Introduce (WIP) ical-feed endpoints

includes/core/classes/endpoints/class-posttype-feed-endpoint.php

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+<?php
+/**
+ * Handles feed-based endpoints for custom post types in GatherPress.
+ *
+ * This file defines the `Posttype_Feed_Endpoint` class, which extends the base `Endpoint`
+ * class to handle custom feeds for post type archives. It allows users to define custom
+ * feed URLs (e.g., RSS feeds) for post types such as `gatherpress_event`, while also allowing 
+ * theme overrides for feed templates.
+ *
+ * @package GatherPress\Core\Endpoints
+ * @since 1.0.0
+ */
+
+namespace GatherPress\Core\Endpoints;
+
+// Exit if accessed directly.
+defined( 'ABSPATH' ) || exit; // @codeCoverageIgnore
+
+use GatherPress\Core\Endpoints\Endpoint;
+
+/**
+ * Manages custom feed endpoints for post types in GatherPress.
+ *
+ * The `Posttype_Feed_Endpoint` class extends the base `Endpoint` class to create
+ * custom feed URLs for post types. It handles URL rewriting for feeds and 
+ * ensures that WordPress hooks into the appropriate feed template. The class also 
+ * supports theme overrides, allowing developers to customize feed templates for
+ * specific post types.
+ *
+ * @since 1.0.0
+ */
+class Posttype_Feed_Endpoint extends Endpoint {
+
+	/**
+	 * Class constructor.
+	 *
+	 * Initializes the `Posttype_Feed_Endpoint` for handling custom feeds for the 
+	 * specified post type. It sets up a regular expression to match custom feed 
+	 * URLs (e.g., `event/feed/custom-endpoint`) and hooks into WordPress to load 
+	 * the appropriate feed template.
+	 *
+	 * @since 1.0.0
+	 *
+	 * @param string          $query_var  The query variable used to identify the feed endpoint in the URL.
+	 * @param Endpoint_Type[] $types      List of endpoint types (templates/redirects) for the feed.
+	 * @param string          $post_type  The post type for which the feed endpoint is being created. Default is `gatherpress_event`.
+	 */
+	 public function __construct(
+		string $query_var,
+		array $types,
+		string $post_type = 'gatherpress_event',
+	) {
+		// Expression for the post type archive feeds,
+		// for example 'event/feed/(custom-endpoint)(/)'.
+		$reg_ex = '%s/feed/(%s)/?$';
+
+		parent::__construct(
+			$query_var,
+			$post_type,
+			array( $this, 'is_valid' ),
+			$types,
+			$reg_ex,
+		);
+
+		// Hook into WordPress' feed handling to load the custom feed template.
+		add_action(
+			sprintf(
+				'do_feed_%s',
+				$this->get_slugs( __NAMESPACE__ . '\Endpoint_Template')[0]
+			),
+			array( $this, 'load_template')
+		);
+	}
+
+	 /**
+	 * Load the theme-overridable feed template from the plugin.
+	 *
+	 * This method ensures that a feed template is loaded when a request is made to
+	 * the custom feed endpoint. If the theme provides an override for the feed template,
+	 * it will be used; otherwise, the default template from the plugin is loaded. The 
+	 * method ensures that WordPress does not return a 404 for custom feed URLs.
+	 *
+	 * A call to any post types /feed/anything endpoint is handled by WordPress
+	 * prior 'Endpoint_Template's template_include hook.
+	 * WordPress will throw an xml'ed 404 error,
+	 * if nothing is hooked onto the 'do_feed_anything' action.
+	 *
+	 * That's the reason for this method, it delivers what WordPress wants
+	 * and re-uses the parameters provided by the class.
+	 *
+	 * We expect that a 'Posttype_Feed_Endpoint' only has one 'Redirect_Template' attached.
+	 * This might be wrong or short sightened, please open an issue in that case: https://github.com/GatherPress/gatherpress/issues
+	 *
+	 * Until then, we *just* use the first of the provided endpoint-types,
+	 * to hook into WordPress.
+	 *
+	 * @since 1.0.0
+	 *
+	 * @return void
+	 */
+	 public function load_template() {
+		load_template( $this->types[0]->template_include( false ) );
+	}
+
+	/**
+	 * Validates if the current request is for a post type archive feed.
+	 *
+	 * This method checks if the current request is for an archive page of the specified
+	 * post type and if it is a valid feed request (i.e., `is_feed()` returns true).
+	 *
+	 * @since 1.0.0
+	 *
+	 * @return bool True if the current request is a valid feed request for the post type archive.
+	 */
+	 public function is_valid(): bool {
+		return is_archive( $this->type_object->name ) && is_feed();
+	}
+
+	/**
+	 * Constructs the rewrite URL for the custom feed endpoint.
+	 *
+	 * This method generates the rewrite URL for the custom feed endpoint based on the
+	 * post type and the custom feed slug.
+	 *
+	 * @since 1.0.0
+	 *
+	 * @return string The rewrite URL for the custom feed.
+	 */
+	public function get_rewrite_url() : string {
+		return add_query_arg(
+			array(
+				'post_type' => $this->type_object->name,
+				'feed'      => '$matches[1]',
+			),
+			'index.php'
+		);
+	}
+}

includes/core/classes/endpoints/class-taxonomy-feed-endpoint.php

@@ -0,0 +1,105 @@
+<?php
+
+namespace GatherPress\Core\Endpoints;
+
+// Exit if accessed directly.
+defined( 'ABSPATH' ) || exit; // @codeCoverageIgnore
+
+use GatherPress\Core\Endpoints\Endpoint;
+
+
+class Taxonomy_Feed_Endpoint extends Endpoint {
+
+
+	 public function __construct(
+		string $query_var,
+		array $types,
+		string $taxonomy = 'gatherpress_topic',
+	) {
+		// Expression for the post type archive feeds,
+		// for example 'event/feed/(custom-endpoint)(/)'.
+		$reg_ex = '%s/feed/(%s)/?$';
+
+		parent::__construct(
+			$query_var,
+			$taxonomy,
+			array( $this, 'is_valid' ),
+			$types,
+			$reg_ex,
+			'taxonomy',
+		);
+
+		// Hook into WordPress' feed handling to load the custom feed template.
+		add_action(
+			sprintf(
+				'do_feed_%s',
+				$this->get_slugs( __NAMESPACE__ . '\Endpoint_Template')[0]
+			),
+			array( $this, 'load_template')
+		);
+	}
+
+	/**
+	 * Load the theme-overridable feed template from the plugin.
+	 *
+	 * This method ensures that a feed template is loaded when a request is made to
+	 * the custom feed endpoint. If the theme provides an override for the feed template,
+	 * it will be used; otherwise, the default template from the plugin is loaded. The 
+	 * method ensures that WordPress does not return a 404 for custom feed URLs.
+	 *
+	 * A call to any post types /feed/anything endpoint is handled by WordPress
+	 * prior 'Endpoint_Template's template_include hook.
+	 * WordPress will throw an xml'ed 404 error,
+	 * if nothing is hooked onto the 'do_feed_anything' action.
+	 *
+	 * That's the reason for this method, it delivers what WordPress wants
+	 * and re-uses the parameters provided by the class.
+	 *
+	 * We expect that a 'Posttype_Feed_Endpoint' only has one 'Redirect_Template' attached.
+	 * This might be wrong or short sightened, please open an issue in that case: https://github.com/GatherPress/gatherpress/issues
+	 *
+	 * Until then, we *just* use the first of the provided endpoint-types,
+	 * to hook into WordPress.
+	 *
+	 * @since 1.0.0
+	 *
+	 * @return void
+	 */
+	 public function load_template() {
+		load_template( $this->types[0]->template_include( false ) );
+	}
+
+	/**
+	 * Validates if the current request is for a post type archive feed.
+	 *
+	 * This method checks if the current request is for an archive page of the specified
+	 * post type and if it is a valid feed request (i.e., `is_feed()` returns true).
+	 *
+	 * @since 1.0.0
+	 *
+	 * @return bool True if the current request is a valid feed request for the post type archive.
+	 */
+	 public function is_valid(): bool {
+		return is_archive( $this->type_object->name ) && is_feed();
+	}
+
+	/**
+	 * Constructs the rewrite URL for the custom feed endpoint.
+	 *
+	 * This method generates the rewrite URL for the custom feed endpoint based on the
+	 * post type and the custom feed slug.
+	 *
+	 * @since 1.0.0
+	 *
+	 * @return string The rewrite URL for the custom feed.
+	 */
+	public function get_rewrite_url() : string {
+		return add_query_arg(
+			array(
+				'taxonomy' => $this->type_object->name,
+				'feed'     => '$matches[1]',
+			),
+			'index.php'
+		);
+	}
+}

includes/templates/endpoints/ical-feed.php

@@ -0,0 +1,37 @@
+<?php
+/**
+ * Template for GatherPress ical feeds
+ *
+ * This template is used to render an ical feed to the browser.
+ *
+ * @package GatherPress\Core
+ * @since 1.0.0
+ */
+
+// Exit if accessed directly.
+defined( 'ABSPATH' ) || exit; // @codeCoverageIgnore
+
+use GatherPress\Core\Event;
+
+// Start collecting all output.
+ob_start();
+
+// Prepare event data.
+$gatherpress_filename = 'all-events.ics';
+
+// Send file headers.
+header( 'Content-Description: .ics for all events' );
+header( 'Content-Disposition: attachment; filename=' . $gatherpress_filename );
+header( 'Content-type: text/calendar; charset=' . get_option( 'blog_charset' ) . ';' );
+header( 'Pragma: 0' );
+header( 'Expires: 0' );
+
+// Generate ical.
+echo wp_kses_post( 'hello subscribeable ical feed.' );
+
+// Get collected output and render it.
+$gatherpress_ics_file = ob_get_contents();
+ob_end_clean();
+echo wp_kses_post( $gatherpress_ics_file );
+
+exit();