feat(ffi): add room alias format validation & room name to alias

bindings/matrix-sdk-ffi/src/lib.rs

@@ -16,6 +16,7 @@ mod notification;
 mod notification_settings;
 mod platform;
 mod room;
+mod room_alias;
 mod room_directory_search;
 mod room_info;
 mod room_list;

bindings/matrix-sdk-ffi/src/room_alias.rs

@@ -0,0 +1,14 @@
+use matrix_sdk::DisplayName;
+use ruma::RoomAliasId;
+
+/// Verifies the passed `String` matches the expected room alias format.
+#[matrix_sdk_ffi_macros::export]
+fn is_room_alias_format_valid(alias: String) -> bool {
+    RoomAliasId::parse(alias).is_ok()
+}
+
+/// Transforms a Room's display name into a valid room alias name.
+#[matrix_sdk_ffi_macros::export]
+fn room_alias_name_from_room_display_name(room_name: String) -> String {
+    DisplayName::Named(room_name).to_room_alias_name()
+}

crates/matrix-sdk-base/Cargo.toml

@@ -67,6 +67,7 @@ tokio = { workspace = true }
 thiserror = { workspace = true }
 tracing = { workspace = true }
 uniffi = { workspace = true, optional = true }
+regex = "1.11.1"
 
 [dev-dependencies]
 assert_matches = { workspace = true }

crates/matrix-sdk-base/src/rooms/mod.rs

@@ -15,6 +15,7 @@ pub use normal::{
     Room, RoomHero, RoomInfo, RoomInfoNotableUpdate, RoomInfoNotableUpdateReasons, RoomState,
     RoomStateFilter,
 };
+use regex::Regex;
 use ruma::{
     assign,
     events::{
@@ -64,6 +65,38 @@ pub enum DisplayName {
     Empty,
 }
 
+const WHITESPACE_REGEX: &str = r"\s+";
+const INVALID_SYMBOLS_REGEX: &str = r"[#,:]+";
+
+impl DisplayName {
+    /// Transforms the current display name into the name part of a
+    /// `RoomAliasId`.
+    pub fn to_room_alias_name(&self) -> String {
+        let room_name = match self {
+            Self::Named(name) => name,
+            Self::Aliased(name) => name,
+            Self::Calculated(name) => name,
+            Self::EmptyWas(name) => name,
+            Self::Empty => "",
+        };
+
+        let whitespace_regex =
+            Regex::new(WHITESPACE_REGEX).expect("`WHITESPACE_REGEX` should be valid");
+        let symbol_regex =
+            Regex::new(INVALID_SYMBOLS_REGEX).expect("`INVALID_SYMBOLS_REGEX` should be valid");
+
+        // Replace whitespaces with `-`
+        let sanitised = whitespace_regex.replace_all(room_name, "-");
+        // Remove non-ASCII characters and ASCII control characters
+        let sanitised =
+            String::from_iter(sanitised.chars().filter(|c| c.is_ascii() && !c.is_ascii_control()));
+        // Remove other problematic ASCII symbols
+        let sanitised = symbol_regex.replace_all(&sanitised, "");
+        // Lowercased
+        sanitised.to_lowercase()
+    }
+}
+
 impl fmt::Display for DisplayName {
     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
         match self {
@@ -541,6 +574,7 @@ mod tests {
     use ruma::events::tag::{TagInfo, TagName, Tags};
 
     use super::{BaseRoomInfo, RoomNotableTags};
+    use crate::DisplayName;
 
     #[test]
     fn test_handle_notable_tags_favourite() {
@@ -571,4 +605,24 @@ mod tests {
         base_room_info.handle_notable_tags(&tags);
         assert!(base_room_info.notable_tags.contains(RoomNotableTags::LOW_PRIORITY).not());
     }
+
+    #[test]
+    fn test_room_alias_from_room_display_name_lowercases() {
+        assert_eq!("roomalias", DisplayName::Named("RoomAlias".to_owned()).to_room_alias_name());
+    }
+
+    #[test]
+    fn test_room_alias_from_room_display_name_removes_whitespace() {
+        assert_eq!("room-alias", DisplayName::Named("Room Alias".to_owned()).to_room_alias_name());
+    }
+
+    #[test]
+    fn test_room_alias_from_room_display_name_removes_non_ascii_symbols() {
+        assert_eq!("roomalias", DisplayName::Named("Room±Alias√".to_owned()).to_room_alias_name());
+    }
+
+    #[test]
+    fn test_room_alias_from_room_display_name_removes_invalid_ascii_symbols() {
+        assert_eq!("roomalias", DisplayName::Named("#Room,Alias:".to_owned()).to_room_alias_name());
+    }
 }