Implement event/date search bar

src/utils/events.js

@@ -139,6 +139,68 @@ export function getDate(event, n, timeZone = DEFAULT_TZ) {
   return null
 }
 
+/**
+ * Return nearest occurrence (past or future) relative to a reference date (date-string yyyy-MM-dd).
+ * Falls back to first/last when reference lies before first or after last (bounded by cap).
+ * Returns { n, dateStr } or null if no recurrence / invalid.
+ */
+export function getNearestOccurrence(event, referenceDateStr, timeZone = DEFAULT_TZ, cap = 5000) {
+  if (!event) return null
+  if (!event.recur) return { n: 0, dateStr: event.startDate }
+  const { recur } = event
+  if (!recur || !['weeks', 'months'].includes(recur.freq)) return { n: 0, dateStr: event.startDate }
+  const refDate = fromLocalString(referenceDateStr, timeZone)
+  const baseDate = fromLocalString(event.startDate, timeZone)
+  if (refDate <= baseDate) return { n: 0, dateStr: event.startDate }
+  const maxCount = recur.count === 'unlimited' ? cap : Math.min(parseInt(recur.count, 10) || 0, cap)
+  if (maxCount <= 0) return null
+  let low = 0
+  let high = maxCount - 1
+  let candidateGE = null
+  while (low <= high) {
+    const mid = (low + high) >> 1
+    const midStr = getDate(event, mid, timeZone)
+    if (!midStr) {
+      // invalid mid (should rarely happen) shrink high
+      high = mid - 1
+      continue
+    }
+    const midDate = fromLocalString(midStr, timeZone)
+    if (midDate >= refDate) {
+      candidateGE = { n: mid, dateStr: midStr, date: midDate }
+      high = mid - 1
+    } else {
+      low = mid + 1
+    }
+  }
+  let candidateLT = null
+  if (candidateGE) {
+    const prevN = candidateGE.n - 1
+    if (prevN >= 0) {
+      const prevStr = getDate(event, prevN, timeZone)
+      if (prevStr) {
+        candidateLT = { n: prevN, dateStr: prevStr, date: fromLocalString(prevStr, timeZone) }
+      }
+    }
+  } else {
+    // All occurrences earlier than ref
+    const lastN = maxCount - 1
+    const lastStr = getDate(event, lastN, timeZone)
+    if (lastStr)
+      candidateLT = { n: lastN, dateStr: lastStr, date: fromLocalString(lastStr, timeZone) }
+  }
+  if (candidateGE && candidateLT) {
+    const diffGE = candidateGE.date - refDate
+    const diffLT = refDate - candidateLT.date
+    return diffLT <= diffGE
+      ? { n: candidateLT.n, dateStr: candidateLT.dateStr }
+      : { n: candidateGE.n, dateStr: candidateGE.dateStr }
+  }
+  if (candidateGE) return { n: candidateGE.n, dateStr: candidateGE.dateStr }
+  if (candidateLT) return { n: candidateLT.n, dateStr: candidateLT.dateStr }
+  return null
+}
+
 export function buildDayEvents(events, dateStr, timeZone = DEFAULT_TZ) {
   const date = fromLocalString(dateStr, timeZone)
   const out = []