random.go

// Copyright 2013 Vedran Vuk. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package strings

import (
	"math/rand"
)

// Default special characters set used in passwords.
// < and > may cause issues on some systems.
const DefSpecialChars = " !\"#$%&'()*+,-./:;<=>?@[\\]^_`{|}~"

// Returns a string containing a random number.
func RandomNum() string {
	return string(Nums[rand.Intn(len(Nums))])
}

// Returns a string of random numbers of "length".
func RandomNums(length int) string {
	if length < 1 {
		return ""
	}
	r := make([]byte, length)
	for i := 0; i < length; i++ {
		r[i] = byte(RandomNum()[0])
	}
	return string(r)
}

// Returns a string containing a random uppercase letter.
func RandomUpper() string {
	return string(AlphaUpper[rand.Intn(len(AlphaUpper))])
}

// Returns a string of random uppercase letters of "length".
func RandomUppers(length int) string {
	if length < 1 {
		return ""
	}
	r := make([]byte, length)
	for i := 0; i < length; i++ {
		r[i] = byte(RandomUpper()[0])
	}
	return string(r)
}

// Returns a string containing a random lowercase letter.
func RandomLower() string {
	return string(AlphaLower[rand.Intn(len(AlphaLower))])
}

// Returns a string of random lowercase letters of "length".
func RandomLowers(length int) string {
	if length < 1 {
		return ""
	}
	r := make([]byte, length)
	for i := 0; i < length; i++ {
		r[i] = byte(RandomLower()[0])
	}
	return string(r)
}

// Returns a string containing a random password special character.
func RandomSpecial() string {
	return string(DefSpecialChars[rand.Intn(len(DefSpecialChars))])
}

// Returns a string of random special characters of "length".
func RandomSpecials(length int) string {
	if length < 1 {
		return ""
	}
	r := make([]byte, length)
	for i := 0; i < length; i++ {
		r[i] = byte(RandomSpecial()[0])
	}
	return string(r)
}

// Returns a random string of "length".
// If "lo" includes lowercase letters.
// If "up" includes uppercase letters.
// If "num" includes numbers.
func RandomString(lo, up, nums bool, length int) string {
	if length < 1 {
		return ""
	}
	f := []func() string{}
	if lo {
		f = append(f, RandomLower)
	}
	if up {
		f = append(f, RandomUpper)
	}
	if nums {
		f = append(f, RandomNum)
	}
	r := make([]byte, length)
	if lo || up || nums {
		for i := 0; i < length; i++ {
			r[i] = byte(f[rand.Intn(len(f))]()[0])
		}
	}
	return string(r)
}