ENH: rewritten checkpoint.ts to use a custom solution instead of svel…

…te-persistent-store for a reduction from 15Kb to less than 1Kb

frontend/src/components/Checkpoint/checkpoint.ts

@@ -1,14 +1,45 @@
-import { writable } from "@macfja/svelte-persistent-store";
+type Checkpoints = Map<string, Set<string>>
 
-const checkpointStore = writable("checkpoints", new Map<string, Set<string>>());
+class Persistent {
+  persistent: Checkpoints = new Map<string, Set<string>>();
+  subscribers:  Array<(checkpoints: Checkpoints) => void> = [];
+
+  constructor() {
+    this.persistent = this.deserialize();
+  }
+
+  private serialize() {
+    const serialized: Array<[string, string[]]> = [...this.persistent.entries()].map(([k, v]) => [k, Array.from(v)]);
+    localStorage.setItem("checkpoints", JSON.stringify(serialized));
+  }
+
+  private deserialize(): Checkpoints {
+    const item = localStorage.getItem("checkpoints") as string;
+    const parsed: Array<[string, string[]]> = item && JSON.parse(item) || [];
+    return new Map(parsed.map(([k, v]) => [k, new Set(v)]));
+  }
+
+  update(callback: (checkpoints: Checkpoints) => Checkpoints) {
+    this.persistent = callback(this.persistent);
+    this.serialize();
+    this.subscribers.forEach((subscriber) => subscriber(this.persistent));
+  }
+
+  subscribe(callback: (checkpoints: Checkpoints) => void) {
+    this.subscribers.push(callback);
+    callback(this.persistent);
+  }
+}
+
+const persistentCheckpoints = new Persistent();
 
 export function add(id: string) {
   const k = id.split("-")[0];
   if (k === undefined) {
     throw "Invalid id";
   }
 
-  checkpointStore.update((checkpoints) => {
+  persistentCheckpoints.update((checkpoints) => {
     const checkpoint = checkpoints.get(k);
     if (checkpoint === undefined) {
       checkpoints.set(k, new Set([id]));
@@ -24,11 +55,11 @@ export function subscribe(id: string, run: (checkpoint: Set<string>) => void) {
   if (k === undefined) {
     throw "Invalid id";
   }
-  checkpointStore.update(
+  persistentCheckpoints.update(
     (checkpoints) =>
       (!checkpoints.has(k) && checkpoints.set(k, new Set([]))) || checkpoints,
   );
-  checkpointStore.subscribe((checkpoints) => {
+  persistentCheckpoints.subscribe((checkpoints) => {
     run(checkpoints.get(k) as Set<string>);
   });
 }
@@ -38,8 +69,8 @@ export function remove(id: string) {
   if (k === undefined) {
     throw "Invalid id";
   }
-  checkpointStore.update((checkpoints) => {
+  persistentCheckpoints.update((checkpoints) => {
     checkpoints.delete(k);
     return checkpoints;
   });
-}
+}