From 2ee04a2d79b12044e684fe0a9df803f823d6fba6 Mon Sep 17 00:00:00 2001
From: Lewis Diamond <lewis@jogogo.co>
Date: Fri, 30 Aug 2019 15:24:38 -0400
Subject: [PATCH] unclean

---
 src/functions/compose.ts | 83 +++++++++++++++++++++++++++++-----------
 src/functions/index.ts   | 10 +----
 2 files changed, 62 insertions(+), 31 deletions(-)

diff --git a/src/functions/compose.ts b/src/functions/compose.ts
index f53aa6c..fea69eb 100644
--- a/src/functions/compose.ts
+++ b/src/functions/compose.ts
@@ -1,4 +1,11 @@
-import { pipeline, Duplex, DuplexOptions } from "stream";
+import {
+    pipeline,
+    Duplex,
+    Transform,
+    Readable,
+    Writable,
+    DuplexOptions,
+} from "stream";
 
 /**
  * Return a Readable stream of readable streams concatenated together
@@ -12,7 +19,7 @@ export function compose(
         NodeJS.ReadableStream | NodeJS.ReadWriteStream | NodeJS.WritableStream
     >,
     options?: DuplexOptions,
-): Duplex {
+): Compose {
     // Maybe just return a new stream here
     if (streams.length < 2) {
         throw new Error("At least two streams are required to compose");
@@ -23,26 +30,41 @@ export function compose(
     return composed;
 }
 
-class Compose extends Duplex {
-    private first:
-        | NodeJS.ReadableStream
-        | NodeJS.ReadWriteStream
-        | NodeJS.WritableStream;
-    private last:
-        | NodeJS.ReadableStream
-        | NodeJS.ReadWriteStream
-        | NodeJS.WritableStream;
-    constructor(
-        streams: Array<
-            | NodeJS.ReadableStream
-            | NodeJS.ReadWriteStream
-            | NodeJS.WritableStream
-        >,
-        options?: DuplexOptions,
-    ) {
+enum EventSubscription {
+    Last = 0,
+    First,
+    All,
+    Self,
+}
+const eventsTarget = {
+    close: EventSubscription.Last,
+    data: EventSubscription.Last,
+    drain: EventSubscription.First,
+    end: EventSubscription.Last,
+    error: EventSubscription.Self,
+    finish: EventSubscription.Last,
+    pause: EventSubscription.Last,
+    pipe: EventSubscription.First,
+    readable: EventSubscription.Last,
+    resume: EventSubscription.Last,
+    unpipe: EventSubscription.First,
+};
+
+type AllStreams =
+    | NodeJS.ReadableStream
+    | NodeJS.ReadWriteStream
+    | NodeJS.WritableStream;
+
+export class Compose extends Duplex {
+    private first: AllStreams;
+    private last: AllStreams;
+    private streams: AllStreams[];
+
+    constructor(streams: AllStreams[], options?: DuplexOptions) {
         super(options);
         this.first = streams[0];
         this.last = streams[streams.length - 1];
+        this.streams = streams;
         pipeline(streams, (err: any) => {
             this.emit("error", err);
         });
@@ -56,11 +78,28 @@ class Compose extends Duplex {
         return (this.first as NodeJS.WritableStream).write(chunk);
     }
 
+    public bubble(...events: string[]) {
+        this.streams.forEach(s => {
+            events.forEach(e => {
+                s.on(e, (...args) => super.emit(e, ...args));
+            });
+        });
+    }
+
     public on(event: string, cb: any) {
-        if (event === "error") {
-            super.on(event, cb);
+        switch (eventsTarget[event]) {
+            case EventSubscription.First:
+                this.first.on(event, cb);
+                break;
+            case EventSubscription.Last:
+                this.last.on(event, cb);
+                break;
+            case EventSubscription.All:
+                this.streams.forEach(s => s.on(event, cb));
+                break;
+            default:
+                super.on(event, cb);
         }
-        this.last.on(event, cb);
         return this;
     }
 }
diff --git a/src/functions/index.ts b/src/functions/index.ts
index 21ad7f9..2e4b8ad 100644
--- a/src/functions/index.ts
+++ b/src/functions/index.ts
@@ -288,12 +288,4 @@ export function accumulatorBy<T, S extends FlushStrategy>(
     return baseFunctions.accumulatorBy(batchRate, flushStrategy, iteratee);
 }
 
-export function compose(
-    streams: Array<Writable | Transform>,
-    options?: DuplexOptions,
-) {
-    return baseFunctions.compose(
-        streams,
-        options,
-    );
-}
+export const compose = baseFunctions.compose;