From 900bb5e845c3ad44defbd427cae3d44a4a43321f Mon Sep 17 00:00:00 2001
From: ivarlovlie <git@ivarlovlie.no>
Date: Sat, 25 Feb 2023 13:15:44 +0100
Subject: feat: Initial commit

---
 code/app/src/utilities/persistent-store.ts | 111 +++++++++++++++++++++++++++++
 1 file changed, 111 insertions(+)
 create mode 100644 code/app/src/utilities/persistent-store.ts

(limited to 'code/app/src/utilities/persistent-store.ts')

diff --git a/code/app/src/utilities/persistent-store.ts b/code/app/src/utilities/persistent-store.ts
new file mode 100644
index 0000000..3f56312
--- /dev/null
+++ b/code/app/src/utilities/persistent-store.ts
@@ -0,0 +1,111 @@
+import { browser } from "$app/environment";
+import { writable as _writable, readable as _readable } from "svelte/store";
+import type { Writable, Readable, StartStopNotifier } from "svelte/store";
+import { log_debug, log_info } from "./logger";
+
+enum StoreType {
+    SESSION = 0,
+    LOCAL = 1
+}
+
+interface StoreOptions {
+    store?: StoreType;
+}
+
+interface WritableStoreInit<T> {
+    name: string,
+    initialState: T,
+    options?: StoreOptions
+}
+
+interface ReadableStoreInit<T> {
+    name: string,
+    initialState: T,
+    callback: StartStopNotifier<any>,
+    options?: StoreOptions
+}
+
+function get_store(type: StoreType): Storage {
+    if (!browser) return undefined;
+    switch (type) {
+        case StoreType.SESSION:
+            return window.sessionStorage;
+        case StoreType.LOCAL:
+            return window.localStorage;
+    }
+}
+
+function prepared_store_value(value: any): string {
+    try {
+        return JSON.stringify(value);
+    } catch (e) {
+        console.error(e);
+        return "__INVALID__";
+    }
+}
+
+function get_store_value<T>(init: WritableStoreInit<T> | ReadableStoreInit<T>): any {
+    try {
+        const storage = get_store(init.options.store);
+        if (!storage) return;
+        const value = storage.getItem(init.name);
+        if (!value) return false;
+        return JSON.parse(value);
+    } catch (e) {
+        console.error(e);
+        return { __INVALID__: true };
+    }
+}
+
+function hydrate<T>(store: Writable<T>, init: WritableStoreInit<T> | ReadableStoreInit<T>): void {
+    const value = get_store_value<T>(init);
+    if (value && store.set) store.set(value);
+}
+
+function subscribe<T>(store: Writable<T> | Readable<T>, init: WritableStoreInit<T> | ReadableStoreInit<T>): void {
+    const storage = get_store(init.options.store);
+    if (!storage) return;
+    if (!store.subscribe) return;
+    store.subscribe((state: any) => {
+        storage.setItem(init.name, prepared_store_value(state));
+    });
+}
+
+function create_writable_persistent<T>(init: WritableStoreInit<T>): Writable<T> {
+    if (!browser) {
+        log_info("WARN: Persistent store is only available in the browser");
+        return;
+    }
+    if (init.options === undefined) throw new Error("init is a required parameter");
+    log_debug("creating writable store with options: ", init);
+    const store = _writable<T>(init.initialState);
+    hydrate(store, init);
+    subscribe(store, init);
+    return store;
+}
+
+function create_readable_persistent<T>(init: ReadableStoreInit<T>): Readable<T> {
+    if (!browser) {
+        log_info("WARN: Persistent store is only available in the browser");
+        return;
+    }
+    if (init.options === undefined) throw new Error("init is a required parameter");
+    log_debug("Creating readable store with options: ", init);
+    const store = _readable<T>(init.initialState, init.callback);
+    // hydrate(store, options);
+    subscribe(store, init);
+    return store;
+}
+
+export {
+    create_writable_persistent,
+    create_readable_persistent,
+    StoreType,
+};
+
+export type {
+    WritableStoreInit as WritableStore,
+    ReadableStoreInit as ReadableStore,
+    StoreOptions,
+};
+
-- 
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