/** @typedef {Event & { prompt: () => Promise<void>, userChoice: Promise<{ outcome: 'accepted' | 'dismissed' }> }} BeforeInstallPromptEvent */

const PROMPT_KEY = '__recipesPwaDeferredPrompt';
const LISTENER_KEY = '__recipesPwaInstallListening';

let ready = $state(false);
let installed = $state(false);
let alreadyOnDevice = $state(false);

function getDeferredPrompt() {
	if (typeof window === 'undefined') return null;
	return /** @type {BeforeInstallPromptEvent | null} */ (window[PROMPT_KEY] ?? null);
}

function setDeferredPrompt(/** @type {BeforeInstallPromptEvent | null} */ event) {
	if (typeof window === 'undefined') return;
	window[PROMPT_KEY] = event;
	ready = event !== null;
}

function isStandaloneDisplay() {
	if (typeof window === 'undefined') return false;
	return (
		window.matchMedia('(display-mode: standalone)').matches ||
		window.matchMedia('(display-mode: window-controls-overlay)').matches ||
		/** @type {Navigator & { standalone?: boolean }} */ (window.navigator).standalone === true
	);
}

function isIosDevice() {
	if (typeof navigator === 'undefined') return false;
	const ua = navigator.userAgent;
	return /iPad|iPhone|iPod/.test(ua) || (navigator.platform === 'MacIntel' && navigator.maxTouchPoints > 1);
}

async function isBrave() {
	if (typeof navigator === 'undefined') return false;
	const brave = /** @type {Navigator & { brave?: { isBrave?: () => Promise<boolean> } }} */ (navigator).brave;
	if (brave?.isBrave) {
		try {
			return await brave.isBrave();
		} catch {
			/* fall through */
		}
	}
	return /Brave/i.test(navigator.userAgent);
}

/**
 * Detect an existing install of this origin's PWA (desktop/Android Chromium).
 */
async function detectRelatedInstall() {
	if (typeof navigator === 'undefined' || !('getInstalledRelatedApps' in navigator)) {
		return false;
	}
	try {
		const apps = await /** @type {{ getInstalledRelatedApps: () => Promise<unknown[]> }} */ (
			navigator
		).getInstalledRelatedApps();
		return Array.isArray(apps) && apps.length > 0;
	} catch {
		return false;
	}
}

async function refreshInstallFlags() {
	installed = isStandaloneDisplay();
	alreadyOnDevice = installed || (await detectRelatedInstall());
	if (alreadyOnDevice) {
		setDeferredPrompt(null);
	} else if (getDeferredPrompt()) {
		ready = true;
	}
}

/**
 * Start listening for install eligibility. Safe to call multiple times.
 * Prompt event is stored on `window` so Vite HMR does not drop it.
 */
export function initPwaInstall() {
	if (typeof window === 'undefined') return;

	// Rehydrate after HMR / remount.
	if (getDeferredPrompt()) ready = true;
	void refreshInstallFlags();

	if (window[LISTENER_KEY]) return;
	window[LISTENER_KEY] = true;

	window.addEventListener('beforeinstallprompt', (event) => {
		event.preventDefault();
		setDeferredPrompt(/** @type {BeforeInstallPromptEvent} */ (event));
		installed = false;
		alreadyOnDevice = false;
	});

	window.addEventListener('appinstalled', () => {
		setDeferredPrompt(null);
		installed = true;
		alreadyOnDevice = true;
	});

	const media = window.matchMedia('(display-mode: standalone)');
	media.addEventListener?.('change', () => {
		void refreshInstallFlags();
	});
}

export function isInstallVisible() {
	// Hide only while running inside the installed app window.
	return !installed;
}

export function isInstallReady() {
	return getDeferredPrompt() !== null && !installed;
}

export function isAlreadyInstalledOnDevice() {
	return alreadyOnDevice && !installed;
}

/**
 * Triggers the native browser install prompt. Must be called from a user gesture.
 */
export async function promptInstall() {
	await refreshInstallFlags();

	if (alreadyOnDevice && !getDeferredPrompt()) {
		return { ok: false, reason: /** @type {const} */ ('already-installed') };
	}

	const event = getDeferredPrompt();
	if (!event) {
		const brave = await isBrave();
		const ios = isIosDevice();
		return {
			ok: false,
			reason: /** @type {const} */ ('unavailable'),
			brave,
			ios
		};
	}

	try {
		await event.prompt();
		const choice = await event.userChoice;
		setDeferredPrompt(null);

		if (choice.outcome === 'accepted') {
			installed = true;
			alreadyOnDevice = true;
			return { ok: true, reason: /** @type {const} */ ('accepted') };
		}

		return { ok: false, reason: /** @type {const} */ ('dismissed') };
	} catch {
		const brave = await isBrave();
		const ios = isIosDevice();
		return {
			ok: false,
			reason: /** @type {const} */ ('unavailable'),
			brave,
			ios
		};
	}
}

if (typeof window !== 'undefined') {
	initPwaInstall();
}