From 025a69f344a11c8875409382d0042b4bd84827ff Mon Sep 17 00:00:00 2001
From: sleepyfran <fgzv@outlook.com>
Date: Thu, 12 Sep 2024 01:35:05 +0200
Subject: [PATCH] Implement skip/previous

---
 packages/components/player/src/player.ts | 29 +++++++++++++---
 packages/services/player/src/player.ts   | 42 ++++++++++++++++++++++--
 2 files changed, 65 insertions(+), 6 deletions(-)

diff --git a/packages/components/player/src/player.ts b/packages/components/player/src/player.ts
index 9f1e233..7ee29d1 100644
--- a/packages/components/player/src/player.ts
+++ b/packages/components/player/src/player.ts
@@ -15,6 +15,8 @@ export class EchoPlayer extends LitElement {
     this,
     () => PlayerService.togglePlayback,
   );
+  private _previousTrack = new EffectFn(this, () => PlayerService.previous);
+  private _skipTrack = new EffectFn(this, () => PlayerService.skip);
 
   render() {
     return this._player.render({
@@ -30,7 +32,10 @@ export class EchoPlayer extends LitElement {
             )}
           </div>
           <div>
-            <button ?disabled=${!player.previouslyPlayedTracks.length}>
+            <button
+              @click=${this._onPreviousTrack}
+              ?disabled=${!player.previouslyPlayedTracks.length}
+            >
               ⏮
             </button>
             <button
@@ -45,13 +50,21 @@ export class EchoPlayer extends LitElement {
             >
               ⏸
             </button>
-            <button ?disabled=${!player.comingUpTracks.length}>⏭</button>
+            <button
+              @click=${this._onSkipTrack}
+              ?disabled=${!player.comingUpTracks.length}
+            >
+              ⏭
+            </button>
           </div>
           <p>
             Previously played tracks:
-            ${JSON.stringify(player.previouslyPlayedTracks)}
+            ${player.previouslyPlayedTracks.map((t) => t.name).join(", ")}
+          </p>
+          <p>
+            Coming up tracks:
+            ${player.comingUpTracks.map((t) => t.name).join(", ")}
           </p>
-          <p>Coming up tracks: ${player.comingUpTracks}</p>
         </div>
       `,
     });
@@ -67,6 +80,14 @@ export class EchoPlayer extends LitElement {
   private _onTogglePlayback() {
     this._togglePlayback.run({});
   }
+
+  private _onPreviousTrack() {
+    this._previousTrack.run({});
+  }
+
+  private _onSkipTrack() {
+    this._skipTrack.run({});
+  }
 }
 
 declare global {
diff --git a/packages/services/player/src/player.ts b/packages/services/player/src/player.ts
index 76dd8e8..113f90e 100644
--- a/packages/services/player/src/player.ts
+++ b/packages/services/player/src/player.ts
@@ -13,6 +13,7 @@ import {
   type Track,
 } from "@echo/core-types";
 import {
+  Array,
   Data,
   Effect,
   Exit,
@@ -86,8 +87,45 @@ const makePlayer = Effect.gen(function* () {
 
       yield* mediaPlayer.value.player.togglePlayback;
     }),
-    previous: Effect.void,
-    skip: Effect.void,
+    previous: Effect.gen(function* () {
+      // TODO: Refactor this to avoid duplication with other play commands.
+      const { previouslyPlayedTracks, comingUpTracks, status } =
+        yield* Ref.get(state);
+      const lastPlayedTrack = Array.last(previouslyPlayedTracks);
+      if (Option.isNone(lastPlayedTrack)) {
+        yield* Effect.logWarning(
+          "Attempted to play previous track, but the previous queue is empty",
+        );
+        return;
+      }
+
+      const { provider, player } = yield* resolveDependenciesForTrack(
+        providerCache,
+        lastPlayedTrack.value,
+      );
+
+      const currentTrack = Match.value(status).pipe(
+        Match.tag("Playing", ({ track }) => [track]),
+        Match.tag("Paused", ({ track }) => [track]),
+        Match.tag("Stopped", () => []),
+        Match.exhaustive,
+      );
+      const previousWithoutLast = Array.dropRight(previouslyPlayedTracks, 1);
+      const comingUpWithCurrent = [...currentTrack, ...comingUpTracks];
+
+      yield* playTrack(provider, player, lastPlayedTrack.value);
+      yield* commandQueue.offer(
+        UpdateState({
+          updateFn: (state) => ({
+            ...state,
+            status: Playing({ track: lastPlayedTrack.value }),
+            previouslyPlayedTracks: previousWithoutLast,
+            comingUpTracks: comingUpWithCurrent,
+          }),
+        }),
+      );
+    }),
+    skip: commandQueue.offer(NextTrack()),
     observe: state,
   });
 });