feat(Index.tsx): add flexible ISO8601 date parsing and fallback note fetching logic

src/pages/Index.tsx

@@ -157,6 +157,94 @@ const Index = () => {
     return trimmedLines.join('\n');
   };
 
+  // Flexible ISO8601 date parsing (supports YYYY, YYYY-MM, YYYY-MM-DD, full ISO)
+  const parseFlexibleIsoDateToMs = (input: string): number | null => {
+    const trimmed = input.trim();
+    if (!trimmed) return null;
+
+    if (/^\d{4}$/.test(trimmed)) {
+      const year = Number(trimmed);
+      const start = Date.UTC(year, 0, 1, 0, 0, 0, 0);
+      const end = Date.UTC(year + 1, 0, 1, 0, 0, 0, 0) - 1;
+      return Math.floor((start + end) / 2);
+    }
+
+    const ym = trimmed.match(/^(\d{4})-(\d{2})$/);
+    if (ym) {
+      const year = Number(ym[1]);
+      const monthIndex = Number(ym[2]) - 1; // 0-based
+      if (monthIndex < 0 || monthIndex > 11) return null;
+      const start = Date.UTC(year, monthIndex, 1, 0, 0, 0, 0);
+      const nextMonthYear = monthIndex === 11 ? year + 1 : year;
+      const nextMonthIndex = (monthIndex + 1) % 12;
+      const end = Date.UTC(nextMonthYear, nextMonthIndex, 1, 0, 0, 0, 0) - 1;
+      return Math.floor((start + end) / 2);
+    }
+
+    const ymd = trimmed.match(/^(\d{4})-(\d{2})-(\d{2})$/);
+    if (ymd) {
+      const year = Number(ymd[1]);
+      const monthIndex = Number(ymd[2]) - 1; // 0-based
+      const day = Number(ymd[3]);
+      if (monthIndex < 0 || monthIndex > 11) return null;
+      const start = Date.UTC(year, monthIndex, day, 0, 0, 0, 0);
+      const end = Date.UTC(year, monthIndex, day + 1, 0, 0, 0, 0) - 1;
+      return Math.floor((start + end) / 2);
+    }
+
+    // YYYY-MM-DD HH
+    const ymdh = trimmed.match(/^(\d{4})-(\d{2})-(\d{2})[ T](\d{2})$/);
+    if (ymdh) {
+      const year = Number(ymdh[1]);
+      const monthIndex = Number(ymdh[2]) - 1;
+      const day = Number(ymdh[3]);
+      const hour = Number(ymdh[4]);
+      if (monthIndex < 0 || monthIndex > 11 || hour < 0 || hour > 23) return null;
+      const start = Date.UTC(year, monthIndex, day, hour, 0, 0, 0);
+      const end = Date.UTC(year, monthIndex, day, hour + 1, 0, 0, 0) - 1;
+      return Math.floor((start + end) / 2);
+    }
+
+    // YYYY-MM-DD HH:mm
+    const ymdhm = trimmed.match(/^(\d{4})-(\d{2})-(\d{2})[ T](\d{2}):(\d{2})$/);
+    if (ymdhm) {
+      const year = Number(ymdhm[1]);
+      const monthIndex = Number(ymdhm[2]) - 1;
+      const day = Number(ymdhm[3]);
+      const hour = Number(ymdhm[4]);
+      const minute = Number(ymdhm[5]);
+      if (monthIndex < 0 || monthIndex > 11 || hour < 0 || hour > 23 || minute < 0 || minute > 59) return null;
+      const start = Date.UTC(year, monthIndex, day, hour, minute, 0, 0);
+      const end = Date.UTC(year, monthIndex, day, hour, minute + 1, 0, 0) - 1;
+      return Math.floor((start + end) / 2);
+    }
+
+    // YYYY-MM-DD HH:mm:ss
+    const ymdhms = trimmed.match(/^(\d{4})-(\d{2})-(\d{2})[ T](\d{2}):(\d{2}):(\d{2})$/);
+    if (ymdhms) {
+      const year = Number(ymdhms[1]);
+      const monthIndex = Number(ymdhms[2]) - 1;
+      const day = Number(ymdhms[3]);
+      const hour = Number(ymdhms[4]);
+      const minute = Number(ymdhms[5]);
+      const second = Number(ymdhms[6]);
+      if (
+        monthIndex < 0 || monthIndex > 11 ||
+        hour < 0 || hour > 23 ||
+        minute < 0 || minute > 59 ||
+        second < 0 || second > 59
+      ) return null;
+      const start = Date.UTC(year, monthIndex, day, hour, minute, second, 0);
+      const end = Date.UTC(year, monthIndex, day, hour, minute, second + 1, 0) - 1;
+      return Math.floor((start + end) / 2);
+    }
+
+    const full = new Date(trimmed);
+    const ms = full.getTime();
+    if (Number.isNaN(ms)) return null;
+    return ms;
+  };
+
   // Create a new note
   const createNote = async (content: string) => {
     try {
@@ -397,6 +485,53 @@ const Index = () => {
         setNoteCache(notes);
         setCurrentNoteIndex(targetIndex);
         setPreviousNote(notes[targetIndex]);
+      } else {
+        // Fallback: fetch a date window around the target note
+        const targetMs = targetNote.epochTime;
+        const headers = {
+          'Content-Type': 'application/json',
+          'Authorization': `Bearer ${MEILISEARCH_API_KEY}`,
+        } as const;
+        let windowMs = 1000 * 60 * 60 * 24 * 90; // 90 days
+        for (let i = 0; i < 3; i++) {
+          const start = targetMs - windowMs;
+          const end = targetMs + windowMs;
+          const resp = await fetch(`${MEILISEARCH_ENDPOINT}/indexes/${NOTE_INDEX}/search`, {
+            method: 'POST',
+            headers,
+            body: JSON.stringify({
+              q: '',
+              filter: `date >= ${start} AND date <= ${end}`,
+              sort: ['date:desc'],
+              limit: 1000,
+            }),
+          });
+          if (resp.ok) {
+            const d = await resp.json();
+            const aroundNotes: Note[] = d.hits.map((hit: any) => ({
+              id: hit.id,
+              epochTime: hit.date,
+              dateISO: hit.dateISO,
+              content: hit.content,
+              topLetter: hit.topLetter,
+              topLetterFrequency: hit.topLetterFrequency,
+              letterCount: hit.letterCount || 0,
+            }));
+            if (aroundNotes.length > 0) {
+              const exactIdx = aroundNotes.findIndex(n => n.id === targetNote.id);
+              const pickIdx = exactIdx >= 0
+                ? exactIdx
+                : aroundNotes.reduce((bestIdx, n, idx) => (
+                    Math.abs(n.epochTime - targetMs) < Math.abs(aroundNotes[bestIdx].epochTime - targetMs) ? idx : bestIdx
+                  ), 0);
+              setNoteCache(aroundNotes);
+              setCurrentNoteIndex(pickIdx);
+              setPreviousNote(aroundNotes[pickIdx]);
+              return;
+            }
+          }
+          windowMs *= 2;
+        }
       }
     } catch (error) {
       console.error('Error loading notes around target:', error);
@@ -483,9 +618,8 @@ const Index = () => {
   // Go to closest note by ISO8601 date
   const goToClosestNoteToDate = async (iso8601: string) => {
     try {
-      const target = new Date(iso8601);
-      const targetMs = target.getTime();
-      if (Number.isNaN(targetMs)) {
+      const targetMs = parseFlexibleIsoDateToMs(iso8601);
+      if (targetMs === null) {
         toast({
           title: 'Invalid date',
           description: 'Please enter a valid ISO8601 date.',