feat: implement paginated outboxes

Mastodon will *only* show posts if they're paginated, fun fact.

public/api/v1/actor.php

@@ -47,33 +47,57 @@ function get_actor(string $preferred_username) {
 	die();
 }
 
-function get_actor_outbox(string $preferred_username) {
+/** /api/v1/actor/:preferred_username/outbox?before=:before_date_iso&limit=:limit
+ * Returns an OrderedCollectionPage of at most `limit` pages published before
+ * `before_date_iso`.
+ *
+ * Parameters:
+ *	before		ISO timestamp string. Only posts published before this time are included
+ *	limit		Integer. Number of posts to include in the result. Default: 20. Max: HOSTAS_MAX_POSTS_PER_PAGE
+ */
+function get_actor_outbox_paged(string $preferred_username) {
 	header('Content-Type: application/activity+json');
 
+	$before = array_key_exists('before', $_GET) ? $_GET['before'] : date(DATE_ISO8601, time());
+	$after = array_key_exists('after', $_GET) ? $_GET['after'] : date(DATE_ISO8601, 0);
+	$limit = array_key_exists('limit', $_GET) ? $_GET['limit'] : 20;
+
+	// Parameters in $_GET with a + character will get replaced with whitespace,
+	// so we've got to change it back
+	$before = str_replace(" ", "+", $before);
+	$after = str_replace(" ", "+", $after);
+
+	// Cap the limit at the configured maximum
+	if ($limit > HOSTAS_MAX_POSTS_PER_PAGE) {
+		$limit = HOSTAS_MAX_POSTS_PER_PAGE;
+	}
+
 	$conn = new SQLite3(HOSTAS_DATABASE_PATH);
 	$actor = get_actor_or_exit($conn, $preferred_username);
 
-	$create_activities_result = prepare_and_execute($conn,
+	$sql_query = <<<'EOT'
-		"select object.id as object_id, object.type as object_type,
+		select object.id as object_id, object.type as object_type,
 			activity.actor as activity_actor, post.id as post_id,
 			post.published as post_published, post.type as post_type,
-			post.content as post_content
+			post.content as post_content, post.published as post_published
 			from object
 			join activity on activity.objectId = object.id
 			join object as post on activity.object = post.id
-			where activity.actor = :actor_id
+			where
-			order by object.published",
+				activity_actor = :actor_id
-/*
+				and post_published < :before
-		"select object.id as object_id, object.type as object_type,
+				and post_published > :after
-			post.id as post_id, post.type as post.type, post.published as post_published,
+			order by object.published desc
-			post.url as post_url, post.content as post_content
+			limit :limit
-			from object
+	EOT;
-			join activity on activity.objectId = object.id
+
-			join object as post on activity.object = post.id
+	$create_activities_result = prepare_and_execute($conn, $sql_query,
-			where activity.actor = :actor_id
+		array(
-			order by object.published",
+			':actor_id' => $actor['id'],
-*/
+			':before' => strtotime($before),
-		array(':actor_id' => $actor['id'])
+			':after' => strtotime($after),
+			':limit' => $limit
+		)
 	);
 
 	$total_items = 0;
@@ -99,12 +123,64 @@ function get_actor_outbox(string $preferred_username) {
 		));
 	}
 
+	$clean_uri = 'https://' . HOSTAS_DOMAIN . strtok($_SERVER['REQUEST_URI'], '?');
+
+	$response = array(
+		'@context' => HOSTAS_CONTEXT,
+		'id' => 'https://' . HOSTAS_DOMAIN . $_SERVER['REQUEST_URI'],
+		'type' => 'OrderedCollectionPage',
+		'partOf' => 'https://' . HOSTAS_DOMAIN . $clean_uri,
+		'orderedItems' => $ordered_items,
+	);
+
+	if ($total_items === 0) {
+		// There may be previous items, so we can reuse the before param. We
+		// need to do some pre-processing to avoid characters getting escaped
+		// from the URL
+		$latest_time = str_replace(" ", "+", $before);
+		$response['prev'] = $clean_uri . "?after=$latest_time";
+	} else {
+		$earliest_time = $ordered_items[array_key_last($ordered_items)]['published'];
+		$latest_time = $ordered_items[0]['published'];
+
+		$response['prev'] = $clean_uri . "?after=$latest_time";
+		$response['next'] = $clean_uri . "?before=$earliest_time";
+	}
+
+	echo json_encode($response);
+
+	die();
+}
+
+function get_actor_outbox(string $preferred_username) {
+	header('Content-Type: application/activity+json');
+
+	$conn = new SQLite3(HOSTAS_DATABASE_PATH);
+	$actor = get_actor_or_exit($conn, $preferred_username);
+
+	$sql_query = <<<'EOT'
+		select count(post.id) as post_count, min(post.published)
+			from object
+			join activity on activity.objectId = object.id
+			join object as post on activity.object = post.id
+			where activity.actor = :actor_id
+	EOT;
+
+	$items_count_result = prepare_and_execute($conn, $sql_query,
+		array(':actor_id' => $actor['id'])
+	);
+	$items_count_row = $items_count_result->fetchArray(SQLITE3_ASSOC);
+	$total_items = $items_count_row['post_count'];
+
+	$collection_id = "https://" . HOSTAS_DOMAIN . "/api/v1/actor/$preferred_username/outbox";
+
 	echo json_encode(array(
 		'@context' => HOSTAS_CONTEXT,
-		'id' => "https://" . HOSTAS_DOMAIN . "/api/v1/actor/$preferred_username/outbox",
+		'id' => $collection_id,
 		'type' => 'OrderedCollection',
 		'totalItems' => $total_items,
-		'orderedItems' => $ordered_items,
+		'first' => $collection_id . '?before=' . date(DATE_ISO8601, time()),
+		'last' => $collection_id . '?after=' . date(DATE_ISO8601, 0),
 	));
 
 	die();
@@ -118,8 +194,15 @@ switch ($_SERVER['REQUEST_METHOD']) {
 	case 'GET':
 		if (sizeof(REQUEST_PATH) === 3) {
 			if (REQUEST_PATH[2] === 'inbox')	get_actor_inbox(REQUEST_PATH[1]);
-			else if (REQUEST_PATH[2] === 'outbox')	get_actor_outbox(REQUEST_PATH[1]);
+			else if (REQUEST_PATH[2] === 'outbox') {
+				if (array_key_exists('before', $_GET) || array_key_exists('after', $_GET)) {
+					get_actor_outbox_paged(REQUEST_PATH[1]);
+				} else {
+					get_actor_outbox(REQUEST_PATH[1]);
 				}
+			}
+		}
+
 		get_actor(REQUEST_PATH[1]);
 		break;
 	default: