gol4ng/logger

package formatter

import (
    "encoding/json"
    "github.com/valyala/bytebufferpool"
    "os"
    "strconv"
    "strings"
    "time"

    "github.com/gol4ng/logger"
)

const (
    // Version is the current Gelf version
    Version string = "1.1"
)

// Gelf formatter will transform Entry into Gelf format
type Gelf struct {
    hostname string
    version  string
}

// Format will return Entry as gelf
func (g *Gelf) Format(entry logger.Entry) string {
    byteBuffer := bytebufferpool.Get()
    defer bytebufferpool.Put(byteBuffer)

    byteBuffer.WriteString(`{"version":"`)
    byteBuffer.WriteString(g.version)

    byteBuffer.WriteString(`","host":"`)
    byteBuffer.WriteString(g.hostname)

    byteBuffer.WriteString(`","level":`)
    byteBuffer.WriteString(strconv.Itoa(int(entry.Level)))

    byteBuffer.WriteString(`,"timestamp":`)
    byteBuffer.WriteString(strconv.FormatFloat(float64(time.Now().UnixNano())/1e9, 'f', 3, 64))

    byteBuffer.WriteString(`,"short_message":"`)
    byteBuffer.WriteString(entry.Message)

    byteBuffer.WriteString(`","full_message":"`)
    logger.EntryToString(entry, byteBuffer)
    byteBuffer.WriteString(`"`)

    if entry.Context != nil {
        for name, field := range *entry.Context {
            byteBuffer.WriteString(`,"_`)
            byteBuffer.WriteString(strings.Replace(name, " ", "_", -1))
            byteBuffer.WriteString(`":`)
            d, _ := json.Marshal(field.Value)
            byteBuffer.Write(d)
        }
    }

    byteBuffer.WriteString("}")

    return byteBuffer.String()
}

// NewGelf will create a new Gelf formatter
func NewGelf() *Gelf {
    hostname, err := os.Hostname()
    if err != nil {
        panic(err)
    }

    return &Gelf{hostname: hostname, version: Version}
}

// GelfTCPFormatter will decorate Gelf formatter in order to add null byte between each entry
// http://docs.graylog.org/en/3.0/pages/gelf.html#gelf-via-tcp
type GelfTCPFormatter struct {
    *Gelf
}

// Format will return Entry as gelf TCP
func (g *GelfTCPFormatter) Format(entry logger.Entry) string {
    return g.Gelf.Format(entry) + "\x00"
}

// NewGelfTCP will create a new GelfTCPFormatter
func NewGelfTCP() *GelfTCPFormatter {
    return &GelfTCPFormatter{Gelf: NewGelf()}
}