From aa4c8a2e354b4fe625e1bd83128d3e755c1d472c Mon Sep 17 00:00:00 2001
From: "Patrik J. Braun" <bra.patrik@gmail.com>
Date: Sat, 2 Dec 2023 09:58:02 +0100
Subject: [PATCH] Propagate input to after handlers #743

---
 extension/package.json                            |  2 +-
 src/backend/model/extension/ExtensionDecorator.ts |  4 ++--
 src/backend/model/extension/ExtensionEvent.ts     | 10 +++++-----
 src/backend/model/extension/IExtension.ts         | 12 +++++++++---
 4 files changed, 17 insertions(+), 11 deletions(-)

diff --git a/extension/package.json b/extension/package.json
index 09bd6fe5..e925055a 100644
--- a/extension/package.json
+++ b/extension/package.json
@@ -1,6 +1,6 @@
 {
   "name": "pigallery2-extension-kit",
-  "version": "2.0.3-edge3",
+  "version": "2.0.3-edge4",
   "description": "Interfaces for developing extensions for pigallery2",
   "author": "Patrik J. Braun",
   "homepage": "https://github.com/bpatrik/pigallery2",
diff --git a/src/backend/model/extension/ExtensionDecorator.ts b/src/backend/model/extension/ExtensionDecorator.ts
index 28784596..2846bec3 100644
--- a/src/backend/model/extension/ExtensionDecorator.ts
+++ b/src/backend/model/extension/ExtensionDecorator.ts
@@ -14,7 +14,7 @@ export const ExtensionDecorator = <I extends unknown[], O>(fn: (ee: IExtensionEv
   return (
     target: unknown,
     propertyName: string,
-    descriptor: TypedPropertyDescriptor<(...args:I)=>Promise<O>>
+    descriptor: TypedPropertyDescriptor<(...args: I) => Promise<O>>
   ) => {
 
     const targetMethod = descriptor.value;
@@ -32,7 +32,7 @@ export const ExtensionDecorator = <I extends unknown[], O>(fn: (ee: IExtensionEv
         return input as O;
       }
       const out = await targetMethod.apply(this, input);
-      return await event.triggerAfter(out);
+      return await event.triggerAfter(input as I, out);
     };
 
     return descriptor;
diff --git a/src/backend/model/extension/ExtensionEvent.ts b/src/backend/model/extension/ExtensionEvent.ts
index 526ed409..489e4a7a 100644
--- a/src/backend/model/extension/ExtensionEvent.ts
+++ b/src/backend/model/extension/ExtensionEvent.ts
@@ -2,7 +2,7 @@ import {IExtensionAfterEventHandler, IExtensionBeforeEventHandler, IExtensionEve
 
 export class ExtensionEvent<I extends unknown[], O> implements IExtensionEvent<I, O> {
   protected beforeHandlers: IExtensionBeforeEventHandler<I, O>[] = [];
-  protected afterHandlers: IExtensionAfterEventHandler<O>[] = [];
+  protected afterHandlers: IExtensionAfterEventHandler<I, O>[] = [];
 
   public before(handler: IExtensionBeforeEventHandler<I, O>): void {
     if (typeof handler !== 'function') {
@@ -11,14 +11,14 @@ export class ExtensionEvent<I extends unknown[], O> implements IExtensionEvent<I
     this.beforeHandlers.push(handler);
   }
 
-  public after(handler: IExtensionAfterEventHandler<O>): void {
+  public after(handler: IExtensionAfterEventHandler<I, O>): void {
     if (typeof handler !== 'function') {
       throw new Error('ExtensionEvent::after: Handler is not a function');
     }
     this.afterHandlers.push(handler);
   }
 
-  public offAfter(handler: IExtensionAfterEventHandler<O>): void {
+  public offAfter(handler: IExtensionAfterEventHandler<I, O>): void {
     this.afterHandlers = this.afterHandlers.filter((h) => h !== handler);
   }
 
@@ -41,11 +41,11 @@ export class ExtensionEvent<I extends unknown[], O> implements IExtensionEvent<I
     return pipe;
   }
 
-  public async triggerAfter(output: O): Promise<O> {
+  public async triggerAfter(input: I, output: O): Promise<O> {
     if (this.afterHandlers && this.afterHandlers.length > 0) {
       const s = this.afterHandlers.slice(0);
       for (let i = 0; i < s.length; ++i) {
-        output = await s[i](output);
+        output = await s[i]({input, output});
       }
     }
     return output;
diff --git a/src/backend/model/extension/IExtension.ts b/src/backend/model/extension/IExtension.ts
index 3ef10049..ea8da419 100644
--- a/src/backend/model/extension/IExtension.ts
+++ b/src/backend/model/extension/IExtension.ts
@@ -19,12 +19,16 @@ import {DirectoryScanSettings} from '../fileaccess/DiskManager';
 
 
 export type IExtensionBeforeEventHandler<I extends unknown[], O> = (input: I, event: { stopPropagation: boolean }) => Promise<I | O>;
-export type IExtensionAfterEventHandler<O> = (output: O) => Promise<O>;
+/**
+ * input: is the original input: this is output of all before handler. This value was also piped to app's function
+ * output: is the output of the app's function or the previous after handler
+ */
+export type IExtensionAfterEventHandler<I extends unknown[], O> = (data: { input: I, output: O }) => Promise<O>;
 
 
 export interface IExtensionEvent<I extends unknown[], O> {
   before: (handler: IExtensionBeforeEventHandler<I, O>) => void;
-  after: (handler: IExtensionAfterEventHandler<O>) => void;
+  after: (handler: IExtensionAfterEventHandler<I, O>) => void;
 }
 
 /**
@@ -59,7 +63,9 @@ export interface IExtensionEvents {
      * Reads exif, iptc, etc.. metadata for photos/videos
      */
     MetadataLoader: {
+      // input: file path
       loadVideoMetadata: IExtensionEvent<[string], VideoMetadata>,
+      // input: file path
       loadPhotoMetadata: IExtensionEvent<[string], PhotoMetadata>
     },
     /**
@@ -122,7 +128,7 @@ export interface IExtensionDB {
   setExtensionTables(tables: Function[]): Promise<void>;
 
   /**
-   * Exposes all tables. You can use this if you van to have a foreign key to a built in table.
+   * Exposes all tables. You can use this if you van to have a foreign key to a built-in table.
    * Use with caution. This exposes the app's internal working.
    */
   // eslint-disable-next-line @typescript-eslint/ban-types