From b7369a834e584d3e949e0ebdfb77b33c7e0fe32b Mon Sep 17 00:00:00 2001
From: Val Lorentz <progval+git@progval.net>
Date: Sat, 26 Oct 2024 18:37:25 +0200
Subject: [PATCH] LATEST impl with blanks to fill

---
 sable_history/src/pg_history_service.rs | 121 +++++++++++++++++++++---
 sable_network/src/history/service.rs    |   4 +-
 2 files changed, 107 insertions(+), 18 deletions(-)

diff --git a/sable_history/src/pg_history_service.rs b/sable_history/src/pg_history_service.rs
index 89590d43..ab65d19d 100644
--- a/sable_history/src/pg_history_service.rs
+++ b/sable_history/src/pg_history_service.rs
@@ -3,14 +3,15 @@ use std::collections::HashMap;
 
 use diesel::dsl::sql;
 use diesel::prelude::*;
-use diesel_async::{AsyncConnection, AsyncPgConnection};
-use futures::stream::StreamExt;
+use diesel_async::{AsyncConnection, AsyncPgConnection, RunQueryDsl};
+use futures::stream::{StreamExt, TryStreamExt};
 use tokio::sync::Mutex;
 use uuid::Uuid;
 
 use sable_network::prelude::*;
 
 use crate::schema::channels;
+use crate::schema::messages;
 
 /// Implementation of [`HistoryService`] backed PostgreSQL
 pub struct PgHistoryService<'a> {
@@ -28,22 +29,22 @@ impl<'a> PgHistoryService<'a> {
 impl<'a> HistoryService for PgHistoryService<'a> {
     async fn list_targets(
         &self,
-        user: UserId,
-        after_ts: Option<i64>,
-        before_ts: Option<i64>,
-        limit: Option<usize>,
+        _user: UserId,
+        _after_ts: Option<i64>,
+        _before_ts: Option<i64>,
+        _limit: Option<usize>,
     ) -> HashMap<TargetId, i64> {
         // TODO: access control
-        match diesel_async::RunQueryDsl::load_stream(
-            channels::dsl::channels.select((
+        // TODO: after_ts, before_ts, limit
+        match channels::dsl::channels
+            .select((
                 channels::dsl::id,
                 sql::<diesel::pg::sql_types::Uuid>(
                     "SELECT MAX(id) FROM messages WHERE target_channel=channels.id",
                 ),
-            )),
-            &mut *self.database_connection.lock().await,
-        )
-        .await
+            ))
+            .load_stream(&mut *self.database_connection.lock().await)
+            .await
         {
             Err(e) => {
                 tracing::error!("Could not get history channels: {e}");
@@ -75,11 +76,101 @@ impl<'a> HistoryService for PgHistoryService<'a> {
 
     async fn get_entries(
         &self,
-        user: UserId,
+        _user: UserId,
         target: TargetId,
         request: HistoryRequest,
     ) -> Result<impl IntoIterator<Item = HistoryLogEntry>, HistoryError> {
-        todo!();
-        Ok(vec![])
+        // TODO: access control
+        let TargetId::Channel(channel_id) = target else {
+            // TODO: PMs
+            return Err(HistoryError::InvalidTarget(target));
+        };
+
+        let mut connection_lock = self.database_connection.lock().await;
+
+        let db_channel_id = i64::try_from(channel_id.as_u64()).expect("channel id overflows u64");
+        if channels::dsl::channels
+            .find(db_channel_id)
+            .select(crate::models::Channel::as_select())
+            .first(&mut *connection_lock)
+            .await
+            .optional()
+            .expect("Could not check if channel exists")
+            .is_none()
+        {
+            return Err(HistoryError::InvalidTarget(target));
+        }
+
+        match request {
+            HistoryRequest::Latest { to_ts, limit } => {
+                let limit = i64::min(10000, i64::try_from(limit).unwrap_or(i64::MAX));
+                Ok(match to_ts {
+                    Some(to_ts) => {
+                        // Lowest UUIDv7 corresponding to the timestamp
+                        let to_uuid = uuid::Builder::from_unix_timestamp_millis(
+                            u64::try_from(to_ts)
+                                .unwrap_or(u64::MIN) // floor timestamps to Epoch
+                                .saturating_mul(1000),
+                            &[u8::MIN; 10],
+                        )
+                        .into_uuid();
+                        Box::new(
+                            messages::dsl::messages
+                                .filter(messages::dsl::target_channel.eq(db_channel_id))
+                                .filter(messages::dsl::id.lt(to_uuid))
+                                .order(messages::dsl::id.desc())
+                                .limit(limit)
+                                .load_stream(&mut *connection_lock),
+                        )
+                    }
+                    None => Box::new(
+                        messages::dsl::messages
+                            .filter(messages::dsl::target_channel.eq(db_channel_id))
+                            .order(messages::dsl::id.desc())
+                            .limit(limit)
+                            .load_stream(&mut *connection_lock),
+                    ),
+                }
+                .await
+                .expect("could not query messages")
+                .map(|row| {
+                    let crate::models::Message {
+                        id,
+                        source_user,
+                        target_channel,
+                        text,
+                    } = row?;
+                    Ok(HistoryLogEntry {
+                        id: (),
+                        details: NetworkStateChange::NewMessage(update::NewMessage {
+                            message: (),
+                            source: (),
+                            target: (),
+                        }),
+                        source_event: (),
+                        timestamp: (),
+                    })
+                })
+                .try_collect::<Vec<_>>()
+                .await
+                .expect("could not parse all records"))
+            }
+            HistoryRequest::Before { from_ts, limit } => {
+                todo!("before")
+            }
+            HistoryRequest::After { start_ts, limit } => {
+                todo!("after")
+            }
+            HistoryRequest::Around { around_ts, limit } => {
+                todo!("around")
+            }
+            HistoryRequest::Between {
+                start_ts,
+                end_ts,
+                limit,
+            } => {
+                todo!("between")
+            }
+        }
     }
 }
diff --git a/sable_network/src/history/service.rs b/sable_network/src/history/service.rs
index 6707851e..f34d1e75 100644
--- a/sable_network/src/history/service.rs
+++ b/sable_network/src/history/service.rs
@@ -99,7 +99,5 @@ pub trait HistoryService {
         user: UserId,
         target: TargetId,
         request: HistoryRequest,
-    ) -> impl Future<Output = Result<impl IntoIterator<Item = HistoryLogEntry>, HistoryError>>
-           + Send
-           + Sync;
+    ) -> impl Future<Output = Result<impl IntoIterator<Item = HistoryLogEntry>, HistoryError>> + Send;
 }