Product::options()

	public function options() {
		$data = json_decode( get_post_meta( $this->post_id(), self::OPTIONS_DATA_META_KEY, true ), true );
		if ( empty( $data ) || ! is_array( $data ) ) {
			return [];
		}

		// ensure we have all the fields we expect for each option
		$data = array_map( function ( $option ) {
			return wp_parse_args( $option, [
				'id'            => 0,
				'display_name'  => '',
				'type'          => '',
				'sort_order'    => 0,
				'option_values' => [],
				'required'      => true,
				'config'        => [],
			] );
		}, $data );

		// filter out option values not present on any of the variants
		$source          = $this->get_source_data();
		$variant_options = [];
		foreach ( $source->variants as $variant ) {
			foreach ( $variant->option_values as $value ) {
				$variant_options[ $value->option_id ][] = $value->id;
			}
		}
		$variant_options = array_map( 'array_unique', $variant_options );
		$data            = array_map( function ( $option ) use ( $variant_options ) {
			$valid_values = isset( $variant_options[ $option['id'] ] ) ? $variant_options[ $option['id'] ] : [];

			$option['option_values'] = array_filter( $option['option_values'], function ( $value ) use ( $valid_values ) {
				return in_array( $value['id'], $valid_values );
			} );

			return $option;
		}, $data );

		// respect the sorting set by the user
		usort( $data, function ( $a, $b ) {
			if ( $a['sort_order'] == $b['sort_order'] ) {
				return ( $a['display_name'] < $b['display_name'] ) ? - 1 : 1;
			}

			return ( $a['sort_order'] < $b['sort_order'] ) ? - 1 : 1;
		} );

		return $data;
	}