refactor: fn pipe no longer needs explicit context unless invoking a …

…method in another instance.

refactor: fn pipe types are now stricter

projects/ng-talk/src/lib/components/channel-list/ng-talk-channel-list.component.html

@@ -14,7 +14,7 @@
 
     <!-- Channel list -->
     <ul>
-      @for (channel of channels() | fn:filterChannels:this:filterQuery; track channel.id) {
+      @for (channel of channels() | fn:filterChannels:filterQuery; track channel.id) {
         <li [class.active]="activeChannel && channel.id == activeChannel.id">
           <!-- Wait 500ms to enable viewport observer while the component render -->
           @if (settings.channelMessagesLoading == MessagesLoading.lazy) {

projects/ng-talk/src/lib/components/channel/message/body/ng-talk-channel-message-body.component.ts

@@ -14,7 +14,7 @@ import {NgTalkChannelMessageWritingComponent} from "./ng-talk-channel-message-wr
   template: `
     @switch (message.type) {
       @case (MessageType.Text) {
-        <div class="text-message" [innerHTML]="message | fn:transformContent:this"></div>
+        <div class="text-message" [innerHTML]="message | fn:transformContent"></div>
       }
       @case (MessageType.Image) {
         <img loading="lazy" style="margin-bottom: 8px" [src]="message.content"/>

projects/ng-talk/src/lib/components/channel/ng-talk-channel.component.html

@@ -25,7 +25,7 @@
     <!-- Messages -->
     @for (message of messages(); track trackMessage($index, message)) {
       <!-- Date separator -->
-      @if (message | fn:isSeparatorVisible:this:messages()[$index - 1]) {
+      @if (message | fn:isSeparatorVisible:messages()[$index - 1]) {
         <div style="clear: both"></div>
         <div class="day-separator">
           <span>{{ message.date | relativeDate : settings }}</span>

projects/ng-talk/src/lib/components/channel/send/emoji/ng-talk-send-emoji.component.ts

@@ -13,7 +13,7 @@ import emojis from './emoji.json';
   template: `
     <input type="search" [placeholder]="chat.settings.search" [(ngModel)]="searchQuery"/>
     <div>
-      @for (pair of emojis | keyvalue | fn:filter:this:searchQuery; track pair) {
+      @for (pair of emojis | keyvalue | fn:filter:searchQuery; track pair) {
         <span (click)="emojiSelected.emit(pair.value)">{{ pair.value }}</span>
       }
     </div>

projects/ng-talk/src/lib/components/channel/send/gif/ng-talk-send-gif.component.ts

@@ -56,7 +56,7 @@ import {NgTalkChannelComponent} from '../../ng-talk-channel.component';
     </div>
     <div class="gif-list">
       @for (gif of gifs$() | async; track gif) {
-        <span style="text-align: center" (click)="onGifSelected(gif)"><img loading="lazy" [src]="gif | fn:getGifURL:this:false"/></span>
+        <span style="text-align: center" (click)="onGifSelected(gif)"><img loading="lazy" [src]="gif | fn:getGifURL:false"/></span>
       }
     </div>
   `,

projects/ng-talk/src/lib/pipes/fn.pipe.ts

@@ -1,21 +1,38 @@
-import {Pipe, PipeTransform} from '@angular/core';
+import {ChangeDetectorRef, EmbeddedViewRef, Inject, Pipe, PipeTransform} from '@angular/core';
 
+// https://stackoverflow.com/questions/67605122/obtain-a-slice-of-a-typescript-parameters-tuple
+type ParametersExceptFirst<F> = F extends (arg0: any, ...rest: infer R) => any ? R : never;
+
+/**
+ * Pipe que permite transformar un valor usando una función, recordando el resultado hasta que el valor cambie.
+ *
+ * Si se necesita indicar un contexto, se puede indicar como un array con el objeto y el nombre del método.
+ *
+ * Ejemplo: user | fn:[userSvc, 'get']
+ *
+ * https://dev.to/this-is-angular/deep-dive-into-angular-pipes-implementation-2g5n
+ */
 @Pipe({
+  standalone: true,
   name: 'fn',
-  pure: true,
-  standalone: true
+  pure: true
 })
 export class FnPipe implements PipeTransform {
+  /**
+   *@inject (ChangeDetectorRef) prevents:
+   * NullInjectorError: No provider for EmbeddedViewRef!
+   */
+  constructor(@Inject(ChangeDetectorRef) private readonly _viewRef: EmbeddedViewRef<unknown>) {
+  }
 
-  // A template syntax: {{ templateValue | fn:componentMethodRef:thisArg:fnArgument }}
-  public transform<P, R>(value: P, fnReference: (arg: P, ...fnArguments: Array<any>) => R, context?: any, ...fnArguments: Array<any>): R {
-    if (fnArguments.length) {
-      fnArguments.unshift(value);
-      return fnReference.apply(context, fnArguments);
-    } else if (context) {
-      return fnReference.call(context, value);
+  public transform<T extends (...args: any) => any>(value: Parameters<T>[0], fn: T, ...args: [...ParametersExceptFirst<T>]): ReturnType<T> {
+    if (args.length) {
+      args.unshift(value);
+      return fn.apply(this._viewRef.context, args);
     } else {
-      return fnReference(value);
+      return fn.call(this._viewRef.context, value);
     }
   }
 }
+
+