package logging

import (
	"fmt"
	"log"

	"github.com/coreos/go-systemd/journal"
)

/*
Setup sets up/configures a SystemDLogger and prepares it for use.
err will always be nil; it's there for interface-compat.
*/
func (l *SystemDLogger) Setup() (err error) {

	// NOOP

	return
}

/*
Shutdown cleanly shuts down a SystemDLogger.
err will always be nil; it's there for interface-compat.
*/
func (l *SystemDLogger) Shutdown() (err error) {

	// NOOP

	return
}

/*
GetPrefix returns the prefix used by this SystemDLogger.
err will always be nil; it's there for interface-compat.
*/
func (l *SystemDLogger) GetPrefix() (prefix string, err error) {

	prefix = l.Prefix

	return
}

/*
DoDebug sets the debug state of this SystemDLogger.
Note that this merely acts as a *safety filter* for debug messages to avoid sensitive information being written to the log.
err will always be nil; it's there for interface-compat.
*/
func (l *SystemDLogger) DoDebug(d bool) (err error) {

	l.EnableDebug = d

	return
}

// GetDebug returns the debug status of this SystemDLogger.
func (l *SystemDLogger) GetDebug() (d bool) {

	d = l.EnableDebug

	return
}

/*
SetPrefix sets the prefix for this SystemDLogger.
err will always be nil; it's there for interface-compat.
*/
func (l *SystemDLogger) SetPrefix(prefix string) (err error) {

	l.Prefix = prefix

	return
}

// Alert writes an ALERT-level message to this SystemDLogger.
func (l *SystemDLogger) Alert(s string, v ...interface{}) (err error) {

	var msg string

	if v != nil {
		msg = fmt.Sprintf(s, v...)
	} else {
		msg = s
	}

	l.renderWrite(msg, journal.PriAlert)

	return
}

// Crit writes an CRITICAL-level message to this SystemDLogger.
func (l *SystemDLogger) Crit(s string, v ...interface{}) (err error) {

	var msg string

	if v != nil {
		msg = fmt.Sprintf(s, v...)
	} else {
		msg = s
	}

	l.renderWrite(msg, journal.PriCrit)

	return
}

// Debug writes a DEBUG-level message to this SystemDLogger.
func (l *SystemDLogger) Debug(s string, v ...interface{}) (err error) {

	if !l.EnableDebug {
		return
	}

	var msg string

	if v != nil {
		msg = fmt.Sprintf(s, v...)
	} else {
		msg = s
	}

	l.renderWrite(msg, journal.PriDebug)

	return
}

// Emerg writes an EMERGENCY-level message to this SystemDLogger.
func (l *SystemDLogger) Emerg(s string, v ...interface{}) (err error) {

	var msg string

	if v != nil {
		msg = fmt.Sprintf(s, v...)
	} else {
		msg = s
	}

	l.renderWrite(msg, journal.PriEmerg)

	return
}

// Err writes an ERROR-level message to this SystemDLogger.
func (l *SystemDLogger) Err(s string, v ...interface{}) (err error) {

	var msg string

	if v != nil {
		msg = fmt.Sprintf(s, v...)
	} else {
		msg = s
	}

	l.renderWrite(msg, journal.PriErr)

	return
}

// Info writes an INFO-level message to this SystemDLogger.
func (l *SystemDLogger) Info(s string, v ...interface{}) (err error) {

	var msg string

	if v != nil {
		msg = fmt.Sprintf(s, v...)
	} else {
		msg = s
	}

	l.renderWrite(msg, journal.PriInfo)

	return
}

// Notice writes a NOTICE-level message to this SystemDLogger.
func (l *SystemDLogger) Notice(s string, v ...interface{}) (err error) {

	var msg string

	if v != nil {
		msg = fmt.Sprintf(s, v...)
	} else {
		msg = s
	}

	l.renderWrite(msg, journal.PriNotice)

	return
}

// Warning writes a WARNING/WARN-level message to this SystemDLogger.
func (l *SystemDLogger) Warning(s string, v ...interface{}) (err error) {

	var msg string

	if v != nil {
		msg = fmt.Sprintf(s, v...)
	} else {
		msg = s
	}

	l.renderWrite(msg, journal.PriWarning)

	return
}

// renderWrite prepares/formats a log message to be written to this SystemDLogger.
func (l *SystemDLogger) renderWrite(msg string, prio journal.Priority) {

	// TODO: implement code line, etc.
	// https://www.freedesktop.org/software/systemd/man/systemd.journal-fields.html
	// CODE_FILE=, CODE_LINE=, CODE_FUNC=
	var err error

	vars := map[string]string{
		"DOCUMENTATION":     "https://git.r00t2.io/Go_GoUtils/",
		"SYSLOG_IDENTIFIER": l.Prefix,
		"SYSLOG_FACILITY":   "1", // USER
	}

	if err = journal.Send(msg, prio, vars); err != nil {
		log.Panicln("could not send to Journald")
	}

	return
}

// ToLogger returns a stdlib log.Logger.
func (l *SystemDLogger) ToLogger(prio logPrio) (stdLibLog *log.Logger) {

	stdLibLog = log.New(&logWriter{backend: l, prio: prio}, "", 0)

	return
}