package io.dropwizard.logging;

import ch.qos.logback.classic.LoggerContext;
import ch.qos.logback.core.FileAppender;
import ch.qos.logback.core.OutputStreamAppender;
import ch.qos.logback.core.rolling.DefaultTimeBasedFileNamingAndTriggeringPolicy;
import ch.qos.logback.core.rolling.FixedWindowRollingPolicy;
import ch.qos.logback.core.rolling.RollingFileAppender;
import ch.qos.logback.core.rolling.SizeAndTimeBasedRollingPolicy;
import ch.qos.logback.core.rolling.SizeBasedTriggeringPolicy;
import ch.qos.logback.core.rolling.TimeBasedFileNamingAndTriggeringPolicy;
import ch.qos.logback.core.rolling.TimeBasedRollingPolicy;
import ch.qos.logback.core.spi.DeferredProcessingAware;
import ch.qos.logback.core.util.FileSize;
import com.fasterxml.jackson.annotation.JsonIgnore;
import com.fasterxml.jackson.annotation.JsonProperty;
import com.fasterxml.jackson.annotation.JsonTypeName;
import io.dropwizard.logging.async.AsyncAppenderFactory;
import io.dropwizard.logging.filter.LevelFilterFactory;
import io.dropwizard.logging.layout.LayoutFactory;
import io.dropwizard.util.Size;
import io.dropwizard.validation.MinSize;
import io.dropwizard.validation.ValidationMethod;

import javax.annotation.Nullable;
import javax.validation.constraints.Min;

import static java.util.Objects.requireNonNull;

An AppenderFactory implementation which provides an appender that writes events to a file, archiving older files as it goes. 

Configuration Parameters:

    

        
Name
        
Default
        
Description
    
    

        
type
        
REQUIRED
        
The appender type. Must be file.
    
    

        
threshold
        
ALL
        
The lowest level of events to write to the file.
    
    

        
currentLogFilename
        
REQUIRED
        
The filename where current events are logged.
    
    

        
archive
        
true
        
Whether or not to archive old events in separate files.
    
    

        
archivedLogFilenamePattern
        
REQUIRED if archive is true.
        
 The filename pattern for archived files. If maxFileSize is specified, rollover is size-based, and the pattern must contain %i for an integer index of the archived file. Otherwise rollover is date-based, and the pattern must contain %d, which is replaced with the date in yyyy-MM-dd form. If the pattern ends with .gz or .zip, files will be compressed as they are archived. 
    
    

        
archivedFileCount
        
5
        
 The number of archived files to keep. Must be greater than or equal to 0. Zero is a special value signifying to keep infinite logs (use with caution) 
    
    

        
maxFileSize
        
(unlimited)
        

            The maximum size of the currently active file before a rollover is triggered. The value can be expressed
            in bytes, kilobytes, megabytes, gigabytes, and terabytes by appending B, K, MB, GB, or TB to the
            numeric value.  Examples include 100MB, 1GB, 1TB.  Sizes can also be spelled out, such as 100 megabytes,
            1 gigabyte, 1 terabyte.
        
    
    

        
timeZone
        
UTC
        
The time zone to which event timestamps will be converted.
    
    

        
logFormat
        
the default format
        

            The Logback pattern with which events will be formatted. See
            the Logback documentation
            for details.
        
    
    

        
bufferSize
        
8KB
        

            The buffer size of the underlying FileAppender (setting added in logback 1.1.10). Increasing this from
            the default of 8KB to 256KB is reported to significantly reduce thread contention.
        
    
     

        
immediateFlush
        
true
        

            If set to true, log events will be immediately flushed to disk. Immediate flushing is safer, but
            it degrades logging throughput.
            See the Logback documentation
            for details.
        
    

See Also:
AbstractAppenderFactory/**
 * An {@link AppenderFactory} implementation which provides an appender that writes events to a file, archiving older
 * files as it goes.
 * <p/>
 * <b>Configuration Parameters:</b>
 * <table>
 *     <tr>
 *         <td>Name</td>
 *         <td>Default</td>
 *         <td>Description</td>
 *     </tr>
 *     <tr>
 *         <td>{@code type}</td>
 *         <td><b>REQUIRED</b></td>
 *         <td>The appender type. Must be {@code file}.</td>
 *     </tr>
 *     <tr>
 *         <td>{@code threshold}</td>
 *         <td>{@code ALL}</td>
 *         <td>The lowest level of events to write to the file.</td>
 *     </tr>
 *     <tr>
 *         <td>{@code currentLogFilename}</td>
 *         <td><b>REQUIRED</b></td>
 *         <td>The filename where current events are logged.</td>
 *     </tr>
 *     <tr>
 *         <td>{@code archive}</td>
 *         <td>{@code true}</td>
 *         <td>Whether or not to archive old events in separate files.</td>
 *     </tr>
 *     <tr>
 *         <td>{@code archivedLogFilenamePattern}</td>
 *         <td><b>REQUIRED</b> if {@code archive} is {@code true}.</td>
 *         <td>
 *             The filename pattern for archived files.
 *             If {@code maxFileSize} is specified, rollover is size-based, and the pattern must contain {@code %i} for
 *             an integer index of the archived file.
 *             Otherwise rollover is date-based, and the pattern must contain {@code %d}, which is replaced with the
 *             date in {@code yyyy-MM-dd} form.
 *             If the pattern ends with {@code .gz} or {@code .zip}, files will be compressed as they are archived.
 *         </td>
 *     </tr>
 *     <tr>
 *         <td>{@code archivedFileCount}</td>
 *         <td>{@code 5}</td>
 *         <td>
 *             The number of archived files to keep. Must be greater than or equal to {@code 0}. Zero is a
 *             special value signifying to keep infinite logs (use with caution)
 *         </td>
 *     </tr>
 *     <tr>
 *         <td>{@code maxFileSize}</td>
 *         <td>(unlimited)</td>
 *         <td>
 *             The maximum size of the currently active file before a rollover is triggered. The value can be expressed
 *             in bytes, kilobytes, megabytes, gigabytes, and terabytes by appending B, K, MB, GB, or TB to the
 *             numeric value.  Examples include 100MB, 1GB, 1TB.  Sizes can also be spelled out, such as 100 megabytes,
 *             1 gigabyte, 1 terabyte.
 *         </td>
 *     </tr>
 *     <tr>
 *         <td>{@code timeZone}</td>
 *         <td>{@code UTC}</td>
 *         <td>The time zone to which event timestamps will be converted.</td>
 *     </tr>
 *     <tr>
 *         <td>{@code logFormat}</td>
 *         <td>the default format</td>
 *         <td>
 *             The Logback pattern with which events will be formatted. See
 *             <a href="http://logback.qos.ch/manual/layouts.html#conversionWord">the Logback documentation</a>
 *             for details.
 *         </td>
 *     </tr>
 *     <tr>
 *         <td>{@code bufferSize}</td>
 *         <td>8KB</td>
 *         <td>
 *             The buffer size of the underlying FileAppender (setting added in logback 1.1.10). Increasing this from
 *             the default of 8KB to 256KB is reported to significantly reduce thread contention.
 *         </td>
 *     </tr>
 *      <tr>
 *         <td>{@code immediateFlush}</td>
 *         <td>{@code true}</td>
 *         <td>
 *             If set to true, log events will be immediately flushed to disk. Immediate flushing is safer, but
 *             it degrades logging throughput.
 *             See <a href="https://logback.qos.ch/manual/appenders.html#immediateFlush">the Logback documentation</a>
 *             for details.
 *         </td>
 *     </tr>
 * </table>
 *
 * @see AbstractAppenderFactory
 */
@JsonTypeName("file")
public class FileAppenderFactory<E extends DeferredProcessingAware> extends AbstractOutputStreamAppenderFactory<E> {

    @Nullable
    private String currentLogFilename;

    private boolean archive = true;

    @Nullable
    private String archivedLogFilenamePattern;

    @Min(0)
    private int archivedFileCount = 5;

    @Nullable
    private Size maxFileSize;

    @MinSize(1)
    private Size bufferSize = Size.bytes(FileAppender.DEFAULT_BUFFER_SIZE);

    private boolean immediateFlush = true;

    @JsonProperty
    @Nullable
    public String getCurrentLogFilename() {
        return currentLogFilename;
    }

    @JsonProperty
    public void setCurrentLogFilename(@Nullable String currentLogFilename) {
        this.currentLogFilename = currentLogFilename;
    }

    @JsonProperty
    public boolean isArchive() {
        return archive;
    }

    @JsonProperty
    public void setArchive(boolean archive) {
        this.archive = archive;
    }

    @JsonProperty
    @Nullable
    public String getArchivedLogFilenamePattern() {
        return archivedLogFilenamePattern;
    }

    @JsonProperty
    public void setArchivedLogFilenamePattern(String archivedLogFilenamePattern) {
        this.archivedLogFilenamePattern = archivedLogFilenamePattern;
    }

    @JsonProperty
    public int getArchivedFileCount() {
        return archivedFileCount;
    }

    @JsonProperty
    public void setArchivedFileCount(int archivedFileCount) {
        this.archivedFileCount = archivedFileCount;
    }

    @JsonProperty
    @Nullable
    public Size getMaxFileSize() {
        return maxFileSize;
    }

    @JsonProperty
    public void setMaxFileSize(Size maxFileSize) {
        this.maxFileSize = maxFileSize;
    }

    @JsonProperty
    public Size getBufferSize() {
        return bufferSize;
    }

    @JsonProperty
    public void setBufferSize(Size bufferSize) {
        this.bufferSize = bufferSize;
    }

    public boolean isImmediateFlush() {
        return immediateFlush;
    }

    @JsonProperty
    public void setImmediateFlush(boolean immediateFlush) {
        this.immediateFlush = immediateFlush;
    }

    @JsonIgnore
    @ValidationMethod(message = "must have archivedLogFilenamePattern if archive is true")
    public boolean isValidArchiveConfiguration() {
        return !archive || (archivedLogFilenamePattern != null);
    }

    @JsonIgnore
    @ValidationMethod(message = "when specifying maxFileSize, archivedLogFilenamePattern must contain %i")
    public boolean isValidForMaxFileSizeSetting() {
        return !archive || maxFileSize == null ||
                (archivedLogFilenamePattern != null && archivedLogFilenamePattern.contains("%i"));
    }

    @JsonIgnore
    @ValidationMethod(message = "when archivedLogFilenamePattern contains %i, maxFileSize must be specified")
    public boolean isMaxFileSizeSettingSpecified() {
        return !archive || !(archivedLogFilenamePattern != null && archivedLogFilenamePattern.contains("%i")) ||
                maxFileSize != null;
    }

    @JsonIgnore
    @ValidationMethod(message = "currentLogFilename can only be null when archiving is enabled")
    public boolean isValidFileConfiguration() {
        return archive || currentLogFilename != null;
    }

    @Override
    protected OutputStreamAppender<E> appender(LoggerContext context) {
        final FileAppender<E> appender = buildAppender(context);
        appender.setName("file-appender");
        appender.setAppend(true);
        appender.setContext(context);
        appender.setImmediateFlush(immediateFlush);
        appender.setPrudent(false);
        return appender;
    }

    protected FileAppender<E> buildAppender(LoggerContext context) {
        if (archive) {
            final RollingFileAppender<E> appender = new RollingFileAppender<>();
            appender.setContext(context);
            appender.setFile(currentLogFilename);
            appender.setBufferSize(new FileSize(bufferSize.toBytes()));

            if (maxFileSize != null && !requireNonNull(archivedLogFilenamePattern).contains("%d")) {
                final FixedWindowRollingPolicy rollingPolicy = new FixedWindowRollingPolicy();
                rollingPolicy.setContext(context);
                rollingPolicy.setMaxIndex(getArchivedFileCount());
                rollingPolicy.setFileNamePattern(getArchivedLogFilenamePattern());
                rollingPolicy.setParent(appender);
                rollingPolicy.start();
                appender.setRollingPolicy(rollingPolicy);

                final SizeBasedTriggeringPolicy<E> triggeringPolicy = new SizeBasedTriggeringPolicy<>();
                triggeringPolicy.setMaxFileSize(new FileSize(maxFileSize.toBytes()));
                triggeringPolicy.setContext(context);
                triggeringPolicy.start();
                appender.setTriggeringPolicy(triggeringPolicy);

                return appender;
            } else {
                final TimeBasedRollingPolicy<E> rollingPolicy;
                if (maxFileSize == null) {
                    rollingPolicy = new TimeBasedRollingPolicy<>();

                    final TimeBasedFileNamingAndTriggeringPolicy<E> triggeringPolicy = new DefaultTimeBasedFileNamingAndTriggeringPolicy<>();
                    triggeringPolicy.setContext(context);
                    triggeringPolicy.setTimeBasedRollingPolicy(rollingPolicy);
                    appender.setTriggeringPolicy(triggeringPolicy);
                } else {
                    // Creating a size and time policy does not need a separate triggering policy set
                    // on the appender because this policy registers the trigger policy
                    final SizeAndTimeBasedRollingPolicy<E> sizeAndTimeBasedRollingPolicy = new SizeAndTimeBasedRollingPolicy<>();
                    sizeAndTimeBasedRollingPolicy.setMaxFileSize(new FileSize(maxFileSize.toBytes()));
                    rollingPolicy = sizeAndTimeBasedRollingPolicy;
                }

                rollingPolicy.setContext(context);
                rollingPolicy.setFileNamePattern(archivedLogFilenamePattern);
                rollingPolicy.setMaxHistory(archivedFileCount);

                appender.setRollingPolicy(rollingPolicy);

                rollingPolicy.setParent(appender);
                rollingPolicy.start();
                return appender;
            }
        }

        final FileAppender<E> appender = new FileAppender<>();
        appender.setContext(context);
        appender.setFile(currentLogFilename);
        appender.setBufferSize(new FileSize(bufferSize.toBytes()));
        return appender;
    }
}