package main

import (
	"fmt"
	"os"
	"strconv"

	"gitlab.wow.st/gmp/rand"
)

func usage() {
	fmt.Println("rand [-d | -l | -s] [num]")
	os.Exit(-1)
}

func main() {
	args := os.Args[1:]
	var f func() (byte,error)
	var n int
	var err error

	func() {
		if len(args) == 0 {
			f = rand.Char
			n = 20
			return
		}
		if len(args) >= 1 {
			switch args[0] {
			case "-d","--digits":
				f = rand.Digit
			case "-l","--letters":
				f = rand.Letter
			case "-s","--symbols":
				f = rand.Symbol
			default:
				f = rand.Char
				n, err = strconv.Atoi(args[0])
				if err != nil {
					usage()
				}
			}
		}
		switch len(args) {
		case 1:
			if n == 0 {
				n = 20
			}
		case 2:
			if n != 0 {
				usage()
			}
			n, err = strconv.Atoi(args[1])
			if err != nil {
				usage()
			}
		default:
			usage()
		}
	}()

	s, err := rand.Slice(f,n)
	if err != nil {
		fmt.Println(err)
		os.Exit(-1)
	}
	os.Stdout.Write(s)
	os.Stdout.Write([]byte("\n"))
}