Ship file viewer, editor improvements, and private package releases

packages/viewer/src/source.ts

@@ -0,0 +1,68 @@
+import type { ResolveOptions, ViewerSource } from "./types.ts";
+
+export function safeSourceUrl(src: string): string | undefined {
+  try {
+    const url = new URL(src, typeof location === "undefined" ? "http://localhost" : location.href);
+    return ["http:", "https:", "blob:", "data:"].includes(url.protocol) ? url.href : undefined;
+  } catch {
+    return undefined;
+  }
+}
+
+/** The source's own http(s) URL, when it has one that an element can load. */
+export function directUrl(source: ViewerSource): string | undefined {
+  if (source.blob || !source.src) return undefined;
+  const url = safeSourceUrl(source.src);
+  return url && /^https?:/i.test(url) ? url : undefined;
+}
+
+export async function readBounded(
+  response: Response,
+  cap: number,
+  prefixOnly = false,
+): Promise<Uint8Array> {
+  if (!response.ok || !response.body) throw new Error("File could not be read");
+  const reader = response.body.getReader();
+  const parts: Uint8Array[] = [];
+  let length = 0;
+  try {
+    while (true) {
+      const next = await reader.read();
+      if (next.done) break;
+      if (!prefixOnly && length + next.value.length > cap)
+        throw new Error("File exceeds preview limit");
+      const part = next.value.subarray(0, cap - length);
+      parts.push(part);
+      length += part.length;
+      if (prefixOnly && length >= cap) break;
+    }
+  } finally {
+    await reader.cancel().catch(() => {});
+    reader.releaseLock();
+  }
+  const bytes = new Uint8Array(length);
+  let offset = 0;
+  for (const part of parts) {
+    bytes.set(part, offset);
+    offset += part.length;
+  }
+  return bytes;
+}
+
+export async function readSource(
+  source: ViewerSource,
+  cap: number,
+  options: ResolveOptions = {},
+): Promise<Blob> {
+  if (source.blob) {
+    if (source.blob.size > cap) throw new Error("File exceeds preview limit");
+    return source.blob;
+  }
+  const url = source.src && safeSourceUrl(source.src);
+  if (!url) throw new Error("No readable file source");
+  const response = await (options.fetch ?? fetch)(url, { signal: options.signal });
+  const bytes = await readBounded(response, cap);
+  return new Blob([bytes as Uint8Array<ArrayBuffer>], {
+    type: response.headers.get("content-type") ?? source.mime ?? "",
+  });
+}