package config

import (
	"io/ioutil"
	"os"
	"strings"

	"github.com/sirupsen/logrus"
	yaml "gopkg.in/yaml.v2"
	"src.dualinventive.com/go/lib/dilog"
)

var (
	// searchPaths contain the list of paths to search for config-files
	//  must include trailing slash
	searchPaths = []string{
		"./",
		"../",
		"/etc/di/",
	}
)

const (
	// DefaultLoglevel is info
	DefaultLoglevel = "info"
	// DefaultLogfile is empty i.e. stdout
	DefaultLogfile = ""
	// ConfigExtension is the default extension of config-files
	ConfigExtension = ".conf"
	// ConfigTrimPrefix is the prefix which is trimmed from names when searching for config-files
	ConfigTrimPrefix = "di-"
)

// Config type which other application configurations can inherit from to
//  comply with Configuration interface
type Config struct {
	Loglevel string
	Logfile  string
}

// GetLoglevel returns the provided loglevel or DefaultLoglevel when empty
func (c *Config) GetLoglevel() string {
	if c.Loglevel == "" {
		return DefaultLoglevel
	}
	return c.Loglevel
}

// GetLogfile returns the provided log-file or DefaultLogfile when empty
func (c *Config) GetLogfile() string {
	if c.Logfile == "" {
		return DefaultLogfile
	}
	return c.Logfile
}

// Configuration interface checks if all log-facility parameters are present
//  for initialization of the logger
type Configuration interface {
	GetLoglevel() string
	GetLogfile() string
}

// Load loads the provided configuration from a file into cfg.
//  first it shall try to load the file as provided with the name, when not found,
//  the file is searched in the search-paths (./, ../, /etc/di/) removing a possible ConfigTrimPrefix
//  it is searched with and without a ConfigExtension
func Load(name string, cfg Configuration) (dilog.Logger, error) {
	// check if a file with the provided name exist
	if _, err := os.Stat(name); err == nil {
		return loadFile(name, cfg)
	}

	namestrip := strings.TrimLeft(name, ConfigTrimPrefix)

	for _, path := range searchPaths {
		if _, err := os.Stat(path + namestrip); err == nil {
			return loadFile(path+namestrip+ConfigExtension, cfg)
		}
		if _, err := os.Stat(path + namestrip + ConfigExtension); err == nil {
			return loadFile(path+namestrip+ConfigExtension, cfg)
		}
	}
	return nil, os.ErrNotExist
}

func loadFile(filePath string, cfg Configuration) (dilog.Logger, error) {
	// #nosec Ignore possible file inclusion warning
	b, errr := ioutil.ReadFile(filePath)
	if errr != nil {
		return nil, errr
	}
	if err := yaml.Unmarshal(b, cfg); err != nil {
		return nil, err
	}
	logger, err := dilog.NewLogger(cfg.GetLogfile(), cfg.GetLoglevel())
	if err != nil {
		logrus.WithError(err).Fatal("invalid logger")
	}
	return logger, nil
}