/**
 * LandveX Finance — Global State Management
 * Sprint 3: UI-refaktorering
 * 
 * Förenklad Redux-pattern för vanilla JS.
 */

const S = {
  // Period
  period: '2026-06',
  periodMode: 'month', // month | quarter | custom
  fiscalYear: 2026,

  // Navigation
  tab: 'overview',
  previousTab: null,

  // Data cache (per tab)
  data: {
    overview: null,
    transactions: null,
    invoices: null,
    vat: null,
    payroll: null,
    period: null,
    tasks: null,
    forecast: null,
  },

  // UI-state
  filters: {
    transactions: { search: '', status: 'all', account: '' },
    invoices: { status: 'all' },
  },

  // Onboarding
  onboarding: {
    completed: false,
    step: 0,
    profile: null,
  },

  // Användare
  user: null,
  tenant: 'landvex',

  // Loading
  loading: new Set(),

  // Errors
  lastError: null,
};

const listeners = new Set();

export const state = {
  get: () => ({ ...S }),

  set: (patch) => {
    Object.assign(S, patch);
    listeners.forEach(fn => {
      try { fn(S); } catch (e) { console.error('[state] listener error:', e); }
    });
  },

  subscribe: (fn) => {
    listeners.add(fn);
    return () => listeners.delete(fn);
  },

  // Helpers
  setTab: (tab) => {
    S.previousTab = S.tab;
    S.tab = tab;
    listeners.forEach(fn => fn(S));
  },

  setPeriod: (period) => {
    S.period = period;
    // Rensa cache vid periodändring
    Object.keys(S.data).forEach(k => S.data[k] = null);
    listeners.forEach(fn => fn(S));
  },

  setLoading: (key, isLoading) => {
    if (isLoading) S.loading.add(key);
    else S.loading.delete(key);
    listeners.forEach(fn => fn(S));
  },

  setData: (key, data) => {
    S.data[key] = data;
    listeners.forEach(fn => fn(S));
  },

  setError: (error) => {
    S.lastError = error;
    listeners.forEach(fn => fn(S));
  },
};

// Persistens i localStorage
function loadFromStorage() {
  try {
    const raw = localStorage.getItem('landvex:state');
    if (raw) {
      const saved = JSON.parse(raw);
      Object.assign(S, {
        period: saved.period || S.period,
        periodMode: saved.periodMode || S.periodMode,
        onboarding: saved.onboarding || S.onboarding,
      });
    }
  } catch { /* ignore */ }
}

function saveToStorage() {
  try {
    localStorage.setItem('landvex:state', JSON.stringify({
      period: S.period,
      periodMode: S.periodMode,
      onboarding: S.onboarding,
    }));
  } catch { /* ignore */ }
}

// Auto-save vid ändringar
state.subscribe(() => saveToStorage());

// Init
loadFromStorage();

export default state;