feat: Preserve minimum info for trashed messages

+ Make `MsgId::trash()` `pub(crate)`, not public.
+ In `delete_expired_messages()`, prepare SQL statements to be executed in a loop.

Author: iequidoo

src/ephemeral.rs

@@ -466,23 +466,18 @@ pub(crate) async fn delete_expired_messages(context: &Context, now: i64) -> Resu
             .transaction(|transaction| {
                 let mut msgs_changed = Vec::with_capacity(rows.len());
                 let mut webxdc_deleted = Vec::new();
-
-                // If you change which information is removed here, also change MsgId::trash() and
-                // which information receive_imf::add_parts() still adds to the db if the chat_id is TRASH
+                // If you change which information is preserved here, also change `MsgId::trash()`
+                // and other places it references.
+                let mut del_msg_stmt = transaction.prepare(
+                    "INSERT OR REPLACE INTO msgs (id, rfc724_mid, timestamp, chat_id)
+                     SELECT ?1, rfc724_mid, timestamp, ? FROM msgs WHERE id=?1",
+                )?;
+                let mut del_location_stmt =
+                    transaction.prepare("DELETE FROM locations WHERE independent=1 AND id=?")?;
                 for (msg_id, chat_id, viewtype, location_id) in rows {
-                    transaction.execute(
-                        "UPDATE msgs
-                     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),
-                    )?;
-
+                    del_msg_stmt.execute((msg_id, DC_CHAT_ID_TRASH))?;
                     if location_id > 0 {
-                        transaction.execute(
-                            "DELETE FROM locations WHERE independent=1 AND id=?",
-                            (location_id,),
-                        )?;
+                        del_location_stmt.execute((location_id,))?;
                     }
 
                     msgs_changed.push((chat_id, msg_id));

src/message.rs

@@ -125,27 +125,16 @@ impl MsgId {
     ///   if all parts of the message are trashed with this flag. `true` if the user explicitly
     ///   deletes the message. As for trashing a partially downloaded message when replacing it with
     ///   a fully downloaded one, see `receive_imf::add_parts()`.
-    pub async fn trash(self, context: &Context, on_server: bool) -> Result<()> {
-        let chat_id = DC_CHAT_ID_TRASH;
-        let deleted_subst = match on_server {
-            true => ", deleted=1",
-            false => "",
-        };
+    pub(crate) async fn trash(self, context: &Context, on_server: bool) -> Result<()> {
         context
             .sql
             .execute(
-                // If you change which information is removed here, also change delete_expired_messages() and
-                // which information receive_imf::add_parts() still adds to the db if the chat_id is TRASH
-                &format!(
-                    "UPDATE msgs SET \
-                     chat_id=?, txt='', txt_normalized=NULL, \
-                     subject='', txt_raw='', \
-                     mime_headers='', \
-                     from_id=0, to_id=0, \
-                     param=''{deleted_subst} \
-                     WHERE id=?"
-                ),
-                (chat_id, self),
+                // If you change which information is preserved here, also change
+                // `delete_expired_messages()` and which information `receive_imf::add_parts()`
+                // still adds to the db if chat_id is TRASH.
+                "INSERT OR REPLACE INTO msgs (id, rfc724_mid, timestamp, chat_id, deleted)
+                 SELECT ?1, rfc724_mid, timestamp, ?, ? FROM msgs WHERE id=?1",
+                (self, DC_CHAT_ID_TRASH, on_server),
             )
             .await?;
 

src/receive_imf.rs

@@ -2055,11 +2055,11 @@ RETURNING id
                     if trash { ContactId::UNDEFINED } else { from_id },
                     if trash { ContactId::UNDEFINED } else { to_id },
                     sort_timestamp,
-                    mime_parser.timestamp_sent,
-                    mime_parser.timestamp_rcvd,
-                    typ,
-                    state,
-                    is_dc_message,
+                    if trash { 0 } else { mime_parser.timestamp_sent },
+                    if trash { 0 } else { mime_parser.timestamp_rcvd },
+                    if trash { Viewtype::Unknown } else { typ },
+                    if trash { MessageState::Undefined } else { state },
+                    if trash { MessengerMessage::No } else { is_dc_message },
                     if trash || hidden { "" } else { msg },
                     if trash || hidden { None } else { message::normalize_text(msg) },
                     if trash || hidden { "" } else { &subject },
@@ -2068,27 +2068,29 @@ RETURNING id
                     } else {
                         param.to_string()
                     },
-                    hidden,
-                    part.bytes as isize,
+                    !trash && hidden,
+                    if trash { 0 } else { part.bytes as isize },
                     if save_mime_modified && !(trash || hidden) {
                         mime_headers.clone()
                     } else {
                         Vec::new()
                     },
-                    mime_in_reply_to,
-                    mime_references,
-                    save_mime_modified,
-                    part.error.as_deref().unwrap_or_default(),
-                    ephemeral_timer,
-                    ephemeral_timestamp,
-                    if is_partial_download.is_some() {
+                    if trash { "" } else { mime_in_reply_to },
+                    if trash { "" } else { mime_references },
+                    !trash && save_mime_modified,
+                    if trash { "" } else { part.error.as_deref().unwrap_or_default() },
+                    if trash { 0 } else { ephemeral_timer.to_u32() },
+                    if trash { 0 } else { ephemeral_timestamp },
+                    if trash {
+                        DownloadState::Done
+                    } else if is_partial_download.is_some() {
                         DownloadState::Available
                     } else if mime_parser.decrypting_failed {
                         DownloadState::Undecipherable
                     } else {
                         DownloadState::Done
                     },
-                    mime_parser.hop_info
+                    if trash { "" } else { &mime_parser.hop_info },
                 ],
                 |row| {
                     let msg_id: MsgId = row.get(0)?;