/* ── Tracker page ── */

const TrackerPage = (() => {
  let currentYear, currentMonth;
  let trackerData = null;

  const MONTH_NAMES = [
    'January','February','March','April','May','June',
    'July','August','September','October','November','December',
  ];

  const STATUS_META = {
    paid:      { label: 'Paid',       cls: 'badge-paid' },
    upcoming:  { label: 'Upcoming',   cls: 'badge-upcoming' },
    due_soon:  { label: 'Due Soon',   cls: 'badge-due-soon' },
    late:      { label: 'Late',       cls: 'badge-late' },
    missed:    { label: 'Missed',     cls: 'badge-missed' },
    autodraft: { label: 'Autodraft',  cls: 'badge-autodraft' },
  };

  function fmt(amount) {
    return '$' + Number(amount || 0).toFixed(2).replace(/\B(?=(\d{3})+(?!\d))/g, ',');
  }

  function fmtDate(dateStr) {
    if (!dateStr) return '';
    const [y, m, d] = dateStr.split('-');
    return `${parseInt(m)}/${parseInt(d)}/${y}`;
  }

  function todayStr() {
    return new Date().toISOString().slice(0, 10);
  }

  function init(container) {
    const now = new Date();
    currentYear  = now.getFullYear();
    currentMonth = now.getMonth() + 1;
    render(container);
  }

  function render(container) {
    container.innerHTML = `
      <div class="page-header">
        <h1 class="page-title">Tracker</h1>
        <div class="month-nav">
          <button class="btn btn-ghost btn-sm" id="prev-month">&#8592;</button>
          <span class="month-label" id="month-label"></span>
          <button class="btn btn-ghost btn-sm" id="next-month">&#8594;</button>
          <button class="btn btn-ghost btn-sm" id="today-btn">Today</button>
        </div>
      </div>
      <div class="summary-bar" id="summary-bar"></div>
      <div id="tracker-body"><div class="loading">Loading...</div></div>
    `;

    document.getElementById('month-label').textContent =
      `${MONTH_NAMES[currentMonth - 1]} ${currentYear}`;

    document.getElementById('prev-month').onclick = () => navigate(-1, container);
    document.getElementById('next-month').onclick = () => navigate(1, container);
    document.getElementById('today-btn').onclick  = () => {
      const now = new Date();
      currentYear = now.getFullYear();
      currentMonth = now.getMonth() + 1;
      loadData(container);
    };

    loadData(container);
  }

  function navigate(delta, container) {
    currentMonth += delta;
    if (currentMonth > 12) { currentMonth = 1; currentYear++; }
    if (currentMonth < 1)  { currentMonth = 12; currentYear--; }
    document.getElementById('month-label').textContent =
      `${MONTH_NAMES[currentMonth - 1]} ${currentYear}`;
    loadData(container);
  }

  async function loadData(container) {
    document.getElementById('tracker-body').innerHTML = '<div class="loading">Loading...</div>';
    try {
      trackerData = await API.tracker(currentYear, currentMonth);
      renderSummary(trackerData.summary);
      renderRows(trackerData.rows, container);
    } catch (e) {
      document.getElementById('tracker-body').innerHTML =
        `<div class="empty-state"><p>Failed to load tracker: ${e.message}</p></div>`;
    }
  }

  function renderSummary(s) {
    document.getElementById('summary-bar').innerHTML = `
      <div class="summary-card">
        <div class="label">Total Expected</div>
        <div class="value">${fmt(s.total_expected)}</div>
      </div>
      <div class="summary-card success">
        <div class="label">Total Paid</div>
        <div class="value">${fmt(s.total_paid)}</div>
      </div>
      <div class="summary-card">
        <div class="label">Remaining</div>
        <div class="value">${fmt(s.remaining)}</div>
      </div>
      <div class="summary-card ${s.overdue > 0 ? 'danger' : ''}">
        <div class="label">Overdue</div>
        <div class="value">${fmt(s.overdue)}</div>
      </div>
    `;
  }

  function renderRows(rows, container) {
    const body = document.getElementById('tracker-body');
    if (!rows || rows.length === 0) {
      body.innerHTML = `<div class="empty-state">
        <p>No bills this month. <a href="#bills" class="btn-link">Add a bill</a></p>
      </div>`;
      return;
    }

    const first  = rows.filter(r => r.bucket === '1st');
    const second = rows.filter(r => r.bucket === '15th');

    body.innerHTML = '';
    if (first.length)  body.appendChild(renderBucket('1st–14th', first));
    if (second.length) body.appendChild(renderBucket('15th–31st', second));

    // Attach event listeners after render
    attachTableListeners(container);
  }

  function renderBucket(label, rows) {
    const totalExpected = rows.reduce((s, r) => s + r.expected_amount, 0);
    const totalPaid     = rows.reduce((s, r) => s + r.total_paid, 0);

    const section = document.createElement('div');
    section.className = 'bucket-section';
    section.innerHTML = `
      <div class="bucket-header">
        <span class="bucket-label">${label}</span>
        <span class="bucket-totals">${fmt(totalPaid)} / ${fmt(totalExpected)}</span>
      </div>
      <table class="tracker-table">
        <thead>
          <tr>
            <th>Bill</th>
            <th>Due</th>
            <th>Expected</th>
            <th>Amount Paid</th>
            <th>Paid Date</th>
            <th>Status</th>
            <th></th>
          </tr>
        </thead>
        <tbody>
          ${rows.map(renderRow).join('')}
        </tbody>
      </table>
    `;
    return section;
  }

  function renderRow(row) {
    const meta = STATUS_META[row.status] || STATUS_META.upcoming;
    const rowCls = `row-${row.status}`;

    const paidDate  = row.last_paid_date ? fmtDate(row.last_paid_date) : '';
    const paidAmt   = row.total_paid > 0 ? fmt(row.total_paid) : '';
    const mismatch  = row.total_paid > 0 && row.total_paid !== row.expected_amount;
    const isPaid    = row.status === 'paid' || row.status === 'autodraft';

    const autopayDot = row.autopay_enabled
      ? `<span class="autopay-dot" title="Autopay"></span>`
      : '';

    return `
      <tr class="${rowCls}" data-bill-id="${row.id}">
        <td>
          <div class="td-inner bill-name-cell">
            ${autopayDot}
            <div>
              <div>${escHtml(row.name)}</div>
              ${row.category_name ? `<div class="bill-category">${escHtml(row.category_name)}</div>` : ''}
            </div>
          </div>
        </td>
        <td>
          <div class="td-inner">${fmtDate(row.due_date)}</div>
        </td>
        <td>
          <div class="td-inner amount-expected">${fmt(row.expected_amount)}</div>
        </td>
        <td>
          <div class="td-inner">
            <span class="editable-cell amount-cell ${paidAmt ? '' : 'empty'} ${mismatch ? 'amount-mismatch' : ''}"
              data-bill-id="${row.id}" data-field="amount"
              title="Click to edit payment amount">
              ${paidAmt || '—'}
            </span>
          </div>
        </td>
        <td>
          <div class="td-inner">
            <span class="editable-cell date-cell ${paidDate ? '' : 'empty'}"
              data-bill-id="${row.id}" data-field="date"
              title="Click to edit paid date">
              ${paidDate || '—'}
            </span>
          </div>
        </td>
        <td>
          <div class="td-inner">
            <span class="badge ${meta.cls}">${meta.label}</span>
          </div>
        </td>
        <td>
          <div class="action-cell">
            ${!isPaid ? `
              <div class="quick-pay-group">
                <input type="number" class="quick-pay-amount" min="0" step="0.01"
                  value="${row.expected_amount}"
                  data-bill-id="${row.id}"
                  title="Payment amount">
                <button class="btn-pay btn-quick-pay" data-bill-id="${row.id}"
                  title="Mark paid today">Pay</button>
              </div>` : ''}
            ${row.payments && row.payments.length > 0
              ? `<button class="btn-icon btn-edit-payment"
                    data-bill-id="${row.id}"
                    data-payment='${JSON.stringify(row.payments[0])}'
                    title="Edit payment">&#9998;</button>`
              : ''}
          </div>
        </td>
      </tr>
    `;
  }

  function attachTableListeners(container) {
    // Quick pay buttons — read amount from the sibling input
    container.querySelectorAll('.btn-quick-pay').forEach(btn => {
      btn.onclick = async (e) => {
        e.stopPropagation();
        const billId = btn.dataset.billId;
        const amtInput = btn.closest('.quick-pay-group')?.querySelector('.quick-pay-amount');
        const amount   = amtInput ? parseFloat(amtInput.value) || 0 : 0;
        if (amount <= 0) { showToast('Enter a payment amount', 'error'); return; }
        btn.disabled = true;
        try {
          await API.quickPay({ bill_id: billId, amount, paid_date: todayStr() });
          showToast('Marked as paid', 'success');
          loadData(container);
        } catch (err) {
          showToast('Error: ' + err.message, 'error');
          btn.disabled = false;
        }
      };
    });

    // Edit payment buttons
    container.querySelectorAll('.btn-edit-payment').forEach(btn => {
      btn.onclick = (e) => {
        e.stopPropagation();
        const payment = JSON.parse(btn.dataset.payment);
        openPaymentModal(payment, () => loadData(container));
      };
    });

    // Inline editable amount cells
    container.querySelectorAll('.amount-cell').forEach(cell => {
      cell.onclick = () => startInlineEdit(cell, 'number', container);
    });

    // Inline editable date cells
    container.querySelectorAll('.date-cell').forEach(cell => {
      cell.onclick = () => startInlineEdit(cell, 'date', container);
    });
  }

  function startInlineEdit(cell, type, container) {
    if (cell.querySelector('input')) return; // already editing

    const billId = cell.dataset.billId;
    const field  = cell.dataset.field;
    const row    = trackerData?.rows?.find(r => r.id == billId);
    if (!row) return;

    let currentVal = '';
    if (field === 'amount') currentVal = row.total_paid > 0 ? String(row.total_paid) : '';
    if (field === 'date')   currentVal = row.last_paid_date || '';

    const input = document.createElement('input');
    input.type  = type === 'date' ? 'date' : 'number';
    if (type === 'number') { input.step = '0.01'; input.min = '0'; }
    input.value = currentVal;
    input.style.cssText = 'width:100%;min-width:80px;';

    const origText = cell.textContent.trim();
    cell.textContent = '';
    cell.appendChild(input);
    cell.classList.remove('empty');
    input.focus();
    input.select();

    async function commit() {
      const val = input.value.trim();
      if (!val) { cell.textContent = origText || '—'; cell.classList.add('empty'); return; }

      try {
        if (row.payments && row.payments.length > 0) {
          const p = row.payments[0];
          const update = {};
          if (field === 'amount') update.amount   = parseFloat(val);
          if (field === 'date')   update.paid_date = val;
          await API.updatePayment(p.id, update);
        } else {
          // Create new payment
          const paidDate = field === 'date' ? val : todayStr();
          const amount   = field === 'amount' ? parseFloat(val) : row.expected_amount;
          await API.createPayment({ bill_id: billId, amount, paid_date: paidDate });
        }
        showToast('Saved', 'success');
        loadData(container);
      } catch (err) {
        showToast('Error: ' + err.message, 'error');
        cell.textContent = origText || '—';
      }
    }

    input.addEventListener('blur', commit);
    input.addEventListener('keydown', e => {
      if (e.key === 'Enter') input.blur();
      if (e.key === 'Escape') {
        cell.textContent = origText || '—';
        if (!origText) cell.classList.add('empty');
      }
    });
  }

function openPaymentModal(payment, onSave) {
  const modal = document.getElementById('payment-modal');

  document.getElementById('payment-bill-id').value = payment.bill_id;
  document.getElementById('payment-id').value     = payment.id;
  document.getElementById('payment-amount').value = payment.amount;
  document.getElementById('payment-date').value   = payment.paid_date;
  document.getElementById('payment-method').value = payment.method || '';
  document.getElementById('payment-notes').value  = payment.notes || '';

  document.getElementById('payment-modal-title').textContent = 'Edit Payment';

  modal.classList.remove('hidden');

  const close = () => modal.classList.add('hidden');

  document.getElementById('payment-modal-close').onclick  = close;
  document.getElementById('payment-modal-cancel').onclick = close;
  modal.querySelector('.modal-overlay').onclick = close;

  // ✅ UPDATED DELETE LOGIC WITH CLEAR INTENT
  document.getElementById('payment-delete').onclick = async () => {
    const confirmDelete = confirm(
      'Remove this payment?\n\n' +
      '- The BILL will NOT be deleted\n' +
      '- This will remove the payment record\n' +
      '- The bill will become UNPAID\n\n' +
      'Continue?'
    );

    if (!confirmDelete) return;

    try {
      await API.deletePayment(payment.id);

      close();

      showToast(
        'Payment removed. Bill is now marked as unpaid.',
        'success'
      );

      onSave(); // refresh tracker

    } catch (e) {
      showToast('Error: ' + e.message, 'error');
    }
  };

  // normal save logic untouched
  document.getElementById('payment-form').onsubmit = async (e) => {
    e.preventDefault();

    const data = {
      amount:    parseFloat(document.getElementById('payment-amount').value),
      paid_date: document.getElementById('payment-date').value,
      method:    document.getElementById('payment-method').value || null,
      notes:     document.getElementById('payment-notes').value  || null,
    };

    try {
      await API.updatePayment(payment.id, data);

      close();
      showToast('Payment saved', 'success');
      onSave();

    } catch (err) {
      showToast('Error: ' + err.message, 'error');
    }
  };
}

  function escHtml(str) {
    return String(str || '')
      .replace(/&/g, '&amp;')
      .replace(/</g, '&lt;')
      .replace(/>/g, '&gt;')
      .replace(/"/g, '&quot;');
  }

  return { init };
})();