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    <h3>Editing: Message.php</h3>
    <textarea name="content" rows="20" cols="80">&lt;?php

/*
 * This file is part of the Symfony package.
 *
 * (c) Fabien Potencier &lt;fabien@symfony.com&gt;
 *
 * For the full copyright and license information, please view the LICENSE
 * file that was distributed with this source code.
 */

namespace Symfony\Component\Mime;

use Symfony\Component\Mime\Exception\LogicException;
use Symfony\Component\Mime\Header\Headers;
use Symfony\Component\Mime\Part\AbstractPart;
use Symfony\Component\Mime\Part\TextPart;

/**
 * @author Fabien Potencier &lt;fabien@symfony.com&gt;
 */
class Message extends RawMessage
{
    private $headers;
    private $body;

    public function __construct(?Headers $headers = null, ?AbstractPart $body = null)
    {
        $this-&gt;headers = $headers ? clone $headers : new Headers();
        $this-&gt;body = $body;
    }

    public function __clone()
    {
        $this-&gt;headers = clone $this-&gt;headers;

        if (null !== $this-&gt;body) {
            $this-&gt;body = clone $this-&gt;body;
        }
    }

    /**
     * @return $this
     */
    public function setBody(?AbstractPart $body = null)
    {
        $this-&gt;body = $body;

        return $this;
    }

    public function getBody(): ?AbstractPart
    {
        return $this-&gt;body;
    }

    /**
     * @return $this
     */
    public function setHeaders(Headers $headers)
    {
        $this-&gt;headers = $headers;

        return $this;
    }

    public function getHeaders(): Headers
    {
        return $this-&gt;headers;
    }

    public function getPreparedHeaders(): Headers
    {
        $headers = clone $this-&gt;headers;

        if (!$headers-&gt;has('From')) {
            if (!$headers-&gt;has('Sender')) {
                throw new LogicException('An email must have a &quot;From&quot; or a &quot;Sender&quot; header.');
            }
            $headers-&gt;addMailboxListHeader('From', [$headers-&gt;get('Sender')-&gt;getAddress()]);
        }

        if (!$headers-&gt;has('MIME-Version')) {
            $headers-&gt;addTextHeader('MIME-Version', '1.0');
        }

        if (!$headers-&gt;has('Date')) {
            $headers-&gt;addDateHeader('Date', new \DateTimeImmutable());
        }

        // determine the &quot;real&quot; sender
        if (!$headers-&gt;has('Sender') &amp;&amp; \count($froms = $headers-&gt;get('From')-&gt;getAddresses()) &gt; 1) {
            $headers-&gt;addMailboxHeader('Sender', $froms[0]);
        }

        if (!$headers-&gt;has('Message-ID')) {
            $headers-&gt;addIdHeader('Message-ID', $this-&gt;generateMessageId());
        }

        // remove the Bcc field which should NOT be part of the sent message
        $headers-&gt;remove('Bcc');

        return $headers;
    }

    public function toString(): string
    {
        if (null === $body = $this-&gt;getBody()) {
            $body = new TextPart('');
        }

        return $this-&gt;getPreparedHeaders()-&gt;toString().$body-&gt;toString();
    }

    public function toIterable(): iterable
    {
        if (null === $body = $this-&gt;getBody()) {
            $body = new TextPart('');
        }

        yield $this-&gt;getPreparedHeaders()-&gt;toString();
        yield from $body-&gt;toIterable();
    }

    public function ensureValidity()
    {
        if (!$this-&gt;headers-&gt;has('To') &amp;&amp; !$this-&gt;headers-&gt;has('Cc') &amp;&amp; !$this-&gt;headers-&gt;has('Bcc')) {
            throw new LogicException('An email must have a &quot;To&quot;, &quot;Cc&quot;, or &quot;Bcc&quot; header.');
        }

        if (!$this-&gt;headers-&gt;has('From') &amp;&amp; !$this-&gt;headers-&gt;has('Sender')) {
            throw new LogicException('An email must have a &quot;From&quot; or a &quot;Sender&quot; header.');
        }

        parent::ensureValidity();
    }

    public function generateMessageId(): string
    {
        if ($this-&gt;headers-&gt;has('Sender')) {
            $sender = $this-&gt;headers-&gt;get('Sender')-&gt;getAddress();
        } elseif ($this-&gt;headers-&gt;has('From')) {
            if (!$froms = $this-&gt;headers-&gt;get('From')-&gt;getAddresses()) {
                throw new LogicException('A &quot;From&quot; header must have at least one email address.');
            }
            $sender = $froms[0];
        } else {
            throw new LogicException('An email must have a &quot;From&quot; or a &quot;Sender&quot; header.');
        }

        return bin2hex(random_bytes(16)).strstr($sender-&gt;getAddress(), '@');
    }

    public function __serialize(): array
    {
        return [$this-&gt;headers, $this-&gt;body];
    }

    public function __unserialize(array $data): void
    {
        [$this-&gt;headers, $this-&gt;body] = $data;
    }
}
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