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

  const page = JSON.parse(root.dataset.page || '{}');
  const settings = page.settings || {};
  const nodes = {
    ratesBody: root.querySelector('[data-bind="rates-body"]'),
    historyHead: root.querySelector('[data-bind="history-head"]'),
    historyBody: root.querySelector('[data-bind="history-body"]'),
    fetchesBody: root.querySelector('[data-bind="fetches-body"]'),
    convertResult: root.querySelector('[data-bind="convert-result"]'),
    convertFrom: root.querySelector('select[name="convert_from"]'),
    convertTo: root.querySelector('select[name="convert_to"]'),
    convertAmount: root.querySelector('input[name="convert_amount"]'),
  };
  const apiBase = '/api/fx-rates/v1';
  const preferredCurrencies = Array.isArray(page.preferred_currencies)
    ? page.preferred_currencies
      .map((item) => String(item || '').trim().toUpperCase())
      .filter(Boolean)
    : [];

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

    const filteredEntries = visibleCurrencies
      ? entries.filter(([code]) => visibleCurrencies.has(String(code || '').trim().toUpperCase()))
      : entries;

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

    nodes.ratesBody.innerHTML = filteredEntries.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 renderFetches = (fetches) => {
    if (!nodes.fetchesBody) {
      return;
    }
    const entries = Array.isArray(fetches) ? fetches : [];
    if (!entries.length) {
      nodes.fetchesBody.innerHTML = '<tr><td colspan="3">Noch keine Abrufe vorhanden.</td></tr>';
      return;
    }
    nodes.fetchesBody.innerHTML = entries.map((entry) => `
      <tr>
        <td>${entry?.fetched_at_display || entry?.fetched_at || ''}</td>
        <td>${entry?.base_currency || ''}</td>
        <td>${entry?.provider || ''}</td>
      </tr>
    `).join('');
  };

  const renderHistory = (rows, currencies) => {
    if (!nodes.historyHead || !nodes.historyBody) {
      return;
    }

    const series = Array.isArray(currencies) ? currencies : [];
    if (!series.length) {
      nodes.historyHead.innerHTML = '<tr><th>Datum</th><th>Kurse</th></tr>';
      nodes.historyBody.innerHTML = '<tr><td colspan="2">Keine bevorzugten Waehrungen fuer den Verlauf vorhanden.</td></tr>';
      return;
    }

    nodes.historyHead.innerHTML = `
      <tr>
        <th>Datum</th>
        ${series.map((currency) => `<th>${currency}</th>`).join('')}
      </tr>
    `;

    const entries = Array.isArray(rows) ? rows : [];
    if (!entries.length) {
      nodes.historyBody.innerHTML = `<tr><td colspan="${series.length + 1}">Noch keine Verlaufsdaten vorhanden.</td></tr>`;
      return;
    }

    nodes.historyBody.innerHTML = entries.map((entry) => `
      <tr>
        <td>${entry.label}</td>
        ${series.map((currency) => {
          const value = entry.rates?.[currency];
          if (typeof value !== 'number' || !Number.isFinite(value)) {
            return '<td>–</td>';
          }
          return `<td>${value.toLocaleString('de-DE', { maximumFractionDigits: 8 })}</td>`;
        }).join('')}
      </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(
      settings.display_base_currency || settings.default_base_currency || 'EUR'
    ).trim().toUpperCase();
    const query = new URLSearchParams();
    query.set('base', base);
    if (preferredCurrencies.length) {
      query.set('symbols', preferredCurrencies.join(','));
    }

    const data = await request(`/latest?${query.toString()}`);
    renderSnapshot(data);
    return data;
  };

  const loadHistory = async () => {
    const base = String(
      settings.display_base_currency || settings.default_base_currency || 'EUR'
    ).trim().toUpperCase();
    const historyCurrencies = preferredCurrencies.filter((currency) => currency !== base);

    if (!historyCurrencies.length) {
      renderHistory([], []);
      return;
    }

    const histories = await Promise.all(historyCurrencies.map(async (currency) => {
      const query = new URLSearchParams({ from: base, to: currency, limit: '20' });
      const rows = await request(`/history?${query.toString()}`);
      return { currency, rows: Array.isArray(rows) ? rows : [] };
    }));

    const byDate = new Map();
    histories.forEach(({ currency, rows }) => {
      rows.forEach((row) => {
        const key = String(row?.fetched_at || row?.rate_date || '').trim();
        if (!key) {
          return;
        }
        if (!byDate.has(key)) {
          byDate.set(key, {
            sortKey: key,
            label: row?.fetched_at_display || row?.fetched_at || row?.rate_date || key,
            rates: {},
          });
        }
        const entry = byDate.get(key);
        if (entry && typeof row?.rate === 'number' && Number.isFinite(row.rate)) {
          entry.rates[currency] = row.rate;
        }
      });
    });

    const mergedRows = Array.from(byDate.values())
      .sort((left, right) => String(left.sortKey).localeCompare(String(right.sortKey)));

    renderHistory(mergedRows, historyCurrencies);
  };

  const calculateConversion = async () => {
    if (!nodes.convertFrom || !nodes.convertTo || !nodes.convertAmount || !nodes.convertResult) {
      return;
    }

    const from = String(nodes.convertFrom.value || '').trim().toUpperCase();
    const to = String(nodes.convertTo.value || '').trim().toUpperCase();
    const amount = Number(nodes.convertAmount.value || '0');

    if (!from || !to || !Number.isFinite(amount)) {
      nodes.convertResult.textContent = 'Bitte Quellwaehrung, Zielwaehrung und Betrag angeben.';
      return;
    }

    if (from === to) {
      nodes.convertResult.textContent = `${amount.toLocaleString('de-DE', { maximumFractionDigits: 8 })} ${from} = ${amount.toLocaleString('de-DE', { maximumFractionDigits: 8 })} ${to}`;
      return;
    }

    try {
      const query = new URLSearchParams({ from, to });
      const data = await request(`/rate?${query.toString()}`);
      const rate = Number(data?.rate || 0);
      if (!Number.isFinite(rate) || rate <= 0) {
        throw new Error('Kein Kurs verfuegbar.');
      }
      const converted = amount * rate;
      nodes.convertResult.textContent = `${amount.toLocaleString('de-DE', { maximumFractionDigits: 8 })} ${from} = ${converted.toLocaleString('de-DE', { maximumFractionDigits: 8 })} ${to} | Kurs ${rate.toLocaleString('de-DE', { maximumFractionDigits: 8 })}`;
    } catch (error) {
      nodes.convertResult.textContent = error.message || 'Umrechnung konnte nicht berechnet werden.';
    }
  };

  [nodes.convertFrom, nodes.convertTo, nodes.convertAmount].forEach((node) => {
    node?.addEventListener('change', () => {
      calculateConversion().catch(() => {});
    });
    node?.addEventListener('input', () => {
      calculateConversion().catch(() => {});
    });
  });

  renderFetches(page.recent_fetches || []);

  loadLatest().catch(() => {});
  loadHistory().catch(() => {
    renderHistory([], preferredCurrencies.filter((currency) => currency !== String(
      settings.display_base_currency || settings.default_base_currency || 'EUR'
    ).trim().toUpperCase()));
  });
  calculateConversion().catch(() => {});
})();