Avoid ok-to-continue pattern in set_draft_raw (#570)

Avoid ok-to-continue pattern in `set_draft_raw`

src/chat.rs

@@ -844,44 +844,55 @@ pub unsafe fn set_draft(context: &Context, chat_id: u32, msg: Option<&mut Messag
     if chat_id <= DC_CHAT_ID_LAST_SPECIAL {
         return;
     }
-    if set_draft_raw(context, chat_id, msg) {
+
-        context.call_cb(Event::MsgsChanged { chat_id, msg_id: 0 });
+    let changed = match msg {
+        None => maybe_delete_draft(context, chat_id),
+        Some(msg) => set_draft_raw(context, chat_id, msg),
     };
+
+    if changed {
+        context.call_cb(Event::MsgsChanged { chat_id, msg_id: 0 });
+    }
 }
 
-// similar to as dc_set_draft() but does not emit an event
+/// Delete draft message in specified chat, if there is one.
-#[allow(non_snake_case)]
+///
-unsafe fn set_draft_raw(context: &Context, chat_id: u32, mut msg: Option<&mut Message>) -> bool {
+/// Return {true}, if message was deleted, {false} otherwise.
-    let mut OK_TO_CONTINUE = true;
+fn maybe_delete_draft(context: &Context, chat_id: u32) -> bool {
-
+    let draft = get_draft_msg_id(context, chat_id);
-    let mut sth_changed = false;
+    if draft != 0 {
-
+        dc_delete_msg_from_db(context, draft);
-    let prev_draft_msg_id = get_draft_msg_id(context, chat_id);
+        return true;
-    if 0 != prev_draft_msg_id {
+    }
-        dc_delete_msg_from_db(context, prev_draft_msg_id);
+    false
-        sth_changed = true;
 }
 
-    if let Some(ref mut msg) = msg {
+/// Set provided message as draft message for specified chat.
-        // save new draft
+///
-        if msg.type_0 == Viewtype::Text {
+/// Return true on success, false on database error.
-            OK_TO_CONTINUE = msg.text.as_ref().map_or(false, |s| !s.is_empty());
+fn do_set_draft(context: &Context, chat_id: u32, msg: &mut Message) -> bool {
-        } else if msgtype_has_file(msg.type_0) {
+    match msg.type_0 {
+        Viewtype::Unknown => return false,
+        Viewtype::Text => {
+            if msg.text.as_ref().map_or(false, |s| s.is_empty()) {
+                return false;
+            }
+        }
+        _ => {
             if let Some(path_filename) = msg.param.get(Param::File) {
                 let mut path_filename = path_filename.to_string();
                 if dc_msg_is_increation(msg) && !dc_is_blobdir_path(context, &path_filename) {
-                    OK_TO_CONTINUE = false;
+                    return false;
-                } else if !dc_make_rel_and_copy(context, &mut path_filename) {
+                }
-                    OK_TO_CONTINUE = false;
+                if !dc_make_rel_and_copy(context, &mut path_filename) {
-                } else {
+                    return false;
+                }
                 msg.param.set(Param::File, path_filename);
             }
         }
-        } else {
-            OK_TO_CONTINUE = false;
     }
-        if OK_TO_CONTINUE {
+
-            if sql::execute(
+    sql::execute(
         context,
         &context.sql,
         "INSERT INTO msgs (chat_id, from_id, timestamp, type, state, txt, param, hidden) \
@@ -898,12 +909,16 @@ unsafe fn set_draft_raw(context: &Context, chat_id: u32, mut msg: Option<&mut Me
         ],
     )
     .is_ok()
-            {
-                sth_changed = true;
 }
-        }
+
-    }
+// similar to as dc_set_draft() but does not emit an event
-    sth_changed
+#[allow(non_snake_case)]
+unsafe fn set_draft_raw(context: &Context, chat_id: u32, msg: &mut Message) -> bool {
+    let deleted = maybe_delete_draft(context, chat_id);
+    let set = do_set_draft(context, chat_id, msg);
+
+    // Can't inline. Both functions above must be called, no shortcut!
+    deleted || set
 }
 
 fn get_draft_msg_id(context: &Context, chat_id: u32) -> u32 {
@@ -1288,7 +1303,7 @@ pub unsafe fn create_group_chat(
         if add_to_chat_contacts_table(context, chat_id, 1) {
             let mut draft_msg = dc_msg_new(Viewtype::Text);
             dc_msg_set_text(&mut draft_msg, draft_txt.as_ptr());
-            set_draft_raw(context, chat_id, Some(&mut draft_msg));
+            set_draft_raw(context, chat_id, &mut draft_msg);
         }
 
         context.call_cb(Event::MsgsChanged {