Update

apps/mobile/src/lib/imageCache.ts

@@ -0,0 +1,95 @@
+import { supabase } from './supabase';
+
+// Cache for signed URLs with expiration tracking
+interface CachedUrl {
+    url: string;
+    expiresAt: number;
+}
+
+const signedUrlCache = new Map<string, CachedUrl>();
+
+// Buffer time before expiration to refresh URL (5 minutes)
+const EXPIRATION_BUFFER_MS = 5 * 60 * 1000;
+// Default signed URL expiry (1 hour)
+const SIGNED_URL_EXPIRY_SECONDS = 3600;
+
+/**
+ * Get a signed URL for a chat media file with caching.
+ * Returns cached URL if still valid, otherwise generates a new one.
+ */
+export async function getCachedSignedUrl(
+    storagePath: string,
+    bucket: string = 'chat-media'
+): Promise<string | null> {
+    const cacheKey = `${bucket}:${storagePath}`;
+    const cached = signedUrlCache.get(cacheKey);
+    const now = Date.now();
+
+    // Return cached URL if it's still valid (with buffer time)
+    if (cached && cached.expiresAt - EXPIRATION_BUFFER_MS > now) {
+        return cached.url;
+    }
+
+    // Generate new signed URL
+    const { data, error } = await supabase.storage
+        .from(bucket)
+        .createSignedUrl(storagePath, SIGNED_URL_EXPIRY_SECONDS);
+
+    if (error || !data?.signedUrl) {
+        console.error('Failed to get signed URL:', error);
+        return null;
+    }
+
+    // Cache the new URL
+    signedUrlCache.set(cacheKey, {
+        url: data.signedUrl,
+        expiresAt: now + SIGNED_URL_EXPIRY_SECONDS * 1000,
+    });
+
+    return data.signedUrl;
+}
+
+/**
+ * Extract storage path from media_path (handles both old full URLs and new path-only format)
+ */
+export function getStoragePath(mediaPath: string): string {
+    if (mediaPath.startsWith('http')) {
+        // Old format: extract path from full URL
+        const match = mediaPath.match(/\/chat-media\/(.+)$/);
+        return match ? match[1] : mediaPath;
+    }
+    return mediaPath;
+}
+
+/**
+ * Clear expired URLs from the cache to free memory.
+ * Call this periodically or when memory pressure is detected.
+ */
+export function clearExpiredUrls(): void {
+    const now = Date.now();
+    for (const [key, cached] of signedUrlCache) {
+        if (cached.expiresAt < now) {
+            signedUrlCache.delete(key);
+        }
+    }
+}
+
+/**
+ * Clear all cached URLs.
+ */
+export function clearUrlCache(): void {
+    signedUrlCache.clear();
+}
+
+/**
+ * Prefetch signed URLs for a list of media paths.
+ * Useful for preloading images when entering a chat.
+ */
+export async function prefetchSignedUrls(
+    mediaPaths: string[],
+    bucket: string = 'chat-media'
+): Promise<void> {
+    await Promise.all(
+        mediaPaths.map(path => getCachedSignedUrl(getStoragePath(path), bucket))
+    );
+}