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function resolve_block_template( $template_type, $template_hierarchy, $fallback_template ) {
	if ( ! $template_type ) {
		return null;
	}

	if ( empty( $template_hierarchy ) ) {
		$template_hierarchy = array( $template_type );
	}

	$slugs = array_map(
		'_strip_template_file_suffix',
		$template_hierarchy
	);

	$object            = get_queried_object();
	$specific_template = $object ? get_page_template_slug( $object ) : null;
	$active_templates  = (array) get_option( 'active_templates', array() );

	// Remove templates slugs that are deactivated, except if it's the specific
	// template or index.
	$slugs = array_filter(
		$slugs,
		function ( $slug ) use ( $specific_template, $active_templates ) {
			$should_ignore = $slug === $specific_template || 'index' === $slug;
			return $should_ignore || ( ! isset( $active_templates[ $slug ] ) || false !== $active_templates[ $slug ] );
		}
	);

	// We expect one template for each slug. Use the active template if it is
	// set and exists. Otherwise use the static template.
	$templates       = array();
	$remaining_slugs = array();

	foreach ( $slugs as $slug ) {
		if ( $slug === $specific_template || empty( $active_templates[ $slug ] ) ) {
			$remaining_slugs[] = $slug;
			continue;
		}

		// TODO: it need to be possible to set a static template as active.
		$post = get_post( $active_templates[ $slug ] );
		if ( ! $post || 'publish' !== $post->post_status ) {
			$remaining_slugs[] = $slug;
			continue;
		}

		$template = _build_block_template_result_from_post( $post );

		// Ensure the active templates are associated with the active theme.
		// See _build_block_template_object_from_post_object.
		if ( get_stylesheet() !== $template->theme ) {
			$remaining_slugs[] = $slug;
			continue;
		}

		$templates[] = $template;
	}

	// Apply the filter to the active templates for backward compatibility.
	/** This filter is documented in wp-includes/block-template-utils.php */
	if ( ! empty( $templates ) ) {
		$templates = apply_filters(
			'get_block_templates',
			$templates,
			array(
				'slug__in' => array_map(
					function ( $template ) {
						return $template->slug;
					},
					$templates
				),
			),
			'wp_template'
		);
	}

	// For any remaining slugs, use the static template.
	$query     = array(
		'slug__in' => $remaining_slugs,
	);
	$templates = array_merge( $templates, get_registered_block_templates( $query ) );

	if ( $specific_template ) {
		$templates = array_merge( $templates, get_block_templates( array( 'slug__in' => array( $specific_template ) ) ) );
	}

	// Order these templates per slug priority.
	// Build map of template slugs to their priority in the current hierarchy.
	$slug_priorities = array_flip( $slugs );

	usort(
		$templates,
		static function ( $template_a, $template_b ) use ( $slug_priorities ) {
			return $slug_priorities[ $template_a->slug ] - $slug_priorities[ $template_b->slug ];
		}
	);

	$theme_base_path        = get_stylesheet_directory() . DIRECTORY_SEPARATOR;
	$parent_theme_base_path = get_template_directory() . DIRECTORY_SEPARATOR;

	// Is the active theme a child theme, and is the PHP fallback template part of it?
	if (
		str_starts_with( $fallback_template, $theme_base_path ) &&
		! str_contains( $fallback_template, $parent_theme_base_path )
	) {
		$fallback_template_slug = substr(
			$fallback_template,
			// Starting position of slug.
			strpos( $fallback_template, $theme_base_path ) + strlen( $theme_base_path ),
			// Remove '.php' suffix.
			-4
		);

		// Is our candidate block template's slug identical to our PHP fallback template's?
		if (
			count( $templates ) &&
			$fallback_template_slug === $templates[0]->slug &&
			'theme' === $templates[0]->source
		) {
			// Unfortunately, we cannot trust $templates[0]->theme, since it will always
			// be set to the active theme's slug by _build_block_template_result_from_file(),
			// even if the block template is really coming from the active theme's parent.
			// (The reason for this is that we want it to be associated with the active theme
			// -- not its parent -- once we edit it and store it to the DB as a wp_template CPT.)
			// Instead, we use _get_block_template_file() to locate the block template file.
			$template_file = _get_block_template_file( 'wp_template', $fallback_template_slug );
			if ( $template_file && get_template() === $template_file['theme'] ) {
				// The block template is part of the parent theme, so we
				// have to give precedence to the child theme's PHP template.
				array_shift( $templates );
			}
		}
	}

	return count( $templates ) ? $templates[0] : null;
}