sorting both ways seems to work

src/common_queries/list_tts_inference_results.rs

@@ -289,6 +289,7 @@ pub async fn list_tts_inference_page(
   mysql_pool: &MySqlPool,
   scope_creator_username: Option<&str>,
   sort_ascending: bool,
+  cursor_is_previous: bool,
   block_mod_disabled : bool,
   limit: u16,
   offset: Option<u64>,
@@ -298,6 +299,7 @@ pub async fn list_tts_inference_page(
     mysql_pool,
     scope_creator_username,
     sort_ascending,
+    cursor_is_previous,
     block_mod_disabled,
     limit,
     offset
@@ -339,6 +341,7 @@ async fn list_tts_inference_results_query (
   mysql_pool: &MySqlPool,
   scope_creator_username: Option<&str>,
   sort_ascending: bool,
+  cursor_is_previous: bool,
   block_mod_disabled : bool,
   limit: u16,
   offset: Option<u64>,
@@ -370,14 +373,39 @@ LEFT OUTER JOIN users
     ON tts_results.maybe_creator_user_token = users.token
   "#.to_string();
 
+  let mut sort_ascending = sort_ascending; // NB: We may need to change the direction.
+  let mut reverse_results = false;
+
   let mut first_predicate_added = false;
 
   if let Some(offset) = offset {
     if !first_predicate_added {
-      query.push_str(r#" WHERE tts_results.id < ? "#);
+      query.push_str(" WHERE ");
       first_predicate_added = true;
     } else {
-      query.push_str(r#" AND tts_results.id < ? "#);
+      query.push_str(" AND ");
+    }
+
+    // TODO: Cleanup, builder class, tests.
+
+    if sort_ascending {
+      if cursor_is_previous {
+        // NB: We're searching backwards.
+        query.push_str(" tts_results.id < ? ");
+        sort_ascending = !sort_ascending;
+        reverse_results = true;
+      } else {
+        query.push_str(" tts_results.id > ? ");
+      }
+    } else {
+      if cursor_is_previous {
+        // NB: We're searching backwards.
+        query.push_str(" tts_results.id > ? ");
+        sort_ascending = !sort_ascending;
+        reverse_results = true;
+      } else {
+        query.push_str(" tts_results.id < ? ");
+      }
     }
   }
 
@@ -425,8 +453,12 @@ LEFT OUTER JOIN users
 
   query = query.bind(limit);
 
-  let results = query.fetch_all(mysql_pool)
+  let mut results = query.fetch_all(mysql_pool)
       .await?;
 
+  if reverse_results {
+    results.reverse()
+  }
+
   Ok(results)
 }

src/http_server/endpoints/users/list_user_tts_inference_results.rs

@@ -40,6 +40,7 @@ pub struct ListTtsInferenceResultsForUserQuery {
   pub sort_ascending: Option<bool>,
   pub limit: Option<u16>,
   pub cursor: Option<String>,
+  pub cursor_is_previous: Option<bool>,
 }
 
 #[derive(Serialize)]
@@ -83,7 +84,11 @@ pub async fn list_user_tts_inference_results_handler(
   let mod_disabled = false;
 
   let limit = query.limit.unwrap_or(25);
-  let limit = std::cmp::max(limit, 100);
+  //let limit = std::cmp::max(limit, 100);
+
+  let sort_ascending = query.sort_ascending.unwrap_or(false);
+
+  let cursor_is_previous = query.cursor_is_previous.unwrap_or(false);
 
   let cursor = if let Some(cursor) = query.cursor.as_deref() {
     let cursor = server_state.sort_key_crypto.decrypt_id(cursor)
@@ -99,7 +104,8 @@ pub async fn list_user_tts_inference_results_handler(
   let query_results = list_tts_inference_page(
     &server_state.mysql_pool,
     Some(path.username.as_ref()),
-    false,
+    sort_ascending,
+    cursor_is_previous,
     mod_disabled,
     limit,
     cursor,

src/util/encrypted_sort_id.rs

@@ -6,6 +6,7 @@ use std::io::Cursor;
 use magic_crypt::new_magic_crypt;
 use crate::util::anyhow_result::AnyhowResult;
 use rand::RngCore;
+use base64::{Config, CharacterSet};
 
 // TODO: A protobuf would be more compact!
 /// This gets encrypted and sent to the frontend as an opaque handle.
@@ -21,12 +22,16 @@ pub struct SortId {
 #[derive(Clone)]
 pub struct SortKeyCrypto {
   crypt: MagicCrypt256,
+  base64_config: Config,
 }
 
 impl SortKeyCrypto {
   pub fn new(secret: &str) -> Self {
+    let base64_config = Config::new(CharacterSet::UrlSafe, false)
+        .decode_allow_trailing_bits(true);
     Self {
       crypt: new_magic_crypt!(secret, 256),
+      base64_config,
     }
   }
 
@@ -44,14 +49,20 @@ impl SortKeyCrypto {
     let mut writer = Vec::new();
 
     self.crypt.encrypt_reader_to_writer2::<U256>(&mut reader, &mut writer)?;
-    let encoded = base64::encode(&writer);
+    let encoded = base64::encode_config(&writer, self.base64_config.clone());
 
     Ok(encoded)
   }
 
   pub fn decrypt_id(&self, base_64_payload: &str) -> AnyhowResult<u64> {
-    let payload = self.crypt.decrypt_base64_to_string(base_64_payload)?;
+    //let payload = self.crypt.decrypt_base64_to_string(base_64_payload)?;
+
+    let decoded_bytes= base64::decode_config(base_64_payload, self.base64_config)?;
+    let decrypted_bytes = self.crypt.decrypt_bytes_to_bytes(&decoded_bytes)?;
+
+    let payload = String::from_utf8(decrypted_bytes)?;
     let payload = serde_json::from_str::<SortId>(&payload)?;
+
     Ok(payload.column_id)
   }
 }