refactor: prepare database/key_value/rooms/search.rs from service/rooms/search/mod.rs

src/database/key_value/rooms/search.rs

@@ -0,0 +1,50 @@
+
+    #[tracing::instrument(skip(self))]
+    pub fn search_pdus<'a>(
+        &'a self,
+        room_id: &RoomId,
+        search_string: &str,
+    ) -> Result<Option<(impl Iterator<Item = Vec<u8>> + 'a, Vec<String>)>> {
+        let prefix = self
+            .get_shortroomid(room_id)?
+            .expect("room exists")
+            .to_be_bytes()
+            .to_vec();
+        let prefix_clone = prefix.clone();
+
+        let words: Vec<_> = search_string
+            .split_terminator(|c: char| !c.is_alphanumeric())
+            .filter(|s| !s.is_empty())
+            .map(str::to_lowercase)
+            .collect();
+
+        let iterators = words.clone().into_iter().map(move |word| {
+            let mut prefix2 = prefix.clone();
+            prefix2.extend_from_slice(word.as_bytes());
+            prefix2.push(0xff);
+
+            let mut last_possible_id = prefix2.clone();
+            last_possible_id.extend_from_slice(&u64::MAX.to_be_bytes());
+
+            self.tokenids
+                .iter_from(&last_possible_id, true) // Newest pdus first
+                .take_while(move |(k, _)| k.starts_with(&prefix2))
+                .map(|(key, _)| key[key.len() - size_of::<u64>()..].to_vec())
+        });
+
+        Ok(utils::common_elements(iterators, |a, b| {
+            // We compare b with a because we reversed the iterator earlier
+            b.cmp(a)
+        })
+        .map(|iter| {
+            (
+                iter.map(move |id| {
+                    let mut pduid = prefix_clone.clone();
+                    pduid.extend_from_slice(&id);
+                    pduid
+                }),
+                words,
+            )
+        }))
+    }
+