text_formatter.go

package log

import (
	"bytes"
	"encoding/json"
	"fmt"
	"sort"
	"strconv"
	"time"
)

var TextFormatter Formatter = textFormatter{}

type textFormatter struct{}

func (f textFormatter) Format(entry *Entry) ([]byte, error) {
	var buffer *bytes.Buffer
	if entry.Buffer != nil {
		buffer = entry.Buffer
	} else {
		buffer = bytes.NewBuffer(make([]byte, 0, 16<<10))
	}
	f.appendKeyValue(buffer, fieldKeyTime, FormatTimeString(entry.Time.In(_beijingLocation)))
	f.appendKeyValue(buffer, fieldKeyLevel, entry.Level.String())
	f.appendKeyValue(buffer, fieldKeyTraceId, entry.TraceId)
	f.appendKeyValue(buffer, fieldKeyLocation, entry.Location)
	f.appendKeyValue(buffer, fieldKeyMessage, entry.Message)
	if fields := entry.Fields; len(fields) > 0 {
		prefixFieldClashes(fields)
		keys := make([]string, 0, len(fields))
		for k := range fields {
			keys = append(keys, k)
		}
		sort.Strings(keys)
		for _, k := range keys {
			v := fields[k]
			f.appendKeyValue(buffer, k, v)
		}
	}
	buffer.WriteByte('\n')
	return buffer.Bytes(), nil
}

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

func (f textFormatter) appendValue(b *bytes.Buffer, value interface{}) {
	var stringVal string
	switch v := value.(type) {
	case string:
		stringVal = v
	case json.RawMessage:
		stringVal = string(v)
	default:
		stringVal = fmt.Sprint(value)
	}
	b.WriteString(stringVal)
}

var _beijingLocation = time.FixedZone("Asia/Shanghai", 8*60*60)

const (
	fieldKeyTime     = "time"
	fieldKeyLevel    = "level"
	fieldKeyTraceId  = "request_id"
	fieldKeyLocation = "location"
	fieldKeyMessage  = "msg"
)

func prefixFieldClashes(data map[string]interface{}) {
	if v, ok := data[fieldKeyTime]; ok {
		delete(data, fieldKeyTime)
		newKey := "fields." + fieldKeyTime
		for key, i := newKey, 2; ; i++ {
			_, ok = data[key]
			if !ok {
				data[key] = v
				break
			}
			key = newKey + "." + strconv.Itoa(i)
		}
	}
	if v, ok := data[fieldKeyLevel]; ok {
		delete(data, fieldKeyLevel)
		newKey := "fields." + fieldKeyLevel
		for key, i := newKey, 2; ; i++ {
			_, ok = data[key]
			if !ok {
				data[key] = v
				break
			}
			key = newKey + "." + strconv.Itoa(i)
		}
	}
	if v, ok := data[fieldKeyTraceId]; ok {
		delete(data, fieldKeyTraceId)
		newKey := "fields." + fieldKeyTraceId
		for key, i := newKey, 2; ; i++ {
			_, ok = data[key]
			if !ok {
				data[key] = v
				break
			}
			key = newKey + "." + strconv.Itoa(i)
		}
	}
	if v, ok := data[fieldKeyLocation]; ok {
		delete(data, fieldKeyLocation)
		newKey := "fields." + fieldKeyLocation
		for key, i := newKey, 2; ; i++ {
			_, ok = data[key]
			if !ok {
				data[key] = v
				break
			}
			key = newKey + "." + strconv.Itoa(i)
		}
	}
	if v, ok := data[fieldKeyMessage]; ok {
		delete(data, fieldKeyMessage)
		newKey := "fields." + fieldKeyMessage
		for key, i := newKey, 2; ; i++ {
			_, ok = data[key]
			if !ok {
				data[key] = v
				break
			}
			key = newKey + "." + strconv.Itoa(i)
		}
	}
}