UPDATE: split the webapp in a widget and the app itself

This splits the webapp in:

* IronCalc (the widget to be published on npmjs)
* The frontend for our "service"
* Adds "dummy code" for the backend using sqlite

webapp/app.ironcalc.com/frontend/src/components/rpc.ts

@@ -0,0 +1,78 @@
+export async function uploadFile(
+  arrayBuffer: ArrayBuffer,
+  fileName: string,
+): Promise<Blob> {
+  // Fetch request to upload the file
+  const response = await fetch(`/api/upload/${fileName}`, {
+    method: "POST",
+    headers: {
+      "Content-Type": "application/octet-stream",
+      "Content-Disposition": `attachment; filename="${fileName}"`,
+    },
+    body: arrayBuffer,
+  });
+  const blob = await response.blob();
+  return blob;
+}
+
+export async function get_model(modelHash: string): Promise<Uint8Array> {
+  return new Uint8Array(
+    await (await fetch(`/api/model/${modelHash}`)).arrayBuffer(),
+  );
+}
+
+export async function get_documentation_model(
+  filename: string,
+): Promise<Uint8Array> {
+  return new Uint8Array(
+    await (await fetch(`/models/${filename}.ic`)).arrayBuffer(),
+  );
+}
+
+export async function downloadModel(bytes: Uint8Array, fileName: string) {
+  const response = await fetch("/api/download", {
+    method: "POST",
+    headers: {
+      "Content-Type": "application/octet-stream",
+      "Content-Disposition": `attachment; filename="${fileName}"`,
+    },
+    body: bytes,
+  });
+  if (!response.ok) {
+    throw new Error("Network response was not ok");
+  }
+  const blob = await response.blob();
+
+  // Create a link element and trigger a download
+  const url = window.URL.createObjectURL(blob);
+  const a = document.createElement("a");
+  a.style.display = "none";
+  a.href = url;
+
+  // Use the same filename or change as needed
+  a.download = `${fileName}.xlsx`;
+  document.body.appendChild(a);
+  a.click();
+
+  // Clean up
+  window.URL.revokeObjectURL(url);
+  a.remove();
+}
+
+export async function shareModel(
+  bytes: Uint8Array,
+  fileName: string,
+): Promise<string> {
+  const response = await fetch("/api/share", {
+    method: "POST",
+    headers: {
+      "Content-Type": "application/octet-stream",
+      "Content-Disposition": `attachment; filename="${fileName}"`,
+    },
+    body: bytes,
+  });
+  if (!response.ok) {
+    throw new Error("Network response was not ok");
+  }
+  return await response.text();
+}