events: introduce custom StateKey type for call member state events

crates/ruma-events/src/call/member.rs

@@ -6,9 +6,11 @@
 
 mod focus;
 mod member_data;
+mod member_state_key;
 
 pub use focus::*;
 pub use member_data::*;
+pub use member_state_key::*;
 use ruma_common::MilliSecondsSinceUnixEpoch;
 use ruma_macros::{EventContent, StringEnum};
 use serde::{Deserialize, Serialize};
@@ -29,7 +31,7 @@ use crate::{
 ///
 /// This struct also exposes allows to call the methods from [`CallMemberEventContent`].
 #[derive(Clone, Debug, Serialize, Deserialize, EventContent, PartialEq)]
-#[ruma_event(type = "org.matrix.msc3401.call.member", kind = State, state_key_type = String, custom_redacted, custom_possibly_redacted)]
+#[ruma_event(type = "org.matrix.msc3401.call.member", kind = State, state_key_type = CallMemberStateKey, custom_redacted, custom_possibly_redacted)]
 #[cfg_attr(not(feature = "unstable-exhaustive-types"), non_exhaustive)]
 #[serde(untagged)]
 pub enum CallMemberEventContent {
@@ -177,7 +179,7 @@ impl RedactContent for CallMemberEventContent {
 pub type PossiblyRedactedCallMemberEventContent = CallMemberEventContent;
 
 impl PossiblyRedactedStateEventContent for PossiblyRedactedCallMemberEventContent {
-    type StateKey = String;
+    type StateKey = CallMemberStateKey;
 }
 
 /// The Redacted version of [`CallMemberEventContent`].
@@ -193,7 +195,7 @@ impl ruma_events::content::EventContent for RedactedCallMemberEventContent {
 }
 
 impl RedactedStateEventContent for RedactedCallMemberEventContent {
-    type StateKey = String;
+    type StateKey = CallMemberStateKey;
 }
 
 /// Legacy content with an array of memberships. See also: [`CallMemberEventContent`]
@@ -231,8 +233,11 @@ mod tests {
     use std::time::Duration;
 
     use assert_matches2::assert_matches;
-    use ruma_common::{MilliSecondsSinceUnixEpoch as TS, OwnedEventId, OwnedRoomId, OwnedUserId};
-    use serde_json::{from_value as from_json_value, json};
+    use ruma_common::{
+        device_id, user_id, MilliSecondsSinceUnixEpoch as TS, OwnedEventId, OwnedRoomId,
+        OwnedUserId,
+    };
+    use serde_json::{from_value as from_json_value, json, Value as JsonValue};
 
     use super::{
         focus::{ActiveFocus, ActiveLivekitFocus, Focus, LivekitFocus},
@@ -467,8 +472,8 @@ mod tests {
         );
     }
 
-    fn deserialize_member_event_helper(state_key: &str) {
-        let ev = json!({
+    fn member_event_json(state_key: &str) -> JsonValue {
+        json!({
             "content":{
                 "application": "m.call",
                 "call_id": "",
@@ -497,7 +502,11 @@ mod tests {
                 "prev_content": {},
                 "prev_sender":"@user:example.org",
             }
-        });
+        })
+    }
+
+    fn deserialize_member_event_helper(state_key: &str) {
+        let ev = member_event_json(state_key);
 
         assert_matches!(
             from_json_value(ev),
@@ -507,7 +516,7 @@ mod tests {
         let event_id = OwnedEventId::try_from("$3qfxjGYSu4sL25FtR0ep6vePOc").unwrap();
         let sender = OwnedUserId::try_from("@user:example.org").unwrap();
         let room_id = OwnedRoomId::try_from("!1234:example.org").unwrap();
-        assert_eq!(member_event.state_key, state_key);
+        assert_eq!(member_event.state_key.as_ref(), state_key);
         assert_eq!(member_event.event_id, event_id);
         assert_eq!(member_event.sender, sender);
         assert_eq!(member_event.room_id, room_id);
@@ -555,12 +564,12 @@ mod tests {
 
     #[test]
     fn deserialize_member_event_with_scoped_state_key_prefixed() {
-        deserialize_member_event_helper("_@user:example.org:THIS_DEVICE");
+        deserialize_member_event_helper("_@user:example.org_THIS_DEVICE");
     }
 
     #[test]
     fn deserialize_member_event_with_scoped_state_key_unprefixed() {
-        deserialize_member_event_helper("@user:example.org:THIS_DEVICE");
+        deserialize_member_event_helper("@user:example.org_THIS_DEVICE");
     }
 
     fn timestamps() -> (TS, TS, TS) {
@@ -632,4 +641,52 @@ mod tests {
             vec![] as Vec<MembershipData<'_>>
         );
     }
+
+    #[test]
+    fn test_parse_rtc_member_event_key() {
+        assert!(from_json_value::<AnyStateEvent>(member_event_json("abc")).is_err());
+        assert!(from_json_value::<AnyStateEvent>(member_event_json("@nocolon")).is_err());
+        assert!(from_json_value::<AnyStateEvent>(member_event_json("@noserverpart:")).is_err());
+        assert!(
+            from_json_value::<AnyStateEvent>(member_event_json("@noserverpart:_suffix")).is_err()
+        );
+
+        let user_id = user_id!("@username:example.org").as_str();
+        let device_id = device_id!("VALID_DEVICE_ID").as_str();
+
+        let parse_result = from_json_value::<AnyStateEvent>(member_event_json(user_id));
+        assert_matches!(parse_result, Ok(_));
+        assert_matches!(
+            from_json_value::<AnyStateEvent>(member_event_json(&format!("{user_id}_{device_id}"))),
+            Ok(_)
+        );
+
+        assert_matches!(
+            from_json_value::<AnyStateEvent>(member_event_json(&format!(
+                "{user_id}:invalid_suffix"
+            ))),
+            Err(_)
+        );
+
+        assert_matches!(
+            from_json_value::<AnyStateEvent>(member_event_json(&format!("_{user_id}"))),
+            Err(_)
+        );
+
+        assert_matches!(
+            from_json_value::<AnyStateEvent>(member_event_json(&format!("_{user_id}_{device_id}"))),
+            Ok(_)
+        );
+
+        assert_matches!(
+            from_json_value::<AnyStateEvent>(member_event_json(&format!(
+                "_{user_id}:invalid_suffix"
+            ))),
+            Err(_)
+        );
+        assert_matches!(
+            from_json_value::<AnyStateEvent>(member_event_json(&format!("{user_id}_"))),
+            Err(_)
+        );
+    }
 }

crates/ruma-events/src/call/member/member_state_key.rs

@@ -0,0 +1,225 @@
+use std::str::FromStr;
+
+use ruma_common::{DeviceId, OwnedDeviceId, OwnedUserId, UserId};
+use serde::{
+    de::{self, Deserialize, Deserializer, Unexpected},
+    Serialize, Serializer,
+};
+/// A type that can be used as the `state_key` for call member state events.
+/// Those state keys can be a combination of UserId and DeviceId.
+#[derive(Clone, Debug, PartialEq, Eq, PartialOrd, Ord)]
+#[allow(clippy::exhaustive_structs)]
+pub struct CallMemberStateKey {
+    key: CallMemberStateKeyEnum,
+    raw: Box<str>,
+}
+
+impl CallMemberStateKey {
+    /// Constructs a new CallMemberStateKey there are three possible formats:
+    /// - "_{UserId}_{DeviceId}" example: "_@test:user.org_DEVICE". `device_id`: Some`, `underscore:
+    ///   true`
+    /// - "{UserId}_{DeviceId}" example: "@test:user.org_DEVICE". `device_id`: Some`, `underscore:
+    ///   false`
+    /// - "{UserId}" example example: "@test:user.org". `device_id`: None`, underscore is ignored:
+    ///   `underscore: false|true`
+    ///
+    /// Dependent on the parameters the correct CallMemberStateKey will be constructed.
+    pub fn new(user_id: OwnedUserId, device_id: Option<OwnedDeviceId>, underscore: bool) -> Self {
+        CallMemberStateKeyEnum::new(user_id, device_id, underscore).into()
+    }
+
+    /// Returns the user id in this state key.
+    /// (This is a cheap operations. The id is already type checked on initialization. And does
+    /// only returns a reference to an existing OwnedUserId.)
+    pub fn user_id(&self) -> &UserId {
+        match &self.key {
+            CallMemberStateKeyEnum::UnderscoreUserDevice(u, _) => u,
+            CallMemberStateKeyEnum::UserDevice(u, _) => u,
+            CallMemberStateKeyEnum::User(u) => u,
+        }
+    }
+
+    /// Returns the device id in this state key (if available)
+    /// (This is a cheap operations. The id is already type checked on initialization. And does
+    /// only returns a reference to an existing OwnedDeviceId.)
+    pub fn device_id(&self) -> Option<&DeviceId> {
+        match &self.key {
+            CallMemberStateKeyEnum::UnderscoreUserDevice(_, d) => Some(d),
+            CallMemberStateKeyEnum::UserDevice(_, d) => Some(d),
+            CallMemberStateKeyEnum::User(_) => None,
+        }
+    }
+}
+
+impl AsRef<str> for CallMemberStateKey {
+    fn as_ref(&self) -> &str {
+        &self.raw
+    }
+}
+
+impl From<CallMemberStateKeyEnum> for CallMemberStateKey {
+    fn from(value: CallMemberStateKeyEnum) -> Self {
+        let raw = value.to_string().into();
+        Self { key: value, raw }
+    }
+}
+
+impl FromStr for CallMemberStateKey {
+    type Err = KeyParseError;
+
+    fn from_str(state_key: &str) -> Result<Self, Self::Err> {
+        // Intentionally do not use CallMemberStateKeyEnum.into since this would reconstruct the
+        // state key string.
+        Ok(Self { key: CallMemberStateKeyEnum::from_str(state_key)?, raw: state_key.into() })
+    }
+}
+
+impl<'de> Deserialize<'de> for CallMemberStateKey {
+    fn deserialize<D>(deserializer: D) -> Result<Self, D::Error>
+    where
+        D: Deserializer<'de>,
+    {
+        let s = ruma_common::serde::deserialize_cow_str(deserializer)?;
+        Self::from_str(&s).map_err(|err| de::Error::invalid_value(Unexpected::Str(&s), &err))
+    }
+}
+
+impl Serialize for CallMemberStateKey {
+    fn serialize<S>(&self, serializer: S) -> Result<S::Ok, S::Error>
+    where
+        S: Serializer,
+    {
+        serializer.serialize_str(self.as_ref())
+    }
+}
+
+/// This enum represents all possible formats for a call member event state key.
+#[derive(Clone, Debug, PartialEq, Eq, PartialOrd, Ord)]
+enum CallMemberStateKeyEnum {
+    UnderscoreUserDevice(OwnedUserId, OwnedDeviceId),
+    UserDevice(OwnedUserId, OwnedDeviceId),
+    User(OwnedUserId),
+}
+
+impl CallMemberStateKeyEnum {
+    fn new(user_id: OwnedUserId, device_id: Option<OwnedDeviceId>, underscore: bool) -> Self {
+        match (device_id, underscore) {
+            (Some(device_id), true) => {
+                CallMemberStateKeyEnum::UnderscoreUserDevice(user_id, device_id)
+            }
+            (Some(device_id), false) => CallMemberStateKeyEnum::UserDevice(user_id, device_id),
+            (None, _) => CallMemberStateKeyEnum::User(user_id),
+        }
+    }
+}
+
+impl std::fmt::Display for CallMemberStateKeyEnum {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        match &self {
+            CallMemberStateKeyEnum::UnderscoreUserDevice(u, d) => write!(f, "_{u}_{d}"),
+            CallMemberStateKeyEnum::UserDevice(u, d) => write!(f, "{u}_{d}"),
+            CallMemberStateKeyEnum::User(u) => f.write_str(u.as_str()),
+        }
+    }
+}
+
+impl FromStr for CallMemberStateKeyEnum {
+    type Err = KeyParseError;
+
+    fn from_str(state_key: &str) -> Result<Self, Self::Err> {
+        // Ignore leading underscore if present
+        // (used for avoiding auth rules on @-prefixed state keys)
+        let (state_key, underscore) = match state_key.strip_prefix('_') {
+            Some(s) => (s, true),
+            None => (state_key, false),
+        };
+
+        // Fail early if we cannot find the index of the ":"
+        let Some(colon_idx) = state_key.find(':') else {
+            return Err(KeyParseError::InvalidUser {
+                user_id: state_key.to_owned(),
+                error: ruma_common::IdParseError::MissingColon,
+            });
+        };
+
+        let (user_id, device_id) = match state_key[colon_idx + 1..].find('_') {
+            None => {
+                return match UserId::parse(state_key) {
+                    Ok(user_id) => {
+                        if underscore {
+                            Err(KeyParseError::LeadingUnderscoreNoDevice)
+                        } else {
+                            Ok(CallMemberStateKeyEnum::new(user_id, None, underscore))
+                        }
+                    }
+                    Err(err) => Err(KeyParseError::InvalidUser {
+                        error: err,
+                        user_id: state_key.to_owned(),
+                    }),
+                }
+            }
+            Some(suffix_idx) => {
+                (&state_key[..colon_idx + 1 + suffix_idx], &state_key[colon_idx + 2 + suffix_idx..])
+            }
+        };
+
+        match (UserId::parse(user_id), OwnedDeviceId::from(device_id)) {
+            (Ok(user_id), device_id) => {
+                if device_id.as_str().is_empty() {
+                    return Err(KeyParseError::EmptyDevice);
+                };
+                Ok(CallMemberStateKeyEnum::new(user_id, Some(device_id), underscore))
+            }
+            (Err(err), _) => {
+                Err(KeyParseError::InvalidUser { user_id: user_id.to_owned(), error: err })
+            }
+        }
+    }
+}
+
+/// Error when trying to parse a call member state key.
+#[derive(Debug, thiserror::Error)]
+#[non_exhaustive]
+pub enum KeyParseError {
+    /// The user part of the state key is invalid.
+    #[error("uses a malformatted UserId in the UserId defined section.")]
+    InvalidUser {
+        /// The user Id that the parser thinks it should have parsed.
+        user_id: String,
+        /// The user Id parse error why if failed to parse it.
+        error: ruma_common::IdParseError,
+    },
+    /// Uses a leading underscore but no trailing device id. The part after the underscore is a
+    /// valid user id.
+    #[error("uses a leading underscore but no trailing device id. The part after the underscore is a valid user id.")]
+    LeadingUnderscoreNoDevice,
+    /// Uses an empty device id. (UserId with trailing underscore)
+    #[error("uses an empty device id. (UserId with trailing underscore)")]
+    EmptyDevice,
+}
+
+impl de::Expected for KeyParseError {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        write!(f, "correct call member event key format. The provided string, {})", self)
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use std::str::FromStr;
+
+    use crate::call::member::{member_state_key::CallMemberStateKeyEnum, CallMemberStateKey};
+
+    #[test]
+    fn convert_state_key_enum_to_state_key() {
+        let key = "_@user:domain.org_DEVICE";
+        let state_key_enum = CallMemberStateKeyEnum::from_str(key).unwrap();
+        // This generates state_key.raw from the enum
+        let state_key: CallMemberStateKey = state_key_enum.into();
+        // This compares state_key.raw (generated) with key (original)
+        assert_eq!(state_key.as_ref(), key);
+        // Compare to the from string without `CallMemberStateKeyEnum` step.
+        let state_key_direct = CallMemberStateKey::from_str(state_key.as_ref()).unwrap();
+        assert_eq!(state_key, state_key_direct);
+    }
+}