Change get_latest_about_message to use streams

src/sbot.rs

@@ -3,7 +3,7 @@ use async_std::{
     net::TcpStream,
     stream::{Stream, StreamExt},
 };
-use futures::TryStreamExt;
+use futures::{pin_mut, TryStreamExt};
 
 use kuska_handshake::async_std::BoxStream;
 use kuska_sodiumoxide::crypto::{auth, sign::ed25519};
@@ -20,7 +20,7 @@ use crate::utils;
 use crate::utils::get_source_stream;
 
 // re-export types from kuska
-pub use kuska_ssb::api::dto::content::SubsetQuery;
+pub use kuska_ssb::api::dto::content::{SubsetQuery, SubsetQueryOptions};
 
 /// A struct representing a connection with a running sbot.
 /// A client and an rpc_reader can together be used to make requests to the sbot
@@ -128,13 +128,19 @@ impl Sbot {
 
     /// Call the `partialReplication getSubset` RPC method
     /// and return a Stream of Result<SsbMessageKVT, GolgiError>
-    // TODO: add args for `descending` and `page` (max number of msgs in response)
+    ///
+    /// # Arguments
+    ///
+    /// * `query` - A `SubsetQuery` which specifies what filters to use.
+    /// * `option` - An Option<`SubsetQueryOptions`> which, if provided, adds additional
+    /// specifications to the query, such as specifying page limit and/or descending.
     pub async fn get_subset_stream(
         &mut self,
         query: SubsetQuery,
+        options: Option<SubsetQueryOptions>
     ) -> Result<impl Stream<Item = Result<SsbMessageKVT, GolgiError>>, GolgiError> {
         let mut sbot_connection = self.get_sbot_connection().await?;
-        let req_id = sbot_connection.client.getsubset_req_send(query).await?;
+        let req_id = sbot_connection.client.getsubset_req_send(query, options).await?;
         let get_subset_stream =
             get_source_stream(sbot_connection.rpc_reader, req_id, utils::kvt_res_parse).await;
         Ok(get_subset_stream)
@@ -241,7 +247,13 @@ impl Sbot {
             op: "author".to_string(),
             feed: ssb_id.to_string(),
         };
-        let get_subset_kvt_stream = self.get_subset_stream(query).await?;
+        // specify that most recent messages should be returned first
+        let query_options = SubsetQueryOptions {
+            descending: Some(true),
+            keys: None,
+            page_limit: None
+        };
+        let get_subset_kvt_stream = self.get_subset_stream(query, Some(query_options)).await?;
         // map into Stream<Item=Result<SsbMessageValue, GolgiError>>
         let ssb_message_stream = get_subset_kvt_stream.map(|msg| match msg {
             Ok(val) => Ok(val.value),
@@ -267,28 +279,39 @@ impl Sbot {
     ) -> Result<Option<String>, GolgiError> {
         // get about_message_stream
         let about_message_stream = self.get_about_message_stream(ssb_id).await?;
-        // TODO: use subset query to order messages instead of doing it this way
-        let mut about_messages: Vec<SsbMessageValue> = about_message_stream.try_collect().await?;
-        about_messages.sort_by(|a, b| b.timestamp.partial_cmp(&a.timestamp).unwrap());
-        // now we have a vector of about messages with most recent at the front of the vector
+        // now we have a stream of about messages with most recent at the front of the vector
+        pin_mut!(about_message_stream);
         // iterate through the vector looking for most recent about message with the given key
-        let latest_about = about_messages
-            .iter()
+        let latest_about_message: Result<SsbMessageValue, GolgiError> = about_message_stream
             // find the first msg that contains the field `key`
-            .find(|msg| msg.content.get(key).is_some())
-            // map the found msg (`Some(SsbMessageValue)`) to a `Some(Some(&Value))`
-            .map(|msg| msg.content.get(key))
-            // flatten `Some(Some(&Value))` into `Some(&Value)`
-            .flatten()
-            // map `Some(&Value)` to `Some(Some(&str))`
-            .map(|msg_val| msg_val.as_str())
-            // flatten `Some(Some(&str))` to `Some(&str)`
-            .flatten()
-            // map `Some(&str))` to `Some(String)`
-            .map(|msg_str| msg_str.to_string());
-
+            .find(|res| {
+                match res {
+                    Ok(msg) => {
+                        msg.content.get(key).is_some()
+                    },
+                    Err(_) => {
+                        false
+                    }
+                }
+            }).await.ok_or(GolgiError::Sbot("error while looking for about message with given key".to_string()))?;
+        let latest_about_value = match latest_about_message {
+            Ok(msg) => {
+                msg
+                    // SsbMessageValue -> Option<&Value>
+                    .content.get(key)
+                    // Option<&Value> -> Option<Option<&str>>
+                    .map(|value| value.as_str())
+                    //  Option<Option<&str>> -> Option<&str>
+                    .flatten()
+                    // Option<&str> -> Option<String>
+                    .map(|value| value.to_string())
+            }
+            Err(_) => {
+                None
+            }
+        };
         // return value is either `Ok(Some(String))` or `Ok(None)`
-        Ok(latest_about)
+        Ok(latest_about_value)
     }
 
     /// Get latest about name from given user