/*
GoCheese -- Python private package repository and caching proxy
Copyright (C) 2019-2021 Sergey Matveev <stargrave@stargrave.org>
              2019-2021 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 (
	"bufio"
	"errors"
	"log"
	"os"
	"strings"
	"sync"
)

var (
	Passwords  map[string]Auther = make(map[string]Auther)
	PasswordsM sync.RWMutex
)

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 passwdReader(fd *os.File) bool {
	isGood := true
	scanner := bufio.NewScanner(fd)
	for scanner.Scan() {
		t := scanner.Text()
		if len(t) == 0 {
			continue
		}
		splitted := strings.Split(t, ":")
		if len(splitted) != 2 {
			log.Println("wrong login:password format:", t)
			isGood = false
			continue
		}
		login := splitted[0]
		passwd := splitted[1]
		if passwd == "" {
			log.Println("deleting login:", login)
			PasswordsM.Lock()
			delete(Passwords, login)
			PasswordsM.Unlock()
			continue
		}
		_, auther, err := strToAuther(passwd)
		if err != nil {
			log.Println("login:", login, "invalid password:", err)
			isGood = false
			continue
		}
		log.Println("adding password for:", login)
		PasswordsM.Lock()
		Passwords[login] = auther
		PasswordsM.Unlock()
	}
	return isGood
}

func passwdLister(fd *os.File) {
	PasswordsM.RLock()
	logins := make([]string, 0, len(Passwords))
	for login := range Passwords {
		logins = append(logins, login)
	}
	PasswordsM.RUnlock()
	for _, login := range logins {
		fd.WriteString(login + "\n")
	}
}