// SPDX-FileCopyrightText: 2018 - 2022 UnionTech Software Technology Co., Ltd.
//
// SPDX-License-Identifier: GPL-3.0-or-later

package users

/*
#cgo CFLAGS: -W -Wall -g  -fstack-protector-all -fPIC
#cgo LDFLAGS: -lcrypt

#include <stdlib.h>
#include <shadow.h>
#include "passwd.h"
*/
import "C"

import (
	"errors"
	"fmt"
	"io/ioutil"
	"math"
	"os"
	"os/user"
	"strconv"
	"strings"
	"sync"
	"unsafe"
)

var (
	wLocker sync.Mutex
)

func EncodePasswd(words string) string {
	cwords := C.CString(words)
	defer C.free(unsafe.Pointer(cwords))

	return C.GoString(C._mkpasswd(cwords))
}

func ExistPwUid(uid uint32) int {
	return int(C._exist_pw_uid(C.uint(uid)))
}

func GetPwName(uid uint32) string {
	return C.GoString(C._get_pw_name(C.uint(uid)))
}

func GetPwGecos(uid uint32) string {
	var pwGecos string
	pwGecos = C.GoString(C._get_pw_gecos(C.uint(uid)))

	return strings.Split(pwGecos, ",")[0]
}

func GetPwUid(uid uint32) string {
	return strconv.FormatUint(uint64(C._get_pw_uid(C.uint(uid))), 10)
}

func GetPwGid(uid uint32) string {
	return strconv.FormatUint(uint64(C._get_pw_gid(C.uint(uid))), 10)
}

func GetPwDir(uid uint32) string {
	return C.GoString(C._get_pw_dir(C.uint(uid)))
}

func GetPwShell(uid uint32) string {
	return C.GoString(C._get_pw_shell(C.uint(uid)))
}

type originShadowInfo struct {
	Name       string
	LastChange int
	MaxDays    int
	ShadowPwdp string // password status
}

func getSpwd(username string) (*originShadowInfo, error) {
	cname := C.CString(username)
	defer C.free(unsafe.Pointer(cname))
	spwd := C.getspnam(cname)
	if spwd == nil {
		return &originShadowInfo{}, errors.New("no such user name")
	}
	sInfo := originShadowInfo{
		Name:       C.GoString(spwd.sp_namp),
		LastChange: int(spwd.sp_lstchg),
		MaxDays:    int(spwd.sp_max),
		ShadowPwdp: C.GoString(spwd.sp_pwdp),
	}
	return &sInfo, nil
}

// password: has been crypt
func updatePasswd(password, username string) error {
	status := C._lock_shadow_file()
	if status != 0 {
		return fmt.Errorf("Lock shadow file failed")
	}
	defer C._unlock_shadow_file()

	content, err := ioutil.ReadFile(userFileShadow)
	if err != nil {
		return err
	}

	lines := strings.Split(string(content), "\n")
	var datas []string
	var found bool
	for _, line := range lines {
		if len(line) == 0 {
			datas = append(datas, line)
			continue
		}

		items := strings.Split(line, ":")
		if items[0] != username {
			datas = append(datas, line)
			continue
		}

		found = true
		if items[1] == password {
			return nil
		}

		var tmp string
		for i, v := range items {
			if i != 0 {
				tmp += ":"
			}

			if i == 1 {
				tmp += password
				continue
			}

			tmp += v
		}

		datas = append(datas, tmp)
	}

	if !found {
		return fmt.Errorf("The username not exist.")
	}

	err = writeStrvToFile(datas, userFileShadow, math.MaxUint32)
	if err != nil {
		return nil
	}

	usr, _ := user.Lookup("root")
	grp, _ := user.LookupGroup("shadow")
	uid, _ := strconv.Atoi(usr.Uid)
	gid, _ := strconv.Atoi(grp.Gid)
	err = os.Chown(userFileShadow, uid, gid)

	return err
}

func writeStrvToFile(datas []string, file string, mode os.FileMode) error {
	var content string
	for i, v := range datas {
		if i != 0 {
			content += "\n"
		}

		content += v
	}

	f, err := os.Create(file + ".bak~")
	if err != nil {
		return err
	}
	defer func() {
		_ = f.Close()
	}()

	wLocker.Lock()
	defer wLocker.Unlock()
	_, err = f.WriteString(content)
	if err != nil {
		return err
	}

	err = f.Sync()
	if err != nil {
		return err
	}

	info, err := os.Stat(file)
	if err == nil && mode == math.MaxUint32 {
		mode = info.Mode()
	}

	os.Rename(file+".bak~", file)
	os.Chmod(file, mode)

	return nil
}
