134 lines
4.0 KiB
Rust
134 lines
4.0 KiB
Rust
use std::cmp::Reverse;
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use std::collections::BTreeMap;
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use std::sync::Arc;
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use common::EventExt;
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use nostr_sdk::prelude::*;
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/// A chat message kept in memory for content search.
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#[derive(Debug, Clone)]
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pub struct SearchMessage {
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/// ID of the room the message belongs to
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pub room: u64,
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/// Author of the message
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pub author: PublicKey,
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/// The content of the message
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pub content: Arc<str>,
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/// When the message was created
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pub created_at: Timestamp,
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}
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#[derive(Debug)]
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struct IndexedMessage {
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message: SearchMessage,
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/// Lowercase content so repeated searches don't re-allocate per message
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normalized: Arc<str>,
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}
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/// In-memory index of chat message rumors, keyed by room and rumor id.
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#[derive(Debug, Default)]
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pub struct MessageSearchIndex(BTreeMap<u64, BTreeMap<EventId, Arc<IndexedMessage>>>);
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impl MessageSearchIndex {
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/// Index a rumor for search, ignoring reactions and empty content.
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pub fn insert(&mut self, rumor: &UnsignedEvent) {
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if !is_chat(rumor.kind) || rumor.content.trim().is_empty() {
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return;
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}
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let Some(id) = rumor.id else { return };
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let indexed = Arc::new(IndexedMessage {
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message: SearchMessage {
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room: rumor.uniq_id(),
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author: rumor.pubkey,
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content: rumor.content.as_str().into(),
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created_at: rumor.created_at,
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},
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normalized: rumor.content.to_lowercase().into(),
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});
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self.0
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.entry(rumor.uniq_id())
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.or_default()
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.entry(id)
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.or_insert(indexed);
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}
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/// Find messages whose content contains all of the terms, newest first.
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pub fn search(&self, terms: &[String], limit: usize) -> Vec<SearchMessage> {
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let mut matches: Vec<&Arc<IndexedMessage>> = self
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.0
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.values()
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.flat_map(|messages| messages.values())
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.filter(|indexed| terms.iter().all(|term| indexed.normalized.contains(term)))
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.collect();
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matches.sort_by_key(|indexed| Reverse(indexed.message.created_at));
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matches.truncate(limit);
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matches
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.into_iter()
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.map(|indexed| indexed.message.clone())
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.collect()
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}
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/// Drop all indexed messages.
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pub fn clear(&mut self) {
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self.0.clear();
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}
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}
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fn is_chat(kind: Kind) -> bool {
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kind == Kind::PrivateDirectMessage || kind == Kind::Custom(15)
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}
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#[cfg(test)]
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mod tests {
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use super::*;
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fn rumor(kind: Kind, content: &str, created_at: u64) -> UnsignedEvent {
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let sender = Keys::generate();
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let peer = Keys::generate().public_key();
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let mut rumor = EventBuilder::new(kind, content)
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.tag(Tag::public_key(peer))
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.finalize_unsigned(sender.public_key());
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rumor.ensure_id();
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rumor.created_at = Timestamp::from(created_at);
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rumor
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}
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#[test]
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fn search_matches_all_terms_newest_first_and_deduplicates() {
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let mut index = MessageSearchIndex::default();
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let first = rumor(Kind::PrivateDirectMessage, "Hello ALICE", 10);
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let second = rumor(Kind::PrivateDirectMessage, "hello again", 20);
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let reaction = rumor(Kind::Reaction, "hello world", 30);
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index.insert(&first);
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index.insert(&first);
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index.insert(&second);
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index.insert(&reaction);
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let hits = index.search(&["hello".to_owned()], 10);
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assert_eq!(hits.len(), 2);
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assert_eq!(&*hits[0].content, "hello again");
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assert_eq!(hits[0].created_at, Timestamp::from(20));
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let hits = index.search(&["hello".to_owned(), "again".to_owned()], 10);
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assert_eq!(hits.len(), 1);
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let hits = index.search(&["hello".to_owned()], 1);
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assert_eq!(hits.len(), 1);
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}
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#[test]
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fn empty_content_is_not_indexed() {
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let mut index = MessageSearchIndex::default();
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index.insert(&rumor(Kind::PrivateDirectMessage, " ", 10));
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assert!(index.search(&["hello".to_owned()], 10).is_empty());
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}
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}
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