feat(playback): add pure remote-command mapper

utils/playback/remoteCommands.test.ts

@@ -0,0 +1,86 @@
+import { describe, expect, test } from "bun:test";
+import { mapRemoteCommand } from "./remoteCommands";
+
+describe("mapRemoteCommand — Playstate", () => {
+  test("maps Pause", () => {
+    expect(
+      mapRemoteCommand({
+        MessageType: "Playstate",
+        Data: { Command: "Pause" },
+      }),
+    ).toEqual({ kind: "pause" });
+  });
+
+  test("maps Stop, PlayPause, Unpause, NextTrack, PreviousTrack", () => {
+    const m = (c: string) =>
+      mapRemoteCommand({ MessageType: "Playstate", Data: { Command: c } });
+    expect(m("Stop")).toEqual({ kind: "stop" });
+    expect(m("PlayPause")).toEqual({ kind: "playPause" });
+    expect(m("Unpause")).toEqual({ kind: "unpause" });
+    expect(m("NextTrack")).toEqual({ kind: "next" });
+    expect(m("PreviousTrack")).toEqual({ kind: "previous" });
+  });
+
+  test("maps Seek, converting ticks to milliseconds", () => {
+    expect(
+      mapRemoteCommand({
+        MessageType: "Playstate",
+        Data: { Command: "Seek", SeekPositionTicks: 600_000_000 },
+      }),
+    ).toEqual({ kind: "seek", positionMs: 60_000 });
+  });
+
+  test("returns null for Seek with no position", () => {
+    expect(
+      mapRemoteCommand({ MessageType: "Playstate", Data: { Command: "Seek" } }),
+    ).toBeNull();
+  });
+
+  test("returns null for an unknown command", () => {
+    expect(
+      mapRemoteCommand({ MessageType: "Playstate", Data: { Command: "Wat" } }),
+    ).toBeNull();
+  });
+});
+
+describe("mapRemoteCommand — GeneralCommand", () => {
+  test("maps SetVolume, converting 0-100 to 0-1", () => {
+    expect(
+      mapRemoteCommand({
+        MessageType: "GeneralCommand",
+        Data: { Name: "SetVolume", Arguments: { Volume: "40" } },
+      }),
+    ).toEqual({ kind: "setVolume", level: 0.4 });
+  });
+
+  test("clamps SetVolume to 0-1", () => {
+    const r = mapRemoteCommand({
+      MessageType: "GeneralCommand",
+      Data: { Name: "SetVolume", Arguments: { Volume: "250" } },
+    });
+    expect(r).toEqual({ kind: "setVolume", level: 1 });
+  });
+
+  test("maps ToggleMute / Mute / Unmute to toggleMute", () => {
+    const m = (n: string) =>
+      mapRemoteCommand({ MessageType: "GeneralCommand", Data: { Name: n } });
+    expect(m("ToggleMute")).toEqual({ kind: "toggleMute" });
+    expect(m("Mute")).toEqual({ kind: "toggleMute" });
+    expect(m("Unmute")).toEqual({ kind: "toggleMute" });
+  });
+
+  test("maps DisplayMessage from Arguments.Text", () => {
+    expect(
+      mapRemoteCommand({
+        MessageType: "GeneralCommand",
+        Data: { Name: "DisplayMessage", Arguments: { Text: "Hello" } },
+      }),
+    ).toEqual({ kind: "displayMessage", text: "Hello" });
+  });
+});
+
+describe("mapRemoteCommand — other", () => {
+  test("returns null for unrelated message types", () => {
+    expect(mapRemoteCommand({ MessageType: "KeepAlive", Data: {} })).toBeNull();
+  });
+});

utils/playback/remoteCommands.ts

@@ -0,0 +1,82 @@
+/**
+ * Pure mapping from a Jellyfin remote-control WebSocket message to a typed
+ * action. Dependency-free so it is unit-testable under `bun test`.
+ */
+
+/** A WebSocket message envelope (subset). */
+export interface RemoteWsMessage {
+  MessageType: string;
+  Data?: unknown;
+}
+
+export type RemoteAction =
+  | { kind: "playPause" }
+  | { kind: "pause" }
+  | { kind: "unpause" }
+  | { kind: "stop" }
+  | { kind: "seek"; positionMs: number }
+  | { kind: "next" }
+  | { kind: "previous" }
+  | { kind: "setVolume"; level: number }
+  | { kind: "toggleMute" }
+  | { kind: "displayMessage"; text: string };
+
+const clamp01 = (n: number): number => Math.min(1, Math.max(0, n));
+
+const mapPlaystate = (data: Record<string, unknown>): RemoteAction | null => {
+  switch (data.Command) {
+    case "PlayPause":
+      return { kind: "playPause" };
+    case "Pause":
+      return { kind: "pause" };
+    case "Unpause":
+      return { kind: "unpause" };
+    case "Stop":
+      return { kind: "stop" };
+    case "NextTrack":
+      return { kind: "next" };
+    case "PreviousTrack":
+      return { kind: "previous" };
+    case "Seek": {
+      const ticks = data.SeekPositionTicks;
+      if (typeof ticks !== "number") return null;
+      return { kind: "seek", positionMs: Math.floor(ticks / 10000) };
+    }
+    default:
+      return null;
+  }
+};
+
+const mapGeneralCommand = (
+  data: Record<string, unknown>,
+): RemoteAction | null => {
+  const args = (data.Arguments ?? {}) as Record<string, unknown>;
+  switch (data.Name) {
+    case "SetVolume": {
+      const volume = Number(args.Volume);
+      if (!Number.isFinite(volume)) return null;
+      return { kind: "setVolume", level: clamp01(volume / 100) };
+    }
+    case "Mute":
+    case "Unmute":
+    case "ToggleMute":
+      return { kind: "toggleMute" };
+    case "DisplayMessage": {
+      const text = args.Text ?? args.Header;
+      if (!text) return null;
+      return { kind: "displayMessage", text: String(text) };
+    }
+    default:
+      return null;
+  }
+};
+
+/** Map a remote-control WS message to a typed action, or null if unhandled. */
+export const mapRemoteCommand = (
+  message: RemoteWsMessage,
+): RemoteAction | null => {
+  const data = (message.Data ?? {}) as Record<string, unknown>;
+  if (message.MessageType === "Playstate") return mapPlaystate(data);
+  if (message.MessageType === "GeneralCommand") return mapGeneralCommand(data);
+  return null;
+};