package circolog

import (
	"bytes"
	"text/template"
	"time"

	"gopkg.in/mcuadros/go-syslog.v2/format"
)

// Formatter is an interface, so that multiple implementations can exist
type Formatter func(format.LogParts) string

var tmplFuncs template.FuncMap
var syslogTmpl *template.Template

func init() {
	tmplFuncs := template.FuncMap{
		"dateFormat": func(dt time.Time, fmt string) string {
			return dt.Format(fmt)
		},
		"rfc822": func(dt time.Time) string {
			return dt.Format(time.RFC822)
		},
	}
	syslogTmpl = template.Must(template.New("syslog").Funcs(tmplFuncs).Parse(
		"{{rfc822 (index . \"timestamp\")}} {{index . \"hostname\"}} " +
			"{{index . \"app_name\"}}" +
			"{{ if (ne (index . \"proc_id\") \"-\")}}[{{index . \"proc_id\"}}]{{end}}: " +
			"{{index . \"message\"}}",
	))
}

// FormatSyslog format a message in the typical format used in /var/log/messages
func FormatSyslog(msg format.LogParts) string {
	var buf bytes.Buffer
	syslogTmpl.Execute(&buf, msg)
	return buf.String()
}