package main

import (
	"fmt"
	"math/rand/v2"
	"os"
	"sort"
	"testing"
	"time"

	"gitlab.com/rhogenson/roseh.moe/internal/cryptoutil"
)

var (
	iterations int

	salt = func() []byte {
		r := rand.New(new(rand.PCG))
		salt := make([]byte, cryptoutil.SaltSize)
		for i := range salt {
			salt[i] = byte(r.IntN(256))
		}
		return salt
	}()
)

func BenchmarkHashIter(b *testing.B) {
	const password = "oboe shortness ether ideology undesired fresh freezable catching mashing glimpse"
	for b.Loop() {
		cryptoutil.HashIter(password, salt, iterations)
	}
}

func run() error {
	const targetDuration = 2 * time.Second

	for iterations = 8192; time.Duration(testing.Benchmark(BenchmarkHashIter).NsPerOp()) < targetDuration; iterations *= 2 {
	}
	lo := iterations / 2
	hi := iterations
	fmt.Println(lo + sort.Search(hi-lo, func(i int) bool {
		iterations = lo + i
		return time.Duration(testing.Benchmark(BenchmarkHashIter).NsPerOp()) > targetDuration
	}))
	return nil
}

func main() {
	if err := run(); err != nil {
		fmt.Fprintln(os.Stderr, err)
		os.Exit(1)
	}
}