Initial independent version of CrAPP

src/lib/avatar-store.ts

@@ -0,0 +1,88 @@
+import { useSyncExternalStore } from "react";
+
+const KEY = "crapp-avatars-v1";
+const listeners = new Set<() => void>();
+let cache: Record<string, string> | undefined;
+
+function read(): Record<string, string> {
+  if (cache) return cache;
+  if (typeof window === "undefined") return {};
+  try {
+    cache = JSON.parse(window.localStorage.getItem(KEY) ?? "{}") as Record<string, string>;
+  } catch {
+    cache = {};
+  }
+  return cache;
+}
+
+function write(next: Record<string, string>) {
+  cache = next;
+  try {
+    window.localStorage.setItem(KEY, JSON.stringify(next));
+  } catch {
+    /* quota o storage non disponibile */
+  }
+  listeners.forEach((l) => l());
+}
+
+const EMPTY: Record<string, string> = {};
+
+export function useAvatars(): Record<string, string> {
+  return useSyncExternalStore(
+    (cb) => {
+      listeners.add(cb);
+      return () => listeners.delete(cb);
+    },
+    () => read(),
+    () => EMPTY,
+  );
+}
+
+export function useAvatar(id: string | undefined): string | null {
+  const all = useAvatars();
+  return id ? (all[id] ?? null) : null;
+}
+
+export function rimuoviAvatar(id: string) {
+  const next = { ...read() };
+  delete next[id];
+  write(next);
+}
+
+export function salvaAvatar(id: string, dataUrl: string) {
+  write({ ...read(), [id]: dataUrl });
+}
+
+/** Ridimensiona e comprime l'immagine scelta per stare in localStorage. */
+export function fileToAvatar(file: File, size = 256): Promise<string> {
+  return new Promise((resolve, reject) => {
+    const reader = new FileReader();
+    reader.onerror = () => reject(new Error("Lettura file fallita"));
+    reader.onload = () => {
+      const img = new Image();
+      img.onerror = () => reject(new Error("Immagine non valida"));
+      img.onload = () => {
+        const lato = Math.min(img.width, img.height);
+        const canvas = document.createElement("canvas");
+        canvas.width = size;
+        canvas.height = size;
+        const ctx = canvas.getContext("2d");
+        if (!ctx) return reject(new Error("Canvas non disponibile"));
+        ctx.drawImage(
+          img,
+          (img.width - lato) / 2,
+          (img.height - lato) / 2,
+          lato,
+          lato,
+          0,
+          0,
+          size,
+          size,
+        );
+        resolve(canvas.toDataURL("image/jpeg", 0.82));
+      };
+      img.src = reader.result as string;
+    };
+    reader.readAsDataURL(file);
+  });
+}