function togglePromoFields(purpose) {
    var discountFields = document.getElementById('discount-fields');
    var trialFields = document.getElementById('trial-fields');
    var codeInput = document.getElementById('pc-code');
    if (purpose === 'discount') {
        discountFields.classList.remove('is-hidden');
        trialFields.classList.remove('is-visible');
        codeInput.required = true;
        codeInput.placeholder = 'e.g. LAUNCH50';
    } else if (purpose === 'free_trial') {
        discountFields.classList.add('is-hidden');
        trialFields.classList.add('is-visible');
        codeInput.required = true;
        codeInput.placeholder = 'e.g. TRIAL14';
    } else {
        discountFields.classList.add('is-hidden');
        trialFields.classList.remove('is-visible');
        codeInput.required = false;
        codeInput.placeholder = 'Auto-generated';
    }
}

/// Show a modal listing redemptions of a single promo code. Fetched on
/// demand so the page-render path doesn't pay for it. Guest checkouts
/// surface as the guest's email; missing item titles render as "—".
function showPromoRedemptions(codeId, codeLabel) {
    var existing = document.getElementById('promo-redemptions-modal');
    if (existing) existing.remove();

    var overlay = document.createElement('div');
    overlay.id = 'promo-redemptions-modal';
    overlay.className = 'modal-overlay';
    overlay.style.display = 'flex';
    overlay.onclick = function (e) { if (e.target === overlay) overlay.remove(); };

    var content = document.createElement('div');
    content.className = 'modal-content';
    content.style.maxWidth = '640px';
    content.style.padding = '2rem';
    content.innerHTML =
        '<div class="modal-header" style="margin-bottom: 1rem;">'
        + '<h2>Redemptions: <code>' + escapeHtml(codeLabel) + '</code></h2>'
        + '<button type="button" class="modal-close" aria-label="Dismiss">&times;</button>'
        + '</div>'
        + '<div id="promo-redemptions-body" class="muted">Loading…</div>';
    // Wire the close button via JS, not an inline onclick — the app CSP has no
    // script-src 'unsafe-inline', so a generated inline handler is dead (Run 20).
    var closeBtn = content.querySelector('.modal-close');
    if (closeBtn) closeBtn.onclick = function () { overlay.remove(); };
    overlay.appendChild(content);
    document.body.appendChild(overlay);

    fetch('/api/promo-codes/' + codeId + '/redemptions', { credentials: 'same-origin' })
        .then(function (r) { return r.ok ? r.json() : Promise.reject(r.status); })
        .then(function (data) {
            var body = document.getElementById('promo-redemptions-body');
            if (!body) return;
            var rows = (data && data.redemptions) || [];
            if (rows.length === 0) {
                body.textContent = 'No redemptions yet.';
                return;
            }
            var html = '<table class="data-table" style="width:100%; font-size: 0.9rem;">'
                + '<thead><tr><th>When</th><th>Who</th><th>Item</th><th>Paid</th></tr></thead><tbody>';
            for (var i = 0; i < rows.length; i++) {
                var r = rows[i];
                var when = new Date(r.redeemed_at).toLocaleDateString();
                var who = r.username
                    ? '@' + escapeHtml(r.username)
                    : (r.guest_email ? escapeHtml(r.guest_email) + ' (guest)' : '—');
                var item = r.item_title ? escapeHtml(r.item_title) : '—';
                var paid = r.amount_cents === 0 ? 'Free' : '$' + (r.amount_cents / 100).toFixed(2);
                html += '<tr><td>' + when + '</td><td>' + who + '</td><td>' + item + '</td><td>' + paid + '</td></tr>';
            }
            html += '</tbody></table>';
            if (rows.length === 500) {
                html += '<p class="muted" style="margin-top: 0.75rem;">Showing the 500 most recent redemptions.</p>';
            }
            body.innerHTML = html;
        })
        .catch(function () {
            var body = document.getElementById('promo-redemptions-body');
            if (body) body.textContent = 'Could not load redemptions.';
        });
}


/// Switch between preset trial lengths and a custom number input. The
/// hidden #pc-trial-days carries the actual submitted value so we can keep
/// the server-side contract (a single `trial_days` field) untouched.
function onTrialPresetChange() {
    var preset = document.getElementById('pc-trial-preset');
    var hidden = document.getElementById('pc-trial-days');
    var custom = document.getElementById('pc-trial-days-custom');
    if (preset.value === 'custom') {
        custom.hidden = false;
        custom.required = true;
        custom.focus();
        hidden.value = custom.value || '';
    } else {
        custom.hidden = true;
        custom.required = false;
        hidden.value = preset.value;
    }
}