Detect #lang: tags

for-sogops.md

@@ -16,6 +16,16 @@ Due to the lack of progress on the [issue of built-in Community tags](https://gi
 
 The obvious benefit is searchability. However, tags such as `#nsfw` or `#test` also help us automatically hide parts of the Community display.
 
+#### Language tags
+
+Mark your Community with a language emoji by adding a tag of the form `#lang:CODE` at the end of your Community description.
+
+You can use any two-letter country code, or use any of the following codes:
+
+- `lang:any` or `lang:all` for 🌐,
+- `lang:en` for 🇬🇧, and
+- `lang:zh` for 🇨🇳.
+
 ### Server-wide icons
 
 You may notice the Host column groups Communities by their host SOGS, and some SOGS are easily recognizable by a unified icon. If you also want your Communities to be linked by a recognizable icon, the requirements are easy:

php/servers/servers-rooms.php

@@ -118,6 +118,14 @@
 		 */
 		private array $tags = [];
 
+		/**
+		 * @var string $language_flag;
+		 * Flag emoji as derived from specifying tags.
+		 *
+		 * Custom attribute.
+		 */
+		private ?string $language_flag;
+
 		private function __construct(CommunityServer $server, array $details) {
 			$this->server = $server;
 			$this->active_users = $details['active_users'];
@@ -154,6 +162,14 @@
 			$room_identifier = $this->get_room_identifier();
 			$server_pubkey = $this->server->get_pubkey();
 
+			if (isset($this->language_flag)) {
+				return $this->language_flag;
+			}
+
+			// Latter only applies to fetching stage
+			// where the language flag is serialized into JSON.
+			// Later stages deserialize the property and detect it above.
+
 			if (isset($languages[$room_identifier])) {
 				return $languages[$room_identifier];
 			} elseif (isset($languages[$server_pubkey])) {
@@ -234,7 +250,10 @@
 			$room = new CommunityRoom($server, $details);
 			$has_tags = isset($details['tags']);
 			if ($has_tags) {
-				$room->tags = $details['tags'];
+				$room->add_tags($details['tags']);
+			}
+			if (isset($details['language_flag'])) {
+				$room->language_flag = $details['language_flag'];
 			}
 			return $room;
 		}
@@ -367,7 +386,48 @@
 		 * @param string[] $tags
 		 */
 		public function add_tags(array $tags) {
-			$this->tags = [...$this->tags, ...$tags];
+			foreach ($tags as $tag) {
+				if (!$this->parse_language_tag($tag)) {
+					$this->tags[] = $tag;
+				}
+			}
+		}
+
+		/**
+		 * Apply language from tag and return true if language tag, return false otherwise.
+		 * @param string $tag
+		 * @return bool
+		 */
+		private function parse_language_tag(string $tag): bool {
+			$matches = [];
+
+			if (preg_match("/^lang:([a-z]+)$/", $tag, $matches) != 1) {
+				return false;
+			}
+
+			if (isset($this->language_flag)) {
+				log_warning("Language is already $this->language_flag, parsing $tag");
+				return true;
+			}
+
+			$lang = $matches[1];
+			if ($lang == "any" || $lang == "all") {
+				$this->language_flag = "🌐";
+			} elseif ($lang == "en") {
+				$this->language_flag = "🇬🇧";
+			} elseif ($lang == "zh") {
+				$this->language_flag = "🇨🇳";
+			} elseif (strlen($lang) == 2) {
+				$chars = str_split($lang);
+				$flag_chars = array_map(function(string $char) {
+					return mb_chr(ord($char) - ord("a") + mb_ord("🇦"));
+				}, $chars);
+				$this->language_flag = implode($flag_chars);
+			} else {
+				return false; // Invalid language flag
+			}
+
+			return true;
 		}
 
 		/**
@@ -1306,7 +1366,7 @@
 			log_info("Fetching pubkey from $preview_url");
 			$room_view_response = yield from FetchingCoroutine
 				::from_url($preview_url)
-				->retryable($has_pubkey || $FAST_FETCH_MODE ? 1 : 5)
+				->retryable(($has_pubkey || $FAST_FETCH_MODE) ? 1 : 5)
 				->run();
 
 			$room_view = $room_view_response
@@ -1318,6 +1378,7 @@
 				return $has_pubkey;
 			}
 
+
 			$links = parse_join_links($room_view);
 			$link = $links[0];