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/storage.ts

@@ -0,0 +1,129 @@
+import { Model } from "@ironcalc/ironcalc";
+import { base64ToBytes, bytesToBase64 } from "./util";
+
+const MAX_WORKBOOKS = 50;
+
+type ModelsMetadata = Record<string, string>;
+
+export function updateNameSelectedWorkbook(model: Model, newName: string) {
+  const uuid = localStorage.getItem("selected");
+  if (uuid) {
+    const modelsJson = localStorage.getItem("models");
+    if (modelsJson) {
+      try {
+        const models = JSON.parse(modelsJson);
+        models[uuid] = newName;
+        localStorage.setItem("models", JSON.stringify(models));
+      } catch (e) {
+        console.warn("Failed saving new name");
+      }
+    }
+    const modeBytes = model.toBytes();
+    localStorage.setItem(uuid, bytesToBase64(modeBytes));
+  }
+}
+
+export function getModelsMetadata(): ModelsMetadata {
+  let modelsJson = localStorage.getItem("models");
+  if (!modelsJson) {
+    modelsJson = "{}";
+  }
+  return JSON.parse(modelsJson);
+}
+
+// Pick a different name Workbook{N} where N = 1, 2, 3
+function getNewName(existingNames: string[]): string {
+  const baseName = "Workbook";
+  let index = 1;
+  while (index < MAX_WORKBOOKS) {
+    const name = `${baseName}${index}`;
+    index += 1;
+    if (!existingNames.includes(name)) {
+      return name;
+    }
+  }
+  // FIXME: Too many workbooks?
+  return "Workbook-Infinity";
+}
+
+export function createNewModel(): Model {
+  const models = getModelsMetadata();
+  const name = getNewName(Object.values(models));
+
+  const model = new Model(name, "en", "UTC");
+  const uuid = crypto.randomUUID();
+  localStorage.setItem("selected", uuid);
+  localStorage.setItem(uuid, bytesToBase64(model.toBytes()));
+
+  models[uuid] = name;
+  localStorage.setItem("models", JSON.stringify(models));
+  return model;
+}
+
+export function loadModelFromStorageOrCreate(): Model {
+  const uuid = localStorage.getItem("selected");
+  if (uuid) {
+    // We try to load the selected model
+    const modelBytesString = localStorage.getItem(uuid);
+    if (modelBytesString) {
+      return Model.from_bytes(base64ToBytes(modelBytesString));
+    }
+    // If it doesn't exist we create one at that uuid
+    const newModel = new Model("Workbook1", "en", "UTC");
+    localStorage.setItem("selected", uuid);
+    localStorage.setItem(uuid, bytesToBase64(newModel.toBytes()));
+    return newModel;
+  }
+  // If there was no selected model we create a new one
+  return createNewModel();
+}
+
+export function saveSelectedModelInStorage(model: Model) {
+  const uuid = localStorage.getItem("selected");
+  if (uuid) {
+    const modeBytes = model.toBytes();
+    localStorage.setItem(uuid, bytesToBase64(modeBytes));
+  }
+}
+
+export function saveModelToStorage(model: Model) {
+  const uuid = crypto.randomUUID();
+  localStorage.setItem("selected", uuid);
+  localStorage.setItem(uuid, bytesToBase64(model.toBytes()));
+  let modelsJson = localStorage.getItem("models");
+  if (!modelsJson) {
+    modelsJson = "{}";
+  }
+  const models = JSON.parse(modelsJson);
+  models[uuid] = model.getName();
+  localStorage.setItem("models", JSON.stringify(models));
+}
+
+export function selectModelFromStorage(uuid: string): Model | null {
+  localStorage.setItem("selected", uuid);
+  const modelBytesString = localStorage.getItem(uuid);
+  if (modelBytesString) {
+    return Model.from_bytes(base64ToBytes(modelBytesString));
+  }
+  return null;
+}
+
+export function getSelectedUuid(): string | null {
+  return localStorage.getItem("selected");
+}
+
+export function deleteSelectedModel(): Model | null {
+  const uuid = localStorage.getItem("selected");
+  if (!uuid) {
+    return null;
+  }
+  localStorage.removeItem(uuid);
+  const metadata = getModelsMetadata();
+  delete metadata[uuid];
+  localStorage.setItem("models", JSON.stringify(metadata));
+  const uuids = Object.keys(metadata);
+  if (uuids.length === 0) {
+    return createNewModel();
+  }
+  return selectModelFromStorage(uuids[0]);
+}