main.go

/*

Q1. We need a way to generate a random sequence of lower case letters and digits, and in the future may need other combinations. For example,
1. 7ns32bkzgg
2. 85674
3. mxxk9gk6a4n9thq59mfx

Please provide a solution in Go (any recent version of Go) - we are mostly interested in the interface and less interested in the implementation.

*/

package main

import (
	"fmt"
	"math/rand"
	"time"
)

// This would allow
type Charset string

const (
	CharsetNumeric           Charset = "0123456789"
	CharsetAlphaLower        Charset = "abcdefghijklmnopqrstuvwxyz"
	CharsetAlphaUpper        Charset = "ABCDEFGHIJKLMNOPQRSTUVWXYZ"
	CharsetAlpha             Charset = CharsetAlphaLower + CharsetAlphaUpper
	CharsetAlphaLowerNumeric Charset = CharsetAlphaLower + CharsetNumeric
	CharsetAlphaNumeric      Charset = CharsetAlpha + CharsetNumeric
)

func generateRandomSequence(length int, charset Charset) string {
	seededRand := rand.New(rand.NewSource(time.Now().UnixNano()))
	randomSequence := make([]byte, length)
	for i := range randomSequence {
		randomSequence[i] = byte(charset[seededRand.Intn(len(charset))])
	}
	return string(randomSequence)
}

func main() {
	fmt.Println(generateRandomSequence(10, CharsetAlphaLowerNumeric))
	fmt.Println(generateRandomSequence(5, CharsetNumeric))
	fmt.Println(generateRandomSequence(20, CharsetAlphaLowerNumeric))
}