package logger

import (
	"fmt"
	"github.com/30x/apid"
	"github.com/Sirupsen/logrus"
	"os"
)

const (
	configLevel = "log_level"

	defaultLevel = logrus.DebugLevel

	moduleField       = "module"
	environmentField = "env"
)

var std apid.LogService
var textFormatter = new(logrus.TextFormatter)
var config apid.ConfigService

func Base() apid.LogService {
	if std == nil {
		config = apid.Config()
		config.SetDefault(configLevel, defaultLevel.String())
		std = newLogger(configLevel)
	}
	return std
}

func ForModule(name string) apid.LogService {
	return Base().ForModule(name)
}

type logger struct {
	*logrus.Entry
}

// creates new logger for module w/ appropriate log level and field
// note: config module xx log level using config var: xx_log_level = "debug"
func (l *logger) ForModule(name string) apid.LogService {

	configKey := fmt.Sprintf("%s_%s", name, configLevel)
	log := newLogger(configKey).WithField(moduleField, name)
	std.Debugf("created logger '%s' at level %s", name, log.(loggerPlus).Level())
	return log
}

func (l *logger) ForEnvironment(name string) apid.LogService {
	return l.WithField(environmentField, name)
}

func (l *logger) WithField(key string, value interface{}) apid.LogService {
	return &logger{l.Entry.WithField(key, value)}
}

func (l *logger) Level() logrus.Level {
	return l.Entry.Logger.Level
}

func newLogger(configKey string) apid.LogService {

	var logLevel logrus.Level
	if std != nil {
		logLevel = std.(loggerPlus).Level()
	} else {
		logLevel = defaultLevel
	}
	lvlString := config.GetString(configKey)
	if lvlString != "" {
		lvl, err := logrus.ParseLevel(lvlString)
		if err == nil {
			logLevel = lvl
		} else {
			std.Warnf("invalid log level '%s' in config key: '%s'", lvlString, configKey)
		}
	}

	log := &logger{
		logrus.NewEntry(
			&logrus.Logger{
				Out:       os.Stderr,
				Formatter: textFormatter,
				Level:     logLevel,
			},
		),
	}

	return log
}

type loggerPlus interface {
	Level() logrus.Level
}