Listing_Fetcher

class Listing_Fetcher implements Import_Processor {
	use No_Cache_Options;

	const STATE_OPTION        = 'bigcommerce_import_listing_id_fetcher_state';
	const PRODUCT_LISTING_MAP = 'bigcommerce_product_listing_map';

	/**
	 * @var ChannelsApi
	 */
	private $channels;

	/**
	 * @var int
	 */
	private $limit;

	/**
	 * @var \WP_Term
	 */
	private $channel_term;

	/**
	 * Listing_Fetcher constructor.
	 *
	 * @param ChannelsApi $channels The Channels API connection to use for the import
	 * @param \WP_Term    $channel_term
	 * @param int         $limit    Number of listing IDs to fetch per request
	 */
	public function __construct( ChannelsApi $channels, \WP_Term $channel_term, $limit = 100 ) {
		$this->limit        = $limit;
		$this->channel_term = $channel_term;
		$this->channels     = $channels;
	}

	public function run() {
		$status = new Status();
		$status->set_status( Status::FETCHING_LISTINGS . '-' . $this->channel_term->term_id );

		$channel_id = get_term_meta( $this->channel_term->term_id, Channel::CHANNEL_ID, true );
		if ( empty( $channel_id ) ) {
			do_action( 'bigcommerce/import/error', __( 'Channel ID is not set. Product import canceled.', 'bigcommerce' ) );

			return;
		}

		$modified_product_ids = [];
		$import_type          = get_option( Import_Type::IMPORT_TYPE );
		if ( $import_type === Import_Type::IMPORT_TYPE_PARTIAL ) {
			/**
			 * Filters modified product ids.
			 *
			 * @param array $modified_product_ids Product ids.
			 */
			$modified_product_ids = apply_filters( 'bigcommerce_modified_product_ids', [] );

			if ( empty( $modified_product_ids ) ) {
				$status->set_status( Status::FETCHED_LISTINGS . '-' . $this->channel_term->term_id );
				$this->clear_state();
				$this->update_option( self::PRODUCT_LISTING_MAP, [], false );

				return;
			}
		}

		$id_map = $this->get_option( self::PRODUCT_LISTING_MAP, [] ) ?: [];
		$next = $this->get_next();

		do_action( 'bigcommerce/log', Error_Log::DEBUG, __( 'Retrieving listings', 'bigcommerce' ), [
			'limit' => $this->limit,
			'after' => $next ?: null,
		] );

		try {
			$response = $this->channels->listChannelListings( $channel_id, [
				'product_id:in' => $modified_product_ids,
				'limit'         => $this->limit,
				'after'         => $next ?: null,
			] );
		} catch ( ApiException $e ) {
			do_action( 'bigcommerce/import/error', $e->getMessage(), [
				'response' => $e->getResponseBody(),
				'headers'  => $e->getResponseHeaders(),
			] );
			do_action( 'bigcommerce/log', Error_Log::DEBUG, $e->getTraceAsString(), [] );

			return;
		}

		foreach ( $response->getData() as $listing ) {
			if ( $listing->getState() === 'deleted' ) {
				continue;
			}
			$data = ObjectSerializer::sanitizeForSerialization( $listing );
			$id_map[ (int) $listing->getProductId() ][ $this->channel_term->term_id ] = wp_json_encode( $data );
		}
		$this->update_option( self::PRODUCT_LISTING_MAP, $id_map, false );

		$next = $this->extract_next_from_response( $response );
		if ( $next ) {
			do_action( 'bigcommerce/log', Error_Log::DEBUG, __( 'Ready for next page of listings', 'bigcommerce' ), [
				'next' => $next,
			] );
			$this->set_next( $next );
		} else {
			$status->set_status( Status::FETCHED_LISTINGS . '-' . $this->channel_term->term_id );
			$this->clear_state();
		}
	}

	/**
	 * @param ListingCollectionResponse $response
	 *
	 * @return int The value for the parameter to use for the next page of results
	 */
	private function extract_next_from_response( ListingCollectionResponse $response ) {
		$next_args = $response->getMeta()->getPagination()->getLinks()->getNext();
		if ( empty( $next_args ) ) {
			return 0;
		}
		$next_args = ltrim( $next_args, '?' );
		parse_str( $next_args, $args );
		// Eventually, the API should change to support the page parameter. Until then, use after.
		if ( empty( $args[ 'after' ] ) ) {
			return 0;
		}

		return (int) $args[ 'after' ];
	}

	private function get_next() {
		$state = $this->get_state();
		if ( ! array_key_exists( 'next', $state ) ) {
			return 0;
		}

		return $state[ 'next' ];
	}

	private function set_next( $next ) {
		$state           = $this->get_state();
		$state[ 'next' ] = (int) $next;
		$this->set_state( $state );
	}

	private function get_state() {
		$state = $this->get_option( $this->state_option(), [] );
		if ( ! is_array( $state ) ) {
			return [];
		}

		return $state;
	}

	private function set_state( array $state ) {
		$this->update_option( $this->state_option(), $state, false );
	}

	private function clear_state() {
		$this->delete_option( $this->state_option() );
	}

	private function state_option() {
		return sprintf( '%s-%d', self::STATE_OPTION, $this->channel_term->term_id );
	}
}