class-push.php

<?php
/**
 * Publish to Apple News: \Apple_Actions\Index\Push class
 *
 * @package Apple_News
 * @subpackage Apple_Actions\Index
 */

namespace Apple_Actions\Index;

require_once dirname( __DIR__ ) . '/class-api-action.php';
require_once __DIR__ . '/class-export.php';

use Admin_Apple_Async;
use Admin_Apple_Notice;
use Admin_Apple_Sections;
use Apple_Exporter\Exporter;
use Apple_Exporter\Settings;
use Apple_Actions\API_Action;
use Apple_Actions\Action_Exception;
use Apple_Push_API\Request\Request_Exception;

/**
 * A class to handle a push request from the admin.
 *
 * @package Apple_News
 * @subpackage Apple_Actions\Index
 */
class Push extends API_Action {

	/**
	 * Checksum for current article being exported.
	 *
	 * @var string
	 * @access private
	 */
	private $checksum;

	/**
	 * Current content ID being exported.
	 *
	 * @var int
	 * @access private
	 */
	private $id;

	/**
	 * Sections for the content being exported.
	 *
	 * @var array
	 * @access private
	 */
	private $sections;

	/**
	 * Current instance of the Exporter.
	 *
	 * @var Exporter
	 * @access private
	 */
	private $exporter;

	/**
	 * Constructor.
	 *
	 * @param Settings $settings A settings object containing settings at load time.
	 * @param int      $id The ID for the content object to be pushed.
	 */
	public function __construct( $settings, $id ) {
		parent::__construct( $settings );
		$this->id       = $id;
		$this->exporter = null;
	}

	/**
	 * Perform the push action.
	 *
	 * @param boolean $doing_async Optional. Whether the action is being performed asynchronously.
	 * @param int     $user_id Optional. The ID of the user performing the action. Defaults to the current user ID.
	 *
	 * @return false|null
	 * @throws Action_Exception If the push fails.
	 */
	public function perform( $doing_async = false, $user_id = null ) {
		if ( 'yes' === $this->settings->__get( 'api_async' ) && false === $doing_async ) {

			// Do not proceed if this is already pending publish.
			$pending = get_post_meta( $this->id, 'apple_news_api_pending', true );

			if ( ! empty( $pending ) ) {
				return false;
			}

			// Track this publish event as pending with the timestamp it was sent.
			update_post_meta( $this->id, 'apple_news_api_pending', time() );

			wp_schedule_single_event( time(), Admin_Apple_Async::ASYNC_PUSH_HOOK, [ $this->id, get_current_user_id() ] );
		} else {
			return $this->push( $user_id );
		}
	}

	/**
	 * Generate a checksum against the article JSON with certain fields ignored.
	 *
	 * @param string $json The JSON to turn into a checksum.
	 * @param array  $meta Optional. Metadata for the article. Defaults to empty array.
	 * @param array  $bundles Optional. Any bundles that will be sent with the article. Defaults to empty array.
	 * @param bool   $force Optional. Allows bypass of local cache for checksum.
	 *
	 * @return string The checksum for the JSON.
	 */
	private function generate_checksum( $json, $meta = [], $bundles = [], $force = false ) {
		// Use cached checksum, if it exists, and if force is false.
		if ( ! $force && ! empty( $this->checksum ) ) {
			return $this->checksum;
		}

		// Try to decode the JSON object.
		$json = json_decode( $json, true );
		if ( empty( $json ) ) {
			return '';
		}

		// Remove any fields from JSON that might change but not affect the article itself, like dates and plugin version.
		unset( $json['metadata']['dateCreated'] );
		unset( $json['metadata']['dateModified'] );
		unset( $json['metadata']['datePublished'] );
		unset( $json['metadata']['generatorVersion'] );

		// Add meta and bundles so we can checksum the whole thing.
		$json['checksum']['meta']    = $meta;
		$json['checksum']['bundles'] = $bundles;

		// Calculate the checksum as a hex value and cache it.
		$this->checksum = dechex( absint( crc32( wp_json_encode( $json ) ) ) );

		return $this->checksum;
	}

	/**
	 * Check if the post is in sync before updating in Apple News.
	 *
	 * @access private
	 *
	 * @param string $json The JSON for this article to check if it is in sync.
	 * @param array  $meta Optional. Metadata for the article. Defaults to empty array.
	 * @param array  $bundles Optional. Any bundles that will be sent with the article. Defaults to empty array.
	 *
	 * @return boolean
	 * @throws Action_Exception If the post could not be found.
	 */
	private function is_post_in_sync( $json, $meta = [], $bundles = [] ) {
		$in_sync = true;

		// Ensure the post (still) exists. Async operations might result in this function being run against a non-existent post.
		$post = get_post( $this->id );
		if ( ! $post ) {
			throw new Action_Exception( esc_html( __( 'Apple News Error: Could not find post with id ', 'apple-news' ) . $this->id ) );
		}

		// Compare checksums to determine whether the article is in sync or not.
		$current_checksum = get_post_meta( $this->id, 'apple_news_article_checksum', true );
		$new_checksum     = $this->generate_checksum( $json, $meta, $bundles );
		if ( empty( $current_checksum ) || $current_checksum !== $new_checksum ) {
			$in_sync = false;
		}

		/**
		 * Allows for custom logic to determine if a post is in sync or not.
		 *
		 * By default, the plugin simply compares the last modified time to the
		 * last time it was pushed to Apple News. If you want to apply custom
		 * logic, you can do that by modifying `$in_sync`. The most common use case
		 * is to not update posts based on custom criteria.
		 *
		 * @param bool $in_sync Whether the current post is in sync or not.
		 * @param int $post_id The ID of the post being checked.
		 * @param string $json The JSON for the current article.
		 * @param array $meta Metadata for the current article.
		 * @param array $bundles Any bundles that will be sent with the current article.
		 *
		 * @since 2.0.2 Added the $post_id, $json, $meta, and $bundles parameters.
		 */
		return apply_filters( 'apple_news_is_post_in_sync', $in_sync, $this->id, $json, $meta, $bundles );
	}

	/**
	 * Get the post using the API data.
	 * Updates the current relevant metadata stored for the post.
	 *
	 * @access private
	 * @throws Action_Exception If there was an error getting the article from the API.
	 */
	private function get(): void {
		// Ensure we have a valid ID.
		$apple_id = get_post_meta( $this->id, 'apple_news_api_id', true );
		if ( empty( $apple_id ) ) {
			throw new Action_Exception( esc_html__( 'This post does not have a valid Apple News ID, so it cannot be retrieved from the API.', 'apple-news' ) );
		}

		// Get the article from the API.
		$result = $this->get_api()->get_article( $apple_id );
		if ( empty( $result->data->revision ) ) {
			throw new Action_Exception( esc_html__( 'The Apple News API returned invalid data for this article since the revision is empty.', 'apple-news' ) );
		}

		// Update the revision.
		update_post_meta( $this->id, 'apple_news_api_revision', sanitize_text_field( $result->data->revision ) );
	}

	/**
	 * Push the post using the API data.
	 *
	 * @param int  $user_id Optional. The ID of the user performing the push. Defaults to current user.
	 * @param bool $display_notices Optional. Whether to display notices. Defaults to true.
	 *
	 * @throws Action_Exception If unable to push.
	 */
	private function push( $user_id = null, $display_notices = true ): void {
		if ( ! $this->is_api_configuration_valid() ) {
			throw new Action_Exception( esc_html__( 'Your Apple News API settings seem to be empty. Please fill in the API key, API secret and API channel fields in the plugin configuration page.', 'apple-news' ) );
		}

		/**
		 * Filters whether the post should be skipped and not pushed to Apple News.
		 *
		 * Allows you to stop publication of a post to Apple News based on your own
		 * custom logic. A common use case is to not publish posts with a certain
		 * category or tag. By default this is always `false` as all posts are
		 * published once they reach this step.
		 *
		 * @param bool $skip Whether the post should be skipped. Defaults to `false`.
		 * @param int $post_id The ID of the post.
		 */
		if ( apply_filters( 'apple_news_skip_push', false, $this->id ) ) {
			throw new Action_Exception(
				sprintf(
				// Translators: Placeholder is a post ID.
					esc_html__( 'Skipped push of article %d due to the apple_news_skip_push filter.', 'apple-news' ),
					absint( $this->id )
				)
			);
		}

		// Special logic only if autosync push is enabled.
		if ( $this->settings->api_autosync ) {
			// Get the list of term IDs that should trigger a skip push from plugin settings.
			$skip_term_ids = json_decode( $this->settings->api_autosync_skip );
			if ( ! is_array( $skip_term_ids ) ) {
				$skip_term_ids = [];
			}

			/**
			 * Filters whether the post should be skipped and not pushed to Apple News
			 * based on taxonomy term IDs that are associated with the post.
			 *
			 * Allows you to stop publication of a post to Apple News based on whether a
			 * certain taxonomy term ID is applied to the post. A common use case is to
			 * not publish posts with a certain category or tag. The default value for
			 * this filter is the value of the skip push term IDs from the API settings
			 * for the plugin, but the list can be modified for individual posts via
			 * this filter.
			 *
			 * @param int[] $term_ids The list of term IDs that should trigger a skipped push. Defaults to the term IDs set in plugin options.
			 * @param int $post_id The ID of the post being exported.
			 *
			 * @since 2.3.0
			 */
			$skip_term_ids = apply_filters( 'apple_news_skip_push_term_ids', $skip_term_ids, $this->id );

			// Compile a list of term IDs for the current post across all supported taxonomies for the post type.
			$term_ids   = [];
			$taxonomies = get_object_taxonomies( get_post_type( $this->id ) );
			foreach ( $taxonomies as $taxonomy ) {
				$term_ids_for_taxonomy = get_the_terms( $this->id, $taxonomy );
				if ( is_array( $term_ids_for_taxonomy ) ) {
					$term_ids = array_merge(
						$term_ids,
						wp_list_pluck( $term_ids_for_taxonomy, 'term_id' )
					);
				}
			}

			// If any of the terms for the current post are in the list of term IDs that should be skipped, bail out.
			if ( array_intersect( $term_ids, $skip_term_ids ) ) {
				throw new Action_Exception(
					sprintf(
					// Translators: Placeholder is a post ID.
						esc_html__( 'Skipped push of article %d due to the presence of a skip push taxonomy term.', 'apple-news' ),
						absint( $this->id )
					)
				);
			}
		}

		/**
		 * The generate_article function uses Exporter->generate, so we MUST
		 * clean the workspace before and after its usage.
		 */
		$this->clean_workspace();

		// Get sections.
		$this->sections = Admin_Apple_Sections::get_sections_for_post( $this->id );

		// Generate the JSON for the article.
		[ $json, $bundles, $errors ] = $this->generate_article();

		// Process errors.
		$this->process_errors( $errors );

		// Sanitize the data before using since it's filterable.
		$json = $this->sanitize_json( $json );

		// Bundles should be an array of URLs.
		if ( ! empty( $bundles ) && is_array( $bundles ) ) {
			$bundles = array_map( 'esc_url_raw', $bundles );
		} else {
			$bundles = [];
		}

		// If there's an API ID, update, otherwise create.
		$remote_id = get_post_meta( $this->id, 'apple_news_api_id', true );
		$result    = null;

		/**
		 * Actions to be taken before the article is pushed to Apple News.
		 *
		 * @param int $post_id The ID of the post.
		 */
		do_action( 'apple_news_before_push', $this->id );

		// Populate optional metadata.
		$meta = [
			'data' => [],
		];

		// Set sections.
		if ( ! empty( $this->sections ) ) {
			sort( $this->sections );
			$meta['data']['links'] = [ 'sections' => $this->sections ];
		}

		// Set boolean metadata. Don't set values at all if they are not set in postmeta, or are set to empty string.
		$metadata_keys = [
			'isHidden'    => 'apple_news_is_hidden',
			'isPaid'      => 'apple_news_is_paid',
			'isPreview'   => 'apple_news_is_preview',
			'isSponsored' => 'apple_news_is_sponsored',
		];
		foreach ( $metadata_keys as $metadata_property => $meta_key ) {
			$meta_value = get_post_meta( $this->id, $meta_key, true );
			if ( 'true' === $meta_value || '1' === $meta_value ) {
				$meta['data'][ $metadata_property ] = true;
			} elseif ( 'false' === $meta_value || '0' === $meta_value ) {
				$meta['data'][ $metadata_property ] = false;
			}
		}

		// Get the maturity rating setting.
		$maturity_rating = get_post_meta( $this->id, 'apple_news_maturity_rating', true );
		if ( ! empty( $maturity_rating ) ) {
			$meta['data']['maturityRating'] = $maturity_rating;
		}

		// Add custom metadata fields.
		$custom_meta = get_post_meta( $this->id, 'apple_news_metadata', true );
		$meta        = $this->get_meta( $custom_meta, $meta );

		/**
		 * Allow article metadata to be filtered.
		 *
		 * @param array $metadata The article metadata to be filtered.
		 * @param int $post_id The ID of the post being pushed to Apple News.
		 *
		 * @since 2.4.0
		 */
		$meta['data'] = apply_filters( 'apple_news_article_metadata', $meta['data'], $this->id );

		// Ignore if the post is already in sync.
		if ( $this->is_post_in_sync( $json, $meta, $bundles ) ) {
			throw new Action_Exception(
				sprintf(
				// Translators: Placeholder is a post ID.
					esc_html__( 'Skipped push of article %d to Apple News because it is already in sync.', 'apple-news' ),
					$this->id // phpcs:ignore WordPress.Security.EscapeOutput.ExceptionNotEscaped
				)
			);
		}

		$original_error_message = null;
		$error_message          = null;

		try {
			if ( $remote_id ) {
				// Update the current article from the API in case the revision changed.
				$this->get();

				// Get the current revision.
				$revision = get_post_meta( $this->id, 'apple_news_api_revision', true );
				$result   = $this->get_api()->update_article( $remote_id, $revision, $json, $bundles, $meta, $this->id );
			} else {
				$result = $this->get_api()->post_article_to_channel( $json, $this->get_setting( 'api_channel' ), $bundles, $meta, $this->id );
			}

			// Save the ID that was assigned to this post in by the API.
			update_post_meta( $this->id, 'apple_news_api_id', sanitize_text_field( $result->data->id ) );
			update_post_meta( $this->id, 'apple_news_api_created_at', sanitize_text_field( $result->data->createdAt ) );
			update_post_meta( $this->id, 'apple_news_api_modified_at', sanitize_text_field( $result->data->modifiedAt ) );
			update_post_meta( $this->id, 'apple_news_api_share_url', sanitize_text_field( $result->data->shareUrl ) );
			update_post_meta( $this->id, 'apple_news_api_revision', sanitize_text_field( $result->data->revision ) );

			// If it's marked as deleted, remove the mark. Ignore otherwise.
			delete_post_meta( $this->id, 'apple_news_api_deleted' );

			// Remove the pending designation if it exists.
			delete_post_meta( $this->id, 'apple_news_api_pending' );

			// Remove the async in progress flag.
			delete_post_meta( $this->id, 'apple_news_api_async_in_progress' );

			// Clear the cache for post status.
			delete_transient( 'apple_news_post_state_' . $this->id );

			// Update the checksum for the article JSON version.
			update_post_meta( $this->id, 'apple_news_article_checksum', $this->generate_checksum( $json, $meta, $bundles ) );

			/**
			 * Actions to be taken after an article was pushed to Apple News.
			 *
			 * @param int $post_id The ID of the post.
			 * @param object $result The JSON returned by the Apple News API.
			 */
			do_action( 'apple_news_after_push', $this->id, $result );
		} catch ( Request_Exception $e ) {

			// Remove the pending designation if it exists.
			delete_post_meta( $this->id, 'apple_news_api_pending' );

			// Remove the async in progress flag.
			delete_post_meta( $this->id, 'apple_news_api_async_in_progress' );

			$this->clean_workspace();

			$original_error_message = $e->getMessage();

			if ( str_contains( $original_error_message, 'WRONG_REVISION' ) ) {
				$error_message = __( 'Apple News Error: It seems like the article was updated by another call. If the problem persists, try removing and pushing again.', 'apple-news' );
			} elseif ( str_contains( $original_error_message, 'NOT_FOUND (keyPath articleId)' ) ) {
				// Reset the API postmeta if the article is deleted in Apple News.
				$this->delete_post_meta( $this->id );

				$error_message = __( 'Publish to Apple News: This article was previously deleted in iCloud News Publisher. Due to your automatic publishing settings, it has been recreated on Apple News.', 'apple-news' );
			} else {
				$error_message = __( 'There has been an error with the Apple News API: ', 'apple-news' ) . esc_html( $original_error_message );
			}
		} finally {
			/**
			 * Reindex the article if it was deleted in the iCloud News Publisher dashboard.
			 *
			 * @see https://github.com/alleyinteractive/apple-news/issues/1154
			 */
			if ( $original_error_message && str_contains( $original_error_message, 'NOT_FOUND (keyPath articleId)' ) ) {
				try {
					self::push(
						user_id: $user_id,
						display_notices: false
					);
				} catch ( Action_Exception $e ) { // phpcs:ignore Generic.CodeAnalysis.EmptyStatement.DetectedCatch
					// Do nothing, even if the second push fails.
				}
			}

			if ( $error_message ) {
				/**
				 * Actions to be taken after an article failed to be pushed to Apple News.
				 *
				 * @param int $post_id The ID of the post.
				 * @param string|null $original_error_message The original error message, if available.
				 * @param string $error_message The error message to be displayed.
				 */
				do_action( 'apple_news_after_push_failure', $this->id, $original_error_message, $error_message );

				throw new Action_Exception( esc_html( $error_message ) );
			}
		}

		// If we're not supposed to display notices, bail out.
		if ( false === $display_notices ) {
			return;
		}

		// Print success message.
		$post = get_post( $this->id );

		$success_message = sprintf(
			// translators: token is the post title.
			__( 'Article %s has been pushed successfully to Apple News!', 'apple-news' ),
			$post->post_title
		);

		if ( $remote_id ) {
			$success_message = sprintf(
				// translators: token is the post title.
				__( 'Article %s has been successfully updated on Apple News!', 'apple-news' ),
				$post->post_title
			);
		}

		Admin_Apple_Notice::success( $success_message, $user_id );

		$this->clean_workspace();
	}

	/**
	 * Processes errors, halts publishing if needed.
	 *
	 * @param array $errors Array of errors to be processed.
	 *
	 * @access private
	 * @throws Action_Exception If set to fail on component errors.
	 */
	private function process_errors( $errors ): void {
		// Get the current alert settings.
		$component_alerts = $this->get_setting( 'component_alerts' );

		// Initialize the alert message.
		$alert_message = '';

		// Get the current user id.
		$user_id = get_current_user_id();

		// Build the component alert error message, if required.
		if ( ! empty( $errors[0]['component_errors'] ) ) {
			// Build a list of the components that caused errors.
			$component_names = implode( ', ', $errors[0]['component_errors'] );

			if ( 'warn' === $component_alerts ) {
				$alert_message .= sprintf(
				// translators: token is a list of component names.
					__( 'The following components are unsupported by Apple News and were removed: %s', 'apple-news' ),
					$component_names
				);
			} elseif ( 'fail' === $component_alerts ) {
				$alert_message .= sprintf(
				// translators: token is a list of component names.
					__( 'The following components are unsupported by Apple News and prevented publishing: %s', 'apple-news' ),
					$component_names
				);
			}
		}

		// See if we found any errors.
		if ( empty( $alert_message ) ) {
			return;
		}

		// Proceed based on component alert settings.
		if ( 'fail' === $component_alerts && ! empty( $errors[0]['component_errors'] ) ) {
			// Remove the pending designation if it exists.
			delete_post_meta( $this->id, 'apple_news_api_pending' );

			// Remove the async in progress flag.
			delete_post_meta( $this->id, 'apple_news_api_async_in_progress' );

			// Clean the workspace.
			$this->clean_workspace();

			// Throw an exception.
			throw new Action_Exception( esc_html( $alert_message ) );
		} elseif ( 'warn' === $component_alerts && ! empty( $errors[0]['component_errors'] ) ) {
			Admin_Apple_Notice::error( $alert_message, $user_id );
		}
	}

	/**
	 * Allows debugging of API requests by dumping the data
	 * that will be sent to the API.
	 */
	public function debug(): void {
		$post_id = $this->id;
		$post    = get_post( $post_id );
		if ( ! $post ) {
			return;
		}

		$this->sections              = Admin_Apple_Sections::get_sections_for_post( $post_id );
		[ $json, $bundles, $errors ] = $this->generate_article();

		// Retrieve the metadata using the same method as in the push() function.
		$meta = [ 'data' => [] ];

		// Set sections.
		if ( ! empty( $this->sections ) ) {
			sort( $this->sections );
			$meta['data']['links'] = [ 'sections' => $this->sections ];
		}

		// Get the various settings.
		$metadata_keys = [
			'isHidden'    => 'apple_news_is_hidden',
			'isPaid'      => 'apple_news_is_paid',
			'isPreview'   => 'apple_news_is_preview',
			'isSponsored' => 'apple_news_is_sponsored',
		];
		foreach ( $metadata_keys as $metadata_property => $meta_key ) {
			$meta_value = get_post_meta( $post_id, $meta_key, true );
			if ( 'true' === $meta_value || '1' === $meta_value ) {
				$meta['data'][ $metadata_property ] = true;
			} elseif ( 'false' === $meta_value || '0' === $meta_value ) {
				$meta['data'][ $metadata_property ] = false;
			}
		}

		$maturity_rating = get_post_meta( $post_id, 'apple_news_maturity_rating', true );
		if ( ! empty( $maturity_rating ) ) {
			$meta['data']['maturityRating'] = $maturity_rating;
		}

		// Add custom metadata fields.
		$custom_meta  = get_post_meta( $post_id, 'apple_news_metadata', true );
		$meta         = $this->get_meta( $custom_meta, $meta );
		$meta['data'] = apply_filters( 'apple_news_article_metadata', $meta['data'], $post_id );

		header( 'Content-Type: text/html' );

		echo '<h1>Apple News API Push</h1><pre style="font-size: 0.9em; background: #f9f9f9; padding: 10px; border: 1px solid #ccc; max-width: 90%; overflow: scroll; white-space: pre-wrap;">';
		echo 'Post ID: ' . esc_html( $post_id ) . "\n";

		echo '<hr>Article:<br>';
		$formatted_json = json_decode( $json );
		echo wp_json_encode( $formatted_json, JSON_PRETTY_PRINT | JSON_UNESCAPED_SLASHES );
		echo "\n";

		echo '<hr>Bundles:<br>';
		echo wp_json_encode( $bundles, JSON_PRETTY_PRINT | JSON_UNESCAPED_SLASHES );
		echo "\n";

		echo '<hr>Meta:<br>';
		echo wp_json_encode( $meta, JSON_PRETTY_PRINT | JSON_UNESCAPED_SLASHES );
		echo "\n";

		echo '</pre>';

		// Clean the workspace after the debug.
		$this->clean_workspace();
	}

	/**
	 * Clean up the workspace.
	 *
	 * @access private
	 */
	private function clean_workspace(): void {
		if ( is_null( $this->exporter ) ) {
			return;
		}

		$this->exporter->workspace()->clean_up();
	}

	/**
	 * Use the export action to get an instance of the Exporter. Use that to
	 * manually generate the workspace for upload, then clean it up.
	 *
	 * @access private
	 * @since 0.6.0
	 */
	private function generate_article() {

		$export_action = new Export( $this->settings, $this->id, $this->sections );
		Export::set_exporting( true );
		$this->exporter = $export_action->fetch_exporter();
		$this->exporter->generate();
		Export::set_exporting( false );

		return [ $this->exporter->get_json(), $this->exporter->get_bundles(), $this->exporter->get_errors() ];
	}

	/**
	 * Sanitize the JSON output based on whether HTML or markdown is used.
	 *
	 * @param string $json The JSON to be sanitized.
	 *
	 * @access private
	 * @return string
	 * @throws Action_Exception If the JSON is invalid.
	 * @since 1.2.7
	 */
	private function sanitize_json( $json ) {
		/**
		 * Apple News format is complex and has too many options to validate otherwise.
		 * Let's just make sure the JSON is valid.
		 */
		$decoded = json_decode( $json );
		if ( ! $decoded ) {
			throw new Action_Exception( esc_html__( 'The Apple News JSON is invalid and cannot be published.', 'apple-news' ) );
		} else {
			return wp_json_encode( $decoded );
		}
	}

	/**
	 * Get the custom post meta data and add it to the article metadata array.
	 *
	 * @access private
	 *
	 * @param mixed $custom_meta The custom meta data.
	 * @param array $meta The article metadata.
	 *
	 * @return array The updated article metadata.
	 */
	private function get_meta( mixed $custom_meta, array $meta ): array {
		if ( ! empty( $custom_meta ) && is_array( $custom_meta ) ) {
			foreach ( $custom_meta as $metadata ) {
				// Ensure required fields are set.
				if ( empty( $metadata['key'] ) || empty( $metadata['type'] ) || ! isset( $metadata['value'] ) ) {
					continue;
				}

				// If the value is an array, we have to decode it from JSON.
				$value = $metadata['value'];
				if ( 'array' === $metadata['type'] ) {
					$value = json_decode( $metadata['value'] );

					// If the user entered a bad value for the array, bail out without adding it.
					if ( empty( $value ) || ! is_array( $value ) ) {
						continue;
					}
				}

				// Add the custom metadata field to the article metadata.
				$meta['data'][ $metadata['key'] ] = $value;
			}
		}

		return $meta;
	}
}