logger_formatter.go

package buffalo

// I really don't want to have this, but until (if) https://github.com/sirupsen/logrus/pull/606 is merged we're stuck with all this code. And yes, this is ALL needed just to remove some blank space in the logs

import (
	"bytes"
	"fmt"
	"io"
	"os"
	"regexp"
	"sort"
	"strings"
	"sync"
	"time"

	"github.com/sirupsen/logrus"
	"golang.org/x/crypto/ssh/terminal"
)

const (
	nocolor = 0
	red     = 31
	green   = 32
	yellow  = 33
	blue    = 36
	gray    = 37
)

// textFormatter formats logs into text
type textFormatter struct {
	ForceColors bool
	isTerminal  bool
	sync.Once
}

func (f *textFormatter) init(entry *logrus.Entry) {
	if entry.Logger != nil {
		f.isTerminal = f.checkIfTerminal(entry.Logger.Out)
	}
}

func (f *textFormatter) checkIfTerminal(w io.Writer) bool {
	switch v := w.(type) {
	case *os.File:
		return terminal.IsTerminal(int(v.Fd()))
	default:
		return false
	}
}

const defaultTimestampFormat = time.RFC3339

// Format renders a single log entry
func (f *textFormatter) Format(entry *logrus.Entry) ([]byte, error) {
	var b *bytes.Buffer
	keys := make([]string, 0, len(entry.Data))
	for k := range entry.Data {
		keys = append(keys, k)
	}

	sort.Strings(keys)
	if entry.Buffer != nil {
		b = entry.Buffer
	} else {
		b = &bytes.Buffer{}
	}

	prefixFieldClashes(entry.Data)

	f.Do(func() { f.init(entry) })

	isColored := (f.ForceColors || f.isTerminal)

	if isColored {
		f.printColored(b, entry, keys)
	} else {
		f.appendKeyValue(b, "level", entry.Level.String())
		if entry.Message != "" {
			f.appendKeyValue(b, "msg", entry.Message)
		}
		for _, key := range keys {
			f.appendKeyValue(b, key, entry.Data[key])
		}
	}

	b.WriteByte('\n')
	return b.Bytes(), nil
}

func (f *textFormatter) printColored(b *bytes.Buffer, entry *logrus.Entry, keys []string) {
	var levelColor int
	switch entry.Level {
	case logrus.DebugLevel:
		levelColor = gray
	case logrus.WarnLevel:
		levelColor = yellow
	case logrus.ErrorLevel, logrus.FatalLevel, logrus.PanicLevel:
		levelColor = red
	default:
		levelColor = blue
	}

	levelText := strings.ToUpper(entry.Level.String())[0:4]

	fmt.Fprintf(b, "\x1b[%dm%s\x1b[0m[%s]", levelColor, levelText, entry.Time.Format(defaultTimestampFormat))

	if entry.Message != "" {
		fmt.Fprintf(b, " %s", entry.Message)
	}

	for _, k := range keys {
		v := entry.Data[k]
		fmt.Fprintf(b, " \x1b[%dm%s\x1b[0m=", levelColor, k)
		f.appendValue(b, v)
	}
}

func (f *textFormatter) needsQuoting(text string) bool {
	if len(text) == 0 {
		return true
	}
	matched, err := regexp.MatchString("[^a-zA-Z\\-\\._\\/@\\^\\+]", text)
	if err != nil {
		return false
	}
	return matched
}

func (f *textFormatter) appendKeyValue(b *bytes.Buffer, key string, value interface{}) {
	if b.Len() > 0 {
		b.WriteByte(' ')
	}
	b.WriteString(key)
	b.WriteByte('=')
	f.appendValue(b, value)
}

func (f *textFormatter) appendValue(b *bytes.Buffer, value interface{}) {
	stringVal, ok := value.(string)
	if !ok {
		stringVal = fmt.Sprint(value)
	}

	if !f.needsQuoting(stringVal) {
		b.WriteString(stringVal)
	} else {
		b.WriteString(fmt.Sprintf("%q", stringVal))
	}
}

func prefixFieldClashes(data logrus.Fields) {
	if t, ok := data["time"]; ok {
		data["fields.time"] = t
	}

	if m, ok := data["msg"]; ok {
		data["fields.msg"] = m
	}

	if l, ok := data["level"]; ok {
		data["fields.level"] = l
	}
}