syslogd/src/main/java/biz/nellemann/syslogd/SyslogPrinter.java

package biz.nellemann.syslogd;

import biz.nellemann.syslogd.msg.Facility;
import biz.nellemann.syslogd.msg.Severity;
import biz.nellemann.syslogd.msg.SyslogMessage;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

public class SyslogPrinter {

    private final static Logger log = LoggerFactory.getLogger(SyslogPrinter.class);

    private final static char SPACE = ' ';


    public static String toString(SyslogMessage msg) {
        StringBuilder sb = new StringBuilder(msg.timestamp.toString());
        sb.append(String.format("  [%8.8s.%-6.6s] ", msg.facility, msg.severity));
        sb.append(String.format(" %-16.16s ", msg.hostname));
        sb.append(String.format(" %-16.16s  ", msg.application));
        sb.append(msg.message);
        return sb.toString();
    }


    public static String toAnsiString(SyslogMessage msg) {
        StringBuilder sb = new StringBuilder(msg.timestamp.toString());

        if (msg.severity.toNumber() < 3) {
            sb.append(Ansi.RED);
        } else if (msg.severity.toNumber() < 5) {
            sb.append(Ansi.YELLOW);
        } else {
            sb.append(Ansi.GREEN);
        }

        sb.append(String.format("  [%8.8s.%-6.6s] ", msg.facility, msg.severity)).append(Ansi.RESET);
        sb.append(Ansi.BLUE).append(String.format(" %-16.16s ", msg.hostname)).append(Ansi.RESET);
        sb.append(Ansi.CYAN).append(String.format(" %-16.16s  ", msg.application)).append(Ansi.RESET);
        sb.append(msg.message);

        return sb.toString();
    }


    /**
     * Return a RFC-3164 formatted string of the SyslogMessage.
     * @param msg
     * @return
     */
    public static String toRfc3164(SyslogMessage msg) {
        StringBuilder sb = new StringBuilder();
        sb.append(getPri(msg.facility, msg.severity));
        sb.append(new java.text.SimpleDateFormat("MMM dd HH:mm:ss").format(new java.util.Date(msg.timestamp.toEpochMilli())));
        sb.append(SPACE).append(msg.hostname);
        sb.append(SPACE).append(msg.application);
        sb.append(":").append(SPACE).append(msg.message);
        log.debug(sb.toString());
        return sb.toString();
    }


    /**
     * Return a RFC-5424 formatted string of the SyslogMessage.
     * @param msg
     * @return
     */
    public static String toRfc5424(SyslogMessage msg) {
        StringBuilder sb = new StringBuilder();
        sb.append(getPri(msg.facility, msg.severity)).append("1");
        sb.append(SPACE).append(new java.text.SimpleDateFormat("yyyy-MM-dd'T'HH:mm:ss.SSS'Z'").format(new java.util.Date(msg.timestamp.toEpochMilli())));
        sb.append(SPACE).append(msg.hostname);
        sb.append(SPACE).append(msg.application);
        sb.append(SPACE).append(msg.processId != null ? msg.processId : "-");
        sb.append(SPACE).append(msg.messageId != null ? msg.messageId : "-");
        sb.append(SPACE).append(msg.structuredData != null ? msg.structuredData : "-");
        sb.append(SPACE).append(msg.message);
        log.debug(sb.toString());
        return sb.toString();
    }


    /**
     * Return a GELF JSON formatted string of the SyslogMessage.
     * https://www.graylog.org/features/gelf
     * @param msg
     * @return
     */
    public static String toGelf(SyslogMessage msg) {
        StringBuilder sb = new StringBuilder("{ \"version\": \"1.1\",");
        sb.append(String.format("\"host\": \"%s\",", msg.hostname));
        sb.append(String.format("\"short_message\": \"%s\",", msg.message));
        //sb.append(String.format("\"full_message\": \"%s\",", msg.message));
        sb.append(String.format("\"timestamp\": %d,", msg.timestamp.getEpochSecond()));
        sb.append(String.format("\"level\": %d,", msg.severity.toNumber()));
        sb.append(String.format("\"_facility\": \"%s\",", msg.facility));
        sb.append(String.format("\"_severity\": \"%s\",", msg.severity));
        sb.append(String.format("\"_application\": \"%s\",", msg.application));
        if(msg.processId != null) { sb.append(String.format("\"_process-id\": \"%s\",", msg.processId)); }
        if(msg.messageId != null) { sb.append(String.format("\"_message-id\": \"%s\",", msg.messageId)); }
        if(msg.structuredData != null) { sb.append(String.format("\"_structured-data\": \"%s\",", msg.structuredData)); }
        sb.append("}");
        return sb.toString();
    }


    /**
     * Return a Loki JSON formatted string of the SyslogMessage.
     * https://grafana.com/docs/loki/latest/api/
     * @param msg
     * @return
     */
    public static String toLoki(SyslogMessage msg) {
        StringBuilder sb = new StringBuilder("{ \"streams\": [ { \"stream\": {");
        sb.append(String.format(" \"hostname\": \"%s\",", msg.hostname));
        sb.append(String.format(" \"facility\": \"%s\",", msg.facility));
        sb.append(String.format(" \"level\": \"%s\",", msg.severity));
        sb.append(String.format(" \"application\": \"%s\"", msg.application));
        sb.append("}, \"values\": [ ");
        sb.append(String.format("[ \"%d\", \"%s\" ]", msg.timestamp.getEpochSecond() * 1000000000l, getMessageLine(msg)));
        sb.append(" ] } ] }");
        return sb.toString();
    }


    private static String getMessageLine(SyslogMessage msg) {
        StringBuilder sb = new StringBuilder();
        sb.append(String.format("[%s.%s] ", msg.facility, msg.severity));
        sb.append(String.format("%s ", msg.hostname));
        sb.append(String.format("%s ", msg.application));
        sb.append(msg.message);
        return sb.toString();
    }


    static private String getPri(Facility facility, Severity severity) {
        int pri = (facility.toNumber() * 8) + severity.toNumber();
        return String.format("%c%d%c", '<', pri, '>');
    }

}