jellytau/src/lib/stores/playbackMode.ts

/**
 * Playback mode store - Thin wrapper over Rust PlaybackModeManager
 *
 * Manages transitions between Local (device playback) and Remote (controlling
 * another Jellyfin session) playback modes.
 *
 * Most business logic moved to Rust (src-tauri/src/playback_mode/mod.rs)
 *
 * TRACES: UR-010 | IR-012 | DR-037
 */

import { writable, get, derived } from "svelte/store";
import { invoke } from "@tauri-apps/api/core";
import { sessions, selectedSession } from "./sessions";
import { auth } from "./auth";
import { ticksToSeconds } from "$lib/utils/playbackUnits";

export type PlaybackMode = "local" | "remote" | "idle";

interface PlaybackModeState {
  mode: PlaybackMode;
  remoteSessionId: string | null;
  isTransferring: boolean;
  transferError: string | null;
}

interface RustPlaybackMode {
  type: "local" | "remote" | "idle";
  session_id?: string;
}

function createPlaybackModeStore() {
  const initialState: PlaybackModeState = {
    mode: "idle",
    remoteSessionId: null,
    isTransferring: false,
    transferError: null,
  };

  const { subscribe, update } = writable<PlaybackModeState>(initialState);

  // Track ongoing transfer promise to allow cancellation
  let currentTransferAbort: (() => void) | null = null;

  /**
   * Refresh mode from Rust backend
   */
  async function refreshMode(): Promise<void> {
    try {
      const rustMode = await invoke<RustPlaybackMode>("playback_mode_get_current");

      update((s) => ({
        ...s,
        mode: rustMode.type,
        remoteSessionId: rustMode.type === "remote" ? rustMode.session_id || null : null,
      }));
    } catch (error) {
      console.error("Failed to get playback mode:", error);
    }
  }

  /**
   * Set playback mode directly (for internal use)
   */
  function setMode(mode: PlaybackMode, remoteSessionId: string | null = null): void {
    update((s) => ({ ...s, mode, remoteSessionId }));
  }

  /**
   * Transfer playback from local to remote session
   * Rust backend handles all the heavy lifting:
   * - Sends play command with StartPositionTicks
   * - Polls remote session until track loads
   * - Stops local playback
   */
  async function transferToRemote(sessionId: string): Promise<void> {
    console.log("[PlaybackMode] Transferring to remote session:", sessionId);
    update((s) => ({ ...s, isTransferring: true, transferError: null }));

    let aborted = false;
    currentTransferAbort = () => {
      aborted = true;
      update((s) => ({
        ...s,
        isTransferring: false,
        transferError: "Transfer cancelled",
      }));
    };

    try {
      // Rust handles everything - just wait for it to complete
      // It includes its own 5-second timeout for track loading
      console.log("[PlaybackMode] About to invoke playback_mode_transfer_to_remote with sessionId:", sessionId);
      await invoke("playback_mode_transfer_to_remote", { sessionId });
      console.log("[PlaybackMode] Invoke completed successfully");

      if (aborted) {
        console.log("[PlaybackMode] Transfer was cancelled");
        return;
      }

      // Update local state
      sessions.selectSession(sessionId);
      update((s) => ({
        ...s,
        mode: "remote",
        remoteSessionId: sessionId,
        isTransferring: false,
      }));

      console.log("[PlaybackMode] Successfully transferred to remote");
    } catch (error) {
      if (aborted) {
        console.log("[PlaybackMode] Transfer was cancelled");
        return;
      }

      const message = error instanceof Error ? error.message : "Failed to transfer playback";
      update((s) => ({
        ...s,
        isTransferring: false,
        transferError: message,
      }));
      console.error("Transfer to remote failed:", error);
      throw error;
    } finally {
      currentTransferAbort = null;
    }
  }

  /**
   * Transfer playback from remote to local
   *
   * Note: Currently hybrid - Rust stops remote, but TypeScript handles
   * loading media since repository isn't migrated yet (Phase 3).
   * Will be fully migrated to Rust after Phase 3.
   */
  async function transferToLocal(): Promise<void> {
    console.log("[PlaybackMode] Transferring to local");
    update((s) => ({ ...s, isTransferring: true, transferError: null }));

    let aborted = false;
    currentTransferAbort = () => {
      aborted = true;
      update((s) => ({
        ...s,
        isTransferring: false,
        transferError: "Transfer cancelled",
      }));
    };

    try {
      const currentMode = get({ subscribe });
      if (currentMode.mode !== "remote" || !currentMode.remoteSessionId) {
        throw new Error("Not in remote mode");
      }

      // Get current remote session state
      const session = get(selectedSession);
      if (!session || !session.nowPlayingItem) {
        // No active playback on remote, just switch to local mode
        sessions.selectSession(null);
        update((s) => ({
          ...s,
          mode: "local",
          remoteSessionId: null,
          isTransferring: false,
        }));
        return;
      }

      const nowPlaying = session.nowPlayingItem;
      const positionTicks = session.playState?.positionTicks ?? 0;
      const positionSeconds = ticksToSeconds(positionTicks);

      // Handle both camelCase and PascalCase field names (API might return either)
      const itemId = (nowPlaying as any).id || (nowPlaying as any).Id;
      const itemName = (nowPlaying as any).name || (nowPlaying as any).Name;

      console.log("[PlaybackMode] Current remote item:", itemName, "position:", positionSeconds, "id:", itemId);

      if (!itemId) {
        throw new Error("Cannot transfer: remote item has no ID");
      }

      if (aborted) return;

      // TODO: After Phase 3 (repository migration), this will be handled by Rust
      // For now, we need to fetch playback info and start local playback from TypeScript

      // Get repository to fetch playback info
      const repository = auth.getRepository();
      const playbackInfo = await repository.getPlaybackInfo(itemId);

      if (aborted) return;

      // Build play item request (handle both camelCase and PascalCase)
      const itemType = (nowPlaying as any).type || (nowPlaying as any).Type;
      const artists = (nowPlaying as any).artists || (nowPlaying as any).Artists;
      const albumName = (nowPlaying as any).albumName || (nowPlaying as any).AlbumName;
      const runTimeTicks = (nowPlaying as any).runTimeTicks || (nowPlaying as any).RunTimeTicks;
      const primaryImageTag = (nowPlaying as any).primaryImageTag || (nowPlaying as any).PrimaryImageTag;

      const playItem = {
        id: itemId,
        title: itemName,
        artist: artists?.[0],
        album: albumName,
        duration: runTimeTicks ? ticksToSeconds(runTimeTicks) : undefined,
        artworkUrl: repository.getImageUrl(itemId, "Primary", {
          tag: primaryImageTag,
        }),
        mediaType: itemType === "Audio" ? "audio" : "video",
        streamUrl: playbackInfo.streamUrl,
        jellyfinItemId: itemId,
      };

      // Start local playback (events allowed through because isTransferring=true)
      await invoke("player_play_item", { item: playItem });

      if (aborted) return;

      // Wait briefly for media to load
      await new Promise((resolve) => setTimeout(resolve, 500));

      // Seek to position if not at the very start
      if (positionSeconds > 0.5) {
        await invoke("player_seek", { position: positionSeconds });
      }

      if (aborted) return;

      // Let Rust handle stopping remote playback
      await invoke("playback_mode_transfer_to_local", {
        currentItemId: itemId,
        positionTicks,
      });

      if (aborted) return;

      // Finalize transfer - now update mode to local
      sessions.selectSession(null);
      update((s) => ({
        ...s,
        mode: "local",
        remoteSessionId: null,
        isTransferring: false,
      }));

      console.log("[PlaybackMode] Successfully transferred to local");
    } catch (error) {
      if (aborted) {
        console.log("[PlaybackMode] Transfer was cancelled");
        return;
      }

      const message = error instanceof Error ? error.message : "Failed to transfer playback";
      update((s) => ({
        ...s,
        isTransferring: false,
        transferError: message,
      }));
      console.error("Transfer to local failed:", error);
      throw error;
    } finally {
      currentTransferAbort = null;
    }
  }

  /**
   * Monitor remote session for disconnection
   */
  function initializeSessionMonitoring(): void {
    // Subscribe to session changes
    selectedSession.subscribe((session) => {
      const currentState = get({ subscribe });

      // If we're in remote mode but session is gone or lost control capability
      // Don't interfere during an active transfer (we intentionally clear the session)
      if (currentState.mode === "remote" && currentState.remoteSessionId && !currentState.isTransferring) {
        if (!session || session.id !== currentState.remoteSessionId || !session.supportsMediaControl) {
          console.warn("[PlaybackMode] Remote session lost or disconnected");
          update((s) => ({
            ...s,
            mode: "idle",
            remoteSessionId: null,
            transferError: "Remote session disconnected",
          }));
        }
      }
    });
  }

  /**
   * Clear transfer error message
   */
  function clearError(): void {
    update((s) => ({ ...s, transferError: null }));
  }

  /**
   * Cancel ongoing transfer operation
   */
  function cancelTransfer(): void {
    if (currentTransferAbort) {
      console.log("[PlaybackMode] Cancelling transfer");
      currentTransferAbort();
    }
  }

  /**
   * Disconnect from remote session without transferring playback
   * This stops controlling the remote device and returns to idle/local state
   */
  async function disconnect(): Promise<void> {
    console.log("[PlaybackMode] Disconnecting from remote session");

    const currentState = get({ subscribe });
    if (currentState.mode !== "remote") {
      console.log("[PlaybackMode] Not in remote mode, nothing to disconnect");
      return;
    }

    try {
      // Notify Rust backend to switch to idle mode
      await invoke("playback_mode_set", { mode: "Idle" });

      // Update local state
      sessions.selectSession(null);
      update((s) => ({
        ...s,
        mode: "idle",
        remoteSessionId: null,
        transferError: null,
      }));

      console.log("[PlaybackMode] Successfully disconnected");
    } catch (error) {
      const message = error instanceof Error ? error.message : "Failed to disconnect";
      console.error("[PlaybackMode] Disconnect failed:", error);
      update((s) => ({
        ...s,
        transferError: message,
      }));
      throw error;
    }
  }

  // Note: initializeSessionMonitoring() and refreshMode() should be called
  // manually from +layout.svelte after auth initialization, not automatically
  // at module load time to avoid race conditions with other Rust commands

  return {
    subscribe,
    setMode,
    transferToRemote,
    transferToLocal,
    disconnect,
    refresh: refreshMode,
    initializeSessionMonitoring,
    clearError,
    cancelTransfer,
  };
}

export const playbackMode = createPlaybackModeStore();

// Derived stores for convenience
export const isRemoteMode = derived(playbackMode, ($mode) => $mode.mode === "remote");
export const isLocalMode = derived(playbackMode, ($mode) => $mode.mode === "local");
export const isIdleMode = derived(playbackMode, ($mode) => $mode.mode === "idle");
export const isTransferring = derived(playbackMode, ($mode) => $mode.isTransferring);
export const transferError = derived(playbackMode, ($mode) => $mode.transferError);