class Envelope

class Envelope {
    private Address $sender;
    private array $recipients = [];
    
    /**
     * @param Address[] $recipients
     */
    public function __construct(Address $sender, array $recipients) {
        $this->setSender($sender);
        $this->setRecipients($recipients);
    }
    public static function create(RawMessage $message) : self {
        if (RawMessage::class === $message::class) {
            throw new LogicException('Cannot send a RawMessage instance without an explicit Envelope.');
        }
        return new DelayedEnvelope($message);
    }
    public function setSender(Address $sender) : void {
        // to ensure deliverability of bounce emails independent of UTF-8 capabilities of SMTP servers
        if (!preg_match('/^[^@\\x80-\\xFF]++@/', $sender->getAddress())) {
            throw new InvalidArgumentException(\sprintf('Invalid sender "%s": non-ASCII characters not supported in local-part of email.', $sender->getAddress()));
        }
        $this->sender = $sender;
    }
    
    /**
     * @return Address Returns a "mailbox" as specified by RFC 2822
     *                 Must be converted to an "addr-spec" when used as a "MAIL FROM" value in SMTP (use getAddress())
     */
    public function getSender() : Address {
        return $this->sender;
    }
    
    /**
     * @param Address[] $recipients
     */
    public function setRecipients(array $recipients) : void {
        if (!$recipients) {
            throw new InvalidArgumentException('An envelope must have at least one recipient.');
        }
        $this->recipients = [];
        foreach ($recipients as $recipient) {
            if (!$recipient instanceof Address) {
                throw new InvalidArgumentException(\sprintf('A recipient must be an instance of "%s" (got "%s").', Address::class, get_debug_type($recipient)));
            }
            $this->recipients[] = new Address($recipient->getAddress());
        }
    }
    
    /**
     * @return Address[]
     */
    public function getRecipients() : array {
        return $this->recipients;
    }
    
    /**
     * Returns true if any address' localpart contains at least one
     * non-ASCII character, and false if all addresses have all-ASCII
     * localparts.
     *
     * This helps to decide whether to the SMTPUTF8 extensions (RFC
     * 6530 and following) for any given message.
     *
     * The SMTPUTF8 extension is strictly required if any address
     * contains a non-ASCII character in its localpart. If non-ASCII
     * is only used in domains (e.g. horst@freiherr-von-mühlhausen.de)
     * then it is possible to send the message using IDN encoding
     * instead of SMTPUTF8. The most common software will display the
     * message as intended.
     */
    public function anyAddressHasUnicodeLocalpart() : bool {
        if ($this->getSender()
            ->hasUnicodeLocalpart()) {
            return true;
        }
        foreach ($this->getRecipients() as $r) {
            if ($r->hasUnicodeLocalpart()) {
                return true;
            }
        }
        return false;
    }

}