get_login_image_html()

function get_login_image_html() {
	/**
	 * Determine whether the login page custom image option is enabled.
	 */
	$login_custom_image_state = (int) get_option( 'login_custom_image_state' );
	$login_custom_image_id    = null;
	$login_custom_image_html  = null;

	if ( $login_custom_image_state === 1 || $login_custom_image_state === 2 ) {
		$login_custom_image_id = (int) get_option( 'login_custom_image_id' );
		if ( $login_custom_image_id ) {
			$attrs = [
				'class'    => 'custom-login-image',
				'itemprop' => 'logo'
			];
			$image_alt = get_post_meta(
				$login_custom_image_id,
				'_wp_attachment_image_alt',
				true
			);
			if ( empty( $image_alt ) ) {
				$attrs['alt'] = get_bloginfo( 'name', 'display' );
			}
			$login_custom_image_html = wp_get_attachment_image(
				$login_custom_image_id,
				'full',
				false,
				$attrs
			);
		}
	}

	if ( ! empty( $login_custom_image_html ) ) {
		$login_header_url   = home_url( '/' );
		$login_header_title = get_bloginfo( 'name', 'display' );
	} elseif ( is_multisite() ) {
		$login_header_url   = network_home_url();
		$login_header_title = get_network()->site_name;
	} else {
		$login_header_url   = 'https://www.classicpress.net/';
		$login_header_title = __( 'Powered by ClassicPress' );
	}

	/**
	 * Filters link URL of the header logo above login form.
	 *
	 * @since WP-2.1.0
	 *
	 * @param string $login_header_url Login header logo URL.
	 */
	$login_header_url = apply_filters( 'login_headerurl', $login_header_url );

	/**
	 * Filters the title attribute of the header logo above login form.
	 *
	 * @since WP-2.1.0
	 *
	 * @param string $login_header_title Login header logo title attribute.
	 */
	$login_header_title = apply_filters( 'login_headertitle', $login_header_title );

	if ( ! empty( $login_custom_image_html ) ) {
		// Generate the custom login image HTML.
		$login_image_class = 'custom-login-image-container';
		if ( $login_custom_image_state === 2 ) {
			$login_image_class .= ' banner';
		}
		$login_image_html = sprintf(
			'<a href="%s" class="%s" rel="home" itemprop="url" title="%s">%s</a>',
			esc_url( $login_header_url ),
			$login_image_class,
			esc_attr( $login_header_title ),
			$login_custom_image_html
		);
		$login_header_text = null;

	} else {
		/**
		 * Otherwise use the ClassicPress logo.
		 *
		 * Set the link text (displayed only for screen readers).
		 *
		 * To match the URL/title set above, Multisite sites have the blog
		 * name, while single sites get the header title.
		 */
		if ( is_multisite() ) {
			$login_header_text = get_bloginfo( 'name', 'display' );
		} else {
			$login_header_text = $login_header_title;
		}

		$login_image_html = (
			'<h1>'
			. '<a href="' . esc_url( $login_header_url ) . '"'
			. ' title="' . esc_attr( $login_header_title ) . '"'
			. ' tabindex="-1">'
			. $login_header_text
			. '</a>'
			. '</h1>'
		);

	}

	/**
	 * Filters the HTML for the image displayed on the login page.
	 *
	 * @since 1.1.0
	 *
	 * @param string $html The proposed login image HTML.
	 * @param array  $args {
	 *     Other relevant arguments (read-only, you must use earlier filters
	 *     such as 'login_headerurl' to modify these values).
	 *     @type int $login_custom_image_state
	 *                                      0 for disabled, 1 for logo
	 *                                      style, 2 for banner style.
	 *     @type int|null $login_custom_image_id
	 *                                      The image ID to use as the custom
	 *                                      login image (or null if disabled).
	 *     @type string $login_header_url   The URL used as a link for the
	 *                                      login page.
	 *     @type string $login_header_title The title attribute for the login
	 *                                      page image.
	 *     @type string $login_header_text  The screen reader text for the login
	 *                                      page image.
	 * }
	 */
	return apply_filters( 'login_image_html', $login_image_html, [
		'login_custom_image_state' => $login_custom_image_state,
		'login_custom_image_id'    => $login_custom_image_id,
		'login_header_url'         => $login_header_url,
		'login_header_title'       => $login_header_title,
		'login_header_text'        => $login_header_text,
	] );
}