package gelfexporter

import (
	"log"

	"time"

	"git.ma-al.com/maal-libraries/observer/pkg/syslog"
	"gopkg.in/Graylog2/go-gelf.v2/gelf"
)

type GELFMessage struct {
	// Name of the application
	Host string `json:"host"`
	// Short, descriptive message
	ShortMessage string `json:"short_message"`
	// Optional long message.
	LongMessage string `json:"long_message,omitempty"`
	// Timestamp in Unix
	Timestamp time.Time `json:"timestamp"`
	// Severity level matching Syslog standard.
	Level syslog.SyslogLevel `json:"level"`

	// All additional field names must start with an underline.
	ExtraFields map[string]interface{} `json:"extrafields,omitempty"`

	Tag string `json:"tag,omitempty"`
}

func Log(writer *gelf.UDPWriter, msg GELFMessage) {
	if writer != nil {
		err := writer.WriteMessage(msg.GELFFormat())
		if err != nil {
			log.Println(err)
		}
	} else {
		log.Fatalln("gelf.UDPWriter is not set!")
	}
}

func (g GELFMessage) GELFFormat() *gelf.Message {
	prefixedExtras := make(map[string]interface{}, len(g.ExtraFields))
	prefixedExtras["tag"] = g.Tag
	for k, v := range g.ExtraFields {
		prefixedExtras["_"+k] = v
	}

	return &gelf.Message{
		Version:  "1.1",
		Host:     g.Host,
		Short:    g.ShortMessage,
		Full:     g.LongMessage,
		TimeUnix: float64(g.Timestamp.Unix()),
		Level:    int32(g.Level),
		Extra:    prefixedExtras,
	}
}