export function setupPWA({failed}) {
    const install = document.getElementById('install');
    const guide = document.getElementById('install-guide');
    const update = document.getElementById('update');
    const standalone = () => window.matchMedia('(display-mode: standalone)').matches || navigator.standalone;
    let prompt;
    guide.hidden = !!standalone();
    window.addEventListener('beforeinstallprompt', event => {
        event.preventDefault();
        prompt = event;
        install.hidden = false;
        guide.hidden = true;
    });
    install.addEventListener('click', async () => {
        if (!prompt) return;
        const pending = prompt;
        prompt = undefined;
        install.hidden = true;
        try {
            await pending.prompt();
            await pending.userChoice;
        } catch {
            // Keep manual installation guidance available if the prompt fails.
        } finally {
            guide.hidden = !!standalone();
        }
    });
    window.addEventListener('appinstalled', () => {
        prompt = undefined;
        install.hidden = true;
        guide.hidden = true;
    });
    if (!('serviceWorker' in navigator)) return;
    let controlled = !!navigator.serviceWorker.controller;
    navigator.serviceWorker.addEventListener('controllerchange', () => {
        if (controlled) window.location.reload();
        controlled = true;
    });
    navigator.serviceWorker.register('./sw.js', {scope: './', type: 'module', updateViaCache: 'none'})
        .then(registration => {
            const showUpdate = () => { update.hidden = !registration.waiting; };
            showUpdate();
            registration.addEventListener('updatefound', () => {
                const worker = registration.installing;
                if (worker) worker.addEventListener('statechange', showUpdate);
            });
            update.addEventListener('click', () => {
                if (registration.waiting) registration.waiting.postMessage('ACTIVATE_UPDATE');
            });
        }).catch(failed);
}