From ff06c96de2e3310c94b794115329b3d177758cc9 Mon Sep 17 00:00:00 2001
From: Jordan Eldredge <jordan@jordaneldredge.com>
Date: Thu, 20 Sep 2018 06:19:28 -0700
Subject: [PATCH] Provide a way to prevent closing Webamp (#655)

* Provide a way to prevent closing Webamp

Fixes #653

* Fix typos for onWillClose in usage and types
---
 docs/usage.md              | 15 +++++++++++++++
 index.d.ts                 |  9 +++++++++
 js/actionCreators/index.ts | 20 +++++++++++++++++---
 js/actionTypes.ts          |  1 +
 js/index.js                |  6 ++++++
 js/types.ts                |  4 ++++
 js/webampLazy.js           |  9 ++++++++-
 7 files changed, 60 insertions(+), 4 deletions(-)

diff --git a/docs/usage.md b/docs/usage.md
index 808e14ed..dfb7e4d1 100644
--- a/docs/usage.md
+++ b/docs/usage.md
@@ -216,6 +216,21 @@ const unsubscribe = webamp.onTrackDidChange((track => {
 unsubscribe();
 ```
 
+### `onWillClose(callback)`
+
+A callback which will be called when Webamp is _about to_ close. Returns an "unsubscribe" function. The callback will be passed a `cancel` function which you can use to conditionally prevent Webamp from being closed.
+
+```JavaScript
+const unsubscribe = webamp.onWillClose((cancel) => {
+    if (!window.confirm("Are you sure you want to close Webamp?")) {
+        cancel();
+    }
+});
+
+// If at some point in the future you want to stop listening to these events:
+unsubscribe();
+```
+
 ### `onClose(callback)`
 
 A callback which will be called when Webamp is closed. Returns an "unsubscribe" function.
diff --git a/index.d.ts b/index.d.ts
index 785c8edd..75491739 100644
--- a/index.d.ts
+++ b/index.d.ts
@@ -160,6 +160,15 @@ export default class Webamp {
    */
   public onTrackDidChange(callback: (track: Track) => any): () => void;
 
+  /**
+   * A callback which will be called when Webamp is _about to_ close. Returns an
+   * "unsubscribe" function. The callback will be passed a `cancel` function
+   * which you can use to conditionally prevent Webamp from being closed.
+   *
+   * @returns An "unsubscribe" function. Useful if at some point in the future you want to stop listening to these events.
+   */
+  public onWillClose(callback: (cancel: () => void) => any): () => void;
+
   /**
    * A callback which will be called when Webamp is closed.
    *
diff --git a/js/actionCreators/index.ts b/js/actionCreators/index.ts
index 14203c1d..baa08af9 100644
--- a/js/actionCreators/index.ts
+++ b/js/actionCreators/index.ts
@@ -1,4 +1,9 @@
-import { CLOSE_WINAMP, STOP, TOGGLE_VISUALIZER_STYLE } from "../actionTypes";
+import {
+  CLOSE_WINAMP,
+  STOP,
+  TOGGLE_VISUALIZER_STYLE,
+  CLOSE_REQUESTED
+} from "../actionTypes";
 import { Dispatchable } from "../types";
 
 export {
@@ -71,8 +76,17 @@ export {
 
 export function close(): Dispatchable {
   return dispatch => {
-    dispatch({ type: STOP });
-    dispatch({ type: CLOSE_WINAMP });
+    // TODO: This could probably be improved by adding a "PREVENT_CLOSE" action
+    // or something, but this works okay for now.
+    let defaultPrevented = false;
+    const cancel = () => {
+      defaultPrevented = true;
+    };
+    dispatch({ type: CLOSE_REQUESTED, cancel });
+    if (!defaultPrevented) {
+      dispatch({ type: STOP });
+      dispatch({ type: CLOSE_WINAMP });
+    }
   };
 }
 
diff --git a/js/actionTypes.ts b/js/actionTypes.ts
index 98243293..ec1ce8f5 100644
--- a/js/actionTypes.ts
+++ b/js/actionTypes.ts
@@ -70,3 +70,4 @@ export const DISABLE_MARQUEE = "DISABLE_MARQUEE";
 export const SET_DUMMY_VIZ_DATA = "SET_DUMMY_VIZ_DATA";
 export const SET_WINDOW_VISIBILITY = "SET_WINDOW_VISIBILITY";
 export const LOADING = "LOADING";
+export const CLOSE_REQUESTED = "CLOSE_REQUESTED";
diff --git a/js/index.js b/js/index.js
index 92153d39..c347e586 100644
--- a/js/index.js
+++ b/js/index.js
@@ -262,6 +262,12 @@ Raven.context(() => {
     });
   }
 
+  webamp.onWillClose(cancel => {
+    if (!window.confirm("Are you sure you want to close Webamp?")) {
+      cancel();
+    }
+  });
+
   webamp.renderWhenReady(document.getElementById("app"));
 
   // Expose webamp instance for debugging and integration tests.
diff --git a/js/types.ts b/js/types.ts
index dc9dc3c9..cf72e23f 100644
--- a/js/types.ts
+++ b/js/types.ts
@@ -336,6 +336,10 @@ export type Action =
     }
   | {
       type: "MINIMIZE_WINAMP";
+    }
+  | {
+      type: "CLOSE_REQUESTED";
+      cancel: () => void;
     };
 
 export interface WebampWindow {
diff --git a/js/webampLazy.js b/js/webampLazy.js
index 0fb88f08..34eb257b 100644
--- a/js/webampLazy.js
+++ b/js/webampLazy.js
@@ -27,7 +27,8 @@ import {
   LOADED,
   REGISTER_VISUALIZER,
   SET_Z_INDEX,
-  SET_MEDIA
+  SET_MEDIA,
+  CLOSE_REQUESTED
 } from "./actionTypes";
 import Emitter from "./emitter";
 
@@ -182,6 +183,12 @@ class Winamp {
     this.store.dispatch(loadMediaFiles(tracks, LOAD_STYLE.PLAY));
   }
 
+  onWillClose(cb) {
+    return this._actionEmitter.on(CLOSE_REQUESTED, action => {
+      cb(action.cancel);
+    });
+  }
+
   onClose(cb) {
     return this._actionEmitter.on(CLOSE_WINAMP, cb);
   }