// Copyright (c) 2026 Micha Hoiting

package main

import (
	"crypto/rand"
	"encoding/binary"
	"errors"
	"flag"
	"fmt"
	"os"

	"git.hoiting.org/micha/triplex/serial"
)

func alreadyUsedByClient(idx uint) bool {
	return idx%2 == 0
}

func myRandomIndex(max uint) (uint, error) {
	if max == 0 {
		return 0, fmt.Errorf("max must be > 0")
	}

	var buf [4]byte
	if _, err := rand.Read(buf[:]); err != nil {
		return 0, err
	}

	return uint(binary.LittleEndian.Uint32(buf[:])) % max, nil
}

func main() {
	complete := flag.String("complete", "", "complete code without checksum in format LLL-NNN-L")
	flag.Parse()

	if *complete != "" {
		full, idx, err := serial.CompleteCode(*complete)
		if err != nil {
			fmt.Println("complete error:", err)
			os.Exit(1)
		}

		fmt.Println("code:", full)
		fmt.Println("idx:", idx)
		os.Exit(0)
	}

	opts := serial.RandomCodeOptions{
		MaxAttempts: 500,
		IsInUse: func(idx uint) bool {
			return alreadyUsedByClient(idx)
		},
		RandomIndex: func(max uint) (uint, error) {
			return myRandomIndex(max)
		},
	}

	code, idx, err := serial.RandomCodeWithOptions(opts)
	if err != nil {
		if errors.Is(err, serial.ErrRandomSourceFailed) {
			fmt.Println("random source failed")
			os.Exit(1)
		}
		if errors.Is(err, serial.ErrNoAvailableIndex) {
			fmt.Println("no available index found")
			os.Exit(1)
		}
		fmt.Println("unexpected error:", err)
		os.Exit(1)
	}

	fmt.Println("code:", code)
	fmt.Println("idx:", idx)
}