(() => {
  const root = document.getElementById('fx-rates-app');
  if (!root) {
    return;
  }

  const page = JSON.parse(root.dataset.page || '{}');
  const settings = page.settings || {};
  const nodes = {
    message: root.querySelector('[data-bind="message"]'),
    lastFetch: root.querySelector('[data-bind="last-fetch"]'),
    defaultBase: root.querySelector('[data-bind="default-base"]'),
    displayBase: root.querySelector('[data-bind="display-base"]'),
    ratesBody: root.querySelector('[data-bind="rates-body"]'),
    defaultBaseInput: root.querySelector('input[name="default_base_currency"]'),
    displayBaseInput: root.querySelector('input[name="display_base_currency"]'),
    preferredCurrenciesInput: root.querySelector('input[name="preferred_currencies"]'),
  };
  const apiBase = '/api/fx-rates/v1';

  const setMessage = (text, type = '') => {
    if (!nodes.message) {
      return;
    }
    nodes.message.textContent = text || '';
    nodes.message.className = `fx-message${type ? ` is-${type}` : ''}`;
  };

  const setLoading = (state) => {
    root.querySelectorAll('button[data-action]').forEach((button) => {
      button.disabled = state;
    });
  };

  const parsePreferredCurrencies = () => String(nodes.preferredCurrenciesInput?.value || '')
    .split(/[\s,;]+/)
    .map((item) => item.trim().toUpperCase())
    .filter(Boolean);

  const renderSnapshot = (snapshot) => {
    const rates = snapshot && snapshot.rates ? snapshot.rates : null;
    const entries = rates ? Object.entries(rates) : [];
    if (!nodes.ratesBody) {
      return;
    }

    if (!entries.length) {
      nodes.ratesBody.innerHTML = '<tr><td colspan="2">Noch keine Wechselkurse fuer die ausgewaehlten Waehrungen gespeichert.</td></tr>';
      return;
    }

    nodes.ratesBody.innerHTML = entries.map(([code, rate]) => {
      const formatted = typeof rate === 'number'
        ? rate.toLocaleString('de-DE', { maximumFractionDigits: 8 })
        : 'n/a';
      return `<tr><td>${code}</td><td>${formatted}</td></tr>`;
    }).join('');
  };

  const request = async (path, options = {}) => {
    const response = await fetch(`${apiBase}${path}`, {
      credentials: 'same-origin',
      headers: {
        Accept: 'application/json',
        ...(options.body ? { 'Content-Type': 'application/json' } : {}),
        ...(options.headers || {}),
      },
      ...options,
    });
    const payload = await response.json().catch(() => ({}));
    if (!response.ok) {
      throw new Error(payload?.context?.message || payload?.error || `HTTP ${response.status}`);
    }
    return payload.data;
  };

  const loadLatest = async () => {
    const base = String(
      nodes.displayBaseInput?.value || settings.display_base_currency || settings.default_base_currency || 'EUR'
    ).trim().toUpperCase();
    const preferred = parsePreferredCurrencies();
    const query = new URLSearchParams();
    query.set('base', base);
    if (preferred.length) {
      query.set('symbols', preferred.join(','));
    }

    const data = await request(`/latest?${query.toString()}`);
    renderSnapshot(data);
    if (nodes.lastFetch) {
      nodes.lastFetch.textContent = data?.fetched_at || 'noch keiner';
    }
    if (nodes.displayBase) {
      nodes.displayBase.textContent = base;
    }
    return data;
  };

  root.querySelector('[data-action="refresh-rates"]')?.addEventListener('click', async () => {
    try {
      setLoading(true);
      setMessage('Ich rufe jetzt die aktuellen Kurse ab.');
      const payload = {
        force: true,
        base: String(nodes.defaultBaseInput?.value || settings.default_base_currency || 'EUR').trim().toUpperCase(),
        currencies: parsePreferredCurrencies(),
      };
      const data = await request('/refresh', { method: 'POST', body: JSON.stringify(payload) });
      setMessage(`Aktuelle Kurse gespeichert. ${data?.updated_count || 0} Werte aktualisiert.`, 'success');
      await loadLatest();
    } catch (error) {
      setMessage(error.message || 'Kurse konnten nicht aktualisiert werden.', 'error');
    } finally {
      setLoading(false);
    }
  });

  root.querySelector('[data-action="save-settings"]')?.addEventListener('click', async () => {
    try {
      setLoading(true);
      setMessage('Ich speichere jetzt die Waehrungs-Auswahl.');
      const payload = {
        default_base_currency: String(nodes.defaultBaseInput?.value || '').trim().toUpperCase(),
        display_base_currency: String(nodes.displayBaseInput?.value || '').trim().toUpperCase(),
        preferred_currencies: parsePreferredCurrencies(),
      };
      const data = await request('/settings', { method: 'PUT', body: JSON.stringify(payload) });
      if (nodes.defaultBase) {
        nodes.defaultBase.textContent = data?.default_base_currency || '';
      }
      if (nodes.displayBase) {
        nodes.displayBase.textContent = data?.display_base_currency || '';
      }
      setMessage('Waehrungs-Auswahl gespeichert.', 'success');
      await loadLatest();
    } catch (error) {
      setMessage(error.message || 'Waehrungs-Auswahl konnte nicht gespeichert werden.', 'error');
    } finally {
      setLoading(false);
    }
  });

  loadLatest().catch((error) => {
    setMessage(error.message || 'Letzter Snapshot konnte nicht geladen werden.', 'error');
  });
})();