import dbus from "dbus-next";

const MPRIS_PREFIX = "org.mpris.MediaPlayer2.";
const PLAYER_IFACE = "org.mpris.MediaPlayer2.Player";
const PROPS_IFACE = "org.freedesktop.DBus.Properties";

// Lowercase substrings matched against the bus name suffix.
// Only players matching this whitelist will be used.
const ALLOWED_PLAYERS = [
	// local players
	"gapless",
	"elisa",
	"rhythmbox",
	"g4music",
	"lollypop",
	"amberol",
	"gnome-music",
	"strawberry",
	"clementine",
	"audacious",
	"quodlibet",
	"deadbeef",
	"cmus",
	"musikcube",
	"aimp",
	"spotify",
	"tidal",
	"deezer",
	"youtube-music",
	"youtubemusic",
	"nuclear",
	"cider",
	"feishin",
	"sonixd",
	"navidrome",
	"plexamp",
];

/**
 * Return the session bus connection.
 */
export function sessionBus() {
	return dbus.sessionBus();
}

/**
 * List all MPRIS player bus names currently registered.
 */
export async function listPlayers(bus) {
	const dbusProxy = await bus.getProxyObject(
		"org.freedesktop.DBus",
		"/org/freedesktop/DBus",
	);
	const iface = dbusProxy.getInterface("org.freedesktop.DBus");
	const names = await iface.ListNames();
	return names.filter((n) => n.startsWith(MPRIS_PREFIX));
}

/**
 * Pick the best player from a list of bus names based on the list mode.
 *   "off"      – return the first player found (ignore the list)
 *   "priority" – prefer listed players, fall back to any player
 *   "on"       – only allow listed players (strict whitelist)
 */
export function selectPlayer(players, mode = "on") {
	if (mode === "off") {
		return players[0] ?? null;
	}

	// Find the first player that matches the list
	for (const name of players) {
		const suffix = name.slice(MPRIS_PREFIX.length).toLowerCase();
		if (ALLOWED_PLAYERS.some((p) => suffix.includes(p))) {
			return name;
		}
	}

	// In priority mode, fall back to any player
	if (mode === "priority") {
		return players[0] ?? null;
	}

	return null;
}

/**
 * Read Metadata, PlaybackStatus, and Position from a player.
 */
export async function getPlayerData(bus, playerName) {
	const proxy = await bus.getProxyObject(playerName, "/org/mpris/MediaPlayer2");
	const props = proxy.getInterface(PROPS_IFACE);

	const [metadata, playbackStatus, position] = await Promise.all([
		props.Get(PLAYER_IFACE, "Metadata"),
		props.Get(PLAYER_IFACE, "PlaybackStatus"),
		props.Get(PLAYER_IFACE, "Position"),
	]);

	return {
		metadata: metadata.value, // dict of Variants
		playbackStatus: playbackStatus.value, // string
		positionUs: Number(position.value), // microseconds
	};
}

/**
 * Subscribe to PropertiesChanged and Seeked signals on the player interface.
 * `onChange` receives (changedProperties: object, invalidated: string[]).
 * `onSeeked` receives (positionUs: number).
 * Returns a cleanup function.
 */
export async function watchPlayer(bus, playerName, onChange, onSeeked) {
	const proxy = await bus.getProxyObject(playerName, "/org/mpris/MediaPlayer2");
	const props = proxy.getInterface(PROPS_IFACE);
	const player = proxy.getInterface(PLAYER_IFACE);

	const propsHandler = (ifaceName, changed, invalidated) => {
		if (ifaceName === PLAYER_IFACE) {
			onChange(changed, invalidated);
		}
	};

	const seekHandler = (positionUs) => {
		onSeeked(Number(positionUs));
	};

	props.on("PropertiesChanged", propsHandler);
	player.on("Seeked", seekHandler);

	return () => {
		props.off("PropertiesChanged", propsHandler);
		player.off("Seeked", seekHandler);
	};
}

/**
 * Watch for new or removed MPRIS players on the bus.
 * `onPlayerChange` is called with no arguments whenever the set of players changes.
 */
export async function watchBus(bus, onPlayerChange) {
	const dbusProxy = await bus.getProxyObject(
		"org.freedesktop.DBus",
		"/org/freedesktop/DBus",
	);
	const iface = dbusProxy.getInterface("org.freedesktop.DBus");

	iface.on("NameOwnerChanged", (name, _oldOwner, _newOwner) => {
		if (name.startsWith(MPRIS_PREFIX)) {
			onPlayerChange();
		}
	});
}