/*
GoCheese -- Python private package repository and caching proxy
Copyright (C) 2019 Sergey Matveev <stargrave@stargrave.org>
              2019 Elena Balakhonova <balakhonova_e@riseup.net>

This program is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation, version 3 of the License.

This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
GNU General Public License for more details.

You should have received a copy of the GNU General Public License
along with this program.  If not, see <http://www.gnu.org/licenses/>.
*/

package main

import (
	"errors"
	"io/ioutil"
	"log"
	"os"
	"strings"
)

var passwords map[string]Auther = make(map[string]Auther)

type Auther interface {
	Auth(password string) bool
}

func strToAuther(verifier string) (string, Auther, error) {
	st := strings.SplitN(verifier, "$", 3)
	if len(st) != 3 || st[0] != "" {
		return "", nil, errors.New("invalid verifier structure")
	}
	algorithm := st[1]
	var auther Auther
	var err error
	switch algorithm {
	case "argon2i":
		auther, err = parseArgon2i(st[2])
	case "sha256":
		auther, err = parseSHA256(st[2])
	default:
		err = errors.New("unknown hashing algorithm")
	}
	return algorithm, auther, err
}

func refreshPasswd() {
	passwd, err := ioutil.ReadFile(*passwdPath)
	if os.IsNotExist(err) {
		return
	}
	if err != nil {
		log.Fatal(err)
	}
	passwordsNew := make(map[string]Auther)
	for i, credentials := range strings.Split(strings.TrimRight(string(passwd), "\n"), "\n") {
		if len(credentials) == 0 || strings.HasPrefix(credentials, "#") {
			continue
		}
		splitted := strings.Split(credentials, ":")
		if len(splitted) != 2 {
			log.Fatalf("%s:%d: Wrong login:password format", *passwdPath, i)
		}
		login := splitted[0]
		if _, exists := passwordsNew[login]; exists {
			log.Fatalf("%s:%d: %s: already exists", *passwdPath, i, login)
		}
		_, auther, err := strToAuther(splitted[1])
		if err != nil {
			log.Fatalf("%s:%d: %s: %s", *passwdPath, i, login, err)
		}
		passwordsNew[login] = auther
		log.Println("Added password for " + login)
	}
	passwords = passwordsNew
}