From d49aec75df76af7b6c2bc4e48cf89893c2dbf835 Mon Sep 17 00:00:00 2001
From: Paul Gschwendtner <paulgschwendtner@gmail.com>
Date: Thu, 1 Jun 2023 13:36:34 +0000
Subject: [PATCH] WIP: implementation of `input` function signature

---
 packages/core/src/signals-wip/index.ts      | 25 +++++++++++++++---
 packages/core/src/signals-wip/test/index.ts | 29 +++++++++++++++++----
 2 files changed, 46 insertions(+), 8 deletions(-)

diff --git a/packages/core/src/signals-wip/index.ts b/packages/core/src/signals-wip/index.ts
index 6198bef4abd..d62c87b42ee 100644
--- a/packages/core/src/signals-wip/index.ts
+++ b/packages/core/src/signals-wip/index.ts
@@ -6,7 +6,26 @@ export interface InputOptions {
   // TODO: transform
 }
 
-// WIP starting point
-export function input<T>(defaultVal: T, opts?: InputOptions): Signal<T> {
-  return signal(defaultVal);
+export interface InputOptionsWithInitialValue<T> extends InputOptions {
+  initialValue?: T;
+}
+
+// it transforms our specific types into primitive origins
+type toPrimitive<T> =
+    T extends string ? string : T extends number ? number : T extends boolean ? boolean : T;
+
+type primitiveValue = string|number|boolean|BigInt|undefined|null|Symbol
+
+export function input<T>(): Signal<T|undefined>;
+export function input<T>(opts: InputOptionsWithInitialValue<T>): Signal<T>;
+export function input<T extends primitiveValue>(
+    defaultVal: T, opts?: InputOptions): Signal<toPrimitive<T>>;
+
+export function input<T extends primitiveValue|InputOptionsWithInitialValue<Y>, Y>(
+    defaultValOrOpts?: T, opts?: InputOptions): Signal<T> {
+  // TODO(signals): implement
+  return signal(
+             typeof defaultValOrOpts === 'object' ?
+                 (defaultValOrOpts as InputOptionsWithInitialValue<T>).initialValue :
+                 defaultValOrOpts) as unknown as Signal<T>;
 }
diff --git a/packages/core/src/signals-wip/test/index.ts b/packages/core/src/signals-wip/test/index.ts
index f3b29549cc7..526a466967c 100644
--- a/packages/core/src/signals-wip/test/index.ts
+++ b/packages/core/src/signals-wip/test/index.ts
@@ -1,19 +1,38 @@
-import {Component, input} from '@angular/core';
+import {Component, input, Input} from '@angular/core';
 import {bootstrapApplication} from '@angular/platform-browser';
 
 @Component({
   selector: 'greet',
   standalone: true,
   signals: true,
-  template: `{{ nameInput() }}`,
+  template: `{{ counter() }}`,
 })
-class Greet {
-  nameInput = input('Jeff');
+export class Greet<T> {
+  counter = input(0);
+  bla = input();  // TODO: should be a diagnostic. no type & no value
+  bla2 = input<string>()
+  bla3 = input({initialValue: 3, required: true});
+  bla4 = input(3, {required: true, alias: 'bla4Public'})
+  gen = input<T>({required: true});
+  gen2 = input<T>();
+
+  works(): T {
+    return this.gen();
+  }
+
+  // TODO: should break, but still supported early prototype.
+  @Input() oldInput: string|undefined;
 }
 
 @Component({
   standalone: true,
-  template: `Hello <greet [nameInput]="'Bla'" />`,
+  template: `
+    Hello <greet [counter]="3" [bla4Public]="10" #ok
+      [bla3]="-10" [gen]="{yes: true}"
+    />
+
+    <button (click)="ok.works().yes">Click</button>
+  `,
   imports: [Greet],
 })
 export class MyApp {