feat: Case-insensitive search for non-ASCII messages (#5052)

SQLite search with `LIKE` is case-insensitive only for ASCII chars. To make it case-insensitive for
all messages, create a new column `msgs.txt_normalized` defaulting to `NULL` (so we do not bump up
the database size in a migration) and storing lowercased/normalized text there when the row is
created/updated. When doing a search, search over `IFNULL(txt_normalized, txt)`.

src/chat.rs

@@ -927,12 +927,13 @@ impl ChatId {
                         .sql
                         .execute(
                             "UPDATE msgs
-                            SET timestamp=?,type=?,txt=?, param=?,mime_in_reply_to=?
+                            SET timestamp=?,type=?,txt=?,txt_normalized=?,param=?,mime_in_reply_to=?
                             WHERE id=?;",
                             (
                                 time(),
                                 msg.viewtype,
                                 &msg.text,
+                                message::normalize_text(&msg.text),
                                 msg.param.to_string(),
                                 msg.in_reply_to.as_deref().unwrap_or_default(),
                                 msg.id,
@@ -956,17 +957,19 @@ impl ChatId {
                  type,
                  state,
                  txt,
+                 txt_normalized,
                  param,
                  hidden,
                  mime_in_reply_to)
-         VALUES (?,?,?, ?,?,?,?,?,?);",
+         VALUES (?,?,?,?,?,?,?,?,?,?);",
                 (
                     self,
                     ContactId::SELF,
                     time(),
                     msg.viewtype,
                     MessageState::OutDraft,
                     &msg.text,
+                    message::normalize_text(&msg.text),
                     msg.param.to_string(),
                     1,
                     msg.in_reply_to.as_deref().unwrap_or_default(),
@@ -2075,7 +2078,7 @@ impl Chat {
                 .execute(
                     "UPDATE msgs
                      SET rfc724_mid=?, chat_id=?, from_id=?, to_id=?, timestamp=?, type=?,
-                         state=?, txt=?, subject=?, param=?,
+                         state=?, txt=?, txt_normalized=?, subject=?, param=?,
                          hidden=?, mime_in_reply_to=?, mime_references=?, mime_modified=?,
                          mime_headers=?, mime_compressed=1, location_id=?, ephemeral_timer=?,
                          ephemeral_timestamp=?
@@ -2089,6 +2092,7 @@ impl Chat {
                         msg.viewtype,
                         msg.state,
                         msg.text,
+                        message::normalize_text(&msg.text),
                         &msg.subject,
                         msg.param.to_string(),
                         msg.hidden,
@@ -2117,6 +2121,7 @@ impl Chat {
                         type,
                         state,
                         txt,
+                        txt_normalized,
                         subject,
                         param,
                         hidden,
@@ -2128,7 +2133,7 @@ impl Chat {
                         location_id,
                         ephemeral_timer,
                         ephemeral_timestamp)
-                        VALUES (?,?,?,?,?,?,?,?,?,?,?,?,?,?,?,1,?,?,?);",
+                        VALUES (?,?,?,?,?,?,?,?,?,?,?,?,?,?,?,?,1,?,?,?);",
                     params_slice![
                         msg.rfc724_mid,
                         msg.chat_id,
@@ -2138,6 +2143,7 @@ impl Chat {
                         msg.viewtype,
                         msg.state,
                         msg.text,
+                        message::normalize_text(&msg.text),
                         &msg.subject,
                         msg.param.to_string(),
                         msg.hidden,
@@ -4370,9 +4376,10 @@ pub async fn add_device_msg_with_importance(
             timestamp_rcvd,
             type,state,
             txt,
+            txt_normalized,
             param,
             rfc724_mid)
-            VALUES (?,?,?,?,?,?,?,?,?,?,?);",
+            VALUES (?,?,?,?,?,?,?,?,?,?,?,?);",
                 (
                     chat_id,
                     ContactId::DEVICE,
@@ -4383,6 +4390,7 @@ pub async fn add_device_msg_with_importance(
                     msg.viewtype,
                     state,
                     &msg.text,
+                    message::normalize_text(&msg.text),
                     msg.param.to_string(),
                     rfc724_mid,
                 ),
@@ -4486,8 +4494,8 @@ pub(crate) async fn add_info_msg_with_cmd(
 
     let row_id =
     context.sql.insert(
-        "INSERT INTO msgs (chat_id,from_id,to_id,timestamp,timestamp_sent,timestamp_rcvd,type,state,txt,rfc724_mid,ephemeral_timer, param,mime_in_reply_to)
-        VALUES (?,?,?, ?,?,?,?,?, ?,?,?, ?,?);",
+        "INSERT INTO msgs (chat_id,from_id,to_id,timestamp,timestamp_sent,timestamp_rcvd,type,state,txt,txt_normalized,rfc724_mid,ephemeral_timer,param,mime_in_reply_to)
+        VALUES (?,?,?,?,?,?,?,?,?,?,?,?,?,?);",
         (
             chat_id,
             from_id.unwrap_or(ContactId::INFO),
@@ -4498,6 +4506,7 @@ pub(crate) async fn add_info_msg_with_cmd(
             Viewtype::Text,
             MessageState::InNoticed,
             text,
+            message::normalize_text(text),
             rfc724_mid,
             ephemeral_timer,
             param.to_string(),
@@ -4542,8 +4551,8 @@ pub(crate) async fn update_msg_text_and_timestamp(
     context
         .sql
         .execute(
-            "UPDATE msgs SET txt=?, timestamp=? WHERE id=?;",
-            (text, timestamp, msg_id),
+            "UPDATE msgs SET txt=?, txt_normalized=?, timestamp=? WHERE id=?;",
+            (text, message::normalize_text(text), timestamp, msg_id),
         )
         .await?;
     context.emit_msgs_changed(chat_id, msg_id);

src/context.rs

@@ -1259,12 +1259,12 @@ impl Context {
         Ok(list)
     }
 
-    /// Searches for messages containing the query string.
+    /// Searches for messages containing the query string case-insensitively.
     ///
     /// If `chat_id` is provided this searches only for messages in this chat, if `chat_id`
     /// is `None` this searches messages from all chats.
     pub async fn search_msgs(&self, chat_id: Option<ChatId>, query: &str) -> Result<Vec<MsgId>> {
-        let real_query = query.trim();
+        let real_query = query.trim().to_lowercase();
         if real_query.is_empty() {
             return Ok(Vec::new());
         }
@@ -1280,7 +1280,7 @@ impl Context {
                  WHERE m.chat_id=?
                    AND m.hidden=0
                    AND ct.blocked=0
-                   AND txt LIKE ?
+                   AND IFNULL(txt_normalized, txt) LIKE ?
                  ORDER BY m.timestamp,m.id;",
                     (chat_id, str_like_in_text),
                     |row| row.get::<_, MsgId>("id"),
@@ -1316,7 +1316,7 @@ impl Context {
                    AND m.hidden=0
                    AND c.blocked!=1
                    AND ct.blocked=0
-                   AND m.txt LIKE ?
+                   AND IFNULL(txt_normalized, txt) LIKE ?
                  ORDER BY m.id DESC LIMIT 1000",
                     (str_like_in_text,),
                     |row| row.get::<_, MsgId>("id"),
@@ -1721,6 +1721,8 @@ mod tests {
         msg2.set_text("barbaz".to_string());
         send_msg(&alice, chat.id, &mut msg2).await?;
 
+        alice.send_text(chat.id, "Δ-Chat").await;
+
         // Global search with a part of text finds the message.
         let res = alice.search_msgs(None, "ob").await?;
         assert_eq!(res.len(), 1);
@@ -1733,6 +1735,12 @@ mod tests {
         assert_eq!(res.first(), Some(&msg2.id));
         assert_eq!(res.get(1), Some(&msg1.id));
 
+        // Search is case-insensitive.
+        for chat_id in [None, Some(chat.id)] {
+            let res = alice.search_msgs(chat_id, "δ-chat").await?;
+            assert_eq!(res.len(), 1);
+        }
+
         // Global search with longer text does not find any message.
         let res = alice.search_msgs(None, "foobarbaz").await?;
         assert!(res.is_empty());

src/ephemeral.rs

@@ -447,7 +447,7 @@ pub(crate) async fn delete_expired_messages(context: &Context, now: i64) -> Resu
                 for (msg_id, chat_id, viewtype, location_id) in rows {
                     transaction.execute(
                         "UPDATE msgs
-                     SET chat_id=?, txt='', subject='', txt_raw='',
+                     SET chat_id=?, txt='', txt_normalized=NULL, subject='', txt_raw='',
                          mime_headers='', from_id=0, to_id=0, param=''
                      WHERE id=?",
                         (DC_CHAT_ID_TRASH, msg_id),

src/message.rs

@@ -113,7 +113,7 @@ impl MsgId {
                 r#"
 UPDATE msgs 
 SET 
-  chat_id=?, txt='', 
+  chat_id=?, txt='', txt_normalized=NULL, 
   subject='', txt_raw='', 
   mime_headers='', 
   from_id=0, to_id=0, 
@@ -2072,6 +2072,15 @@ impl Viewtype {
     }
 }
 
+/// Returns text for storing in the `msgs.txt_normalized` column (to make case-insensitive search
+/// possible for non-ASCII messages).
+pub(crate) fn normalize_text(text: &str) -> Option<String> {
+    if text.is_ascii() {
+        return None;
+    };
+    Some(text.to_lowercase()).filter(|t| t != text)
+}
+
 #[cfg(test)]
 mod tests {
     use num_traits::FromPrimitive;

src/receive_imf.rs

@@ -1540,7 +1540,7 @@ INSERT INTO msgs
     rfc724_mid, chat_id,
     from_id, to_id, timestamp, timestamp_sent, 
     timestamp_rcvd, type, state, msgrmsg, 
-    txt, subject, txt_raw, param, hidden,
+    txt, txt_normalized, subject, txt_raw, param, hidden,
     bytes, mime_headers, mime_compressed, mime_in_reply_to,
     mime_references, mime_modified, error, ephemeral_timer,
     ephemeral_timestamp, download_state, hop_info
@@ -1550,15 +1550,16 @@ INSERT INTO msgs
     ?, ?, ?, ?,
     ?, ?, ?, ?,
     ?, ?, ?, ?, ?,
-    ?, ?, ?, ?, 1,
+    ?, ?, ?, ?, ?, 1,
     ?, ?, ?, ?,
     ?, ?, ?, ?
   )
 ON CONFLICT (id) DO UPDATE
 SET rfc724_mid=excluded.rfc724_mid, chat_id=excluded.chat_id,
     from_id=excluded.from_id, to_id=excluded.to_id, timestamp_sent=excluded.timestamp_sent,
     type=excluded.type, msgrmsg=excluded.msgrmsg,
-    txt=excluded.txt, subject=excluded.subject, txt_raw=excluded.txt_raw, param=excluded.param,
+    txt=excluded.txt, txt_normalized=excluded.txt_normalized, subject=excluded.subject,
+    txt_raw=excluded.txt_raw, param=excluded.param,
     hidden=excluded.hidden,bytes=excluded.bytes, mime_headers=excluded.mime_headers,
     mime_compressed=excluded.mime_compressed, mime_in_reply_to=excluded.mime_in_reply_to,
     mime_references=excluded.mime_references, mime_modified=excluded.mime_modified, error=excluded.error, ephemeral_timer=excluded.ephemeral_timer,
@@ -1578,6 +1579,7 @@ RETURNING id
                     state,
                     is_dc_message,
                     if trash { "" } else { msg },
+                    if trash { None } else { message::normalize_text(msg) },
                     if trash { "" } else { &subject },
                     // txt_raw might contain invalid utf8
                     if trash { "" } else { &txt_raw },

src/sql/migrations.rs

@@ -937,6 +937,11 @@ CREATE INDEX msgs_status_updates_index2 ON msgs_status_updates (uid);
             .await?;
     }
 
+    if dbversion < 115 {
+        sql.execute_migration("ALTER TABLE msgs ADD COLUMN txt_normalized TEXT", 115)
+            .await?;
+    }
+
     let new_version = sql
         .get_raw_config_int(VERSION_CFG)
         .await?