package main

import (
	"fmt"

	"golang.org/x/crypto/cryptobyte"
)

func main() {
	var b bool

	// This should read the booleanDER successfully and set 'b' to TRUE
	//
	// It fails to read the optional BOOLEAN because it updates the String to check
	// the presence and then tries to read from the updated string instead of the
	// extracted child
	var booleanDER = cryptobyte.String{0x01, 0x01, 0xFF}

	if !booleanDER.ReadOptionalASN1Boolean(&b, false) {
		fmt.Println("Couldn't read booleanDER")
	} else {
		fmt.Printf("Read optional booleanDER: %t\n", b)
	}

	fmt.Println("===")

	// This should read the boolean and set 'b' to FALSE. compositeDER should then
	// be updated to point at the start of the encoded integer.
	//
	// It actually checks the presence of the boolean with a BOOLEAN tag, then
	// proceeds reading the value from the updated String as above.
	// Since ReadASN1Boolean uses the INTEGER tag, it reads the following INTEGER
	// and sets 'b' to TRUE (0xFF), updating the String again.
	// At the end of the operation compositeDER has no bytes left, due to the double
	// update.
	var compositeDER = cryptobyte.String{0x01, 0x01, 0x00, 0x02, 0x01, 0xFF}

	if !compositeDER.ReadOptionalASN1Boolean(&b, false) {
		fmt.Println("Couldn't read compositeDER")
	} else {
		fmt.Printf("Read compositeDER: %t\n", b)
		fmt.Printf("Remaining bytes: \"%X\"\n", compositeDER)
	}
}