/**
 * LandveX Finance — Entry Point
 * Sprint 3: UI-refaktorering
 *
 * Initierar appen, laddar state, sätter upp event listeners.
 */

import state from './state.mjs';
import { getHealth } from './api.mjs';
import { $, on } from './utils.mjs';

// ── Tab-modules (lazy-loaded) ──
const tabModules = {
  overview: () => import('./tabs/overview.mjs'),
  transactions: () => import('./tabs/transactions.mjs'),
  invoices: () => import('./tabs/invoices.mjs'),
  vat: () => import('./tabs/vat.mjs'),
  payroll: () => import('./tabs/payroll.mjs'),
  period: () => import('./tabs/period.mjs'),
  tasks: () => import('./tabs/tasks.mjs'),
  forecast: () => import('./tabs/forecast.mjs'),
};

let currentTabModule = null;

// ── Init ──
export async function init() {
  console.log('[finance] init start');

  // 1. Bygg period-väljare
  buildPeriodSelects();

  // 2. Sätt upp globala event listeners
  setupGlobalEvents();

  // 3. Ladda initial tab
  await switchTab(state.get().tab);

  // 4. Kolla health
  checkHealth();

  // 5. Sätt upp state-subscribers
  state.subscribe(onStateChange);

  console.log('[finance] init done');
}

// ── Tab-switching ──
export async function switchTab(tab) {
  if (!tabModules[tab]) {
    console.error('[finance] unknown tab:', tab);
    return;
  }

  // Deaktivera nuvarande tab
  if (currentTabModule?.deactivate) {
    currentTabModule.deactivate();
  }

  // Uppdatera UI
  document.querySelectorAll('.tab-sec').forEach(s => s.classList.remove('active'));
  document.querySelectorAll('.tab-btn').forEach(b => b.classList.remove('active'));

  const tabEl = $(`tab-${tab}`);
  if (tabEl) tabEl.classList.add('active');

  const tabIndex = {
    overview: 0, transactions: 1, invoices: 2, vat: 3,
    payroll: 4, period: 5, tasks: 6, forecast: 7
  };
  const tabBtns = document.querySelectorAll('.tab-btn');
  if (tabBtns[tabIndex[tab] ?? 0]) {
    tabBtns[tabIndex[tab] ?? 0].classList.add('active');
  }

  // Uppdatera state
  state.setTab(tab);

  // Lazy-load modul
  try {
    const module = await tabModules[tab]();
    currentTabModule = module;

    if (module.activate) {
      await module.activate(state.get().period);
    }
  } catch (e) {
    console.error('[finance] failed to load tab:', tab, e);
    showError(`Kunde inte ladda ${tab}`);
  }
}

// ── Period ──
function buildPeriodSelects() {
  const FISCAL = state.get().fiscalYear;
  const ms = $('sel-month');
  if (!ms) return;

  ms.innerHTML = '';
  for (let m = 1; m <= 12; m++) {
    const v = `${FISCAL}-${String(m).padStart(2, '0')}`;
    const o = document.createElement('option');
    o.value = v;
    o.textContent = `${MN[m - 1]} ${FISCAL}`;
    if (v === state.get().period) o.selected = true;
    ms.appendChild(o);
  }
  ms.onchange = () => state.setPeriod(ms.value);

  const qs = $('sel-quarter');
  if (qs) {
    qs.innerHTML = '';
    const curM = parseInt((state.get().period || '').split('-')[1] || 6);
    for (let q = 1; q <= 4; q++) {
      const o = document.createElement('option');
      o.value = `Q${q}-${FISCAL}`;
      o.textContent = `Q${q} ${['Jan–Mar', 'Apr–Jun', 'Jul–Sep', 'Okt–Dec'][q - 1]} ${FISCAL}`;
      if (Math.ceil(curM / 3) === q) o.selected = true;
      qs.appendChild(o);
    }
    qs.onchange = () => state.setPeriod(qs.value);
  }
}

// ── Globala events ──
function setupGlobalEvents() {
  // Escape stänger modaler
  on(document, 'keydown', (e) => {
    if (e.key === 'Escape') {
      closeAllModals();
    }
  });

  // Window resize (debounced)
  let resizeTimer;
  on(window, 'resize', () => {
    clearTimeout(resizeTimer);
    resizeTimer = setTimeout(() => {
      state.set({ windowWidth: window.innerWidth });
    }, 250);
  });
}

// ── State change handler ──
function onStateChange(s) {
  // Uppdatera loading-indikatorer
  const isLoading = s.loading.size > 0;
  const statusEl = $('data-status');
  if (statusEl) {
    statusEl.innerHTML = isLoading
      ? '<span class="sdot"></span><span>Laddar…</span>'
      : '<span class="sdot live"></span><span>Live</span>';
  }
}

// ── Health check ──
async function checkHealth() {
  try {
    await getHealth();
    console.log('[finance] health: ok');
  } catch (e) {
    console.warn('[finance] health check failed:', e.message);
  }
}

// ── Modaler ──
export function openModal(id) {
  const el = $(id);
  if (el) el.classList.remove('hidden');
}

export function closeModal(id) {
  const el = $(id);
  if (el) el.classList.add('hidden');
}

export function closeAllModals() {
  document.querySelectorAll('.modal-bg').forEach(m => m.classList.add('hidden'));
}

// ── Felhantering ──
export function showError(msg) {
  console.error('[finance]', msg);
  // TODO: Toast/notifikation
  alert(msg); // Fallback
}

// ── Start ──
if (document.readyState === 'loading') {
  document.addEventListener('DOMContentLoaded', init);
} else {
  init();
}