New group consistency algorithm on the receiver side

src/receive_imf.rs

@@ -333,9 +333,29 @@ pub(crate) async fn receive_imf_inner(
             }
         };
 
+    let recipients = if mime_parser.get_header(HeaderDef::ChatVersion).is_some() {
+        // Chat messages should not have `Cc` field.
+        // Use only the `To` field.
+        &mime_parser.to
+    } else {
+        // Use `To` and `Cc` fields as recipients.
+        &mime_parser.recipients
+    };
     let to_ids = add_or_lookup_contacts_by_address_list(
         context,
-        &mime_parser.recipients,
+        recipients,
+        if !mime_parser.incoming {
+            Origin::OutgoingTo
+        } else if incoming_origin.is_known() {
+            Origin::IncomingTo
+        } else {
+            Origin::IncomingUnknownTo
+        },
+    )
+    .await?;
+    let past_ids = add_or_lookup_contacts_by_address_list(
+        context,
+        &mime_parser.past_members,
         if !mime_parser.incoming {
             Origin::OutgoingTo
         } else if incoming_origin.is_known() {
@@ -418,6 +438,7 @@ pub(crate) async fn receive_imf_inner(
             &mut mime_parser,
             imf_raw,
             &to_ids,
+            &past_ids,
             rfc724_mid_orig,
             from_id,
             seen,
@@ -689,6 +710,7 @@ async fn add_parts(
     mime_parser: &mut MimeMessage,
     imf_raw: &[u8],
     to_ids: &[ContactId],
+    past_ids: &[ContactId],
     rfc724_mid: &str,
     from_id: ContactId,
     seen: bool,
@@ -906,6 +928,7 @@ async fn add_parts(
                 group_chat_id,
                 from_id,
                 to_ids,
+                past_ids,
                 is_partial_download.is_some(),
                 &verified_encryption,
             )
@@ -1175,6 +1198,7 @@ async fn add_parts(
                 chat_id,
                 from_id,
                 to_ids,
+                past_ids,
                 is_partial_download.is_some(),
                 &verified_encryption,
             )
@@ -2081,6 +2105,8 @@ async fn create_group(
 /// original system message. If the better message is empty, the original system message should be
 /// just omitted.
 ///
+/// * `to_ids` - contents of the `To` header for chat messages
+///              or combined `To` and `Cc` for non-chat messages
 /// * `is_partial_download` - whether the message is not fully downloaded.
 #[allow(clippy::too_many_arguments)]
 async fn apply_group_changes(
@@ -2089,6 +2115,7 @@ async fn apply_group_changes(
     chat_id: ChatId,
     from_id: ContactId,
     to_ids: &[ContactId],
+    past_ids: &[ContactId],
     is_partial_download: bool,
     verified_encryption: &VerifiedEncryption,
 ) -> Result<(Vec<String>, Option<String>)> {
@@ -2106,6 +2133,59 @@ async fn apply_group_changes(
     let mut better_msg = None;
     let mut group_changes_msgs = Vec::new();
 
+    if let Some(chat_group_member_timestamps) =
+        mime_parser.get_header(HeaderDef::ChatGroupMemberTimestamps)
+    {
+        let chat_group_member_timestamps: Vec<i64> = chat_group_member_timestamps
+            .split_ascii_whitespace()
+            .filter_map(|ts| ts.parse::<i64>().ok())
+            .collect();
+
+        let expected_timestamps_count = to_ids.len() + past_ids.len();
+        if chat_group_member_timestamps.len() == expected_timestamps_count {
+            context
+                .sql
+                .transaction(|transaction| {
+                    for (contact_id, ts) in std::iter::zip(
+                        to_ids.iter(),
+                        chat_group_member_timestamps.iter().take(to_ids.len()),
+                    ) {
+                        transaction.execute(
+                            "INSERT INTO chats_contacts (chat_id, contact_id, add_timestamp)
+                             VALUES                     (?1,      ?2,         ?3)
+                             ON CONFLICT (chat_id, contact_id)
+                             DO UPDATE SET add_timestamp=MAX(add_timestamp, ?3)",
+                            (chat_id, contact_id, ts),
+                        )?;
+                    }
+
+                    for (contact_id, ts) in std::iter::zip(
+                        past_ids.iter(),
+                        chat_group_member_timestamps.iter().skip(to_ids.len()),
+                    ) {
+                        transaction.execute(
+                            "UPDATE chats_contacts
+                             SET remove_timestamp=MAX(remove_timestamp, ?)
+                             WHERE chat_id=? AND contact_id=?",
+                            (ts, chat_id, contact_id),
+                        )?;
+                    }
+
+                    Ok(())
+                })
+                .await?;
+        } else {
+            warn!(
+                context,
+                "Chat-Group-Member-Timestamps has wrong number of timestamps, got {}, expected {}.",
+                chat_group_member_timestamps.len(),
+                expected_timestamps_count
+            );
+        }
+
+        return Ok((group_changes_msgs, better_msg));
+    }
+
     // True if a Delta Chat client has explicitly added our current primary address.
     let self_added =
         if let Some(added_addr) = mime_parser.get_header(HeaderDef::ChatGroupMemberAdded) {