From e50f90f277004141e3098be7d176184db8f48ba2 Mon Sep 17 00:00:00 2001
From: Leo Vasanko <leo@git>
Date: Mon, 25 Aug 2025 19:05:14 -0600
Subject: [PATCH] Faster event updates (avoid full re-render)

---
 src/components/CalendarView.vue | 10 +++-
 src/plugins/virtualWeeks.js     | 85 +++++++++++++++++++++++++++++++--
 2 files changed, 88 insertions(+), 7 deletions(-)

diff --git a/src/components/CalendarView.vue b/src/components/CalendarView.vue
index f0c4c8d..cb278c4 100644
--- a/src/components/CalendarView.vue
+++ b/src/components/CalendarView.vue
@@ -87,7 +87,7 @@ const vwm = createVirtualWeekManager({
   contentHeight,
 })
 const visibleWeeks = vwm.visibleWeeks
-const { scheduleWindowUpdate, resetWeeks } = vwm
+const { scheduleWindowUpdate, resetWeeks, refreshEvents } = vwm
 
 // Scroll managers (after scheduleWindowUpdate available)
 const scrollManager = createScrollManager({ viewport, scheduleRebuild: scheduleWindowUpdate })
@@ -395,11 +395,17 @@ watch(
 watch(
   () => calendarStore.events,
   () => {
-    resetWeeks('events')
+    refreshEvents('events')
   },
   { deep: true },
 )
 
+// Reflect selection & events by rebuilding day objects in-place
+watch(
+  () => [selection.value.startDate, selection.value.dayCount],
+  () => refreshEvents('selection'),
+)
+
 // Rebuild if viewport height changes (e.g., resize)
 window.addEventListener('resize', () => {
   if (viewport.value) viewportHeight.value = viewport.value.clientHeight
diff --git a/src/plugins/virtualWeeks.js b/src/plugins/virtualWeeks.js
index a9dbdc9..ad6dcbf 100644
--- a/src/plugins/virtualWeeks.js
+++ b/src/plugins/virtualWeeks.js
@@ -69,17 +69,14 @@ export function createVirtualWeekManager({
       }
     }
 
-    for (let i = 0; i < 7; i++) {
-      const dateStr = toLocalString(cur, DEFAULT_TZ)
+    const collectEventsForDate = (dateStr, curDateObj) => {
       const storedEvents = []
-
       for (const ev of calendarStore.events.values()) {
         if (!ev.isRepeating && dateStr >= ev.startDate && dateStr <= ev.endDate) {
           storedEvents.push(ev)
         }
       }
       const dayEvents = [...storedEvents]
-      // Expand repeating events
       for (const base of repeatingBases) {
         if (dateStr >= base.startDate && dateStr <= base.endDate) {
           dayEvents.push({ ...base, _recurrenceIndex: 0, _baseId: base.id })
@@ -88,7 +85,7 @@ export function createVirtualWeekManager({
         const baseStart = fromLocalString(base.startDate, DEFAULT_TZ)
         const baseEnd = fromLocalString(base.endDate, DEFAULT_TZ)
         const spanDays = Math.max(0, differenceInCalendarDays(baseEnd, baseStart))
-        const currentDate = fromLocalString(dateStr, DEFAULT_TZ)
+        const currentDate = curDateObj
         let occurrenceFound = false
         for (let offset = 0; offset <= spanDays && !occurrenceFound; offset++) {
           const candidateStart = addDays(currentDate, -offset)
@@ -114,6 +111,12 @@ export function createVirtualWeekManager({
           }
         }
       }
+      return dayEvents
+    }
+
+    for (let i = 0; i < 7; i++) {
+      const dateStr = toLocalString(cur, DEFAULT_TZ)
+      const dayEvents = collectEventsForDate(dateStr, fromLocalString(dateStr, DEFAULT_TZ))
       const dow = cur.getDay()
       const isFirst = cur.getDate() === 1
       if (isFirst) {
@@ -281,6 +284,77 @@ export function createVirtualWeekManager({
     scheduleWindowUpdate(reason)
   }
 
+  // Reflective update of only events inside currently visible weeks (keeps week objects stable)
+  function refreshEvents(reason = 'events-refresh') {
+    if (!visibleWeeks.value.length) return
+    const repeatingBases = []
+    if (calendarStore.events) {
+      for (const ev of calendarStore.events.values()) if (ev.isRepeating) repeatingBases.push(ev)
+    }
+    const selStart = selection.value.startDate
+    const selCount = selection.value.dayCount
+    const selEnd = selStart && selCount > 0 ? addDaysStr(selStart, selCount - 1) : null
+    for (const week of visibleWeeks.value) {
+      for (const day of week.days) {
+        const dateStr = day.date
+        // Update selection flag
+        if (selStart && selEnd) day.isSelected = dateStr >= selStart && dateStr <= selEnd
+        else day.isSelected = false
+        // Rebuild events list for this day
+        const storedEvents = []
+        for (const ev of calendarStore.events.values()) {
+          if (!ev.isRepeating && dateStr >= ev.startDate && dateStr <= ev.endDate) {
+            storedEvents.push(ev)
+          }
+        }
+        const dayEvents = [...storedEvents]
+        for (const base of repeatingBases) {
+          if (dateStr >= base.startDate && dateStr <= base.endDate) {
+            dayEvents.push({ ...base, _recurrenceIndex: 0, _baseId: base.id })
+            continue
+          }
+          const baseStart = fromLocalString(base.startDate, DEFAULT_TZ)
+          const baseEnd = fromLocalString(base.endDate, DEFAULT_TZ)
+          const spanDays = Math.max(0, differenceInCalendarDays(baseEnd, baseStart))
+          const currentDate = fromLocalString(dateStr, DEFAULT_TZ)
+          let occurrenceFound = false
+          for (let offset = 0; offset <= spanDays && !occurrenceFound; offset++) {
+            const candidateStart = addDays(currentDate, -offset)
+            const candidateStartStr = toLocalString(candidateStart, DEFAULT_TZ)
+            const occurrenceIndex = getOccurrenceIndex(base, candidateStartStr, DEFAULT_TZ)
+            if (occurrenceIndex !== null) {
+              const virtualEndDate = getVirtualOccurrenceEndDate(
+                base,
+                candidateStartStr,
+                DEFAULT_TZ,
+              )
+              if (dateStr >= candidateStartStr && dateStr <= virtualEndDate) {
+                const virtualId = base.id + '_v_' + candidateStartStr
+                const alreadyExists = dayEvents.some((ev) => ev.id === virtualId)
+                if (!alreadyExists) {
+                  dayEvents.push({
+                    ...base,
+                    id: virtualId,
+                    startDate: candidateStartStr,
+                    endDate: virtualEndDate,
+                    _recurrenceIndex: occurrenceIndex,
+                    _baseId: base.id,
+                  })
+                }
+                occurrenceFound = true
+              }
+            }
+          }
+        }
+        day.events = dayEvents
+      }
+    }
+    if (process.env.NODE_ENV !== 'production') {
+      // eslint-disable-next-line no-console
+      console.debug('[VirtualWeeks] refreshEvents', reason, { weeks: visibleWeeks.value.length })
+    }
+  }
+
   function goToToday() {
     const top = addDays(new Date(calendarStore.now), -21)
     const targetWeekIndex = getWeekIndex(top)
@@ -300,6 +374,7 @@ export function createVirtualWeekManager({
     scheduleWindowUpdate,
     resetWeeks,
     updateVisibleWeeks,
+    refreshEvents,
     getWeekIndex,
     getFirstDayForVirtualWeek,
     goToToday,