1 files changed, 98 insertions, 0 deletions
diff --git a/lib/eventstats.cpp b/lib/eventstats.cpp
new file mode 100644
index 00000000..9fa7f5ff
--- /dev/null
+++ b/lib/eventstats.cpp
@@ -0,0 +1,98 @@
+// SPDX-FileCopyrightText: 2021 Quotient contributors
+// SPDX-License-Identifier: LGPL-2.1-or-later
+
+#include "eventstats.h"
+
+using namespace Quotient;
+
+EventStats EventStats::fromRange(const Room* room, const Room::rev_iter_t& from,
+                                 const Room::rev_iter_t& to,
+                                 const EventStats& init)
+{
+    Q_ASSERT(to <= room->historyEdge());
+    Q_ASSERT(from >= Room::rev_iter_t(room->syncEdge()));
+    Q_ASSERT(from <= to);
+    QElapsedTimer et;
+    et.start();
+    const auto result =
+        accumulate(from, to, init,
+                   [room](EventStats acc, const TimelineItem& ti) {
+                       acc.notableCount += room->isEventNotable(ti);
+                       acc.highlightCount += room->notificationFor(ti).type
+                                             == Notification::Highlight;
+                       return acc;
+                   });
+    if (et.nsecsElapsed() > profilerMinNsecs() / 10)
+        qCDebug(PROFILER).nospace()
+            << "Event statistics collection over index range [" << from->index()
+            << "," << (to - 1)->index() << "] took " << et;
+    return result;
+}
+
+EventStats EventStats::fromMarker(const Room* room,
+                                  const EventStats::marker_t& marker)
+{
+    const auto s = fromRange(room, marker_t(room->syncEdge()), marker,
+                             { 0, 0, marker == room->historyEdge() });
+    Q_ASSERT(s.isValidFor(room, marker));
+    return s;
+}
+
+EventStats EventStats::fromCachedCounters(Omittable<int> notableCount,
+                                          Omittable<int> highlightCount)
+{
+    const auto hCount = std::max(0, highlightCount.value_or(0));
+    if (!notableCount.has_value())
+        return { 0, hCount, true };
+    auto nCount = notableCount.value_or(0);
+    return { std::max(0, nCount), hCount, nCount != -1 };
+}
+
+bool EventStats::updateOnMarkerMove(const Room* room, const marker_t& oldMarker,
+                                    const marker_t& newMarker)
+{
+    if (newMarker == oldMarker)
+        return false;
+
+    // Double-check consistency between the old marker and the old stats
+    Q_ASSERT(isValidFor(room, oldMarker));
+    Q_ASSERT(oldMarker > newMarker);
+
+    // A bit of optimisation: only calculate the difference if the marker moved
+    // less than half the remaining timeline ahead; otherwise, recalculation
+    // over the remaining timeline will very likely be faster.
+    if (oldMarker != room->historyEdge()
+        && oldMarker - newMarker < newMarker - marker_t(room->syncEdge())) {
+        const auto removedStats = fromRange(room, newMarker, oldMarker);
+        Q_ASSERT(notableCount >= removedStats.notableCount
+                 && highlightCount >= removedStats.highlightCount);
+        notableCount -= removedStats.notableCount;
+        highlightCount -= removedStats.highlightCount;
+        return removedStats.notableCount > 0 || removedStats.highlightCount > 0;
+    }
+
+    const auto newStats = EventStats::fromMarker(room, newMarker);
+    if (!isEstimate && newStats == *this)
+        return false;
+    *this = newStats;
+    return true;
+}
+
+bool EventStats::isValidFor(const Room* room, const marker_t& marker) const
+{
+    const auto markerAtHistoryEdge = marker == room->historyEdge();
+    // Either markerAtHistoryEdge and isEstimate are in the same state, or it's
+    // a special case of no notable events and the marker at history edge
+    // (then isEstimate can assume any value).
+    return markerAtHistoryEdge == isEstimate
+           || (markerAtHistoryEdge && notableCount == 0);
+}
+
+QDebug Quotient::operator<<(QDebug dbg, const EventStats& es)
+{
+    QDebugStateSaver _(dbg);
+    dbg.nospace() << es.notableCount << '/' << es.highlightCount;
+    if (es.isEstimate)
+        dbg << " (estimated)";
+    return dbg;
+}