cleanup generating calendar data

src/pages/index.tsx

@@ -36,15 +36,25 @@ export default function OpenSourceHeatmap() {
     startDate.setMonth(today.getMonth() - 11);
     startDate.setDate(1);
 
+    // create a map to store counts for each provider and date
+    const countMap: Record<string, Record<string, number>> = {};
+
+    modelData.forEach(item => {
+      const dateString = item.createdAt.split('T')[0];
+      Object.entries(PROVIDERS_MAP).forEach(([provider, { authors }]) => {
+        if (authors.some(author => item.id.startsWith(author))) {
+          countMap[provider] = countMap[provider] || {};
+          countMap[provider][dateString] = (countMap[provider][dateString] || 0) + 1;
+        }
+      });
+    });
+
+    // fill in with 0s for days with no activity
     for (let d = new Date(startDate); d <= today; d.setDate(d.getDate() + 1)) {
       const dateString = d.toISOString().split('T')[0];
       
-      Object.entries(PROVIDERS_MAP).forEach(([provider, { authors }]) => {
-        const count = modelData.filter(item => 
-          item.createdAt.startsWith(dateString) && 
-          authors.some(author => item.id.startsWith(author))
-        ).length;
-        
+      Object.entries(PROVIDERS_MAP).forEach(([provider]) => {
+        const count = countMap[provider]?.[dateString] || 0;
         data[provider].push({ date: dateString, count, level: 0 });
       });
     }