1 files changed, 86 insertions, 0 deletions
diff --git a/src/utils/nowPlaying.ts b/src/utils/nowPlaying.ts
new file mode 100644
index 0000000..a307f5c
--- /dev/null
+++ b/src/utils/nowPlaying.ts
@@ -0,0 +1,86 @@
+import type { FlatpakApp, RunningFlatpakApp } from "../api/lsfgApi";
+import type { GameTarget } from "./gameTargets";
+
+export type NowPlayingTarget =
+  | {
+      kind: "flatpak";
+      app: FlatpakApp;
+      launcher: GameTarget | null;
+    }
+  | {
+      kind: "steam";
+      game: GameTarget;
+    }
+  | {
+      kind: "nonSteam";
+      game: GameTarget;
+    };
+
+function numericValue(value: number | null | undefined): number {
+  return typeof value === "number" && Number.isFinite(value) ? value : -1;
+}
+
+function numericPid(value: string | undefined): number {
+  return value && /^\d+$/.test(value) ? Number(value) : -1;
+}
+
+function compareRunningProcesses(a: RunningFlatpakApp, b: RunningFlatpakApp): number {
+  if (a.active !== b.active) return a.active ? -1 : 1;
+  const startDifference = numericValue(b.start_time) - numericValue(a.start_time);
+  if (startDifference !== 0) return startDifference;
+  return numericPid(b.pid) - numericPid(a.pid);
+}
+
+export function selectMostRecentRunningFlatpak(
+  apps: FlatpakApp[],
+  runningApps: RunningFlatpakApp[],
+): FlatpakApp | null {
+  const newestProcessByApp = new Map<string, RunningFlatpakApp>();
+  for (const running of runningApps) {
+    const current = newestProcessByApp.get(running.app_id);
+    if (!current || compareRunningProcesses(running, current) < 0) {
+      newestProcessByApp.set(running.app_id, running);
+    }
+  }
+
+  const candidates = Array.from(newestProcessByApp.values())
+    .map((running) => ({
+      running,
+      app: apps.find((app) => app.app_id === running.app_id) || null,
+    }))
+    .filter((candidate): candidate is { running: RunningFlatpakApp; app: FlatpakApp } => candidate.app !== null);
+  const activeCandidates = candidates.filter(({ running }) => running.active);
+  const eligibleCandidates = activeCandidates.length > 0
+    ? activeCandidates
+    : candidates.length === 1
+      ? candidates
+      : [];
+
+  eligibleCandidates.sort((a, b) => {
+    const processDifference = compareRunningProcesses(a.running, b.running);
+    if (processDifference !== 0) return processDifference;
+    return a.running.app_id.localeCompare(b.running.app_id);
+  });
+
+  return eligibleCandidates[0]?.app || null;
+}
+
+export function resolveNowPlayingTarget(
+  runningGame: GameTarget | null,
+  runningFlatpak: FlatpakApp | null,
+): NowPlayingTarget | null {
+  if (runningGame?.source === "steam") {
+    return runningGame.configured ? { kind: "steam", game: runningGame } : null;
+  }
+  if (runningFlatpak) {
+    return {
+      kind: "flatpak",
+      app: runningFlatpak,
+      launcher: runningGame?.source === "nonSteam" ? runningGame : null,
+    };
+  }
+  if (runningGame?.source === "nonSteam" && runningGame.configured) {
+    return { kind: "nonSteam", game: runningGame };
+  }
+  return null;
+}