package main

import (
	"errors"
	"io/ioutil"

	yaml "gopkg.in/yaml.v2"
)

type auth interface {
	Login(string, string) (bool, error)
	Groups(string) ([]string, error)
}

type FileAuth struct {
	path string
}

type fileAuthContent struct {
	Users map[string]struct {
		Password string
		Groups   []string
	}
}

func NewFileAuth(path string) FileAuth {
	return FileAuth{path: path}
}

func (fileAuth FileAuth) Login(u, p string) (bool, error) {
	content, err := fileAuth.load()
	if err != nil {
		return false, err
	}
	entry, ok := content.Users[u]
	return ok && entry.Password == p, nil
}

func (fileAuth FileAuth) Groups(u string) ([]string, error) {
	content, err := fileAuth.load()
	if err != nil {
		return nil, err
	}
	entry, ok := content.Users[u]
	if !ok {
		return nil, errors.New("invalid user")
	}
	return entry.Groups, nil
}

func (fileAuth FileAuth) load() (fileAuthContent, error) {
	var fileAuthContent fileAuthContent
	b, err := ioutil.ReadFile(fileAuth.path)
	if err != nil {
		return fileAuthContent, err
	}
	if err := yaml.Unmarshal(b, &fileAuthContent); err != nil {
		return fileAuthContent, err
	}
	return fileAuthContent, nil
}