Chore: Port over Reader & Tracking

src/lib/core/cache/pageCache.ts

@@ -0,0 +1,107 @@
+import { getBlobUrl, preloadBlobUrls } from "$lib/core/cache/imageCache";
+import { settingsState }               from "$lib/state/settings.svelte";
+
+const pageCache        = new Map<number, string[]>();
+const inflight         = new Map<number, Promise<string[]>>();
+const resolvedUrlCache = new Map<string, Promise<string>>();
+const aspectCache      = new Map<string, number>();
+
+function getServerUrl(): string {
+  return settingsState.settings.serverUrl ?? "http://localhost:4567";
+}
+
+async function fetchChapterPagesFromServer(chapterId: number): Promise<string[]> {
+  const base    = getServerUrl();
+  const headers: Record<string, string> = { "Content-Type": "application/json" };
+  const mode    = settingsState.settings.serverAuthMode ?? "NONE";
+  if (mode === "BASIC_AUTH") {
+    const u = settingsState.settings.serverAuthUser?.trim() ?? "";
+    const p = settingsState.settings.serverAuthPass?.trim() ?? "";
+    if (u && p) headers["Authorization"] = `Basic ${btoa(`${u}:${p}`)}`;
+  }
+  const query = `mutation FetchChapterPages($chapterId: Int!) { fetchChapterPages(input: { chapterId: $chapterId }) { pages } }`;
+  const res   = await fetch(`${base}/api/graphql`, {
+    method: "POST",
+    headers,
+    body: JSON.stringify({ query, variables: { chapterId } }),
+  });
+  if (!res.ok) throw new Error(`HTTP ${res.status}`);
+  const json = await res.json();
+  if (json.errors?.length) throw new Error(json.errors[0].message);
+  return (json.data.fetchChapterPages.pages as string[]).map(p =>
+    p.startsWith("http") ? p : `${base}${p}`
+  );
+}
+
+export function resolveUrl(url: string, useBlob: boolean, priority = 0): Promise<string> {
+  if (!useBlob) return Promise.resolve(url);
+  const cached = resolvedUrlCache.get(url);
+  if (cached) return cached;
+  const p = getBlobUrl(url, priority).catch(err => {
+    resolvedUrlCache.delete(url);
+    return Promise.reject(err);
+  });
+  resolvedUrlCache.set(url, p);
+  return p;
+}
+
+export function fetchPages(
+  chapterId: number,
+  useBlob: boolean,
+  signal?: AbortSignal,
+  priorityPage = 0,
+): Promise<string[]> {
+  const cached = pageCache.get(chapterId);
+  if (cached) return Promise.resolve(cached);
+  if (signal?.aborted) return Promise.reject(new DOMException("Aborted", "AbortError"));
+
+  if (!inflight.has(chapterId)) {
+    const p = fetchChapterPagesFromServer(chapterId)
+      .then(urls => {
+        if (useBlob && urls[priorityPage]) getBlobUrl(urls[priorityPage], 999);
+        pageCache.set(chapterId, urls);
+        return urls;
+      })
+      .finally(() => inflight.delete(chapterId));
+    inflight.set(chapterId, p);
+  }
+
+  const base = inflight.get(chapterId)!;
+  if (!signal) return base;
+  return new Promise((resolve, reject) => {
+    signal.addEventListener("abort", () => reject(new DOMException("Aborted", "AbortError")), { once: true });
+    base.then(resolve, reject);
+  });
+}
+
+export function measureAspect(url: string, useBlob: boolean): Promise<number> {
+  if (aspectCache.has(url)) return Promise.resolve(aspectCache.get(url)!);
+  return resolveUrl(url, useBlob).then(src => new Promise(res => {
+    const img   = new Image();
+    img.onload  = () => { const r = img.naturalHeight > 0 ? img.naturalWidth / img.naturalHeight : 0.67; aspectCache.set(url, r); res(r); };
+    img.onerror = () => res(0.67);
+    img.src     = src;
+  }));
+}
+
+export function preloadImage(url: string, useBlob: boolean): void {
+  if (useBlob) { preloadBlobUrls([url], 0); return; }
+  resolveUrl(url, useBlob).then(src => { new Image().src = src; }).catch(() => {});
+}
+
+export function clearResolvedUrlCache(): void {
+  resolvedUrlCache.clear();
+  aspectCache.clear();
+}
+
+export function clearPageCache(chapterId?: number): void {
+  if (chapterId !== undefined) {
+    pageCache.delete(chapterId);
+    inflight.delete(chapterId);
+  } else {
+    pageCache.clear();
+    inflight.clear();
+    resolvedUrlCache.clear();
+    aspectCache.clear();
+  }
+}