feat: Add emoji usage tracking hook and integrate with EmojiBoard for usage statistics

src/app/components/emoji-board/EmojiBoard.tsx

@@ -22,6 +22,7 @@ import { preventScrollWithArrowKey, stopPropagation } from '../../utils/keyboard
 import { useRelevantImagePacks } from '../../hooks/useImagePacks';
 import { useMatrixClient } from '../../hooks/useMatrixClient';
 import { useRecentEmoji } from '../../hooks/useRecentEmoji';
+import { useEmojiUsage } from '../../hooks/useEmojiUsage';
 import { isUserId, mxcUrlToHttp } from '../../utils/matrix';
 import { editableActiveElement, targetFromEvent } from '../../utils/dom';
 import { useAsyncSearch, UseAsyncSearchOptions } from '../../hooks/useAsyncSearch';
@@ -378,13 +379,30 @@ export function EmojiBoard({
   addToRecentEmoji = true,
 }: EmojiBoardProps) {
   const mx = useMatrixClient();
+  const { trackEmojiUsage, getMostUsedEmoji } = useEmojiUsage();
 
   const emojiTab = tab === EmojiBoardTab.Emoji;
   const usage = emojiTab ? ImageUsage.Emoticon : ImageUsage.Sticker;
 
+  // Get default emoji - use most used or fallback to slight_smile
+  const defaultPreview = useMemo((): PreviewData => {
+    if (!emojiTab) return undefined;
+    
+    const mostUsedShortcode = getMostUsedEmoji();
+    if (mostUsedShortcode) {
+      // Find emoji by shortcode
+      const emoji = emojis.find((e) => e.shortcode === mostUsedShortcode);
+      if (emoji) {
+        return { key: emoji.unicode, shortcode: emoji.shortcode };
+      }
+    }
+    // Fallback to default
+    return DefaultEmojiPreview;
+  }, [emojiTab, getMostUsedEmoji]);
+
   const previewAtom = useMemo(
-    () => createPreviewDataAtom(emojiTab ? DefaultEmojiPreview : undefined),
-    [emojiTab]
+    () => createPreviewDataAtom(defaultPreview),
+    [defaultPreview]
   );
   const activeGroupIdAtom = useMemo(() => atom<string | undefined>(undefined), []);
   const setActiveGroupId = useSetAtom(activeGroupIdAtom);
@@ -439,6 +457,10 @@ export function EmojiBoard({
       onEmojiSelect?.(emojiInfo.data, emojiInfo.shortcode);
       if (!evt.altKey && !evt.shiftKey && addToRecentEmoji) {
         addRecentEmoji(mx, emojiInfo.data);
+        // Track emoji usage for favorites
+        trackEmojiUsage(emojiInfo.shortcode).catch((err) => {
+          console.error('Failed to track emoji usage:', err);
+        });
       }
     }
     if (emojiInfo.type === EmojiType.CustomEmoji) {

src/app/hooks/useEmojiUsage.ts

@@ -0,0 +1,104 @@
+import { useCallback, useMemo } from 'react';
+import { useMatrixClient } from './useMatrixClient';
+import { useAccountData } from './useAccountData';
+
+const PAARROT_EMOJI_USAGE_EVENT = 'paarrot.favemojis';
+const MAX_TRACKED_EMOJIS = 50;
+
+export type EmojiUsageData = {
+  [shortcode: string]: {
+    count: number;
+    lastUsed: number;
+  };
+};
+
+/**
+ * Hook for tracking emoji usage and storing favorites in Matrix account data
+ * Stores emoji usage stats under paarrot.favemojis in user's account data
+ */
+export function useEmojiUsage() {
+  const mx = useMatrixClient();
+  const event = useAccountData(PAARROT_EMOJI_USAGE_EVENT);
+
+  const emojiUsage = useMemo((): EmojiUsageData => {
+    const content = event?.getContent<EmojiUsageData>();
+    return content || {};
+  }, [event]);
+
+  /**
+   * Track emoji usage (max 1 per message as per spec)
+   * @param shortcode - Emoji shortcode (e.g., 'thumbsup', 'smile')
+   */
+  const trackEmojiUsage = useCallback(
+    async (shortcode: string) => {
+      const now = Date.now();
+      const currentUsage = { ...emojiUsage };
+
+      // Update or create emoji entry
+      currentUsage[shortcode] = {
+        count: (currentUsage[shortcode]?.count || 0) + 1,
+        lastUsed: now,
+      };
+
+      // Keep only top MAX_TRACKED_EMOJIS by usage count
+      const entries = Object.entries(currentUsage);
+      if (entries.length > MAX_TRACKED_EMOJIS) {
+        entries.sort((a, b) => b[1].count - a[1].count);
+        const topEmojis = entries.slice(0, MAX_TRACKED_EMOJIS);
+        const newUsage: EmojiUsageData = {};
+        topEmojis.forEach(([key, value]) => {
+          newUsage[key] = value;
+        });
+        await mx.setAccountData(PAARROT_EMOJI_USAGE_EVENT, newUsage);
+      } else {
+        await mx.setAccountData(PAARROT_EMOJI_USAGE_EVENT, currentUsage);
+      }
+    },
+    [mx, emojiUsage]
+  );
+
+  /**
+   * Get most used emoji shortcode
+   * @returns Shortcode of most used emoji, or undefined if none tracked
+   */
+  const getMostUsedEmoji = useCallback((): string | undefined => {
+    const entries = Object.entries(emojiUsage);
+    if (entries.length === 0) return undefined;
+
+    // Sort by count descending, then by lastUsed descending
+    entries.sort((a, b) => {
+      if (b[1].count !== a[1].count) {
+        return b[1].count - a[1].count;
+      }
+      return b[1].lastUsed - a[1].lastUsed;
+    });
+
+    return entries[0][0];
+  }, [emojiUsage]);
+
+  /**
+   * Get top N most used emojis
+   * @param count - Number of top emojis to return
+   * @returns Array of shortcodes sorted by usage
+   */
+  const getTopEmojis = useCallback(
+    (count: number = 10): string[] => {
+      const entries = Object.entries(emojiUsage);
+      entries.sort((a, b) => {
+        if (b[1].count !== a[1].count) {
+          return b[1].count - a[1].count;
+        }
+        return b[1].lastUsed - a[1].lastUsed;
+      });
+      return entries.slice(0, count).map(([shortcode]) => shortcode);
+    },
+    [emojiUsage]
+  );
+
+  return {
+    emojiUsage,
+    trackEmojiUsage,
+    getMostUsedEmoji,
+    getTopEmojis,
+  };
+}