Add new filters for manipulating supported posts

These filters allow more control over what posts are exported
en masse and whether individual posts should be exported.

Closes #119.

CHANGELOG.md

@@ -4,6 +4,9 @@ This change log follows the [Keep a Changelog standards]. Versions follows [Sema
 
 ### [Unreleased] ###
 
+* New filters:
+    * `wpghs_pre_fetch_all_supported`: Filter the query args before all supported posts are queried.
+    * `wpghs_is_post_supported`: Determines whether the post is supported by importing/exporting.
 * Bugfix: Set secret to password field. See [#124].
 * Bugfix: Fix error when importing branch-deletion webhooks.
 * Bugfix: Fix "semaphore is locked" response from webhook. See [#121].

lib/database.php

@@ -45,12 +45,14 @@ public function __construct( WordPress_GitHub_Sync $app ) {
 	 * @return WordPress_GitHub_Sync_Post[]|WP_Error
 	 */
 	public function fetch_all_supported() {
-		$query = new WP_Query( array(
+		$args  = array(
 			'post_type'   => $this->get_whitelisted_post_types(),
 			'post_status' => $this->get_whitelisted_post_statuses(),
 			'nopaging'    => true,
 			'fields'      => 'ids',
-		) );
+		);
+
+		$query = new WP_Query( apply_filters( 'wpghs_pre_fetch_all_supported', $args ) );
 
 		$post_ids = $query->get_posts();
 
@@ -338,7 +340,7 @@ protected function is_post_supported( WordPress_GitHub_Sync_Post $post ) {
 			return false;
 		}
 
-		return true;
+		return apply_filters( 'wpghs_is_post_supported', true, $post );
 	}
 
 	/**