TodosState

packages/example/src/todo/TodosState.ts

@@ -0,0 +1,48 @@
+import { Todo } from "@/domain"
+import { KeyValueStore } from "@effect/platform"
+import { Chunk, Console, Effect, Option, Schema, Stream, SubscriptionRef } from "effect"
+import { SubscriptionSubRef } from "effect-fc/types"
+
+
+export class TodosState extends Effect.Service<TodosState>()("TodosState", {
+    effect: Effect.fnUntraced(function*(key: string) {
+        const kv = yield* KeyValueStore.KeyValueStore
+
+        const readFromLocalStorage = Console.log("Reading todos from local storage...").pipe(
+            Effect.andThen(kv.get(key)),
+            Effect.flatMap(Option.match({
+                onSome: Schema.decode(
+                    Schema.parseJson(Schema.Chunk(Todo.TodoFromJson))
+                ),
+                onNone: () => Effect.succeed(Chunk.empty()),
+            }))
+        )
+
+        const saveToLocalStorage = (todos: Chunk.Chunk<Todo.Todo>) => Effect.andThen(
+            Console.log("Saving todos to local storage..."),
+            Chunk.isNonEmpty(todos)
+                ? Effect.flatMap(
+                    Schema.encode(
+                        Schema.parseJson(Schema.Chunk(Todo.TodoFromJson))
+                    )(todos),
+                    v => kv.set(key, v),
+                )
+                : kv.remove(key)
+        )
+
+        const ref = yield* SubscriptionRef.make(yield* readFromLocalStorage)
+
+        const makeSubRef = (index: number) => SubscriptionSubRef.makeFromGetSet(ref, {
+            get: parent => Chunk.unsafeGet(parent, index),
+            set: (parent, v) => Chunk.replace(parent, index, v),
+        })
+
+        yield* Effect.forkScoped(ref.changes.pipe(
+            Stream.debounce("500 millis"),
+            Stream.runForEach(saveToLocalStorage),
+        ))
+        yield* Effect.addFinalizer(() => Effect.flatMap(ref, saveToLocalStorage))
+
+        return { ref, makeSubRef } as const
+    })
+}) {}