/**
 * push.js — Push Notifications client for ObsiGate
 * ROADMAP #67
 *
 * Handles:
 *  - Subscribing to Web Push via VAPID
 *  - Unsubscribing
 *  - UI rendering in the config modal
 */

import { t } from './i18n.js';

let _vapidPublicKey = null;

// ── Helpers ──────────────────────────────────────────────────────────────────

function _api(method, path, body) {
  const opts = {
    method,
    headers: { 'Content-Type': 'application/json' },
    credentials: 'same-origin',
  };
  if (body !== undefined) opts.body = JSON.stringify(body);
  return fetch(path, opts).then((r) => {
    if (!r.ok) throw new Error(`${r.status} ${r.statusText}`);
    return r.json();
  });
}

function _urlBase64ToUint8Array(base64String) {
  const padding = '='.repeat((4 - (base64String.length % 4)) % 4);
  const base64 = (base64String + padding).replace(/-/g, '+').replace(/_/g, '/');
  const rawData = atob(base64);
  const outputArray = new Uint8Array(rawData.length);
  for (let i = 0; i < rawData.length; ++i) {
    outputArray[i] = rawData.charCodeAt(i);
  }
  return outputArray;
}

// ── VAPID key ────────────────────────────────────────────────────────────────

async function getVapidPublicKey() {
  if (_vapidPublicKey) return _vapidPublicKey;
  const data = await _api('GET', '/api/push/vapid-public-key');
  _vapidPublicKey = data.public_key;
  return _vapidPublicKey;
}

// ── Subscription management ──────────────────────────────────────────────────

async function subscribePush(vault) {
  if (!('serviceWorker' in navigator) || !('PushManager' in window)) {
    throw new Error('Push notifications not supported by this browser');
  }

  const reg = await navigator.serviceWorker.ready;
  const vapidKey = await getVapidPublicKey();

  // Check existing subscription
  let subscription = await reg.pushManager.getSubscription();

  if (!subscription) {
    // Subscribe to push
    subscription = await reg.pushManager.subscribe({
      userVisibleOnly: true,
      applicationServerKey: _urlBase64ToUint8Array(vapidKey),
    });
  }

  // Register subscription with backend
  const subJSON = subscription.toJSON();
  await _api('POST', '/api/push/subscribe', {
    subscription: {
      endpoint: subJSON.endpoint,
      keys: subJSON.keys,
    },
    vault,
  });

  return { success: true };
}

async function unsubscribePush() {
  if (!('serviceWorker' in navigator)) return;

  const reg = await navigator.serviceWorker.ready;
  const subscription = await reg.pushManager.getSubscription();
  if (!subscription) return;

  // Unsubscribe from browser
  await subscription.unsubscribe();

  // Unsubscribe from backend
  const endpoint = subscription.endpoint;
  try {
    await _api('DELETE', `/api/push/subscribe?endpoint=${encodeURIComponent(endpoint)}`);
  } catch {
    // Best-effort: endpoint may already be expired
  }
}

async function isSubscribed() {
  if (!('serviceWorker' in navigator) || !('PushManager' in window)) return false;
  const reg = await navigator.serviceWorker.ready;
  const sub = await reg.pushManager.getSubscription();
  return !!sub;
}

async function getSubscriptions() {
  return _api('GET', '/api/push/subscriptions');
}

// ── Config UI ────────────────────────────────────────────────────────────────

export async function renderPushSection() {
  const container = document.getElementById('push-settings');
  if (!container) return;

  const supported = 'serviceWorker' in navigator && 'PushManager' in window;
  const subscribed = await isSubscribed();

  if (!supported) {
    container.innerHTML = `
      <div class="mfa-status-row">
        <span class="mfa-status-label">Notifications push</span>
        <span class="mfa-badge mfa-badge-off">Non supportées par ce navigateur</span>
      </div>`;
    return;
  }

  container.innerHTML = `
    <div class="mfa-status-row">
      <span class="mfa-status-label">Notifications push</span>
      <span id="push-status-badge" class="mfa-badge ${subscribed ? 'mfa-badge-on' : 'mfa-badge-off'}">${subscribed ? 'Activées' : 'Désactivées'}</span>
    </div>
    <div class="config-row" style="margin-top:12px">
      <label class="config-label" for="push-vault-select">Vault cible</label>
      <select id="push-vault-select" class="config-input" style="max-width:240px"></select>
    </div>
    <div class="config-row" style="margin-top:8px">
      <button id="push-toggle-btn" class="config-save-btn" style="${subscribed ? 'background:var(--danger-bg);color:var(--danger);border-color:var(--danger)' : ''}">
        ${subscribed ? 'Désactiver les notifications' : 'Activer les notifications'}
      </button>
    </div>
    <div id="push-sub-count" style="margin-top:8px;font-size:12px;color:var(--text-muted)"></div>`;

  // Populate vault select
  const vaultSelect = document.getElementById('push-vault-select');
  try {
    const vaultData = await _api('GET', '/api/vaults');
    const vaults = vaultData.vaults || vaultData || [];
    (Array.isArray(vaults) ? vaults : []).forEach((v) => {
      const name = typeof v === 'string' ? v : v.name;
      const opt = document.createElement('option');
      opt.value = name;
      opt.textContent = name;
      vaultSelect.appendChild(opt);
    });
  } catch {
    const opt = document.createElement('option');
    opt.value = 'default';
    opt.textContent = 'default';
    vaultSelect.appendChild(opt);
  }

  // Toggle button
  document.getElementById('push-toggle-btn')?.addEventListener('click', async () => {
    const btn = document.getElementById('push-toggle-btn');
    const badge = document.getElementById('push-status-badge');
    try {
      btn.disabled = true;
      btn.textContent = '…';
      if (subscribed) {
        await unsubscribePush();
        badge.textContent = 'Désactivées';
        badge.className = 'mfa-badge mfa-badge-off';
        btn.textContent = 'Activer les notifications';
        btn.style.background = '';
        btn.style.color = '';
        btn.style.borderColor = '';
      } else {
        const vault = vaultSelect.value || 'default';
        await subscribePush(vault);
        badge.textContent = 'Activées';
        badge.className = 'mfa-badge mfa-badge-on';
        btn.textContent = 'Désactiver les notifications';
        btn.style.background = 'var(--danger-bg)';
        btn.style.color = 'var(--danger)';
        btn.style.borderColor = 'var(--danger)';
      }
    } catch (err) {
      console.error('[Push] Toggle error:', err);
      alert('Erreur: ' + err.message);
    } finally {
      btn.disabled = false;
    }
  });

  // Show subscription count
  try {
    const data = await getSubscriptions();
    const count = (data.subscriptions || []).length;
    document.getElementById('push-sub-count').textContent =
      count > 0 ? `${count} abonnement(s) actif(s)` : '';
  } catch {
    // Ignore
  }
}

// ── Init ─────────────────────────────────────────────────────────────────────

export function initPush() {
  // Render push section when config modal opens
  document.addEventListener('DOMContentLoaded', () => {
    // Observe the config modal becoming visible
    const observer = new MutationObserver(() => {
      const section = document.getElementById('cfg-push');
      if (section && section.offsetParent !== null) {
        renderPushSection();
      }
    });
    const modal = document.getElementById('config-modal');
    if (modal) observer.observe(modal, { attributes: true, attributeFilter: ['class'] });
  });
}

export default { initPush, subscribePush, unsubscribePush, isSubscribed, renderPushSection };