public function importRecipients()
	{
		if (Input::get('key') != 'import')
		{
			return '';
		}

		/** @var FileUpload $objUploader */
		$objUploader = new FileUpload();

		// Import recipients
		if (Input::post('FORM_SUBMIT') == 'tl_recipients_import')
		{
			$arrUploaded = $objUploader->uploadTo('system/tmp');

			if (empty($arrUploaded))
			{
				Message::addError($GLOBALS['TL_LANG']['ERR']['all_fields']);
				$this->reload();
			}

			$time = time();
			$intTotal = 0;
			$intInvalid = 0;

			foreach ($arrUploaded as $strCsvFile)
			{
				$objFile = new File($strCsvFile);

				if ($objFile->extension != 'csv')
				{
					Message::addError(sprintf($GLOBALS['TL_LANG']['ERR']['filetype'], $objFile->extension));
					continue;
				}

				// Get separator
				switch (Input::post('separator'))
				{
					case 'semicolon':
						$strSeparator = ';';
						break;

					case 'tabulator':
						$strSeparator = "\t";
						break;

					case 'linebreak':
						$strSeparator = "\n";
						break;

					default:
						$strSeparator = ',';
						break;
				}

				$arrRecipients = array();
				$resFile = $objFile->handle;

				while(($arrRow = @fgetcsv($resFile, null, $strSeparator)) !== false)
				{
					$arrRecipients[] = $arrRow;
				}

				if (!empty($arrRecipients))
				{
					$arrRecipients = array_merge(...$arrRecipients);
				}

				$arrRecipients = array_filter(array_unique($arrRecipients));

				foreach ($arrRecipients as $strRecipient)
				{
					// Skip invalid entries
					if (!Validator::isEmail($strRecipient))
					{
						$this->log('The recipient address "' . $strRecipient . '" seems to be invalid and was not imported', __METHOD__, TL_ERROR);
						++$intInvalid;
						continue;
					}

					// Check whether the e-mail address exists
					$objRecipient = $this->Database->prepare("SELECT COUNT(*) AS count FROM tl_newsletter_recipients WHERE pid=? AND email=?")
												   ->execute(Input::get('id'), $strRecipient);

					if ($objRecipient->count > 0)
					{
						continue;
					}

					// Check whether the e-mail address has been blacklisted
					$objBlacklist = $this->Database->prepare("SELECT COUNT(*) AS count FROM tl_newsletter_blacklist WHERE pid=? AND hash=?")
												   ->execute(Input::get('id'), md5($strRecipient));

					if ($objBlacklist->count > 0)
					{
						$this->log('Recipient "' . $strRecipient . '" has unsubscribed from channel ID "' . Input::get('id') . '" and was not imported', __METHOD__, TL_ERROR);
						continue;
					}

					$this->Database->prepare("INSERT INTO tl_newsletter_recipients SET pid=?, tstamp=$time, email=?, active=1")
								   ->execute(Input::get('id'), $strRecipient);

					++$intTotal;
				}
			}

			Message::addConfirmation(sprintf($GLOBALS['TL_LANG']['tl_newsletter_recipients']['confirm'], $intTotal));

			if ($intInvalid > 0)
			{
				Message::addInfo(sprintf($GLOBALS['TL_LANG']['tl_newsletter_recipients']['invalid'], $intInvalid));
			}

			System::setCookie('BE_PAGE_OFFSET', 0, 0);
			$this->reload();
		}

		// Return form
		return '
<div id="tl_buttons">
<a href="'.ampersand(str_replace('&key=import', '', Environment::get('request'))).'" class="header_back" title="'.StringUtil::specialchars($GLOBALS['TL_LANG']['MSC']['backBTTitle']).'" accesskey="b">'.$GLOBALS['TL_LANG']['MSC']['backBT'].'</a>
</div>
'.Message::generate().'
<form action="'.ampersand(Environment::get('request'), true).'" id="tl_recipients_import" class="tl_form tl_edit_form" method="post" enctype="multipart/form-data">
<div class="tl_formbody_edit">
<input type="hidden" name="FORM_SUBMIT" value="tl_recipients_import">
<input type="hidden" name="REQUEST_TOKEN" value="'.REQUEST_TOKEN.'">
<input type="hidden" name="MAX_FILE_SIZE" value="'.Config::get('maxFileSize').'">

<fieldset class="tl_tbox nolegend">
  <div class="widget w50">
    <h3><label for="separator">'.$GLOBALS['TL_LANG']['MSC']['separator'][0].'</label></h3>
    <select name="separator" id="separator" class="tl_select" onfocus="Backend.getScrollOffset()">
      <option value="comma">'.$GLOBALS['TL_LANG']['MSC']['comma'].'</option>
      <option value="semicolon">'.$GLOBALS['TL_LANG']['MSC']['semicolon'].'</option>
      <option value="tabulator">'.$GLOBALS['TL_LANG']['MSC']['tabulator'].'</option>
      <option value="linebreak">'.$GLOBALS['TL_LANG']['MSC']['linebreak'].'</option>
    </select>'.(($GLOBALS['TL_LANG']['MSC']['separator'][1] != '') ? '
    <p class="tl_help tl_tip">'.$GLOBALS['TL_LANG']['MSC']['separator'][1].'</p>' : '').'
  </div>
  <div class="widget clr">
    <h3>'.$GLOBALS['TL_LANG']['MSC']['source'][0].'</h3>'.$objUploader->generateMarkup().(isset($GLOBALS['TL_LANG']['MSC']['source'][1]) ? '
    <p class="tl_help tl_tip">'.$GLOBALS['TL_LANG']['MSC']['source'][1].'</p>' : '').'
  </div>
</fieldset>

</div>

<div class="tl_formbody_submit">

<div class="tl_submit_container">
  <button type="submit" name="save" id="save" class="tl_submit" accesskey="s">'.$GLOBALS['TL_LANG']['tl_newsletter_recipients']['import'][0].'</button>
</div>

</div>
</form>';
	}
public function importRecipients()
	{
		if (Input::get('key') != 'import')
		{
			return '';
		}

		/** @var FileUpload $objUploader */
		$objUploader = new FileUpload();

		// Import recipients
		if (Input::post('FORM_SUBMIT') == 'tl_recipients_import')
		{
			$arrUploaded = $objUploader->uploadTo('system/tmp');

			if (empty($arrUploaded))
			{
				Message::addError($GLOBALS['TL_LANG']['ERR']['all_fields']);
				$this->reload();
			}

			$time = time();
			$intTotal = 0;
			$intInvalid = 0;

			foreach ($arrUploaded as $strCsvFile)
			{
				$objFile = new File($strCsvFile);

				if ($objFile->extension != 'csv')
				{
					Message::addError(sprintf($GLOBALS['TL_LANG']['ERR']['filetype'], $objFile->extension));
					continue;
				}

				// Get separator
				switch (Input::post('separator'))
				{
					case 'semicolon':
						$strSeparator = ';';
						break;

					case 'tabulator':
						$strSeparator = "\t";
						break;

					case 'linebreak':
						$strSeparator = "\n";
						break;

					default:
						$strSeparator = ',';
						break;
				}

				$arrRecipients = array();
				$resFile = $objFile->handle;

				while(($arrRow = @fgetcsv($resFile, null, $strSeparator)) !== false)
				{
					$arrRecipients[] = $arrRow;
				}

				if (!empty($arrRecipients))
				{
					$arrRecipients = array_merge(...$arrRecipients);
				}

				$arrRecipients = array_filter(array_unique($arrRecipients));

				foreach ($arrRecipients as $strRecipient)
				{
					// Skip invalid entries
					if (!Validator::isEmail($strRecipient))
					{
						$this->log('The recipient address "' . $strRecipient . '" seems to be invalid and was not imported', __METHOD__, TL_ERROR);
						++$intInvalid;
						continue;
					}

					// Check whether the e-mail address exists
					$objRecipient = $this->Database->prepare("SELECT COUNT(*) AS count FROM tl_newsletter_recipients WHERE pid=? AND email=?")
												   ->execute(Input::get('id'), $strRecipient);

					if ($objRecipient->count > 0)
					{
						continue;
					}

					// Check whether the e-mail address has been blacklisted
					$objBlacklist = $this->Database->prepare("SELECT COUNT(*) AS count FROM tl_newsletter_blacklist WHERE pid=? AND hash=?")
												   ->execute(Input::get('id'), md5($strRecipient));

					if ($objBlacklist->count > 0)
					{
						$this->log('Recipient "' . $strRecipient . '" has unsubscribed from channel ID "' . Input::get('id') . '" and was not imported', __METHOD__, TL_ERROR);
						continue;
					}

					$this->Database->prepare("INSERT INTO tl_newsletter_recipients SET pid=?, tstamp=$time, email=?, active=1")
								   ->execute(Input::get('id'), $strRecipient);

					++$intTotal;
				}
			}

			Message::addConfirmation(sprintf($GLOBALS['TL_LANG']['tl_newsletter_recipients']['confirm'], $intTotal));

			if ($intInvalid > 0)
			{
				Message::addInfo(sprintf($GLOBALS['TL_LANG']['tl_newsletter_recipients']['invalid'], $intInvalid));
			}

			System::setCookie('BE_PAGE_OFFSET', 0, 0);
			$this->reload();
		}

		// Return form
		return '
<div id="tl_buttons">
<a href="'.ampersand(str_replace('&key=import', '', Environment::get('request'))).'" class="header_back" title="'.StringUtil::specialchars($GLOBALS['TL_LANG']['MSC']['backBTTitle']).'" accesskey="b">'.$GLOBALS['TL_LANG']['MSC']['backBT'].'</a>
</div>
'.Message::generate().'
<form action="'.ampersand(Environment::get('request'), true).'" id="tl_recipients_import" class="tl_form tl_edit_form" method="post" enctype="multipart/form-data">
<div class="tl_formbody_edit">
<input type="hidden" name="FORM_SUBMIT" value="tl_recipients_import">
<input type="hidden" name="REQUEST_TOKEN" value="'.REQUEST_TOKEN.'">
<input type="hidden" name="MAX_FILE_SIZE" value="'.Config::get('maxFileSize').'">

<fieldset class="tl_tbox nolegend">
  <div class="widget w50">
    <h3><label for="separator">'.$GLOBALS['TL_LANG']['MSC']['separator'][0].'</label></h3>
    <select name="separator" id="separator" class="tl_select" onfocus="Backend.getScrollOffset()">
      <option value="comma">'.$GLOBALS['TL_LANG']['MSC']['comma'].'</option>
      <option value="semicolon">'.$GLOBALS['TL_LANG']['MSC']['semicolon'].'</option>
      <option value="tabulator">'.$GLOBALS['TL_LANG']['MSC']['tabulator'].'</option>
      <option value="linebreak">'.$GLOBALS['TL_LANG']['MSC']['linebreak'].'</option>
    </select>'.(($GLOBALS['TL_LANG']['MSC']['separator'][1] != '') ? '
    <p class="tl_help tl_tip">'.$GLOBALS['TL_LANG']['MSC']['separator'][1].'</p>' : '').'
  </div>
  <div class="widget clr">
    <h3>'.$GLOBALS['TL_LANG']['MSC']['source'][0].'</h3>'.$objUploader->generateMarkup().(isset($GLOBALS['TL_LANG']['MSC']['source'][1]) ? '
    <p class="tl_help tl_tip">'.$GLOBALS['TL_LANG']['MSC']['source'][1].'</p>' : '').'
  </div>
</fieldset>

</div>

<div class="tl_formbody_submit">

<div class="tl_submit_container">
  <button type="submit" name="save" id="save" class="tl_submit" accesskey="s">'.$GLOBALS['TL_LANG']['tl_newsletter_recipients']['import'][0].'</button>
</div>

</div>
</form>';
	}
Return a form to choose a CSV file and import it

@return string