/*
 *  Copyright (c) 2026 Kaiy Ragur
 *  Original Copyright (c) 2021 Neil Alexander
 *
 *  This Source Code Form is subject to the terms of the Mozilla Public
 *  License, v. 2.0. If a copy of the MPL was not distributed with this
 *  file, You can obtain one at http://mozilla.org/MPL/2.0/.
 */

package utils

import (
	"crypto/ed25519"
	"encoding/base32"
	"fmt"
	"strings"
)

func CreateAddress(aPk, dPk ed25519.PublicKey) string {
	return fmt.Sprintf(
		"%s@%s",
		EncodeString(aPk), EncodeString(dPk),
	)
}

func EncodeString(k []byte) string {
	return strings.ToLower(base32.HexEncoding.WithPadding(base32.NoPadding).EncodeToString(k))
}

func DecodeString(s string) ([]byte, error) {
	pk, err := base32.HexEncoding.WithPadding(base32.NoPadding).DecodeString(strings.ToUpper(s))
	if err != nil {
		return nil, fmt.Errorf("hex.DecodeString: %w", err)
	}
	if len(pk) == 0 {
		return nil, fmt.Errorf("utils.DecodeStrings: len %d", len(pk))
	}
	return pk, nil
}

func ParseAddress(email string) (ed25519.PublicKey, ed25519.PublicKey, error) {
	at := strings.LastIndex(email, "@")
	if at == 0 {
		return nil, nil, fmt.Errorf("invalid email address")
	}
	// Domain key
	host := email[at+1:]
	hostPk, err := DecodeString(host)
	if err != nil {
		return nil, nil, fmt.Errorf("invalid email domain: %w", err)
	} else if len(hostPk) != ed25519.PublicKeySize {
		return nil, nil, fmt.Errorf("invalid email domain: invalid keysize")
	}
	// Account key
	user := email[:at]
	userPk, err := DecodeString(user)
	if err != nil {
		return nil, nil, fmt.Errorf("invalid email account: %w", err)
	} else if len(userPk) != ed25519.PublicKeySize {
		return nil, nil, fmt.Errorf("invalid email account: invalid keysize")
	}
	return hostPk, userPk, nil
}