From 1d0a86697db2e86019fa6d1d4c4e25b111571356 Mon Sep 17 00:00:00 2001
From: Muthu Kumar <muthukumar@thefeathers.in>
Date: Sun, 12 Nov 2023 22:23:13 +0530
Subject: [PATCH] feat(state): better state functions

---
 hyper/domutils.ts | 19 +++++++-----
 hyper/state.ts    | 75 +++++++++++++++++++++++++++++++++++++----------
 2 files changed, 70 insertions(+), 24 deletions(-)

diff --git a/hyper/domutils.ts b/hyper/domutils.ts
index 7fe5b73..7a86d32 100644
--- a/hyper/domutils.ts
+++ b/hyper/domutils.ts
@@ -1,13 +1,16 @@
 import type { HyperNode } from "./node.ts";
 import { State } from "./state.ts";
+import { HTMLInputElement } from "./vendor/dom.slim.ts";
+
+export const bind = <N extends HyperNode<"input">, S extends State>(node: N, state: S): N => {
+	const oldRef = node.attrs.ref || (() => {});
+
+	node.attrs.ref = (el: HTMLInputElement) => {
+		el.value = state.value;
+		state.listen(value => (el.value = value));
+		el.addEventListener("input", e => state.publish((e?.target as unknown as { value: string }).value));
+		oldRef(el as any);
+	};
 
-export const bind = <N extends HyperNode, State extends State.Simple>(node: N, state: State): N => {
-	// const oldRef = node.attrs.ref || (() => {});
-	// // @ts-expect-error do element-aware init and publish
-	// node.attrs.value = state.init;
-	// node.attrs.ref = el => {
-	// 	oldRef(el);
-	// 	el.addEventListener("input", e => state.publish((e?.target as unknown as { value: string }).value));
-	// };
 	return node;
 };
diff --git a/hyper/state.ts b/hyper/state.ts
index 5c58210..21fe183 100644
--- a/hyper/state.ts
+++ b/hyper/state.ts
@@ -1,42 +1,69 @@
-export type Subscriber<T> = (val: T) => void;
+import { Keyof as K } from "./util.ts";
 
-export class ReadonlyRef<T = any> {
+type StateEntries<Obj extends Record<string, State>> = { [k in K<Obj>]: { key: k; value: Obj[k]["value"] } }[K<Obj>];
+type MapEntries<Rs extends State[]> = { [k in keyof Rs]: { key: k; value: Rs[k]["value"] } }[number];
+
+export type Subscriber<T> = (value: T, unused?: unknown) => void;
+export type KeyedSubscriber<K extends { key: unknown; value: unknown }> = (value: K["value"], key: K["key"]) => void;
+export type StateType<R extends State> = R extends State<infer U> ? U : never;
+
+export class ReadonlyState<T = any> {
 	protected subscribers: Subscriber<T>[] = [];
 
 	constructor(public value: T) {}
 
-	listen(f: Subscriber<T>) {
-		this.subscribers.push(f);
+	static isState<X>(x: X): x is Extract<X, State | ReadonlyState> {
+		return x instanceof ReadonlyState;
+	}
+
+	listen(listener: Subscriber<T>) {
+		this.subscribers.push(listener);
 	}
 
 	map<U>(mapper: (t: T) => U) {
-		const s = new Ref(mapper(this.value));
+		const s = new State(mapper(this.value));
 		// publish mapped changes when value changes
 		this.listen(value => s.publish(mapper(value)));
 		// return readonly so mapped state can't be published into
 		return s.readonly();
 	}
 
-	effect(effector: (t: T) => void) {
-		// trigger effect when value changes
-		this.listen(effector);
-	}
-
-	into(state: Ref<T>) {
+	into(state: State<T>) {
 		this.listen(value => state.publish(value));
 	}
 }
 
-export class Ref<T = any> extends ReadonlyRef<T> {
+export class State<T = any> extends ReadonlyState<T> {
 	constructor(value: T) {
 		super(value);
 	}
 
-	static isRef<X>(x: X): x is Extract<X, Ref | ReadonlyRef> {
-		return x instanceof ReadonlyRef;
+	/**
+	 * Merge multiple refs into a single Ref
+	 */
+	static merge<T>(...states: [State<T>, ...State<T>[]]): MergedState<MapEntries<State<T>[]>>;
+
+	static merge<RefMap extends { [k: string]: State }>(refs: RefMap): MergedState<StateEntries<RefMap>>;
+
+	static merge<T, RefMap extends { [k: string]: State }>(
+		...refs: [State<T> | RefMap, ...State<T>[]]
+	): State<T> | MergedState<MapEntries<State<T>[]>> | MergedState<StateEntries<RefMap>> {
+		if (State.isState(refs[0])) {
+			const ref = new MergedState<MapEntries<State<T>[]>>(refs[0].value);
+			for (let i = 0; i < refs.length; i++) {
+				const r = refs[i] as State<T>;
+				r.listen(x => ref.publish(x, i));
+			}
+			return ref;
+		} else {
+			const ref = new MergedState<StateEntries<RefMap>>(null);
+			const rs = refs[0];
+			for (const r in rs) rs[r].listen(c => ref.publish(c, r));
+			return ref;
+		}
 	}
 
-	publish(next: T | Promise<T>) {
+	publish(next: T | Promise<T>, unused?: unknown) {
 		return Promise.resolve(next).then(val => {
 			this.value = val;
 			this.subscribers.forEach(subscriber => subscriber(val));
@@ -44,6 +71,22 @@ export class Ref<T = any> extends ReadonlyRef<T> {
 	}
 
 	readonly() {
-		return new ReadonlyRef(this.value);
+		return new ReadonlyState(this.value);
+	}
+}
+
+export class MergedState<T extends { key: string | number; value: unknown }> extends State<T["value"]> {
+	// @ts-expect-error
+	protected subscribers: KeyedSubscriber<T>[];
+
+	listen(listener: KeyedSubscriber<T>): void {
+		this.subscribers.push(listener);
+	}
+
+	publish(value: T["value"] | Promise<T["value"]>, key: T["key"]) {
+		return Promise.resolve(value).then(val => {
+			this.value = val;
+			this.subscribers.forEach(subscriber => subscriber(val, key));
+		});
 	}
 }