Add User::is_anonymous and User::is_channel functions

Also add documentation for `User::{full_name, mention, url}`

CHANGELOG.md

@@ -17,6 +17,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 - `Limits::messages_per_min_channel` ([#121][pr121])
 - `media_group_id` field to `MediaDocument` and `MediaAudio` ([#139][pr139])
 - `caption_entities` method to `InputMediaPhoto` ([#140][pr140])
+- `User::is_anonymous` and `User::is_channel` functions ([#151][pr151])
 
 [pr109]: https://github.com/teloxide/teloxide-core/pull/109
 [pr116]: https://github.com/teloxide/teloxide-core/pull/116
@@ -25,6 +26,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 [pr139]: https://github.com/teloxide/teloxide-core/pull/139
 [pr140]: https://github.com/teloxide/teloxide-core/pull/140
 [pr143]: https://github.com/teloxide/teloxide-core/pull/143
+[pr151]: https://github.com/teloxide/teloxide-core/pull/151
 
 ### Changed
 

src/types/user.rs

@@ -28,6 +28,8 @@ pub struct User {
 }
 
 impl User {
+    /// Returns full name of this user, ie first and last names joined with a
+    /// space.
     pub fn full_name(&self) -> String {
         match &self.last_name {
             Some(last_name) => (format!("{0} {1}", self.first_name, last_name)),
@@ -35,12 +37,52 @@ impl User {
         }
     }
 
+    /// Returns a username mention of this user. Returns `None` if
+    /// `self.username.is_none()`.
     pub fn mention(&self) -> Option<String> {
         Some(format!("@{}", self.username.as_ref()?))
     }
 
+    /// Returns an URL that links to this user in the form of
+    /// `tg://user/?id=<...>`
     pub fn url(&self) -> reqwest::Url {
-        reqwest::Url::parse(format!("tg://user/?id={}", self.id).as_str()).unwrap()
+        reqwest::Url::parse(&format!("tg://user/?id={}", self.id)).unwrap()
+    }
+
+    /// Returns `true` if this is special user used by telegram bot API to
+    /// denote an annonymous user that sends messages on behalf of a group.
+    pub fn is_anonymous(&self) -> bool {
+        // https://github.com/tdlib/td/blob/4791fb6a2af0257f6cad8396e10424a79ee5f768/td/telegram/ContactsManager.cpp#L4941-L4943
+        const ANON_ID: i64 = 1087968824;
+
+        // Sanity check
+        debug_assert!(
+            (self.id != ANON_ID)
+                || (self.is_bot
+                    && self.first_name == "Group"
+                    && self.last_name.is_none()
+                    && self.username.as_deref() == Some("GroupAnonymousBot"))
+        );
+
+        self.id == ANON_ID
+    }
+
+    /// Returns `true` if this is special user used by telegram bot API to
+    /// denote an annonymous user that sends messages on behalf of a channel.
+    pub fn is_channel(&self) -> bool {
+        // https://github.com/tdlib/td/blob/4791fb6a2af0257f6cad8396e10424a79ee5f768/td/telegram/ContactsManager.cpp#L4945-L4947
+        const ANON_CHANNEL_ID: i64 = 136817688;
+
+        // Sanity check
+        debug_assert!(
+            (self.id != ANON_CHANNEL_ID)
+                || (self.is_bot
+                    && self.first_name == "Group"
+                    && self.last_name.is_none()
+                    && self.username.as_deref() == Some("GroupAnonymousBot"))
+        );
+
+        self.id == ANON_CHANNEL_ID
     }
 }