org.apache.logging.log4j.core.appender.ManagerFactory;
import org.apache.logging.log4j.core.appender.rolling.action.AbstractAction;
import org.apache.logging.log4j.core.appender.rolling.action.Action;
import org.apache.logging.log4j.core.util.Constants;
import org.apache.logging.log4j.core.util.Log4jThread;

/**
 * The Rolling File Manager.
 */
public class RollingFileManager extends FileManager {

    private static RollingFileManagerFactory factory = new RollingFileManagerFactory();

    protected long size;
    private long initialTime;
    private final PatternProcessor patternProcessor;
    private final Semaphore semaphore = new Semaphore(1);
    private volatile TriggeringPolicy triggeringPolicy;
    private volatile RolloverStrategy rolloverStrategy;

    private static final AtomicReferenceFieldUpdater<RollingFileManager, TriggeringPolicy> triggeringPolicyUpdater =
            AtomicReferenceFieldUpdater.newUpdater(RollingFileManager.class, TriggeringPolicy.class, "triggeringPolicy");

    private static final AtomicReferenceFieldUpdater<RollingFileManager, RolloverStrategy> rolloverStrategyUpdater =
            AtomicReferenceFieldUpdater.newUpdater(RollingFileManager.class, RolloverStrategy.class, "rolloverStrategy");

    @Deprecated
    protected RollingFileManager(final String fileName, final String pattern, final OutputStream os,
            final boolean append, final long size, final long time, final TriggeringPolicy triggeringPolicy,
            final RolloverStrategy rolloverStrategy, final String advertiseURI,
            final Layout<? extends Serializable> layout, final int bufferSize, final boolean writeHeader) {
        this(fileName, pattern, os, append, size, time, triggeringPolicy, rolloverStrategy, advertiseURI, layout,
                writeHeader, ByteBuffer.wrap(new byte[Constants.ENCODER_BYTE_BUFFER_SIZE]));
    }

    protected RollingFileManager(final String fileName, final String pattern, final OutputStream os,
            final boolean append, final long size, final long time, final TriggeringPolicy triggeringPolicy,
            final RolloverStrategy rolloverStrategy, final String advertiseURI,
            final Layout<? extends Serializable> layout, final boolean writeHeader, final ByteBuffer buffer) {
        super(fileName, os, append, false, advertiseURI, layout, writeHeader, buffer);
        this.size = size;
        this.initialTime = time;
        this.triggeringPolicy = triggeringPolicy;
        this.rolloverStrategy = rolloverStrategy;
        this.patternProcessor = new PatternProcessor(pattern);
        triggeringPolicy.initialize(this);
    }

    /**
     * Returns a RollingFileManager.
     * @param fileName The file name.
     * @param pattern The pattern for rolling file.
     * @param append true if the file should be appended to.
     * @param bufferedIO true if data should be buffered.
     * @param policy The TriggeringPolicy.
     * @param strategy The RolloverStrategy.
     * @param advertiseURI the URI to use when advertising the file
     * @param layout The Layout.
     * @param bufferSize buffer size to use if bufferedIO is true
     * @return A RollingFileManager.
     */
    public static RollingFileManager getFileManager(final String fileName, final String pattern, final boolean append,
            final boolean bufferedIO, final TriggeringPolicy policy, final RolloverStrategy strategy,
            final String advertiseURI, final Layout<? extends Serializable> layout, final int bufferSize,
            final boolean immediateFlush) {

        return (RollingFileManager) getManager(fileName, new FactoryData(pattern, append,
            bufferedIO, policy, strategy, advertiseURI, layout, bufferSize, immediateFlush), factory);
    }

    // override to make visible for unit tests
    @Override
    protected synchronized void write(final byte[] bytes, final int offset, final int length,
            final boolean immediateFlush) {
        super.write(bytes, offset, length, immediateFlush);
    }

    @Override
    protected synchronized void writeToDestination(final byte[] bytes, final int offset, final int length) {
        size += length;
        super.writeToDestination(bytes, offset, length);
    }

    /**
     * Returns the current size of the file.
     * @return The size of the file in bytes.
     */
    public long getFileSize() {
        return size + byteBuffer.position();
    }

    /**
     * Returns the time the file was created.
     * @return The time the file was created.
     */
    public long getFileTime() {
        return initialTime;
    }

    /**
     * Determine if a rollover should occur.
     * @param event The LogEvent.
     */
    public synchronized void checkRollover(final LogEvent event) {
        if (triggeringPolicy.isTriggeringEvent(event)) {
            rollover();
        }
    }

    public synchronized void rollover() {
        if (rollover(rolloverStrategy)) {
            try {
                size = 0;
                initialTime = System.currentTimeMillis();
                createFileAfterRollover();
            } catch (final IOException e) {
                logError("failed to create file after rollover", e);
            }
        }
    }

    protected void createFileAfterRollover() throws IOException  {
        final OutputStream os = new FileOutputStream(getFileName(), isAppend());
        setOutputStream(os);
    }

    /**
     * Returns the pattern processor.
     * @return The PatternProcessor.
     */
    public PatternProcessor getPatternProcessor() {
        return patternProcessor;
    }

    public void setTriggeringPolicy(final TriggeringPolicy triggeringPolicy) {
        triggeringPolicy.initialize(this);
        triggeringPolicyUpdater.compareAndSet(this, this.triggeringPolicy, triggeringPolicy);
    }

    public void setRolloverStrategy(final RolloverStrategy rolloverStrategy) {
        rolloverStrategyUpdater.compareAndSet(this, this.rolloverStrategy, rolloverStrategy);
    }

    /**
     * Returns the triggering policy.
     * @param <T> TriggeringPolicy type
     * @return The TriggeringPolicy
     */
    @SuppressWarnings("unchecked")
    public <T extends TriggeringPolicy> T getTriggeringPolicy() {
        // TODO We could parameterize this class with a TriggeringPolicy instead of type casting here.
        return (T) this.triggeringPolicy;
    }

    /**
     * Returns the rollover strategy.
     * @return The RolloverStrategy
     */
    public RolloverStrategy getRolloverStrategy() {
        return this.rolloverStrategy;
    }

    private boolean rollover(final RolloverStrategy strategy) {

        try {
            // Block until the asynchronous operation is completed.
            semaphore.acquire();
        } catch (final InterruptedException e) {
            logError("Thread interrupted while attempting to check rollover", e);
            return false;
        }

        boolean success = false;
        Thread thread = null;

        try {
            final RolloverDescription descriptor = strategy.rollover(this);
            if (descriptor != null) {
                writeFooter();
                close();
                if (descriptor.getSynchronous() != null) {
                    LOGGER.debug("RollingFileManager executing synchronous {}", descriptor.getSynchronous());
                    try {
                        success = descriptor.getSynchronous().execute();
                    } catch (final Exception ex) {
                        logError("caught error in synchronous task", ex);
                    }
                }

                if (success && descriptor.getAsynchronous() != null) {
                    LOGGER.debug("RollingFileManager executing async {}", descriptor.getAsynchronous());
                    thread = new Log4jThread(new AsyncAction(descriptor.getAsynchronous(), this));
                    thread.start();
                }
                return true;
            }
            return false;
        } finally {
            if (thread == null || !thread.isAlive()) {
                semaphore.release();
            }
        }

    }

    /**
     * Performs actions asynchronously.
     */
    private static class AsyncAction extends AbstractAction {

        private final Action action;
        private final RollingFileManager manager;

        /**
         * Constructor.
         * @param act The action to perform.
         * @param manager The manager.
         */
        public AsyncAction(final Action act, final RollingFileManager manager) {
            this.action = act;
            this.manager = manager;
        }

        /**
         * Perform an action.
         *
         * @return true if action was successful.  A return value of false will cause
         *         the rollover to be aborted if possible.
         * @throws java.io.IOException if IO error, a thrown exception will cause the rollover
         *                             to be aborted if possible.
         */
        @Override
        public boolean execute() throws IOException {
            try {
                return action.execute();
            } finally {
                manager.semaphore.release();
            }
        }

        /**
         * Cancels the action if not already initialized or waits till completion.
         */
        @Override
        public void close() {
            action.close();
        }

        /**
         * Determines if action has been completed.
         *
         * @return true if action is complete.
         */
        @Override
        public boolean isComplete() {
            return action.isComplete();
        }

        @Override
        public String toString() {
            final StringBuilder builder = new StringBuilder();
            builder.append(super.toString());
            builder.append("[action=");
            builder.append(action);
            builder.append(", manager=");
            builder.append(manager);
            builder.append(", isComplete()=");
            builder.append(isComplete());
            builder.append(", isInterrupted()=");
            builder.append(isInterrupted());
            builder.append("]");
            return builder.toString();
        }
    }

    /**
     * Factory data.
     */
    private static class FactoryData {
        private final String pattern;
        private final boolean append;
        private final boolean bufferedIO;
        private final int bufferSize;
        private final boolean immediateFlush;
        private final TriggeringPolicy policy;
        private final RolloverStrategy strategy;
        private final String advertiseURI;
        private final Layout<? extends Serializable> layout;

        /**
         * Create the data for the factory.
         * @param pattern The pattern.
         * @param append The append flag.
         * @param bufferedIO The bufferedIO flag.
         * @param advertiseURI
         * @param layout The Layout.
         * @param bufferSize the buffer size
         * @param immediateFlush flush on every write or not
         */
        public FactoryData(final String pattern, final boolean append, final boolean bufferedIO,
                final TriggeringPolicy policy, final RolloverStrategy strategy, final String advertiseURI,
                final Layout<? extends Serializable> layout, final int bufferSize, final boolean immediateFlush) {
            this.pattern = pattern;
            this.append = append;
            this.bufferedIO = bufferedIO;
            this.bufferSize = bufferSize;
            this.policy = policy;
            this.strategy = strategy;
            this.advertiseURI = advertiseURI;
            this.layout = layout;
            this.immediateFlush = immediateFlush;
        }

        public TriggeringPolicy getTriggeringPolicy()
        {
            return this.policy;
        }

        public RolloverStrategy getRolloverStrategy()
        {
            return this.strategy;
        }

        @Override
        public String toString() {
            final StringBuilder builder = new StringBuilder();
            builder.append(super.toString());
            builder.append("[pattern=");
            builder.append(pattern);
            builder.append(", append=");
            builder.append(append);
            builder.append(", bufferedIO=");
            builder.append(bufferedIO);
            builder.append(", bufferSize=");
            builder.append(bufferSize);
            builder.append(", policy=");
            builder.append(policy);
            builder.append(", strategy=");
            builder.append(strategy);
            builder.append(", advertiseURI=");
            builder.append(advertiseURI);
            builder.append(", layout=");
            builder.append(layout);
            builder.append("]");
            return builder.toString();
        }
    }

    @Override
    public void updateData(final Object data)
    {
        final FactoryData factoryData = (FactoryData) data;
        setRolloverStrategy(factoryData.getRolloverStrategy());
        setTriggeringPolicy(factoryData.getTriggeringPolicy());
    }

    /**
     * Factory to create a RollingFileManager.
     */
    private static class RollingFileManagerFactory implements ManagerFactory<RollingFileManager, FactoryData> {

        /**
         * Creates a RollingFileManager.
         * @param name The name of the entity to manage.
         * @param data The data required to create the entity.
         * @return a RollingFileManager.
         */
        @Override
        public RollingFileManager createManager(final String name, final FactoryData data) {
            final File file = new File(name);
            final File parent = file.getParentFile();
            if (null != parent && !parent.exists()) {
                parent.mkdirs();
            }
            // LOG4J2-1140: check writeHeader before creating the file
            final boolean writeHeader = !data.append || !file.exists();
            try {
                file.createNewFile();
            } catch (final IOException ioe) {
                LOGGER.error("Unable to create file " + name, ioe);
                return null;
            }
            final long size = data.append ? file.length() : 0;

            OutputStream os;
            try {
                os = new FileOutputStream(name, data.append);
                final int actualSize = data.bufferedIO ? data.bufferSize : Constants.ENCODER_BYTE_BUFFER_SIZE;
                final ByteBuffer buffer = ByteBuffer.wrap(new byte[actualSize]);

                final long time = file.lastModified(); // LOG4J2-531 create file first so time has valid value
                return new RollingFileManager(name, data.pattern, os, data.append, size, time, data.policy,
                    data.strategy, data.advertiseURI, data.layout, writeHeader, buffer);
            } catch (final FileNotFoundException ex) {
                LOGGER.error("FileManager (" + name + ") " + ex, ex);
            }
            return null;
        }
    }

}
