package log

import (
	"io"
	"os"

	"github.com/juju/errors"
	"github.com/sirupsen/logrus"

	"git.dev.m-and-m.ovh/mderasse/gocommon/log/hooks/file"
	"git.dev.m-and-m.ovh/mderasse/gocommon/log/hooks/gelf"
)

// Init will try to initialize logger by trying to retrieve config from multiple source.
func Init() (*logrus.Entry, error) {

	// loading configuration
	c, err := loadConfig()
	if err != nil {
		return nil, errors.Trace(err)
	}

	return initFromSource(c)
}

// InitFromCustomVaultSecret will initialize logger with a vault secret.
func InitFromCustomVaultSecret(secret string) (*logrus.Entry, error) {

	c, err := loadConfigFromVault(secret)
	if err != nil {
		return nil, errors.Trace(err)
	}

	return initFromSource(c)
}

// InitFromCustomFile will initialize logger with a config file.
func InitFromCustomFile(path string) (*logrus.Entry, error) {

	c, err := loadConfigFromFile(path)
	if err != nil {
		return nil, errors.Trace(err)
	}

	return initFromSource(c)
}

func initFromSource(c *ConfigStruct) (*logrus.Entry, error) {
	err := c.applyEnv()
	if err != nil {
		return nil, errors.Trace(err)
	}

	c.applyDefault()

	return InitFromCustomConfig(c)
}

// InitFromCustomConfig will initialize logger from a gaven config.
func InitFromCustomConfig(c *ConfigStruct) (*logrus.Entry, error) {

	err := c.IsValid()
	if err != nil {
		return nil, errors.Trace(err)
	}

	level, err := logrus.ParseLevel(*c.Level)
	if err != nil {
		return nil, errors.Trace(err)
	}

	// init logger
	log := logrus.New()
	log.SetLevel(level)

	if *c.EnableStdOut {
		log.SetOutput(os.Stdout)
	} else {
		log.SetOutput(io.Discard)
	}

	for _, provider := range c.Providers {
		switch provider {
		case ProviderName_FILE:
			hook, err := file.NewHook(c.FileConfig)
			if err != nil {
				return nil, errors.Trace(err)
			}
			log.AddHook(hook)
		case ProviderName_GELF:
			hook, err := gelf.NewHook(c.GelfConfig)
			if err != nil {
				return nil, errors.Trace(err)
			}
			log.AddHook(hook)
		case ProviderName_NONE:
			// Do nothing, None can be use in case of StdOut Only.
		default:
			return nil, errors.BadRequestf("Provider is not handled.")
		}
	}

	return c.applyExtraFields(logrus.NewEntry(log)), nil
}

// applyExtraFileds will take a logrus.Entry and will add fields that are in the configuration.
func (c *ConfigStruct) applyExtraFields(l *logrus.Entry) *logrus.Entry {
	return l.WithFields(c.ExtrasFields)
}