Add mentioned_users to update types where it makes sense

crates/teloxide-core/src/lib.rs

@@ -117,6 +117,7 @@ mod bot;
 
 // implementation details
 mod serde_multipart;
+mod util;
 
 #[cfg(test)]
 mod codegen;

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

@@ -49,6 +49,20 @@ pub struct CallbackQuery {
     pub game_short_name: Option<String>,
 }
 
+impl CallbackQuery {
+    /// Returns all users that are "contained" in this `CallbackQuery`
+    /// structure.
+    ///
+    /// This might be useful to track information about users.
+    /// Note that this function can return duplicate users.
+    pub fn mentioned_users(&self) -> impl Iterator<Item = &User> {
+        use crate::util::flatten;
+        use std::iter::once;
+
+        once(&self.from).chain(flatten(self.message.as_ref().map(Message::mentioned_users)))
+    }
+}
+
 #[cfg(test)]
 mod tests {
     use crate::types::UserId;

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

@@ -1,6 +1,6 @@
 use serde::{Deserialize, Serialize};
 
-use crate::types::{ChatId, ChatLocation, ChatPermissions, ChatPhoto, Message, True};
+use crate::types::{ChatId, ChatLocation, ChatPermissions, ChatPhoto, Message, True, User};
 
 /// This object represents a chat.
 ///
@@ -493,6 +493,23 @@ impl Chat {
             _ => None,
         }
     }
+
+    /// Returns all users that are "contained" in this `Chat`
+    /// structure.
+    ///
+    /// This might be useful to track information about users.
+    ///
+    /// Note that this function can return duplicate users.
+    pub fn mentioned_users(&self) -> impl Iterator<Item = &User> {
+        crate::util::flatten(self.pinned_message.as_ref().map(|m| m.mentioned_users()))
+    }
+
+    /// `{Message, Chat}::mentioned_users` are mutually recursive, as such we
+    /// can't use `->impl Iterator` everywhere, as it would make an infinite
+    /// type. So we need to box somewhere.
+    pub(crate) fn mentioned_users_rec(&self) -> impl Iterator<Item = &User> {
+        crate::util::flatten(self.pinned_message.as_ref().map(|m| m.mentioned_users_rec()))
+    }
 }
 
 mod serde_helper {

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

@@ -18,3 +18,15 @@ pub struct ChatJoinRequest {
     /// Chat invite link that was used by the user to send the join request
     pub invite_link: Option<ChatInviteLink>,
 }
+
+impl ChatJoinRequest {
+    /// Returns all users that are "contained" in this `ChatJoinRequest`
+    /// structure.
+    ///
+    /// This might be useful to track information about users.
+    ///
+    /// Note that this function can return duplicate users.
+    pub fn mentioned_users(&self) -> impl Iterator<Item = &User> {
+        std::iter::once(&self.from).chain(self.chat.mentioned_users())
+    }
+}

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

@@ -20,3 +20,21 @@ pub struct ChatMemberUpdated {
     /// joining by invite link events only.
     pub invite_link: Option<ChatInviteLink>,
 }
+
+impl ChatMemberUpdated {
+    /// Returns all users that are "contained" in this `ChatMemberUpdated`
+    /// structure.
+    ///
+    /// This might be useful to track information about users.
+    ///
+    /// Note that this function can return duplicate users.
+    pub fn mentioned_users(&self) -> impl Iterator<Item = &User> {
+        [
+            &self.from,
+            /* ignore `old_chat_member.user`, it should always be the same as the new one */
+            &self.new_chat_member.user,
+        ]
+        .into_iter()
+        .chain(self.chat.mentioned_users())
+    }
+}

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

@@ -1,6 +1,6 @@
 use serde::{Deserialize, Serialize};
 
-use crate::types::{Animation, MessageEntity, PhotoSize};
+use crate::types::{Animation, MessageEntity, PhotoSize, User};
 
 /// This object represents a game.
 ///
@@ -39,3 +39,17 @@ pub struct Game {
     /// [@Botfather]: https://t.me/botfather
     pub animation: Option<Animation>,
 }
+
+impl Game {
+    /// Returns all users that are "contained" in this `Game`
+    /// structure.
+    ///
+    /// This might be useful to track information about users.
+    ///
+    /// Note that this function can return duplicate users.
+    pub fn mentioned_users(&self) -> impl Iterator<Item = &User> {
+        use crate::util::{flatten, mentioned_users_from_entities};
+
+        flatten(self.text_entities.as_deref().map(mentioned_users_from_entities))
+    }
+}

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

@@ -1406,6 +1406,42 @@ impl Message {
     pub fn parse_caption_entities(&self) -> Option<Vec<MessageEntityRef<'_>>> {
         self.caption().zip(self.caption_entities()).map(|(t, e)| MessageEntityRef::parse(t, e))
     }
+
+    /// Returns all users that are "contained" in this `Message` structure.
+    ///
+    /// This might be useful to track information about users.
+    ///
+    /// Note that this function may return quite a few users as it scans
+    /// replies, pinned messages, message entities and more. Also note that this
+    /// function can return duplicate users.
+    pub fn mentioned_users(&self) -> impl Iterator<Item = &User> {
+        use crate::util::{flatten, mentioned_users_from_entities};
+
+        // Lets just hope we didn't forget something here...
+
+        self.from()
+            .into_iter()
+            .chain(self.via_bot.as_ref())
+            .chain(self.chat.mentioned_users_rec())
+            .chain(flatten(self.reply_to_message().map(Self::mentioned_users_rec)))
+            .chain(flatten(self.new_chat_members()))
+            .chain(self.left_chat_member())
+            .chain(self.forward_from_user())
+            .chain(flatten(self.forward_from_chat().map(Chat::mentioned_users_rec)))
+            .chain(flatten(self.game().map(Game::mentioned_users)))
+            .chain(flatten(self.entities().map(mentioned_users_from_entities)))
+            .chain(flatten(self.caption_entities().map(mentioned_users_from_entities)))
+            .chain(flatten(self.poll().map(Poll::mentioned_users)))
+            .chain(flatten(self.proximity_alert_triggered().map(|a| [&a.traveler, &a.watcher])))
+            .chain(flatten(self.video_chat_participants_invited().and_then(|i| i.users.as_deref())))
+    }
+
+    /// `Message::mentioned_users` is recursive (due to replies), as such we
+    /// can't use `->impl Iterator` everywhere, as it would make an infinite
+    /// type. So we need to box somewhere.
+    pub(crate) fn mentioned_users_rec(&self) -> Box<dyn Iterator<Item = &User> + Send + Sync + '_> {
+        Box::new(self.mentioned_users())
+    }
 }
 
 #[cfg(test)]

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

@@ -1,4 +1,4 @@
-use crate::types::{MessageEntity, PollType};
+use crate::types::{MessageEntity, PollType, User};
 
 use chrono::{DateTime, Utc};
 use serde::{Deserialize, Serialize};
@@ -67,6 +67,20 @@ pub struct PollOption {
     pub voter_count: i32,
 }
 
+impl Poll {
+    /// Returns all users that are "contained" in this `Poll`
+    /// structure.
+    ///
+    /// This might be useful to track information about users.
+    ///
+    /// Note that this function can return duplicate users.
+    pub fn mentioned_users(&self) -> impl Iterator<Item = &User> {
+        use crate::util::{flatten, mentioned_users_from_entities};
+
+        flatten(self.explanation_entities.as_deref().map(mentioned_users_from_entities))
+    }
+}
+
 #[cfg(test)]
 mod tests {
     use super::*;

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

@@ -59,6 +59,48 @@ impl Update {
         Some(from)
     }
 
+    /// Returns all users that are "contained" in this `Update` structure.
+    ///
+    /// This might be useful to track information about users.
+    ///
+    /// Note that this function may return quite a few users as it scans
+    /// replies, pinned messages, message entities, "via bot" fields and more.
+    /// Also note that this function can return duplicate users.
+    pub fn mentioned_users(&self) -> impl Iterator<Item = &User> {
+        use either::Either::{Left, Right};
+        use std::iter::{empty, once};
+
+        let i0 = Left;
+        let i1 = |x| Right(Left(x));
+        let i2 = |x| Right(Right(Left(x)));
+        let i3 = |x| Right(Right(Right(Left(x))));
+        let i4 = |x| Right(Right(Right(Right(Left(x)))));
+        let i5 = |x| Right(Right(Right(Right(Right(Left(x))))));
+        let i6 = |x| Right(Right(Right(Right(Right(Right(x))))));
+
+        match &self.kind {
+            UpdateKind::Message(message)
+            | UpdateKind::EditedMessage(message)
+            | UpdateKind::ChannelPost(message)
+            | UpdateKind::EditedChannelPost(message) => i0(message.mentioned_users()),
+
+            UpdateKind::InlineQuery(query) => i1(once(&query.from)),
+            UpdateKind::ChosenInlineResult(query) => i1(once(&query.from)),
+            UpdateKind::CallbackQuery(query) => i2(query.mentioned_users()),
+            UpdateKind::ShippingQuery(query) => i1(once(&query.from)),
+            UpdateKind::PreCheckoutQuery(query) => i1(once(&query.from)),
+            UpdateKind::Poll(poll) => i3(poll.mentioned_users()),
+
+            UpdateKind::PollAnswer(answer) => i1(once(&answer.user)),
+
+            UpdateKind::MyChatMember(member) | UpdateKind::ChatMember(member) => {
+                i4(member.mentioned_users())
+            }
+            UpdateKind::ChatJoinRequest(request) => i5(request.mentioned_users()),
+            UpdateKind::Error(_) => i6(empty()),
+        }
+    }
+
     /// Returns the chat in which is update has happened, if any.
     #[must_use]
     pub fn chat(&self) -> Option<&Chat> {

crates/teloxide-core/src/util.rs

@@ -0,0 +1,56 @@
+use crate::types::{MessageEntity, User};
+
+/// Converts an optional iterator to a flattened iterator.
+pub(crate) fn flatten<I>(opt: Option<I>) -> impl Iterator<Item = I::Item>
+where
+    I: IntoIterator,
+{
+    struct Flat<I>(Option<I>);
+
+    impl<I> Iterator for Flat<I>
+    where
+        I: Iterator,
+    {
+        type Item = I::Item;
+
+        fn next(&mut self) -> Option<Self::Item> {
+            self.0.as_mut()?.next()
+        }
+
+        fn size_hint(&self) -> (usize, Option<usize>) {
+            match &self.0 {
+                None => (0, Some(0)),
+                Some(i) => i.size_hint(),
+            }
+        }
+    }
+
+    Flat(opt.map(<_>::into_iter))
+}
+
+pub(crate) fn mentioned_users_from_entities(
+    entities: &[MessageEntity],
+) -> impl Iterator<Item = &User> {
+    use crate::types::MessageEntityKind::*;
+
+    entities.iter().filter_map(|entity| match &entity.kind {
+        TextMention { user } => Some(user),
+
+        Mention
+        | Hashtag
+        | Cashtag
+        | BotCommand
+        | Url
+        | Email
+        | PhoneNumber
+        | Bold
+        | Italic
+        | Underline
+        | Strikethrough
+        | Spoiler
+        | Code
+        | Pre { language: _ }
+        | TextLink { url: _ }
+        | CustomEmoji { custom_emoji_id: _ } => None,
+    })
+}