Assorted user/chat id additions

crates/teloxide-core/CHANGELOG.md

@@ -16,9 +16,13 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 - `Seconds` type, which represents a duration is seconds ([#859][pr859])
 - `VideoChatEnded::duration` field that was previously missed ([#859][pr859])
 - `ThreadId` newtype over `MessageId`, used for identifying reply threads ([#887][pr887])
+- `ChatId::as_user` ([#905][pr905])
+- Implement `PartialEq<ChatId> for UserId` and `PartialEq<UserId> for ChatId` ([#905][pr905])
+- `ChatId::{MIN, MAX}` ([#905][pr905])
 
 [pr851]: https://github.com/teloxide/teloxide/pull/851
 [pr887]: https://github.com/teloxide/teloxide/pull/887
+[pr905]: https://github.com/teloxide/teloxide/pull/905
 
 ### Fixed
 

crates/teloxide-core/src/types/chat_id.rs

@@ -50,6 +50,15 @@ impl ChatId {
         matches!(self.to_bare(), BareChatId::Channel(_))
     }
 
+    /// Returns user id, if this is an id of a user.
+    #[must_use]
+    pub fn as_user(self) -> Option<UserId> {
+        match self.to_bare() {
+            BareChatId::User(u) => Some(u),
+            BareChatId::Group(_) | BareChatId::Channel(_) => None,
+        }
+    }
+
     /// Converts this id to "bare" MTProto peer id.
     ///
     /// See [`BareChatId`] for more.
@@ -73,6 +82,12 @@ impl From<UserId> for ChatId {
     }
 }
 
+impl PartialEq<UserId> for ChatId {
+    fn eq(&self, other: &UserId) -> bool {
+        self.is_user() && *self == ChatId::from(*other)
+    }
+}
+
 impl BareChatId {
     /// Converts bare chat id back to normal bot API [`ChatId`].
     #[allow(unused)]
@@ -92,8 +107,8 @@ const MIN_MARKED_CHANNEL_ID: i64 = -1997852516352;
 const MAX_MARKED_CHANNEL_ID: i64 = -1000000000000;
 const MIN_MARKED_CHAT_ID: i64 = MAX_MARKED_CHANNEL_ID + 1;
 const MAX_MARKED_CHAT_ID: i64 = MIN_USER_ID - 1;
-const MIN_USER_ID: i64 = 0;
-const MAX_USER_ID: i64 = (1 << 40) - 1;
+pub(crate) const MIN_USER_ID: i64 = 0;
+pub(crate) const MAX_USER_ID: i64 = (1 << 40) - 1;
 
 #[cfg(test)]
 mod tests {
@@ -143,4 +158,16 @@ mod tests {
     fn display() {
         assert_eq!(ChatId(1).to_string(), "1");
     }
+
+    #[test]
+    fn user_id_eq() {
+        assert_eq!(ChatId(12), UserId(12));
+        assert_eq!(ChatId(4652762), UserId(4652762));
+        assert_ne!(ChatId(17), UserId(42));
+
+        // The user id is not well formed, so even though `-1 == max` is true,
+        // we don't want user id to match
+        assert_eq!(-1i64, u64::MAX as i64);
+        assert_ne!(ChatId(-1), UserId(u64::MAX));
+    }
 }

crates/teloxide-core/src/types/user_id.rs

@@ -1,5 +1,7 @@
 use serde::{Deserialize, Serialize};
 
+use crate::types::{ChatId, MAX_USER_ID, MIN_USER_ID};
+
 /// Identifier of a user.
 #[derive(Clone, Copy)]
 #[derive(Debug, derive_more::Display)]
@@ -50,6 +52,19 @@ impl UserId {
 
         self == TELEGRAM_USER_ID
     }
+
+    /// The smallest user id that could possibly be returned by Telegram.
+    pub const MIN: Self = Self(MIN_USER_ID as u64);
+
+    /// The largest user id that could possibly be returned by Telegram.
+    pub const MAX: Self = Self(MAX_USER_ID as u64);
+}
+
+impl PartialEq<ChatId> for UserId {
+    fn eq(&self, other: &ChatId) -> bool {
+        // Reuse `PartialEq<UserId> for ChatId` impl
+        other == self
+    }
 }
 
 #[cfg(test)]