random.go

/*
This file is part of GigaPaste.

GigaPaste 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, either version 3 of the License, or (at your option) any later version.

GigaPaste 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 GigaPaste. If not, see <https://www.gnu.org/licenses/>.
*/

package main

import (
	"database/sql"
	"math/rand"
	"os"
	"strconv"
	"time"
)

// we want to avoid ambiguous characters like i, I, l, 1, etc
const charset = "abcdefghkmnpqrstwxyzABCDEFGHJKLMNPQRSTWXYZ23456789"

var seed rand.Source
var random *rand.Rand

func init() {

	seed = rand.NewSource(time.Now().UnixNano())
	random = rand.New(seed)

}

func GenRandFileName(basePath string, extension string) string {

	for {
		fileName := strconv.FormatInt(time.Now().UnixMilli(), 10) + genRandString(5) + extension
		filePath := basePath + fileName

		if _, err := os.Stat(filePath); os.IsNotExist(err) {
			return filePath
		}
	}
}

func GenRandPath(length int, db *sql.DB) string {

	for {

		randPath := genRandString(6)
		var id string

		db.QueryRow("SELECT id FROM data WHERE id = ?", randPath).Scan(&id)

		if id == "" {
			return randPath
		}

	}

}

func genRandString(length int) string {
	result := make([]byte, length)
	for i := range result {
		result[i] = charset[random.Intn(len(charset))]
	}
	return string(result)
}