package io.dropwizard.logging;

import ch.qos.logback.classic.LoggerContext;
import ch.qos.logback.classic.net.SyslogAppender;
import ch.qos.logback.classic.spi.ILoggingEvent;
import ch.qos.logback.core.Appender;
import ch.qos.logback.core.net.SyslogConstants;
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 javax.validation.constraints.Max;
import javax.validation.constraints.Min;
import javax.validation.constraints.NotNull;
import java.lang.management.ManagementFactory;
import java.util.Locale;
import java.util.regex.Matcher;
import java.util.regex.Pattern;

import static com.google.common.base.Strings.isNullOrEmpty;

An AppenderFactory implementation which provides an appender that sends events to a syslog server. 

Configuration Parameters:

    

        
Name
        
Default
        
Description
    
    

        
host
        
localhost
        
The hostname of the syslog server.
    
    

        
port
        
514
        
The port on which the syslog server is listening.
    
    

        
facility
        
local0
        
 The syslog facility to use. Can be either auth, authpriv, daemon, cron, ftp, lpr, kern, mail, news, syslog, user, uucp, local0, local1, local2, local3, local4, local5, local6, or local7. 
    
    

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

        
logFormat
        
the default format
        

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

See Also:
AbstractAppenderFactory/**
 * An {@link AppenderFactory} implementation which provides an appender that sends events to a
 * syslog server.
 * <p/>
 * <b>Configuration Parameters:</b>
 * <table>
 *     <tr>
 *         <td>Name</td>
 *         <td>Default</td>
 *         <td>Description</td>
 *     </tr>
 *     <tr>
 *         <td>{@code host}</td>
 *         <td>{@code localhost}</td>
 *         <td>The hostname of the syslog server.</td>
 *     </tr>
 *     <tr>
 *         <td>{@code port}</td>
 *         <td>{@code 514}</td>
 *         <td>The port on which the syslog server is listening.</td>
 *     </tr>
 *     <tr>
 *         <td>{@code facility}</td>
 *         <td>{@code local0}</td>
 *         <td>
 *             The syslog facility to use. Can be either {@code auth}, {@code authpriv},
 *             {@code daemon}, {@code cron}, {@code ftp}, {@code lpr}, {@code kern}, {@code mail},
 *             {@code news}, {@code syslog}, {@code user}, {@code uucp}, {@code local0},
 *             {@code local1}, {@code local2}, {@code local3}, {@code local4}, {@code local5},
 *             {@code local6}, or {@code local7}.
 *         </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 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>
 * </table>
 *
 * @see AbstractAppenderFactory
 */
@JsonTypeName("syslog")
public class SyslogAppenderFactory extends AbstractAppenderFactory<ILoggingEvent> {
    public enum Facility {
        AUTH,
        AUTHPRIV,
        DAEMON,
        CRON,
        FTP,
        LPR,
        KERN,
        MAIL,
        NEWS,
        SYSLOG,
        USER,
        UUCP,
        LOCAL0,
        LOCAL1,
        LOCAL2,
        LOCAL3,
        LOCAL4,
        LOCAL5,
        LOCAL6,
        LOCAL7
    }

    private static final String LOG_TOKEN_NAME = "%app";
    private static final String LOG_TOKEN_PID = "%pid";

    private static final Pattern PID_PATTERN = Pattern.compile("(\\d+)@");
    private static String pid = "";

    // make an attempt to get the PID of the process
    // this will only work on UNIX platforms; for others, the PID will be "unknown"
    static {
        final Matcher matcher = PID_PATTERN.matcher(ManagementFactory.getRuntimeMXBean().getName());
        if (matcher.find()) {
            pid = "[" + matcher.group(1) + "]";
        }
    }

    @NotNull
    private String host = "localhost";

    @Min(1)
    @Max(65535)
    private int port = SyslogConstants.SYSLOG_PORT;

    @NotNull
    private Facility facility = Facility.LOCAL0;

    // PrefixedThrowableProxyConverter does not apply to syslog appenders, as stack traces are sent separately from
    // the main message. This means that the standard prefix of `!` is not used for syslog
    @NotNull
    private String stackTracePrefix = SyslogAppender.DEFAULT_STACKTRACE_PATTERN;

    private boolean includeStackTrace = true;

    public SyslogAppenderFactory() {
        // prefix the logFormat with the application name and PID (if available)
        this.logFormat = LOG_TOKEN_NAME + LOG_TOKEN_PID + ": " + SyslogAppender.DEFAULT_SUFFIX_PATTERN;
    }

    
Returns the hostname of the syslog server.
/**
     * Returns the hostname of the syslog server.
     */
    @JsonProperty
    public String getHost() {
        return host;
    }

    @JsonProperty
    public void setHost(String host) {
        this.host = host;
    }

    @JsonProperty
    public Facility getFacility() {
        return facility;
    }

    @JsonProperty
    public void setFacility(Facility facility) {
        this.facility = facility;
    }

    @JsonProperty
    public int getPort() {
        return port;
    }

    @JsonProperty
    public void setPort(int port) {
        this.port = port;
    }

    @JsonProperty
    public boolean getIncludeStackTrace() {
        return includeStackTrace;
    }

    @JsonProperty
    public void setIncludeStackTrace(boolean includeStackTrace) {
        this.includeStackTrace = includeStackTrace;
    }

    @JsonProperty
    public String getStackTracePrefix() {
        return stackTracePrefix;
    }

    @JsonProperty
    public void setStackTracePrefix(String stackTracePrefix) {
        this.stackTracePrefix = stackTracePrefix;
    }

    @Override
    public Appender<ILoggingEvent> build(LoggerContext context, String applicationName, LayoutFactory<ILoggingEvent> layoutFactory,
                                         LevelFilterFactory<ILoggingEvent> levelFilterFactory, AsyncAppenderFactory<ILoggingEvent> asyncAppenderFactory) {
        final SyslogAppender appender = new SyslogAppender();
        appender.setName("syslog-appender");
        appender.setContext(context);
        if (!isNullOrEmpty(logFormat)) {
            appender.setSuffixPattern(logFormat
                    .replaceAll(LOG_TOKEN_PID, pid)
                    .replaceAll(LOG_TOKEN_NAME, Matcher.quoteReplacement(applicationName)));
        }
        appender.setSyslogHost(host);
        appender.setPort(port);
        appender.setFacility(facility.toString().toLowerCase(Locale.ENGLISH));
        appender.setThrowableExcluded(!includeStackTrace);
        appender.setStackTracePattern(stackTracePrefix);
        appender.addFilter(levelFilterFactory.build(threshold));
        getFilterFactories().forEach(f -> appender.addFilter(f.build()));
        appender.start();
        return wrapAsync(appender, asyncAppenderFactory);
    }
}