my-log/models/meta.go

package models

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

type Meta struct {
	Key   string
	Value any
}

func (m Meta) MarshalText() ([]byte, error) {
	if regexp.MustCompile(`\s`).MatchString(m.Key) {
		return []byte{}, fmt.Errorf("whitespace is now allowed in key: %s", m.Key)
	}
	buff := &bytes.Buffer{}
	buff.WriteRune('@')
	buff.WriteString(m.Key)
	buff.WriteRune(' ')
	switch v := m.Value.(type) {
	default:
		return nil, fmt.Errorf("Unknown type %T", v)
	case nil:
		return []byte{}, nil
	case string:
		buff.WriteString(v)
	case int:
		buff.WriteString(strconv.Itoa(v))
	case float64:
		buff.WriteString(strconv.FormatFloat(v, 'f', -1, 64))
	case json.Number:
		buff.WriteString(v.String())
	case json.RawMessage:
		buff.Write(v)
	case []byte:
		buff.Write(v)
	case byte:
		buff.WriteByte(v)
	case rune:
		buff.WriteString(string(v))
	case bool:
		buff.WriteString(strconv.FormatBool(v))
	case time.Time:
		buff.WriteString(v.Format(time.RFC3339))
	}

	return buff.Bytes(), nil
}