From a787c57c34eb98ebc10add29a8fc35c634845182 Mon Sep 17 00:00:00 2001
From: Kitsune Ral <Kitsune-Ral@users.sf.net>
Date: Fri, 17 Jan 2025 10:42:20 +0100
Subject: [PATCH] QuaternionRoom::getSingleEvent()

Also fixes the current FTBFS due to a part of this functionality
sneaking into a previous commit. Otherwise, it's unused for now, will be
used in subsequent commits.
---
 client/quaternionroom.cpp | 39 ++++++++++++++++++++++++++++++++++++++-
 client/quaternionroom.h   | 23 ++++++++++++++++++++---
 2 files changed, 58 insertions(+), 4 deletions(-)

diff --git a/client/quaternionroom.cpp b/client/quaternionroom.cpp
index 60174e0f..16167fe3 100644
--- a/client/quaternionroom.cpp
+++ b/client/quaternionroom.cpp
@@ -10,8 +10,10 @@
 
 #include "logging_categories.h"
 
-#include <Quotient/user.h>
 #include <Quotient/events/roommessageevent.h>
+
+#include <Quotient/user.h>
+
 #include <QtCore/QRegularExpression>
 
 #include <ranges>
@@ -88,6 +90,41 @@ bool QuaternionRoom::canRedact(const Quotient::EventId& eventId) const
     return false;
 }
 
+void QuaternionRoom::onGettingSingleEvent(const QString& evtId)
+{
+    std::erase_if(singleEventRequests, [this, evtId](SingleEventRequest& r) {
+        if (!r.requestHandle.isFinished())
+            r.requestHandle.abandon();
+        std::ranges::for_each(r.eventIdsToRefresh, std::bind_front(&Room::updatedEvent, this));
+        return r.eventId == evtId;
+    });
+}
+
+const RoomEvent* QuaternionRoom::getSingleEvent(const QString& eventId, const QString& originEventId)
+{
+    if (auto timelineIt = findInTimeline(eventId); timelineIt != historyEdge())
+        return timelineIt->event();
+    if (auto cachedIt = cachedEvents.find(eventId); cachedIt != cachedEvents.cend())
+        return cachedIt->second.get();
+
+    auto requestIt = std::ranges::find(singleEventRequests, eventId, &SingleEventRequest::eventId);
+    if (requestIt == singleEventRequests.cend())
+        requestIt = singleEventRequests.insert(
+            requestIt,
+            { eventId, connection()
+                           ->callApi<GetOneRoomEventJob>(id(), eventId)
+                           .then([this](RoomEventPtr&& pEvt) {
+                               const auto [it, cachedEventInserted] =
+                                   cachedEvents.insert_or_assign(pEvt->id(), std::move(pEvt));
+                               if (QUO_ALARM(!cachedEventInserted))
+                                   emit updatedEvent(it->first); // At least notify clients...
+                               onGettingSingleEvent(it->first);
+                           }) });
+    requestIt->eventIdsToRefresh.push_back(originEventId);
+
+    return nullptr;
+}
+
 void QuaternionRoom::onAddNewTimelineEvents(timeline_iter_t from)
 {
     std::for_each(from, messageEvents().cend(),
diff --git a/client/quaternionroom.h b/client/quaternionroom.h
index bf805e80..b33f8994 100644
--- a/client/quaternionroom.h
+++ b/client/quaternionroom.h
@@ -8,6 +8,8 @@
 
 #pragma once
 
+#include <Quotient/csapi/rooms.h>
+
 #include <Quotient/room.h>
 
 #include <QtCore/QDeadlineTimer>
@@ -16,6 +18,8 @@ class QuaternionRoom: public Quotient::Room
 {
     Q_OBJECT
 public:
+    using RoomEvent = Quotient::RoomEvent;
+
     QuaternionRoom(Quotient::Connection* connection, QString roomId,
                    Quotient::JoinState joinState);
 
@@ -46,7 +50,12 @@ class QuaternionRoom: public Quotient::Room
     //!         is not found
     Q_INVOKABLE EventFuture ensureHistory(const QString& upToEventId, quint16 maxWaitSeconds = 20);
 
-  private:
+    //! \brief Obtain an arbitrary room event by its id that is available locally
+    //!
+    Q_INVOKABLE const Quotient::RoomEvent* getSingleEvent(const QString& eventId,
+                                                          const QString& originEventId);
+
+private:
     using EventPromise = QPromise<void>;
     using EventId = Quotient::EventId;
 
@@ -57,13 +66,21 @@ class QuaternionRoom: public Quotient::Room
     };
     std::vector<HistoryRequest> historyRequests;
 
-    QSet<const Quotient::RoomEvent*> highlights;
+    struct SingleEventRequest {
+        EventId eventId;
+        Quotient::JobHandle<Quotient::GetOneRoomEventJob> requestHandle;
+        std::vector<QString> eventIdsToRefresh{};
+    };
+    std::vector<SingleEventRequest> singleEventRequests;
+    std::unordered_map<EventId, Quotient::event_ptr_tt<const RoomEvent>> cachedEvents;
+
+    QSet<const RoomEvent*> highlights;
     QString m_cachedUserFilter;
-    int m_requestedEventsCount = 0;
 
     void onAddNewTimelineEvents(timeline_iter_t from) override;
     void onAddHistoricalTimelineEvents(rev_iter_t from) override;
 
     void checkForHighlights(const Quotient::TimelineItem& ti);
     void checkForRequestedEvents(const rev_iter_t& from);
+    void onGettingSingleEvent(const QString& evtId);
 };