/*
 * Copyright 2020 Signal Messenger, LLC
 * SPDX-License-Identifier: AGPL-3.0-only
 */

package org.signal.storageservice.metrics;


import ch.qos.logback.classic.LoggerContext;
import ch.qos.logback.classic.spi.ILoggingEvent;
import ch.qos.logback.classic.util.LevelToSyslogSeverity;
import ch.qos.logback.core.Appender;
import ch.qos.logback.core.AppenderBase;
import ch.qos.logback.core.Layout;
import com.fasterxml.jackson.annotation.JsonProperty;
import com.fasterxml.jackson.annotation.JsonTypeName;
import io.dropwizard.logging.AbstractAppenderFactory;
import io.dropwizard.logging.async.AsyncAppenderFactory;
import io.dropwizard.logging.filter.LevelFilterFactory;
import io.dropwizard.logging.layout.LayoutFactory;
import io.dropwizard.validation.PortRange;
import org.hibernate.validator.constraints.NotEmpty;
import org.productivity.java.syslog4j.SyslogConfigIF;
import org.productivity.java.syslog4j.SyslogIF;
import org.productivity.java.syslog4j.SyslogRuntimeException;
import org.productivity.java.syslog4j.impl.net.tcp.ssl.SSLTCPNetSyslogConfig;

import javax.validation.constraints.NotNull;
import java.util.TimeZone;

@JsonTypeName("papertrail")
public class LoggingNetworkAppenderFactory extends AbstractAppenderFactory<ILoggingEvent> {

  @JsonProperty
  @NotEmpty
  private String ident;

  @JsonProperty
  @NotEmpty
  private String host;

  @JsonProperty
  @PortRange(min = 1)
  @NotNull
  private Integer port;

  @JsonProperty
  private TimeZone timeZone = TimeZone.getTimeZone("UTC");

  @JsonProperty
  @NotEmpty
  private String facility = "USER";

  @JsonProperty
  private boolean sendLocalName = true;

  public String getIdent() {
    return ident;
  }

  public void setIdent(final String ident) {
    this.ident = ident;
  }

  public String getHost() {
    return host;
  }

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

  public Integer getPort() {
    return port;
  }

  public void setPort(final Integer port) {
    this.port = port;
  }

  public TimeZone getTimeZone() {
    return timeZone;
  }

  public void setTimeZone(final TimeZone timeZone) {
    this.timeZone = timeZone;
  }

  public String getFacility() {
    return facility;
  }

  public void setFacility(final String facility) {
    this.facility = facility;
  }

  public boolean isSendLocalName() {
    return sendLocalName;
  }

  public void setSendLocalName(final boolean sendLocalName) {
    this.sendLocalName = sendLocalName;
  }

  @Override
  public Appender<ILoggingEvent> build(LoggerContext context,
                                       String applicationName,
                                       LayoutFactory<ILoggingEvent> layoutFactory,
                                       LevelFilterFactory<ILoggingEvent> levelFilterFactory,
                                       AsyncAppenderFactory<ILoggingEvent> asyncAppenderFactory)
  {
    final Syslog4jAppender<ILoggingEvent> syslogAppender = new Syslog4jAppender<>();
    syslogAppender.setContext(context);
    syslogAppender.setLayout(buildLayout(context, layoutFactory));
    syslogAppender.setName("SYSLOG-TLS");
    final SSLTCPNetSyslogConfig syslogConfig = new SSLTCPNetSyslogConfig();

    syslogConfig.setIdent(ident);
    syslogConfig.setHost(host);
    syslogConfig.setPort(port);
    syslogConfig.setFacility(facility);
    syslogConfig.setSendLocalName(sendLocalName);

    syslogAppender.setSyslogConfig(syslogConfig);

    syslogAppender.addFilter(levelFilterFactory.build(threshold));
    syslogAppender.start();

    return syslogAppender;
  }


  private static class Syslog4jAppender<E> extends AppenderBase<E> {
    SyslogIF syslog;
    SyslogConfigIF syslogConfig;
    Layout<E> layout;

    @Override
    protected void append(E loggingEvent) {
      syslog.log(getSeverityForEvent(loggingEvent), layout.doLayout(loggingEvent));
    }

    @Override
    public void start() {
      super.start();

      synchronized (this) {
        try {
          Class syslogClass = syslogConfig.getSyslogClass();
          syslog = (SyslogIF) syslogClass.newInstance();

          syslog.initialize(syslogClass.getSimpleName(), syslogConfig);
        } catch (ClassCastException | IllegalAccessException | InstantiationException cse) {
          throw new SyslogRuntimeException(cse);
        }
      }
    }

    @Override
    public void stop() {
      super.stop();

      synchronized(this) {
        if (syslog != null) {
          syslog.shutdown();
          syslog = null;
        }
      }
    }

    /**
     * Convert a level to equivalent syslog severity. Only levels for printing
     * methods i.e DEBUG, WARN, INFO and ERROR are converted.
     *
     * @see ch.qos.logback.core.net.SyslogAppenderBase#getSeverityForEvent(Object)
     */
    public int getSeverityForEvent(Object eventObject) {
      if (eventObject instanceof ILoggingEvent) {
        ILoggingEvent event = (ILoggingEvent) eventObject;
        return LevelToSyslogSeverity.convert(event);
      } else {
        return SyslogIF.LEVEL_INFO;
      }
    }

    public SyslogConfigIF getSyslogConfig() {
      return syslogConfig;
    }

    public void setSyslogConfig(SyslogConfigIF syslogConfig) {
      this.syslogConfig = syslogConfig;
    }

    public Layout<E> getLayout() {
      return layout;
    }

    public void setLayout(Layout<E> layout) {
      this.layout = layout;
    }
  }
}