const fs = require('fs');
const prisma = require('../config/db');
const { sendMail, emailWrapper, ctaButton, fallbackLink, divider, callout, paymentOption } = require('./email');
const { computeRegistrationTotalDue, computeOptionLineTotal } = require('./pricing');

// ─── Formatting helpers ───────────────────────────────────────────────────────

const ff = `-apple-system,BlinkMacSystemFont,'Segoe UI',Roboto,Helvetica,Arial,sans-serif`;

function fmtAmount(amt) {
  const n = Number(amt || 0);
  return `R${n.toFixed(2)}`;
}

function fmtDate(d) {
  try { return new Date(d).toLocaleString('en-GB', { day: 'numeric', month: 'short', year: 'numeric', hour: '2-digit', minute: '2-digit' }); } catch { return String(d); }
}

function fmtDateShort(d) {
  try { return new Date(d).toLocaleDateString('en-GB', { weekday: 'long', day: 'numeric', month: 'long', year: 'numeric' }); } catch { return String(d); }
}

const { getSettingSync } = require('./settingsCache');

function getOrg() {
  return {
    name:  getSettingSync('org_name', process.env.ORG_NAME || 'Cross Code'),
    email: process.env.EMAIL_FROM || process.env.EMAIL_USER || '',
    url:   (process.env.FRONTEND_URL || process.env.APP_BASE_URL || 'http://localhost:3001').replace(/\/$/, ''),
  };
}

function getRegistrationsInbox() {
  // Supports comma-separated list; return the first address for single-recipient use
  const raw = getSettingSync('reg_notification_emails', process.env.REGISTRATIONS_EMAIL || '');
  return raw.split(',')[0].trim() || '';
}

function getRegistrationsInboxAll() {
  // Returns the full comma-separated string for multi-recipient sends
  return getSettingSync('reg_notification_emails', process.env.REGISTRATIONS_EMAIL || '');
}

/**
 * Resolves who should receive registration/payment/daily-summary notices for an event:
 * the event's configured `notifyRecipients`, or the event creator when none are set.
 */
function getEventNotifyEmails(event) {
  const recipients = Array.isArray(event?.notifyRecipients) ? event.notifyRecipients : [];
  const emails = recipients.map(u => u?.email).filter(Boolean);
  if (emails.length) return emails;
  return event?.createdBy?.email ? [event.createdBy.email] : [];
}

/**
 * Builds the deduplicated admin "to" list for an event notification: the global
 * registrations inbox plus that event's notify recipients (or its creator as fallback).
 */
function buildEventNotifyRecipientList(event) {
  const inbox = getRegistrationsInbox();
  const seen = new Set();
  const to = [];
  if (inbox) { seen.add(inbox); to.push(inbox); }
  for (const email of getEventNotifyEmails(event)) {
    if (!seen.has(email)) { seen.add(email); to.push(email); }
  }
  return to;
}

// ─── Data loaders ─────────────────────────────────────────────────────────────

async function loadRegistrationFull(registrationId) {
  return prisma.registration.findUnique({
    where: { id: registrationId },
    include: {
      registrationOptions: { include: { eventOption: { include: { earlyBirdTiers: true } }, variant: true, tranches: true } },
      payments: true,
      user: { select: { id: true, name: true, email: true, phoneNumber: true, isActive: true, notificationPreference: true } },
      event: { include: { createdBy: { select: { id: true, name: true, email: true } }, notifyRecipients: { select: { id: true, name: true, email: true } } } },
    },
  });
}

async function loadTicketFull(ticketId) {
  return prisma.ticket.findUnique({
    where: { id: ticketId },
    include: {
      user: { select: { id: true, name: true, email: true, phoneNumber: true, notificationPreference: true } },
      event: true,
      registrationOption: { include: { eventOption: true, variant: true } },
    },
  });
}

async function loadPaymentFull(paymentId) {
  return prisma.payment.findUnique({
    where: { id: paymentId },
    include: {
      user: { select: { id: true, name: true, email: true, phoneNumber: true, notificationPreference: true } },
      registration: {
        include: {
          registrationOptions: { include: { eventOption: { include: { earlyBirdTiers: true } }, variant: true, tranches: true } },
          payments: true,
          user: { select: { id: true, name: true, email: true, phoneNumber: true, isActive: true, notificationPreference: true } },
          event: { include: { createdBy: { select: { id: true, name: true, email: true } }, notifyRecipients: { select: { id: true, name: true, email: true } } } },
        },
      },
      event: { include: { createdBy: { select: { id: true, name: true, email: true } }, notifyRecipients: { select: { id: true, name: true, email: true } } } },
    },
  });
}

// ─── Shared building blocks ───────────────────────────────────────────────────

/** Renders the selections summary table. */
function selectionsTable(registrationOptions) {
  const rows = (registrationOptions || []).map(ro => {
    const name = ro.eventOption?.name || 'Option';
    const qty = ro.quantity || 1;
    const lineTotal = computeOptionLineTotal(ro, null, new Date());
    return `<tr>
      <td style="padding:10px 16px 10px 0;font-size:14px;color:#374151;font-family:${ff};border-bottom:1px solid #f1f5f9">${name}</td>
      <td style="padding:10px 0;font-size:14px;color:#374151;text-align:center;font-family:${ff};border-bottom:1px solid #f1f5f9">×${qty}</td>
      <td style="padding:10px 0 10px 16px;font-size:14px;color:#374151;text-align:right;font-weight:500;font-family:${ff};border-bottom:1px solid #f1f5f9">${fmtAmount(lineTotal)}</td>
    </tr>`;
  });

  if (!rows.length) return `<p style="color:#94a3b8;font-size:14px;margin:0">No items</p>`;

  return `<table role="presentation" width="100%" cellpadding="0" cellspacing="0" style="border:1px solid #e2e8f0;border-radius:8px;overflow:hidden;margin:0 0 4px 0">
    <tr style="background:#f8fafc">
      <th style="padding:10px 16px 10px 0;font-size:12px;font-weight:700;color:#64748b;text-align:left;text-transform:uppercase;letter-spacing:0.5px;font-family:${ff}">Item</th>
      <th style="padding:10px 0;font-size:12px;font-weight:700;color:#64748b;text-align:center;text-transform:uppercase;letter-spacing:0.5px;font-family:${ff}">Qty</th>
      <th style="padding:10px 0 10px 16px;font-size:12px;font-weight:700;color:#64748b;text-align:right;text-transform:uppercase;letter-spacing:0.5px;font-family:${ff}">Amount</th>
    </tr>
    ${rows.join('')}
  </table>`;
}

/** Renders a financial summary line. */
function financialSummary(totalDue, totalPaid, balance) {
  const ff2 = ff;
  return `<table role="presentation" width="100%" cellpadding="0" cellspacing="0" style="margin:16px 0 0 0">
    <tr>
      <td style="padding:6px 0;font-size:13px;color:#64748b;font-family:${ff2}">Total due</td>
      <td style="padding:6px 0;font-size:13px;color:#374151;text-align:right;font-weight:500;font-family:${ff2}">${fmtAmount(totalDue)}</td>
    </tr>
    <tr>
      <td style="padding:6px 0;font-size:13px;color:#64748b;font-family:${ff2}">Amount paid</td>
      <td style="padding:6px 0;font-size:13px;color:#374151;text-align:right;font-weight:500;font-family:${ff2}">${fmtAmount(totalPaid)}</td>
    </tr>
    <tr style="border-top:2px solid #e2e8f0">
      <td style="padding:10px 0 6px 0;font-size:15px;font-weight:800;color:#${balance <= 0 ? '059669' : '1e293b'};font-family:${ff2}">${balance <= 0 ? 'Fully paid' : 'Balance due'}</td>
      <td style="padding:10px 0 6px 0;font-size:15px;font-weight:800;color:#${balance <= 0 ? '059669' : '1e293b'};text-align:right;font-family:${ff2}">${fmtAmount(balance)}</td>
    </tr>
  </table>`;
}

/**
 * Renders the account CTA section at the bottom of user-facing registration emails.
 * isActive: true → Login prompt; false → Create account prompt.
 */
function accountCta(isActive, siteUrl) {
  if (isActive) {
    return `${divider()}
    <p style="font-size:14px;font-weight:700;color:#0f172a;margin:0 0 6px 0;font-family:${ff}">Manage your registration online</p>
    <p style="font-size:13px;color:#64748b;margin:0 0 16px 0;font-family:${ff}">
      Log in to your account to view your registration, make payments, and download your tickets.
    </p>
    ${ctaButton('Log in to your account', siteUrl + '/login', { bg: '#0f172a' })}`;
  }
  return `${divider()}
  <p style="font-size:14px;font-weight:700;color:#0f172a;margin:0 0 6px 0;font-family:${ff}">Create your account</p>
  <p style="font-size:13px;color:#64748b;margin:0 0 16px 0;font-family:${ff}">
    Create a free account to manage your registrations, make payments online, and access your tickets — all in one place.
  </p>
  ${ctaButton('Create your account', siteUrl + '/register', { bg: '#0f172a' })}`;
}

/**
 * Renders the payment options section for registration emails.
 * @param {{ balance, yocoLink, source, siteUrl, formRequired }}
 *   source: 'admin' (manual/self-service/at-door) | 'user' (self-register via website)
 */
function paymentSection({ balance, yocoLink, source, siteUrl, formRequired, isUserActive }) {
  if (balance <= 0 && !formRequired) {
    return callout(
      `<strong style="font-size:15px">🎟️ You\'re all set!</strong><br/>
       <span style="font-size:13px">No payment required. Your tickets have been sent in a separate email.</span>`,
      'success'
    );
  }

  if (balance <= 0 && formRequired) {
    return callout(
      `<strong>One more step — attendee form required</strong><br/>
       <span style="font-size:13px">This event requires an attendee information form before tickets can be issued. The form was presented during registration. If you haven't submitted it yet, please contact us.</span>`,
      'warning'
    );
  }

  // Balance due — build payment options
  const isAdmin = source === 'admin';
  let optNum = 1;
  const options = [];

  if (isAdmin && yocoLink) {
    options.push(paymentOption(
      optNum++,
      'Pay online now (quickest)',
      `<a href="${yocoLink}" style="color:#2563eb;font-weight:600;text-decoration:underline">${yocoLink}</a><br/>
       <span style="color:#94a3b8;font-style:italic">Already paid? You can safely ignore this option.</span>`
    ));
  }

  options.push(paymentOption(
    optNum++,
    `Pay via our website`,
    `Visit <a href="${siteUrl}" style="color:#2563eb">${siteUrl}</a> to pay online.${
      isUserActive === false
        ? `<br/><span style="color:#64748b">You'll need to create a free account to pay online.</span>`
        : isUserActive === true
        ? `<br/><span style="color:#64748b">Log in to access your registration and pay.</span>`
        : ''
    }`
  ));

  options.push(paymentOption(
    optNum++,
    'Pay at the door',
    'Cash and card accepted at the event entrance. No need to pre-pay — your registration is already confirmed.'
  ));

  return `<p style="font-size:16px;font-weight:700;color:#0f172a;margin:32px 0 8px 0;font-family:${ff}">How to pay</p>
  <p style="font-size:13px;color:#64748b;margin:0 0 16px 0;font-family:${ff}">Choose any of the following payment methods:</p>
  <table role="presentation" width="100%" cellpadding="0" cellspacing="0">${options.join('')}</table>
  <p style="font-size:13px;color:#64748b;margin:16px 0 0 0;font-family:${ff}">Your tickets will be emailed once your payment is confirmed.</p>`;
}

// ─── Registration confirmation (user self-registered via website) ──────────────

function buildRegistrationConfirmation(reg, { isNew = true } = {}) {
  const org = getOrg();
  const eventTitle = reg.event?.title || 'the event';
  const eventDate = reg.event?.startDate ? fmtDateShort(reg.event.startDate) : '';
  const totalDue = computeRegistrationTotalDue(reg, new Date());
  const totalPaid = (reg.payments || []).reduce((s, p) => s + (p.amount || 0), 0);
  const balance = Math.max(totalDue - totalPaid, 0);
  const isUserActive = reg.user?.isActive;

  const heading = isNew ? 'Registration confirmed!' : 'Registration updated';
  const subtext = isNew
    ? `Thank you for registering for <strong>${eventTitle}</strong>.`
    : `Your registration for <strong>${eventTitle}</strong> has been updated.`;
  const subject = isNew ? `Registration confirmed – ${eventTitle}` : `Registration updated – ${eventTitle}`;
  const preheader = isNew
    ? `You\'re registered for ${eventTitle}${eventDate ? ' on ' + eventDate : ''}!`
    : `Your registration for ${eventTitle} has been updated.`;

  const body = `
    <p style="font-size:22px;font-weight:800;color:#0f172a;margin:0 0 8px 0;letter-spacing:-0.3px">${heading}</p>
    <p style="font-size:14px;color:#64748b;margin:0 0 32px 0">${isNew ? 'Your spot is reserved' : 'Changes saved'}</p>

    <p style="margin:0 0 4px 0;color:#374151;font-family:${ff}">Hi <strong>${reg.user?.name || 'there'}</strong>,</p>
    <p style="margin:0 0 28px 0;color:#374151;font-family:${ff}">${subtext}${eventDate ? ` — <strong>${eventDate}</strong>` : ''}</p>

    <p style="font-size:16px;font-weight:700;color:#0f172a;margin:0 0 12px 0;font-family:${ff}">Your registration</p>
    ${selectionsTable(reg.registrationOptions)}
    ${financialSummary(totalDue, totalPaid, balance)}

    ${paymentSection({ balance, yocoLink: null, source: 'user', siteUrl: org.url, formRequired: false, isUserActive })}
    ${accountCta(isUserActive, org.url)}`;

  const itemsText = (reg.registrationOptions || []).map(ro => `  • ${ro.eventOption?.name || 'Option'} ×${ro.quantity} — ${fmtAmount(computeOptionLineTotal(ro, null, new Date()))}`).join('\n');
  const text = `${heading}\n\nHi ${reg.user?.name || 'there'},\n\n${isNew ? `You are registered for ${eventTitle}` : `Your registration for ${eventTitle} has been updated`}${eventDate ? ' on ' + eventDate : ''}.\n\nYour selections:\n${itemsText || '  —'}\n\nTotal due: ${fmtAmount(totalDue)}\nAmount paid: ${fmtAmount(totalPaid)}\nBalance: ${fmtAmount(balance)}\n\n${balance > 0 ? `Payment options:\n  1. On our website: ${org.url}\n  2. At the door (cash or card)\n\nYour tickets will be sent once payment is confirmed.` : 'No payment required — your tickets have been sent separately.'}\n\n${org.name} — ${org.email}\n${org.url}`;

  return { subject, text, html: emailWrapper(body, { preheader }) };
}

// ─── Registration confirmation (admin / self-service / at-door) ───────────────

function buildAdminInitiatedRegistrationConfirmation(reg, { yocoLink = null, formRequired = false, isNew = true } = {}) {
  const org = getOrg();
  const eventTitle = reg.event?.title || 'the event';
  const eventDate = reg.event?.startDate ? fmtDateShort(reg.event.startDate) : '';
  const totalDue = computeRegistrationTotalDue(reg, new Date());
  const totalPaid = (reg.payments || []).reduce((s, p) => s + (p.amount || 0), 0);
  const balance = Math.max(totalDue - totalPaid, 0);
  const isUserActive = reg.user?.isActive;

  const heading = isNew ? 'Registration confirmed!' : 'Registration updated';
  const subtext = isNew
    ? `You have been registered for <strong>${eventTitle}</strong>.`
    : `Your registration for <strong>${eventTitle}</strong> has been updated.`;
  const subject = isNew ? `Registration confirmed – ${eventTitle}` : `Registration updated – ${eventTitle}`;
  const preheader = isNew
    ? `You\'re registered for ${eventTitle}${eventDate ? ' on ' + eventDate : ''}!`
    : `Your registration for ${eventTitle} has been updated.`;

  const body = `
    <p style="font-size:22px;font-weight:800;color:#0f172a;margin:0 0 8px 0;letter-spacing:-0.3px">${heading}</p>
    <p style="font-size:14px;color:#64748b;margin:0 0 32px 0">${isNew ? 'Your spot is reserved' : 'Changes saved'}</p>

    <p style="margin:0 0 4px 0;color:#374151;font-family:${ff}">Hi <strong>${reg.user?.name || 'there'}</strong>,</p>
    <p style="margin:0 0 28px 0;color:#374151;font-family:${ff}">${subtext}${eventDate ? ` The event takes place on <strong>${eventDate}</strong>.` : ''}</p>

    <p style="font-size:16px;font-weight:700;color:#0f172a;margin:0 0 12px 0;font-family:${ff}">Your registration</p>
    ${selectionsTable(reg.registrationOptions)}
    ${financialSummary(totalDue, totalPaid, balance)}

    ${paymentSection({ balance, yocoLink, source: 'admin', siteUrl: org.url, formRequired, isUserActive })}
    ${accountCta(isUserActive, org.url)}`;

  const itemsText = (reg.registrationOptions || []).map(ro => `  • ${ro.eventOption?.name || 'Option'} ×${ro.quantity} — ${fmtAmount(computeOptionLineTotal(ro, null, new Date()))}`).join('\n');
  const payText = balance > 0
    ? `Payment options:\n${yocoLink ? `  1. Pay online (Yoco): ${yocoLink}\n     (Already paid? Ignore this option)\n` : ''}  ${yocoLink ? '2' : '1'}. On our website: ${org.url}\n  ${yocoLink ? '3' : '2'}. At the door (cash or card)\n\nYour tickets will be sent once payment is confirmed.`
    : formRequired
    ? 'An attendee form is required before your tickets are issued. Please complete it at the registration desk.'
    : 'No payment required — your tickets have been sent in a separate email.';
  const text = `${heading}\n\nHi ${reg.user?.name || 'there'},\n\n${isNew ? `You have been registered for ${eventTitle}` : `Your registration for ${eventTitle} has been updated`}${eventDate ? ' on ' + eventDate : ''}.\n\nYour selections:\n${itemsText || '  —'}\n\nTotal due: ${fmtAmount(totalDue)}\nAmount paid: ${fmtAmount(totalPaid)}\nBalance: ${fmtAmount(balance)}\n\n${payText}\n\n${org.name} — ${org.email}\n${org.url}`;

  return { subject, text, html: emailWrapper(body, { preheader }) };
}

// ─── Admin notification (internal) ───────────────────────────────────────────

function buildRegistrationAdminNotice(reg, { isNew = true, isUpdated = false } = {}) {
  const org = getOrg();
  const eventTitle = reg.event?.title || 'Event';
  const totalDue = computeRegistrationTotalDue(reg, new Date());
  const totalPaid = (reg.payments || []).reduce((s, p) => s + (p.amount || 0), 0);
  const balance = Math.max(totalDue - totalPaid, 0);
  const verb = isUpdated ? 'updated' : (isNew ? 'created' : 'modified');
  const subject = isUpdated
    ? `Registration updated: ${eventTitle} — ${reg.user?.name || 'Unknown'}`
    : `New registration: ${eventTitle} — ${reg.user?.name || 'Unknown'}`;

  const itemRows = (reg.registrationOptions || []).map(ro =>
    `<tr>
      <td style="padding:8px 12px;font-size:13px;color:#374151;font-family:${ff};border-bottom:1px solid #f1f5f9">${ro.eventOption?.name || 'Option'}</td>
      <td style="padding:8px 12px;font-size:13px;color:#374151;text-align:center;font-family:${ff};border-bottom:1px solid #f1f5f9">×${ro.quantity}</td>
      <td style="padding:8px 12px;font-size:13px;color:#374151;text-align:right;font-family:${ff};border-bottom:1px solid #f1f5f9">${fmtAmount(computeOptionLineTotal(ro, null, new Date()))}</td>
    </tr>`).join('');

  const body = `
    <p style="font-size:20px;font-weight:800;color:#0f172a;margin:0 0 4px 0">Registration ${verb}</p>
    <p style="font-size:13px;color:#64748b;margin:0 0 28px 0">${org.name} — internal notification</p>

    <table role="presentation" width="100%" cellpadding="0" cellspacing="0" style="border:1px solid #e2e8f0;border-radius:8px;overflow:hidden;margin:0 0 24px 0">
      <tr style="background:#f8fafc">
        <td colspan="2" style="padding:12px 16px;font-size:12px;font-weight:700;color:#64748b;text-transform:uppercase;letter-spacing:0.5px;font-family:${ff}">Registrant details</td>
      </tr>
      <tr>
        <td style="padding:10px 16px;font-size:13px;color:#64748b;font-weight:600;width:30%;font-family:${ff};border-top:1px solid #f1f5f9">Name</td>
        <td style="padding:10px 16px;font-size:14px;color:#1e293b;font-weight:500;font-family:${ff};border-top:1px solid #f1f5f9">${reg.user?.name || '—'}</td>
      </tr>
      <tr>
        <td style="padding:10px 16px;font-size:13px;color:#64748b;font-weight:600;font-family:${ff};border-top:1px solid #f1f5f9">Email</td>
        <td style="padding:10px 16px;font-size:14px;color:#1e293b;font-weight:500;font-family:${ff};border-top:1px solid #f1f5f9">${reg.user?.email || '—'}</td>
      </tr>
      ${reg.user?.phoneNumber ? `<tr>
        <td style="padding:10px 16px;font-size:13px;color:#64748b;font-weight:600;font-family:${ff};border-top:1px solid #f1f5f9">Phone</td>
        <td style="padding:10px 16px;font-size:14px;color:#1e293b;font-weight:500;font-family:${ff};border-top:1px solid #f1f5f9">${reg.user.phoneNumber}</td>
      </tr>` : ''}
      <tr>
        <td style="padding:10px 16px;font-size:13px;color:#64748b;font-weight:600;font-family:${ff};border-top:1px solid #f1f5f9">Event</td>
        <td style="padding:10px 16px;font-size:14px;color:#1e293b;font-weight:500;font-family:${ff};border-top:1px solid #f1f5f9">${eventTitle}</td>
      </tr>
      <tr>
        <td style="padding:10px 16px;font-size:13px;color:#64748b;font-weight:600;font-family:${ff};border-top:1px solid #f1f5f9">Status</td>
        <td style="padding:10px 16px;font-size:14px;color:#1e293b;font-weight:500;font-family:${ff};border-top:1px solid #f1f5f9">${reg.status || 'pending'}</td>
      </tr>
      <tr>
        <td style="padding:10px 16px;font-size:13px;color:#64748b;font-weight:600;font-family:${ff};border-top:1px solid #f1f5f9">Reg ID</td>
        <td style="padding:10px 16px;font-size:14px;color:#1e293b;font-family:${ff};border-top:1px solid #f1f5f9;font-size:12px">${reg.id}</td>
      </tr>
    </table>

    ${itemRows ? `<p style="font-size:14px;font-weight:700;color:#0f172a;margin:0 0 8px 0;font-family:${ff}">Items</p>
    <table role="presentation" width="100%" cellpadding="0" cellspacing="0" style="border:1px solid #e2e8f0;border-radius:8px;overflow:hidden;margin:0 0 16px 0">
      <tr style="background:#f8fafc">
        <th style="padding:10px 12px;font-size:12px;color:#64748b;text-align:left;font-family:${ff}">Option</th>
        <th style="padding:10px 12px;font-size:12px;color:#64748b;text-align:center;font-family:${ff}">Qty</th>
        <th style="padding:10px 12px;font-size:12px;color:#64748b;text-align:right;font-family:${ff}">Amount</th>
      </tr>${itemRows}
    </table>` : ''}

    <table role="presentation" width="100%" cellpadding="0" cellspacing="0" style="margin:16px 0 0 0">
      <tr>
        <td style="font-size:13px;color:#64748b;padding:4px 0;font-family:${ff}">Total due</td>
        <td style="font-size:13px;color:#374151;text-align:right;font-weight:500;padding:4px 0;font-family:${ff}">${fmtAmount(totalDue)}</td>
      </tr>
      <tr>
        <td style="font-size:13px;color:#64748b;padding:4px 0;font-family:${ff}">Paid</td>
        <td style="font-size:13px;color:#374151;text-align:right;font-weight:500;padding:4px 0;font-family:${ff}">${fmtAmount(totalPaid)}</td>
      </tr>
      <tr>
        <td style="font-size:14px;font-weight:700;color:#0f172a;padding:8px 0 0 0;border-top:1px solid #e2e8f0;font-family:${ff}">Balance</td>
        <td style="font-size:14px;font-weight:700;color:#${balance <= 0 ? '059669' : '0f172a'};text-align:right;padding:8px 0 0 0;border-top:1px solid #e2e8f0;font-family:${ff}">${fmtAmount(balance)}</td>
      </tr>
    </table>`;

  const to = buildEventNotifyRecipientList(reg.event);
  const text = `Registration ${verb}\n\nEvent: ${eventTitle}\nName: ${reg.user?.name || '—'}\nEmail: ${reg.user?.email || '—'}\nStatus: ${reg.status || 'pending'}\nTotal due: ${fmtAmount(totalDue)} | Paid: ${fmtAmount(totalPaid)} | Balance: ${fmtAmount(balance)}\nReg ID: ${reg.id}`;
  return { to, subject, text, html: emailWrapper(body) };
}

// ─── Payment receipt ──────────────────────────────────────────────────────────

function buildPaymentReceipt(payment) {
  const org = getOrg();
  const isReg = !!payment.registrationId && payment.registration;
  const eventTitle = isReg
    ? (payment.registration?.event?.title || 'the event')
    : (payment.event?.title || 'the event');

  if (isReg) {
    const reg = payment.registration;
    const totalDue = computeRegistrationTotalDue(reg, payment.createdAt || new Date());
    const totalPaid = (reg.payments || []).reduce((s, p) => s + (p.amount || 0), 0);
    const balance = Math.max(totalDue - totalPaid, 0);
    const isUserActive = reg.user?.isActive;
    const subject = `Payment received – ${eventTitle}`;
    const preheader = `We received your payment of ${fmtAmount(payment.amount)} for ${eventTitle}.`;

    const historyRows = (reg.payments || [])
      .sort((a, b) => new Date(a.createdAt) - new Date(b.createdAt))
      .map(p => `<tr>
        <td style="padding:8px 12px;font-size:13px;color:#374151;font-family:${ff};border-bottom:1px solid #f1f5f9">${fmtDate(p.createdAt)}</td>
        <td style="padding:8px 12px;font-size:13px;color:#374151;font-family:${ff};border-bottom:1px solid #f1f5f9">${p.method || '—'}</td>
        <td style="padding:8px 12px;font-size:13px;color:#374151;text-align:right;font-weight:600;font-family:${ff};border-bottom:1px solid #f1f5f9">${fmtAmount(p.amount)}</td>
      </tr>`).join('');

    const body = `
      <p style="font-size:22px;font-weight:800;color:#0f172a;margin:0 0 8px 0;letter-spacing:-0.3px">Payment received</p>
      <p style="font-size:14px;color:#64748b;margin:0 0 32px 0">Thank you — we've got your payment</p>

      <p style="margin:0 0 4px 0;color:#374151;font-family:${ff}">Hi <strong>${payment.user?.name || 'there'}</strong>,</p>
      <p style="margin:0 0 28px 0;color:#374151;font-family:${ff}">
        We received your payment of <strong>${fmtAmount(payment.amount)}</strong> for <strong>${eventTitle}</strong>.
      </p>

      ${callout(`<strong style="font-size:15px">${fmtAmount(payment.amount)} received</strong><br/>
        <span style="font-size:13px">Payment method: ${payment.method || '—'} &bull; Date: ${fmtDate(payment.createdAt)}</span>`,
        'success')}

      <table role="presentation" width="100%" cellpadding="0" cellspacing="0" style="margin:24px 0">
        <tr>
          <td style="font-size:13px;color:#64748b;padding:5px 0;font-family:${ff}">Total due</td>
          <td style="font-size:13px;text-align:right;font-weight:500;color:#374151;padding:5px 0;font-family:${ff}">${fmtAmount(totalDue)}</td>
        </tr>
        <tr>
          <td style="font-size:13px;color:#64748b;padding:5px 0;font-family:${ff}">Total paid</td>
          <td style="font-size:13px;text-align:right;font-weight:500;color:#374151;padding:5px 0;font-family:${ff}">${fmtAmount(totalPaid)}</td>
        </tr>
        <tr>
          <td style="font-size:14px;font-weight:700;color:#0f172a;padding:10px 0 5px 0;border-top:1px solid #e2e8f0;font-family:${ff}">${balance <= 0 ? 'Fully paid ✓' : 'Balance remaining'}</td>
          <td style="font-size:14px;font-weight:700;color:#${balance <= 0 ? '059669' : '0f172a'};text-align:right;padding:10px 0 5px 0;border-top:1px solid #e2e8f0;font-family:${ff}">${fmtAmount(balance)}</td>
        </tr>
      </table>

      ${historyRows ? `<p style="font-size:14px;font-weight:700;color:#0f172a;margin:24px 0 8px 0;font-family:${ff}">Payment history</p>
      <table role="presentation" width="100%" cellpadding="0" cellspacing="0" style="border:1px solid #e2e8f0;border-radius:8px;overflow:hidden;margin:0 0 24px 0">
        <tr style="background:#f8fafc">
          <th style="padding:10px 12px;font-size:12px;color:#64748b;text-align:left;font-family:${ff}">Date</th>
          <th style="padding:10px 12px;font-size:12px;color:#64748b;text-align:left;font-family:${ff}">Method</th>
          <th style="padding:10px 12px;font-size:12px;color:#64748b;text-align:right;font-family:${ff}">Amount</th>
        </tr>${historyRows}
      </table>` : ''}

      ${balance <= 0
        ? callout('<strong>You\'re fully paid!</strong> Your tickets have been emailed to you separately.', 'success')
        : ''}

      ${accountCta(isUserActive, org.url)}`;

    const text = `Payment received\n\nHi ${payment.user?.name || 'there'},\n\nWe received your payment of ${fmtAmount(payment.amount)} for ${eventTitle}.\n\nTotal due: ${fmtAmount(totalDue)}\nTotal paid: ${fmtAmount(totalPaid)}\nBalance: ${fmtAmount(balance)}\n\nThank you!\n\n${org.name} — ${org.email}`;
    return { subject, text, html: emailWrapper(body, { preheader }) };
  }

  // Donation receipt
  const subject = `Donation received – ${eventTitle}`;
  const preheader = `Thank you for your donation of ${fmtAmount(payment.amount)} to ${eventTitle}.`;
  const body = `
    <p style="font-size:22px;font-weight:800;color:#0f172a;margin:0 0 8px 0;letter-spacing:-0.3px">Thank you for your donation!</p>
    <p style="font-size:14px;color:#64748b;margin:0 0 32px 0">Your generosity makes a difference</p>

    <p style="margin:0 0 4px 0;color:#374151;font-family:${ff}">Hi <strong>${payment.user?.name || 'there'}</strong>,</p>
    <p style="margin:0 0 28px 0;color:#374151;font-family:${ff}">
      We received your donation of <strong>${fmtAmount(payment.amount)}</strong> to <strong>${eventTitle}</strong>. Your support means the world to us.
    </p>

    ${callout(`<strong style="font-size:15px">${fmtAmount(payment.amount)} donated</strong><br/>
      <span style="font-size:13px">Method: ${payment.method || '—'} &bull; Date: ${fmtDate(payment.createdAt)}</span>`,
      'success')}

    <p style="margin:24px 0 0 0;font-size:13px;color:#94a3b8;font-family:${ff}">We appreciate your generous support. Thank you!</p>`;

  const text = `Thank you for your donation!\n\nHi ${payment.user?.name || 'there'},\n\nWe received your donation of ${fmtAmount(payment.amount)} to ${eventTitle}.\n\nMethod: ${payment.method || '—'}\nDate: ${fmtDate(payment.createdAt)}\n\nThank you!\n\n${org.name} — ${org.email}`;
  return { subject, text, html: emailWrapper(body, { preheader }) };
}

// ─── Check-in confirmation (Main Tickets, door check-in) ───────────────────────

function buildCheckInConfirmation(ticket, qtyRedeemed, totalRedeemed, remaining) {
  const org = getOrg();
  const eventTitle = ticket.event?.title || 'the event';
  const optionName = ticket.registrationOption?.eventOption?.name || 'Main Ticket';
  const fullyCheckedIn = remaining <= 0;
  const subject = `Checked in – ${eventTitle}`;
  const preheader = `${qtyRedeemed} checked in for ${eventTitle}.`;

  const body = `
    <p style="font-size:22px;font-weight:800;color:#0f172a;margin:0 0 8px 0;letter-spacing:-0.3px">You're checked in! ✅</p>
    <p style="font-size:14px;color:#64748b;margin:0 0 32px 0">See you inside</p>

    <p style="margin:0 0 4px 0;color:#374151;font-family:${ff}">Hi <strong>${ticket.user?.name || 'there'}</strong>,</p>
    <p style="margin:0 0 28px 0;color:#374151;font-family:${ff}">
      <strong>${qtyRedeemed}</strong> ${optionName}${qtyRedeemed === 1 ? '' : 's'} just checked in for <strong>${eventTitle}</strong>.
    </p>

    ${callout(`<strong style="font-size:15px">${totalRedeemed} of ${ticket.quantity || 1} checked in</strong>${
      fullyCheckedIn ? '' : `<br/><span style="font-size:13px">${remaining} remaining on this ticket</span>`
    }`, fullyCheckedIn ? 'success' : 'info')}`;

  const text = `You're checked in!\n\nHi ${ticket.user?.name || 'there'},\n\n${qtyRedeemed} ${optionName}(s) just checked in for ${eventTitle}.\n\n${totalRedeemed} of ${ticket.quantity || 1} checked in${fullyCheckedIn ? '' : `, ${remaining} remaining`}.\n\n${org.name} — ${org.email}`;
  return { subject, text, html: emailWrapper(body, { preheader }) };
}

// ─── Donation applied to a registration ────────────────────────────────────────
//
// Distinct from buildPaymentReceipt: this is sent to the REGISTRANT when staff apply
// someone else's donation to their registration — they didn't pay anything themselves,
// so "payment received" wording would be wrong. Kept anonymous (no donor name) by design.

function buildDonationAppliedToRegistrant(payment) {
  const org = getOrg();
  const reg = payment.registration;
  const eventTitle = reg?.event?.title || 'the event';
  const totalDue = computeRegistrationTotalDue(reg, payment.createdAt || new Date());
  const totalPaid = (reg?.payments || []).reduce((s, p) => s + (p.amount || 0), 0);
  const balance = Math.max(totalDue - totalPaid, 0);
  const isUserActive = reg?.user?.isActive;
  const subject = `A donation was applied to your registration – ${eventTitle}`;
  const preheader = `A donation of ${fmtAmount(payment.amount)} was applied to your registration for ${eventTitle}.`;

  const body = `
    <p style="font-size:22px;font-weight:800;color:#0f172a;margin:0 0 8px 0;letter-spacing:-0.3px">A donation was applied to your registration</p>
    <p style="font-size:14px;color:#64748b;margin:0 0 32px 0">Good news about your balance</p>

    <p style="margin:0 0 4px 0;color:#374151;font-family:${ff}">Hi <strong>${reg?.user?.name || 'there'}</strong>,</p>
    <p style="margin:0 0 28px 0;color:#374151;font-family:${ff}">
      A donation of <strong>${fmtAmount(payment.amount)}</strong> was applied to your registration for <strong>${eventTitle}</strong> by our team.
    </p>

    ${callout(`<strong style="font-size:15px">${fmtAmount(payment.amount)} applied</strong><br/>
      <span style="font-size:13px">Date: ${fmtDate(payment.createdAt)}</span>`,
      'success')}

    <table role="presentation" width="100%" cellpadding="0" cellspacing="0" style="margin:24px 0">
      <tr>
        <td style="font-size:13px;color:#64748b;padding:5px 0;font-family:${ff}">Total due</td>
        <td style="font-size:13px;text-align:right;font-weight:500;color:#374151;padding:5px 0;font-family:${ff}">${fmtAmount(totalDue)}</td>
      </tr>
      <tr>
        <td style="font-size:13px;color:#64748b;padding:5px 0;font-family:${ff}">Total paid</td>
        <td style="font-size:13px;text-align:right;font-weight:500;color:#374151;padding:5px 0;font-family:${ff}">${fmtAmount(totalPaid)}</td>
      </tr>
      <tr>
        <td style="font-size:14px;font-weight:700;color:#0f172a;padding:10px 0 5px 0;border-top:1px solid #e2e8f0;font-family:${ff}">${balance <= 0 ? 'Fully paid ✓' : 'Balance remaining'}</td>
        <td style="font-size:14px;font-weight:700;color:#${balance <= 0 ? '059669' : '0f172a'};text-align:right;padding:10px 0 5px 0;border-top:1px solid #e2e8f0;font-family:${ff}">${fmtAmount(balance)}</td>
      </tr>
    </table>

    ${balance <= 0
      ? callout('<strong>You\'re fully paid!</strong> Your tickets have been emailed to you separately.', 'success')
      : ''}

    ${accountCta(isUserActive, org.url)}`;

  const text = `A donation was applied to your registration\n\nHi ${reg?.user?.name || 'there'},\n\nA donation of ${fmtAmount(payment.amount)} was applied to your registration for ${eventTitle} by our team.\n\nTotal due: ${fmtAmount(totalDue)}\nTotal paid: ${fmtAmount(totalPaid)}\nBalance: ${fmtAmount(balance)}\n\n${org.name} — ${org.email}`;
  return { subject, text, html: emailWrapper(body, { preheader }) };
}

// ─── Payment admin notification ───────────────────────────────────────────────

function buildPaymentAdminNotice(payment) {
  const isReg = !!payment.registrationId && payment.registration;
  const eventTitle = isReg ? (payment.registration?.event?.title || 'Event') : (payment.event?.title || 'Event');
  const payerName = payment.user?.name || '—';
  const payerEmail = payment.user?.email || '—';
  const subject = `Payment recorded: ${fmtAmount(payment.amount)} — ${payerName} (${eventTitle})`;
  const type = isReg ? 'Registration payment' : 'Donation';

  const body = `
    <p style="font-size:20px;font-weight:800;color:#0f172a;margin:0 0 4px 0">Payment recorded</p>
    <p style="font-size:13px;color:#64748b;margin:0 0 28px 0">Internal notification</p>

    <table role="presentation" width="100%" cellpadding="0" cellspacing="0" style="border:1px solid #e2e8f0;border-radius:8px;overflow:hidden;margin:0 0 24px 0">
      <tr style="background:#f8fafc">
        <td colspan="2" style="padding:12px 16px;font-size:12px;font-weight:700;color:#64748b;text-transform:uppercase;letter-spacing:0.5px;font-family:${ff}">Payment details</td>
      </tr>
      <tr>
        <td style="padding:10px 16px;font-size:13px;color:#64748b;font-weight:600;width:30%;font-family:${ff};border-top:1px solid #f1f5f9">Amount</td>
        <td style="padding:10px 16px;font-size:15px;color:#059669;font-weight:800;font-family:${ff};border-top:1px solid #f1f5f9">${fmtAmount(payment.amount)}</td>
      </tr>
      <tr>
        <td style="padding:10px 16px;font-size:13px;color:#64748b;font-weight:600;font-family:${ff};border-top:1px solid #f1f5f9">Type</td>
        <td style="padding:10px 16px;font-size:14px;color:#1e293b;font-weight:500;font-family:${ff};border-top:1px solid #f1f5f9">${type}</td>
      </tr>
      <tr>
        <td style="padding:10px 16px;font-size:13px;color:#64748b;font-weight:600;font-family:${ff};border-top:1px solid #f1f5f9">Payer</td>
        <td style="padding:10px 16px;font-size:14px;color:#1e293b;font-weight:500;font-family:${ff};border-top:1px solid #f1f5f9">${payerName} &lt;${payerEmail}&gt;</td>
      </tr>
      <tr>
        <td style="padding:10px 16px;font-size:13px;color:#64748b;font-weight:600;font-family:${ff};border-top:1px solid #f1f5f9">Event</td>
        <td style="padding:10px 16px;font-size:14px;color:#1e293b;font-weight:500;font-family:${ff};border-top:1px solid #f1f5f9">${eventTitle}</td>
      </tr>
      <tr>
        <td style="padding:10px 16px;font-size:13px;color:#64748b;font-weight:600;font-family:${ff};border-top:1px solid #f1f5f9">Method</td>
        <td style="padding:10px 16px;font-size:14px;color:#1e293b;font-weight:500;font-family:${ff};border-top:1px solid #f1f5f9">${payment.method || '—'}</td>
      </tr>
      <tr>
        <td style="padding:10px 16px;font-size:13px;color:#64748b;font-weight:600;font-family:${ff};border-top:1px solid #f1f5f9">Date</td>
        <td style="padding:10px 16px;font-size:14px;color:#1e293b;font-weight:500;font-family:${ff};border-top:1px solid #f1f5f9">${fmtDate(payment.createdAt)}</td>
      </tr>
      <tr>
        <td style="padding:10px 16px;font-size:13px;color:#64748b;font-weight:600;font-family:${ff};border-top:1px solid #f1f5f9">Payment ID</td>
        <td style="padding:10px 16px;font-size:12px;color:#94a3b8;font-family:${ff};border-top:1px solid #f1f5f9">${payment.id}</td>
      </tr>
      ${payment.externalId ? `<tr>
        <td style="padding:10px 16px;font-size:13px;color:#64748b;font-weight:600;font-family:${ff};border-top:1px solid #f1f5f9">External ID</td>
        <td style="padding:10px 16px;font-size:12px;color:#94a3b8;font-family:${ff};border-top:1px solid #f1f5f9">${payment.externalId}</td>
      </tr>` : ''}
    </table>`;

  const event = isReg ? payment.registration?.event : payment.event;
  const to = buildEventNotifyRecipientList(event);
  const text = `Payment recorded\n\nAmount: ${fmtAmount(payment.amount)}\nType: ${type}\nPayer: ${payerName} <${payerEmail}>\nEvent: ${eventTitle}\nMethod: ${payment.method || '—'}\nDate: ${fmtDate(payment.createdAt)}\nID: ${payment.id}`;
  return { to, subject, text, html: emailWrapper(body) };
}

// ─── Donation unassignment ─────────────────────────────────────────────────────
//
// Sent when staff reverse a previous donation-assignment. Distinct from
// buildDonationAppliedToRegistrant: the leg payment no longer exists by the time this runs
// (it's hard-deleted before the notification fires), so callers pass a synthetic payment-shaped
// object — { amount, createdAt, registration } — built from the leg's captured values plus a
// freshly re-fetched registration so the balance table reflects the post-removal total.
// Kept anonymous (no donor name), same reasoning as the "applied" email.

function buildDonationUnassignedFromRegistrant(payment) {
  const org = getOrg();
  const reg = payment.registration;
  const eventTitle = reg?.event?.title || 'the event';
  const totalDue = computeRegistrationTotalDue(reg, new Date());
  const totalPaid = (reg?.payments || []).reduce((s, p) => s + (p.amount || 0), 0);
  const balance = Math.max(totalDue - totalPaid, 0);
  const isUserActive = reg?.user?.isActive;
  const subject = `A donation was removed from your registration – ${eventTitle}`;
  const preheader = `A donation of ${fmtAmount(payment.amount)} was removed from your registration for ${eventTitle}.`;

  const body = `
    <p style="font-size:22px;font-weight:800;color:#0f172a;margin:0 0 8px 0;letter-spacing:-0.3px">A donation was removed from your registration</p>
    <p style="font-size:14px;color:#64748b;margin:0 0 32px 0">Your balance has changed</p>

    <p style="margin:0 0 4px 0;color:#374151;font-family:${ff}">Hi <strong>${reg?.user?.name || 'there'}</strong>,</p>
    <p style="margin:0 0 28px 0;color:#374151;font-family:${ff}">
      A donation of <strong>${fmtAmount(payment.amount)}</strong> previously applied to your registration for <strong>${eventTitle}</strong> has been removed by our team.
    </p>

    ${callout(`<strong style="font-size:15px">${fmtAmount(payment.amount)} removed</strong><br/>
      <span style="font-size:13px">Date: ${fmtDate(new Date())}</span>`,
      'warning')}

    <table role="presentation" width="100%" cellpadding="0" cellspacing="0" style="margin:24px 0">
      <tr>
        <td style="font-size:13px;color:#64748b;padding:5px 0;font-family:${ff}">Total due</td>
        <td style="font-size:13px;text-align:right;font-weight:500;color:#374151;padding:5px 0;font-family:${ff}">${fmtAmount(totalDue)}</td>
      </tr>
      <tr>
        <td style="font-size:13px;color:#64748b;padding:5px 0;font-family:${ff}">Total paid</td>
        <td style="font-size:13px;text-align:right;font-weight:500;color:#374151;padding:5px 0;font-family:${ff}">${fmtAmount(totalPaid)}</td>
      </tr>
      <tr>
        <td style="font-size:14px;font-weight:700;color:#0f172a;padding:10px 0 5px 0;border-top:1px solid #e2e8f0;font-family:${ff}">${balance <= 0 ? 'Fully paid ✓' : 'Balance remaining'}</td>
        <td style="font-size:14px;font-weight:700;color:#${balance <= 0 ? '059669' : '0f172a'};text-align:right;padding:10px 0 5px 0;border-top:1px solid #e2e8f0;font-family:${ff}">${fmtAmount(balance)}</td>
      </tr>
    </table>

    ${balance > 0
      ? callout(`<strong>A balance is now owing.</strong> Please arrange payment of ${fmtAmount(balance)} to secure your registration.`, 'warning')
      : ''}

    ${accountCta(isUserActive, org.url)}`;

  const text = `A donation was removed from your registration\n\nHi ${reg?.user?.name || 'there'},\n\nA donation of ${fmtAmount(payment.amount)} previously applied to your registration for ${eventTitle} has been removed by our team.\n\nTotal due: ${fmtAmount(totalDue)}\nTotal paid: ${fmtAmount(totalPaid)}\nBalance: ${fmtAmount(balance)}\n\n${org.name} — ${org.email}`;
  return { subject, text, html: emailWrapper(body, { preheader }) };
}

// Internal admin notice for a donation-assignment — same table layout as
// buildPaymentAdminNotice (which reads payment.user as "Payer" — for a leg that's the donor,
// since legs copy userId from the original donation, not the registrant), relabeled so it
// doesn't read as a fresh incoming payment: no new money changed hands here, an
// already-recorded donation was just reallocated to a registration.
function buildDonationAssignmentAdminNotice(payment) {
  const notice = buildPaymentAdminNotice(payment);
  const eventTitle = payment.registration?.event?.title || 'Event';
  const payerName = payment.user?.name || '—';
  const subject = `Donation applied: ${fmtAmount(payment.amount)} — ${payerName} (${eventTitle})`;
  return {
    ...notice,
    subject,
    html: notice.html
      .replace('Payment recorded', 'Donation applied')
      .replace('Internal notification', 'Internal notification — donation applied to a registration')
      .replace('>Registration payment<', '>Donation applied<'),
    text: notice.text
      .replace('Payment recorded', 'Donation applied')
      .replace('Type: Registration payment', 'Type: Donation applied'),
  };
}

// Internal admin notice for a donation-unassignment — same table layout as
// buildPaymentAdminNotice (which reads payment.user as "Payer" — for a leg that's the donor,
// since legs copy userId from the original donation, not the registrant), with copy adjusted
// for a removal rather than a new payment.
function buildDonationUnassignmentAdminNotice(payment) {
  const notice = buildPaymentAdminNotice(payment);
  const eventTitle = payment.registration?.event?.title || 'Event';
  const payerName = payment.user?.name || '—';
  const subject = `Donation unassigned: ${fmtAmount(payment.amount)} — ${payerName} (${eventTitle})`;
  return {
    ...notice,
    subject,
    html: notice.html
      .replace('Payment recorded', 'Donation unassigned')
      .replace('Internal notification', 'Internal notification — donation removed from registration')
      .replace('>Registration payment<', '>Donation unassigned<'),
    text: notice.text
      .replace('Payment recorded', 'Donation unassigned')
      .replace('Type: Registration payment', 'Type: Donation unassigned'),
  };
}

// ─── Refund email ─────────────────────────────────────────────────────────────

function buildRefundEmail(payment) {
  const org = getOrg();
  const user = payment.user;
  const amt = Math.abs(payment.amount || 0);
  const eventTitle = payment.registration?.event?.title || payment.event?.title || 'the event';
  const subject = `Refund processed – ${fmtAmount(amt)} for ${eventTitle}`;
  const preheader = `Your refund of ${fmtAmount(amt)} for ${eventTitle} has been processed.`;

  const body = `
    <p style="font-size:22px;font-weight:800;color:#0f172a;margin:0 0 8px 0;letter-spacing:-0.3px">Refund processed</p>
    <p style="font-size:14px;color:#64748b;margin:0 0 32px 0">Your refund is on its way</p>

    <p style="margin:0 0 4px 0;color:#374151;font-family:${ff}">Hi <strong>${user?.name || 'there'}</strong>,</p>
    <p style="margin:0 0 28px 0;color:#374151;font-family:${ff}">
      A refund of <strong>${fmtAmount(amt)}</strong> has been processed for <strong>${eventTitle}</strong>.
      ${payment.status ? `<br/>Reason: ${payment.status}` : ''}
    </p>

    ${callout(`<strong style="font-size:15px">${fmtAmount(amt)} refunded</strong><br/>
      <span style="font-size:13px">Method: ${payment.method || 'original payment method'} &bull; Date: ${fmtDate(payment.createdAt)}</span>`,
      'info')}

    <p style="margin:24px 0 0 0;font-size:14px;color:#374151;font-family:${ff}">
      Refunds may take a few business days to appear depending on your bank and payment method.
      If you have any questions, contact us at <a href="mailto:${org.email}" style="color:#2563eb">${org.email}</a>.
    </p>`;

  const text = `Refund processed\n\nHi ${user?.name || 'there'},\n\nA refund of ${fmtAmount(amt)} for ${eventTitle} has been processed.\n\nMethod: ${payment.method || 'original method'}\nDate: ${fmtDate(payment.createdAt)}\n\n${org.name} — ${org.email}`;
  return { subject, text, html: emailWrapper(body, { preheader }) };
}

// ─── Daily event summary ──────────────────────────────────────────────────────

function buildDailySummary(ev, registrations, payments, now) {
  const org = getOrg();
  const subject = `Daily summary: ${ev.title} — ${new Date(now).toLocaleDateString('en-GB', { day: 'numeric', month: 'long', year: 'numeric' })}`;

  const regRows = registrations.map(r => {
    const totalDue = computeRegistrationTotalDue(r, now);
    const totalPaid = (r.payments || []).reduce((s, p) => s + (p.amount || 0), 0);
    const balance = Math.max(totalDue - totalPaid, 0);
    return { name: r.user?.name || '?', email: r.user?.email || '', status: r.status, totalDue, totalPaid, balance };
  });

  const payRows = payments.map(p => ({
    date: fmtDate(p.createdAt),
    amount: p.amount,
    method: p.method || '—',
    isDonation: p.isDonation || !p.registrationId,
    payerName: p.registration?.user?.name || p.user?.name || '?',
    payerEmail: p.user?.email || p.registration?.user?.email || '',
  }));

  const totalRegistrations = regRows.length;
  const totalRevenue = payRows.reduce((s, p) => s + (p.amount || 0), 0);
  const paidCount = regRows.filter(r => r.status === 'paid').length;
  const pendingCount = regRows.filter(r => r.status === 'pending' || r.status === 'partial_paid').length;

  const statsRow = (label, value, color = '#1e293b') =>
    `<td style="text-align:center;padding:16px;border-right:1px solid #f1f5f9">
      <div style="font-size:24px;font-weight:800;color:${color};font-family:${ff}">${value}</div>
      <div style="font-size:12px;color:#64748b;margin-top:4px;font-family:${ff}">${label}</div>
    </td>`;

  const regTableHtml = regRows.length
    ? `<table role="presentation" width="100%" cellpadding="0" cellspacing="0" style="border:1px solid #e2e8f0;border-radius:8px;overflow:hidden;font-size:13px">
        <tr style="background:#f8fafc">
          <th style="padding:10px 12px;text-align:left;color:#64748b;font-weight:700;font-family:${ff};font-size:12px;text-transform:uppercase;letter-spacing:0.4px">Name</th>
          <th style="padding:10px 12px;text-align:left;color:#64748b;font-weight:700;font-family:${ff};font-size:12px;text-transform:uppercase;letter-spacing:0.4px">Email</th>
          <th style="padding:10px 12px;text-align:left;color:#64748b;font-weight:700;font-family:${ff};font-size:12px;text-transform:uppercase;letter-spacing:0.4px">Status</th>
          <th style="padding:10px 12px;text-align:right;color:#64748b;font-weight:700;font-family:${ff};font-size:12px;text-transform:uppercase;letter-spacing:0.4px">Total</th>
          <th style="padding:10px 12px;text-align:right;color:#64748b;font-weight:700;font-family:${ff};font-size:12px;text-transform:uppercase;letter-spacing:0.4px">Paid</th>
          <th style="padding:10px 12px;text-align:right;color:#64748b;font-weight:700;font-family:${ff};font-size:12px;text-transform:uppercase;letter-spacing:0.4px">Balance</th>
        </tr>
        ${regRows.map((r, i) => `<tr style="background:${i % 2 === 0 ? '#ffffff' : '#f8fafc'}">
          <td style="padding:10px 12px;color:#1e293b;font-weight:500;font-family:${ff};border-top:1px solid #f1f5f9">${r.name}</td>
          <td style="padding:10px 12px;color:#64748b;font-family:${ff};border-top:1px solid #f1f5f9;font-size:12px">${r.email}</td>
          <td style="padding:10px 12px;border-top:1px solid #f1f5f9">
            <span style="background:${r.status === 'paid' ? '#dcfce7' : r.status === 'partial_paid' ? '#fef9c3' : '#f1f5f9'};color:${r.status === 'paid' ? '#166534' : r.status === 'partial_paid' ? '#854d0e' : '#475569'};padding:2px 8px;border-radius:20px;font-size:11px;font-weight:700;font-family:${ff}">${r.status}</span>
          </td>
          <td style="padding:10px 12px;text-align:right;color:#374151;font-weight:500;font-family:${ff};border-top:1px solid #f1f5f9">${fmtAmount(r.totalDue)}</td>
          <td style="padding:10px 12px;text-align:right;color:#374151;font-weight:500;font-family:${ff};border-top:1px solid #f1f5f9">${fmtAmount(r.totalPaid)}</td>
          <td style="padding:10px 12px;text-align:right;color:${r.balance > 0 ? '#b45309' : '#059669'};font-weight:700;font-family:${ff};border-top:1px solid #f1f5f9">${fmtAmount(r.balance)}</td>
        </tr>`).join('')}
      </table>`
    : `<p style="color:#94a3b8;font-size:14px;margin:0;font-family:${ff}">No registrations yet.</p>`;

  const payTableHtml = payRows.length
    ? `<table role="presentation" width="100%" cellpadding="0" cellspacing="0" style="border:1px solid #e2e8f0;border-radius:8px;overflow:hidden;font-size:13px">
        <tr style="background:#f8fafc">
          <th style="padding:10px 12px;text-align:left;color:#64748b;font-weight:700;font-family:${ff};font-size:12px;text-transform:uppercase;letter-spacing:0.4px">Date</th>
          <th style="padding:10px 12px;text-align:left;color:#64748b;font-weight:700;font-family:${ff};font-size:12px;text-transform:uppercase;letter-spacing:0.4px">Payer</th>
          <th style="padding:10px 12px;text-align:left;color:#64748b;font-weight:700;font-family:${ff};font-size:12px;text-transform:uppercase;letter-spacing:0.4px">Type</th>
          <th style="padding:10px 12px;text-align:left;color:#64748b;font-weight:700;font-family:${ff};font-size:12px;text-transform:uppercase;letter-spacing:0.4px">Method</th>
          <th style="padding:10px 12px;text-align:right;color:#64748b;font-weight:700;font-family:${ff};font-size:12px;text-transform:uppercase;letter-spacing:0.4px">Amount</th>
        </tr>
        ${payRows.map((p, i) => `<tr style="background:${i % 2 === 0 ? '#ffffff' : '#f8fafc'}">
          <td style="padding:10px 12px;color:#64748b;font-family:${ff};border-top:1px solid #f1f5f9;font-size:12px">${p.date}</td>
          <td style="padding:10px 12px;color:#1e293b;font-weight:500;font-family:${ff};border-top:1px solid #f1f5f9">${p.payerName}${p.payerEmail ? `<br/><span style="font-size:11px;color:#94a3b8">${p.payerEmail}</span>` : ''}</td>
          <td style="padding:10px 12px;border-top:1px solid #f1f5f9">
            <span style="background:${p.isDonation ? '#eff6ff' : '#f0fdf4'};color:${p.isDonation ? '#1e40af' : '#166534'};padding:2px 8px;border-radius:20px;font-size:11px;font-weight:700;font-family:${ff}">${p.isDonation ? 'Donation' : 'Registration'}</span>
          </td>
          <td style="padding:10px 12px;color:#64748b;font-family:${ff};border-top:1px solid #f1f5f9">${p.method}</td>
          <td style="padding:10px 12px;text-align:right;color:#059669;font-weight:700;font-family:${ff};border-top:1px solid #f1f5f9">${fmtAmount(p.amount)}</td>
        </tr>`).join('')}
      </table>`
    : `<p style="color:#94a3b8;font-size:14px;margin:0;font-family:${ff}">No payments recorded yet.</p>`;

  const body = `
    <p style="font-size:20px;font-weight:800;color:#0f172a;margin:0 0 4px 0;font-family:${ff}">Daily Summary</p>
    <p style="font-size:13px;color:#64748b;margin:0 0 4px 0;font-family:${ff}">${new Date(now).toLocaleDateString('en-GB', { weekday: 'long', day: 'numeric', month: 'long', year: 'numeric' })}</p>
    <p style="font-size:16px;font-weight:700;color:#1e293b;margin:0 0 24px 0;font-family:${ff}">${ev.title}</p>

    <table role="presentation" width="100%" cellpadding="0" cellspacing="0" style="border:1px solid #e2e8f0;border-radius:8px;overflow:hidden;margin:0 0 32px 0;text-align:center">
      <tr>
        ${statsRow('Total registrations', totalRegistrations)}
        ${statsRow('Confirmed paid', paidCount, '#059669')}
        ${statsRow('Awaiting payment', pendingCount, '#d97706')}
        <td style="text-align:center;padding:16px">
          <div style="font-size:24px;font-weight:800;color:#2563eb;font-family:${ff}">${fmtAmount(totalRevenue)}</div>
          <div style="font-size:12px;color:#64748b;margin-top:4px;font-family:${ff}">Total collected</div>
        </td>
      </tr>
    </table>

    ${divider()}
    <p style="font-size:16px;font-weight:700;color:#0f172a;margin:0 0 16px 0;font-family:${ff}">Registrations</p>
    ${regTableHtml}

    <p style="font-size:16px;font-weight:700;color:#0f172a;margin:32px 0 16px 0;font-family:${ff}">Payments &amp; Donations</p>
    ${payTableHtml}

    <p style="font-size:12px;color:#94a3b8;margin:24px 0 0 0;font-family:${ff}">
      Event starts: ${fmtDate(ev.startDate)} &bull; Event ends: ${fmtDate(ev.endDate)}
    </p>`;

  const text = [
    `Daily Summary — ${ev.title}`,
    new Date(now).toLocaleDateString(),
    '',
    `Registrations: ${totalRegistrations} | Paid: ${paidCount} | Pending: ${pendingCount} | Revenue: ${fmtAmount(totalRevenue)}`,
    '',
    'Registrations:',
    ...(regRows.length ? regRows.map(r => `  ${r.name} <${r.email}> — ${r.status} — due: ${fmtAmount(r.totalDue)} paid: ${fmtAmount(r.totalPaid)} balance: ${fmtAmount(r.balance)}`) : ['  (none)']),
    '',
    'Payments:',
    ...(payRows.length ? payRows.map(p => `  ${p.date} — ${fmtAmount(p.amount)} via ${p.method} — ${p.isDonation ? 'Donation' : 'Registration'} — ${p.payerName}`) : ['  (none)']),
  ].join('\n');

  return { subject, text, html: emailWrapper(body) };
}

// ─── Send functions ───────────────────────────────────────────────────────────

/**
 * Generates an invoice PDF for a registration when it still has an outstanding balance,
 * reusing (or, if none was supplied, creating) a Yoco checkout link so the invoice can carry
 * a clickable "pay now" link and a scannable QR code. Returns null when nothing is owed or
 * PDF generation fails — callers fall back to the existing text-only notification either way.
 */
/**
 * Resolves a Yoco checkout link for an invoice's "pay now" link/QR code. Returns the given
 * hint as-is when supplied; otherwise creates a fresh checkout, or null if nothing is owed
 * (no point paying) or checkout creation fails (invoice still generates, just without a link).
 */
async function resolveInvoicePaymentUrl(reg, { totalDue, totalPaid, paymentUrlHint = null }) {
  if (paymentUrlHint) return paymentUrlHint;
  if (totalDue - totalPaid <= 0.01) return null;
  try {
    const { createRegistrationCheckoutInternal } = require('../controllers/paymentController');
    const baseUrl = process.env.FRONTEND_URL || process.env.APP_BASE_URL || 'http://localhost:3001';
    const checkout = await createRegistrationCheckoutInternal(reg.id, reg.userId, {
      successUrl: `${baseUrl}/payment/success`,
      cancelUrl: `${baseUrl}/payment/cancel`,
      failureUrl: `${baseUrl}/payment/failure`,
    });
    return checkout.redirectUrl || null;
  } catch (e) {
    console.warn('Could not create Yoco checkout for invoice PDF:', e?.message || e);
    return null;
  }
}

// Only used by the automatic registration-confirmation sends, which should stay silent (no
// invoice attached) when nothing is owed — receipts already cover the fully-paid case.
async function maybeGenerateInvoicePdf(reg, { totalDue, totalPaid, paymentUrlHint = null }) {
  if (totalDue - totalPaid <= 0.01) return null;
  const paymentUrl = await resolveInvoicePaymentUrl(reg, { totalDue, totalPaid, paymentUrlHint });
  try {
    const { generateInvoicePdf } = require('./pdfDocs');
    return await generateInvoicePdf(reg, { paymentUrl, totalDue, totalPaid });
  } catch (e) {
    console.error('Failed to generate invoice PDF:', e);
    return null;
  }
}

async function sendRegistrationEmails(registrationId) {
  let invoicePdf = null;
  try {
    const reg = await loadRegistrationFull(registrationId);
    if (!reg) return;
    const { shouldEmail, waPdf, waText } = require('./notify');
    const { buildWARegistration } = require('./waMessages');
    const { computeRegistrationTotalDue } = require('./pricing');

    const sends = [];
    const totalDue  = computeRegistrationTotalDue(reg, new Date());
    const totalPaid = (reg.payments || []).reduce((s, p) => s + (p.amount || 0), 0);
    invoicePdf = await maybeGenerateInvoicePdf(reg, { totalDue, totalPaid });

    // Email: only for real addresses (skip guest.local placeholders)
    if (reg.user?.email && !reg.user.email.endsWith('@guest.local')) {
      const msg = buildRegistrationConfirmation(reg, { isNew: true });
      if (shouldEmail(reg.user)) sends.push(sendMail({
        to: reg.user.email, subject: msg.subject, html: msg.html, text: msg.text,
        ...(invoicePdf ? { attachments: [{ filename: invoicePdf.filename, path: invoicePdf.filePath, contentType: 'application/pdf' }] } : {}),
      }));
    }
    // WhatsApp: always attempt — waText/waPdf check canWhatsApp (preference + valid phone) internally
    const waCaption = buildWARegistration(reg, { isNew: true, totalDue, totalPaid, balance: Math.max(totalDue - totalPaid, 0) });
    sends.push(invoicePdf ? waPdf(reg.user, invoicePdf.filePath, invoicePdf.filename, waCaption) : waText(reg.user, waCaption));

    const adminMsg = buildRegistrationAdminNotice(reg, { isNew: true });
    if (adminMsg.to && adminMsg.to.length) {
      sends.push(sendMail({ to: adminMsg.to.join(','), subject: adminMsg.subject, html: adminMsg.html, text: adminMsg.text }));
    }
    await Promise.all(sends);
  } catch (e) {
    console.error('Failed to send registration emails:', e);
  } finally {
    if (invoicePdf) try { fs.unlinkSync(invoicePdf.filePath); } catch {}
  }
}

async function sendRegistrationUpdatedEmails(registrationId) {
  let invoicePdf = null;
  try {
    const reg = await loadRegistrationFull(registrationId);
    if (!reg) return;
    const { shouldEmail, waPdf, waText } = require('./notify');
    const { buildWARegistration } = require('./waMessages');
    const { computeRegistrationTotalDue } = require('./pricing');

    const sends = [];
    const totalDue  = computeRegistrationTotalDue(reg, new Date());
    const totalPaid = (reg.payments || []).reduce((s, p) => s + (p.amount || 0), 0);
    invoicePdf = await maybeGenerateInvoicePdf(reg, { totalDue, totalPaid });

    if (reg.user?.email && !reg.user.email.endsWith('@guest.local')) {
      const msg = buildRegistrationConfirmation(reg, { isNew: false });
      if (shouldEmail(reg.user)) sends.push(sendMail({
        to: reg.user.email, subject: msg.subject, html: msg.html, text: msg.text,
        ...(invoicePdf ? { attachments: [{ filename: invoicePdf.filename, path: invoicePdf.filePath, contentType: 'application/pdf' }] } : {}),
      }));
    }
    const waCaption = buildWARegistration(reg, { isNew: false, totalDue, totalPaid, balance: Math.max(totalDue - totalPaid, 0) });
    sends.push(invoicePdf ? waPdf(reg.user, invoicePdf.filePath, invoicePdf.filename, waCaption) : waText(reg.user, waCaption));
    const adminMsg = buildRegistrationAdminNotice(reg, { isNew: false, isUpdated: true });
    if (adminMsg.to && adminMsg.to.length) {
      sends.push(sendMail({ to: adminMsg.to.join(','), subject: adminMsg.subject, html: adminMsg.html, text: adminMsg.text }));
    }
    await Promise.all(sends);
  } catch (e) {
    console.error('Failed to send registration updated emails:', e);
  } finally {
    if (invoicePdf) try { fs.unlinkSync(invoicePdf.filePath); } catch {}
  }
}

async function sendSelfServiceRegistrationEmails(registrationId, { paymentUrl = null, formRequired = false, isNew = true } = {}) {
  let invoicePdf = null;
  try {
    const reg = await loadRegistrationFull(registrationId);
    if (!reg) return;
    const { shouldEmail, waPdf, waText } = require('./notify');
    const { buildWARegistration } = require('./waMessages');
    const { computeRegistrationTotalDue } = require('./pricing');

    const sends = [];
    const totalDue  = computeRegistrationTotalDue(reg, new Date());
    const totalPaid = (reg.payments || []).reduce((s, p) => s + (p.amount || 0), 0);
    invoicePdf = await maybeGenerateInvoicePdf(reg, { totalDue, totalPaid, paymentUrlHint: paymentUrl });

    if (reg.user?.email && !reg.user.email.endsWith('@guest.local')) {
      const msg = buildAdminInitiatedRegistrationConfirmation(reg, { yocoLink: paymentUrl, formRequired, isNew });
      if (shouldEmail(reg.user)) sends.push(sendMail({
        to: reg.user.email, subject: msg.subject, html: msg.html, text: msg.text,
        ...(invoicePdf ? { attachments: [{ filename: invoicePdf.filename, path: invoicePdf.filePath, contentType: 'application/pdf' }] } : {}),
      }));
    }
    const waCaption = buildWARegistration(reg, { isNew, totalDue, totalPaid, balance: Math.max(totalDue - totalPaid, 0) });
    sends.push(invoicePdf ? waPdf(reg.user, invoicePdf.filePath, invoicePdf.filename, waCaption) : waText(reg.user, waCaption));
    const adminMsg = buildRegistrationAdminNotice(reg, { isNew, isUpdated: !isNew });
    if (adminMsg.to && adminMsg.to.length) {
      sends.push(sendMail({ to: adminMsg.to.join(','), subject: adminMsg.subject, html: adminMsg.html, text: adminMsg.text }));
    }
    await Promise.all(sends);
  } catch (e) {
    console.error('Failed to send self-service registration emails:', e);
  } finally {
    if (invoicePdf) try { fs.unlinkSync(invoicePdf.filePath); } catch {}
  }
}

async function sendPaymentEmails(paymentId) {
  let receiptPdf = null;
  try {
    const payment = await loadPaymentFull(paymentId);
    if (!payment) return;
    const user = payment.registration?.user || payment.user;
    const { shouldEmail, waPdf, waPdfAny, waText, waTextAny } = require('./notify');
    const { buildWAPayment } = require('./waMessages');
    const { generateReceiptPdf } = require('./pdfDocs');

    try { receiptPdf = await generateReceiptPdf(payment); } catch (e) { console.error('Failed to generate receipt PDF:', e); }

    const sends = [];
    const hasValidEmail = user?.email && !user.email.endsWith('@guest.local') && !user.email.endsWith('@deleted.invalid');
    if (hasValidEmail) {
      const msg = buildPaymentReceipt(payment);
      if (shouldEmail(user)) sends.push(sendMail({
        to: user.email, subject: msg.subject, html: msg.html, text: msg.text,
        ...(receiptPdf ? { attachments: [{ filename: receiptPdf.filename, path: receiptPdf.filePath, contentType: 'application/pdf' }] } : {}),
      }));
    }
    // WhatsApp: respect preference when email is available; use as unconditional fallback when it isn't.
    // Send the receipt PDF (with the usual text as its caption) when generation succeeded,
    // otherwise fall back to the plain text message so a PDF failure never blocks delivery.
    const waCaption = buildWAPayment(payment);
    if (hasValidEmail) {
      sends.push(receiptPdf ? waPdf(user, receiptPdf.filePath, receiptPdf.filename, waCaption) : waText(user, waCaption));
    } else {
      sends.push(receiptPdf ? waPdfAny(user, receiptPdf.filePath, receiptPdf.filename, waCaption) : waTextAny(user, waCaption));
    }
    const hasEvent = !!(payment.registration?.eventId || payment.eventId);
    if (hasEvent) {
      const adminMsg = buildPaymentAdminNotice(payment);
      if (adminMsg.to && adminMsg.to.length) {
        sends.push(sendMail({ to: adminMsg.to.join(','), subject: adminMsg.subject, html: adminMsg.html, text: adminMsg.text }));
      }
    }
    await Promise.all(sends);
  } catch (e) {
    console.error('Failed to send payment emails:', e);
  } finally {
    if (receiptPdf) try { fs.unlinkSync(receiptPdf.filePath); } catch {}
  }
}

async function sendRefundEmail(refundPaymentId) {
  try {
    const payment = await loadPaymentFull(refundPaymentId);
    if (!payment) return;

    const user = payment.user;
    if (!user?.email || user.email.endsWith('@guest.local')) return;

    const msg = buildRefundEmail(payment);
    const sends = [sendMail({ to: user.email, subject: msg.subject, html: msg.html, text: msg.text })];

    const adminMsg = buildPaymentAdminNotice(payment);
    if (adminMsg.to && adminMsg.to.length) {
      sends.push(sendMail({ to: adminMsg.to.join(','), subject: `Refund: ${adminMsg.subject}`, html: adminMsg.html, text: adminMsg.text }));
    }
    await Promise.all(sends);
  } catch (e) {
    console.error('Failed to send refund email:', e);
  }
}

async function sendCheckInEmails(ticketId, qtyRedeemed, totalRedeemed, remaining) {
  try {
    const ticket = await loadTicketFull(ticketId);
    if (!ticket) return;
    const user = ticket.user;
    const { shouldEmail, waText, waTextAny } = require('./notify');
    const { buildWACheckIn } = require('./waMessages');

    const sends = [];
    const hasValidEmail = user?.email && !user.email.endsWith('@guest.local') && !user.email.endsWith('@deleted.invalid');
    if (hasValidEmail && shouldEmail(user)) {
      const msg = buildCheckInConfirmation(ticket, qtyRedeemed, totalRedeemed, remaining);
      sends.push(sendMail({ to: user.email, subject: msg.subject, html: msg.html, text: msg.text }));
    }
    const waMsg = buildWACheckIn(ticket, qtyRedeemed, totalRedeemed, remaining);
    if (hasValidEmail) {
      sends.push(waText(user, waMsg));
    } else {
      sends.push(waTextAny(user, waMsg));
    }
    await Promise.all(sends);
  } catch (e) {
    console.error('Failed to send check-in emails:', e);
  }
}

// Sent when staff apply a donation to someone's registration. Only the registrant is
// notified (anonymously, per design) — the donor already received their donation-received
// notification when the donation was originally made, so they are deliberately not emailed
// again here, and any leftover/unassigned remainder from a partial allocation is silent too.
async function sendDonationAssignmentEmails(paymentId) {
  try {
    const payment = await loadPaymentFull(paymentId);
    if (!payment || !payment.registration) return;
    const user = payment.registration.user;
    const { shouldEmail, waText, waTextAny } = require('./notify');
    const { buildWADonationAppliedToRegistrant } = require('./waMessages');

    const sends = [];
    const hasValidEmail = user?.email && !user.email.endsWith('@guest.local') && !user.email.endsWith('@deleted.invalid');
    if (hasValidEmail) {
      const msg = buildDonationAppliedToRegistrant(payment);
      if (shouldEmail(user)) sends.push(sendMail({ to: user.email, subject: msg.subject, html: msg.html, text: msg.text }));
    }
    if (hasValidEmail) {
      sends.push(waText(user, buildWADonationAppliedToRegistrant(payment)));
    } else {
      sends.push(waTextAny(user, buildWADonationAppliedToRegistrant(payment)));
    }
    const adminMsg = buildDonationAssignmentAdminNotice(payment);
    if (adminMsg.to && adminMsg.to.length) {
      sends.push(sendMail({ to: adminMsg.to.join(','), subject: adminMsg.subject, html: adminMsg.html, text: adminMsg.text }));
    }
    await Promise.all(sends);
  } catch (e) {
    console.error('Failed to send donation-assignment emails:', e);
  }
}

// Sent when staff reverse a previous donation-assignment (the leg payment is hard-deleted
// before this runs, so it can't be re-fetched by id like loadPaymentFull does elsewhere —
// callers pass a snapshot of the leg's fields captured just before deletion instead).
// Notifies the registrant (balance likely increased) and logs an internal admin notice showing
// the donor as "Payer", same as the original assignment notice did.
async function sendDonationUnassignmentEmails(leg) {
  try {
    const [registration, donor] = await Promise.all([
      prisma.registration.findUnique({
        where: { id: leg.registrationId },
        include: {
          registrationOptions: { include: { eventOption: { include: { earlyBirdTiers: true } }, tranches: true } },
          payments: true,
          user: { select: { id: true, name: true, email: true, phoneNumber: true, isActive: true, notificationPreference: true } },
          event: { include: { createdBy: { select: { id: true, name: true, email: true } }, notifyRecipients: { select: { id: true, name: true, email: true } } } },
        },
      }),
      leg.userId ? prisma.user.findUnique({ where: { id: leg.userId }, select: { id: true, name: true, email: true } }) : null,
    ]);
    if (!registration) return;

    // Synthetic payment-shaped object matching what buildDonationUnassignedFromRegistrant and
    // buildPaymentAdminNotice (via buildDonationUnassignmentAdminNotice) expect.
    const pseudoPayment = {
      id: leg.id,
      amount: leg.amount,
      createdAt: leg.createdAt,
      method: leg.method,
      externalId: leg.externalId,
      registrationId: leg.registrationId,
      registration,
      user: donor,
    };

    const user = registration.user;
    const { shouldEmail, waText, waTextAny } = require('./notify');
    const { buildWADonationUnassignedFromRegistrant } = require('./waMessages');

    const sends = [];
    const hasValidEmail = user?.email && !user.email.endsWith('@guest.local') && !user.email.endsWith('@deleted.invalid');
    if (hasValidEmail) {
      const msg = buildDonationUnassignedFromRegistrant(pseudoPayment);
      if (shouldEmail(user)) sends.push(sendMail({ to: user.email, subject: msg.subject, html: msg.html, text: msg.text }));
    }
    if (hasValidEmail) {
      sends.push(waText(user, buildWADonationUnassignedFromRegistrant(pseudoPayment)));
    } else {
      sends.push(waTextAny(user, buildWADonationUnassignedFromRegistrant(pseudoPayment)));
    }
    const adminMsg = buildDonationUnassignmentAdminNotice(pseudoPayment);
    if (adminMsg.to && adminMsg.to.length) {
      sends.push(sendMail({ to: adminMsg.to.join(','), subject: adminMsg.subject, html: adminMsg.html, text: adminMsg.text }));
    }
    await Promise.all(sends);
  } catch (e) {
    console.error('Failed to send donation-unassignment emails:', e);
  }
}

// ─── Manual "send to me" requests ──────────────────────────────────────────────
// Unlike the fire-and-forget sends above, these are awaited directly from a
// request handler (dashboard "Email/WhatsApp invoice|receipt" buttons) — they
// throw an Error with a `statusCode` on failure instead of swallowing it, so the
// controller can surface a real error to the user rather than failing silently.

function userFacingError(message, statusCode) {
  const e = new Error(message);
  e.statusCode = statusCode;
  return e;
}

/**
 * (re)generates and sends a registration's invoice PDF to the registrant on a single,
 * explicitly-chosen channel. Only the registrant themself may request their own invoice.
 * @param {string} registrationId
 * @param {string} requesterId - req.user.id of the caller
 * @param {'email'|'whatsapp'} channel
 */
async function sendInvoiceToUser(registrationId, requesterId, channel) {
  if (channel !== 'email' && channel !== 'whatsapp') throw userFacingError('Invalid channel', 400);

  const reg = await loadRegistrationFull(registrationId);
  if (!reg) throw userFacingError('Registration not found', 404);
  if (reg.userId !== requesterId) throw userFacingError('Not authorized to access this registration', 403);

  if (channel === 'email' && (!reg.user?.email || reg.user.email.endsWith('@guest.local'))) {
    throw userFacingError('No valid email address on file. Add one in your profile.', 400);
  }
  if (channel === 'whatsapp' && !reg.user?.phoneNumber) {
    throw userFacingError('No phone number on file. Add one in your profile.', 400);
  }

  const totalDue = computeRegistrationTotalDue(reg, new Date());
  const totalPaid = (reg.payments || []).reduce((s, p) => s + (p.amount || 0), 0);

  // Unlike the automatic post-registration send, a manually-requested invoice is generated
  // regardless of balance — someone may want it as a paid-in-full record too.
  const paymentUrl = await resolveInvoicePaymentUrl(reg, { totalDue, totalPaid });
  let invoicePdf;
  try {
    const { generateInvoicePdf } = require('./pdfDocs');
    invoicePdf = await generateInvoicePdf(reg, { paymentUrl, totalDue, totalPaid });
  } catch (e) {
    console.error('Failed to generate invoice PDF:', e);
    throw userFacingError('Could not generate the invoice right now. Please try again shortly.', 500);
  }

  try {
    const eventTitle = reg.event?.title || 'your registration';
    if (channel === 'email') {
      await sendMail({
        to: reg.user.email,
        subject: `Your invoice for ${eventTitle}`,
        html: emailWrapper(
          `<p style="font-size:18px;font-weight:700;color:#0f172a;margin:0 0 12px 0">Your invoice is attached</p>
           <p style="margin:0;color:#374151;font-family:${ff}">Hi <strong>${reg.user?.name || 'there'}</strong>, here's the invoice you requested for <strong>${eventTitle}</strong>.</p>`
        ),
        text: `Hi ${reg.user?.name || 'there'},\n\nHere's the invoice you requested for ${eventTitle} — see the attached PDF.`,
        attachments: [{ filename: invoicePdf.filename, path: invoicePdf.filePath, contentType: 'application/pdf' }],
      });
    } else {
      // Explicit user-requested channel — bypass the notification-preference gate (waPdfAny)
      // the same way ticket resends do, so "WhatsApp invoice" works even if the user's saved
      // preference is email-only.
      const { waPdfAny } = require('./notify');
      const { buildWARegistration } = require('./waMessages');
      const caption = buildWARegistration(reg, { isNew: false, totalDue, totalPaid, balance: Math.max(totalDue - totalPaid, 0) });
      await waPdfAny(reg.user, invoicePdf.filePath, invoicePdf.filename, caption);
    }
  } finally {
    try { fs.unlinkSync(invoicePdf.filePath); } catch {}
  }
}

/**
 * (Re)generates and sends a payment's receipt PDF to the payer on a single, explicitly-chosen
 * channel. Only the person the payment belongs to (via the payment itself or its registration)
 * may request their own receipt.
 * @param {string} paymentId
 * @param {string} requesterId - req.user.id of the caller
 * @param {'email'|'whatsapp'} channel
 */
async function sendReceiptToUser(paymentId, requesterId, channel) {
  if (channel !== 'email' && channel !== 'whatsapp') throw userFacingError('Invalid channel', 400);

  const payment = await loadPaymentFull(paymentId);
  if (!payment) throw userFacingError('Payment not found', 404);
  const owner = payment.registration?.user || payment.user;
  const ownerId = payment.registration?.userId || payment.userId;
  if (ownerId !== requesterId) throw userFacingError('Not authorized to access this payment', 403);

  if (channel === 'email' && (!owner?.email || owner.email.endsWith('@guest.local'))) {
    throw userFacingError('No valid email address on file. Add one in your profile.', 400);
  }
  if (channel === 'whatsapp' && !owner?.phoneNumber) {
    throw userFacingError('No phone number on file. Add one in your profile.', 400);
  }

  const { generateReceiptPdf } = require('./pdfDocs');
  let receiptPdf;
  try {
    receiptPdf = await generateReceiptPdf(payment);
  } catch (e) {
    console.error('Failed to generate receipt PDF:', e);
    throw userFacingError('Could not generate the receipt right now. Please try again shortly.', 500);
  }

  try {
    const eventTitle = payment.registration?.event?.title || payment.event?.title || 'your registration';
    if (channel === 'email') {
      await sendMail({
        to: owner.email,
        subject: `Your payment receipt for ${eventTitle}`,
        html: emailWrapper(
          `<p style="font-size:18px;font-weight:700;color:#0f172a;margin:0 0 12px 0">Your receipt is attached</p>
           <p style="margin:0;color:#374151;font-family:${ff}">Hi <strong>${owner?.name || 'there'}</strong>, here's the receipt you requested for your payment of <strong>${fmtAmount(payment.amount)}</strong> towards <strong>${eventTitle}</strong>.</p>`
        ),
        text: `Hi ${owner?.name || 'there'},\n\nHere's the receipt you requested for your payment of ${fmtAmount(payment.amount)} towards ${eventTitle} — see the attached PDF.`,
        attachments: [{ filename: receiptPdf.filename, path: receiptPdf.filePath, contentType: 'application/pdf' }],
      });
    } else {
      const { waPdfAny } = require('./notify');
      const { buildWAPayment } = require('./waMessages');
      await waPdfAny(owner, receiptPdf.filePath, receiptPdf.filename, buildWAPayment(payment));
    }
  } finally {
    try { fs.unlinkSync(receiptPdf.filePath); } catch {}
  }
}

async function sendDailyEventSummaries(now = new Date()) {
  try {
    const today = new Date(now);
    const notifyInclude = { createdBy: { select: { id: true, name: true, email: true } }, notifyRecipients: { select: { id: true, name: true, email: true } } };
    let events = await prisma.event.findMany({
      where: { isActive: true, startDate: { gte: today }, requiresRegistration: true },
      include: notifyInclude,
      orderBy: { startDate: 'asc' },
    });

    try {
      events = await prisma.event.findMany({
        where: { isActive: true, startDate: { gte: today }, goLiveAt: { lte: today }, requiresRegistration: true },
        include: notifyInclude,
        orderBy: { startDate: 'asc' },
      });
    } catch {}

    await Promise.allSettled(events.map(async ev => {
      const registrations = await prisma.registration.findMany({
        where: { eventId: ev.id },
        include: {
          user: { select: { id: true, name: true, email: true, phoneNumber: true } },
          registrationOptions: { include: { eventOption: { include: { earlyBirdTiers: true } }, tranches: true } },
          payments: true,
        },
        orderBy: { createdAt: 'asc' },
      });

      const payments = await prisma.payment.findMany({
        where: { OR: [{ eventId: ev.id }, { registration: { eventId: ev.id } }] },
        include: {
          user: { select: { id: true, name: true, email: true } },
          registration: { select: { id: true, user: { select: { id: true, name: true, email: true } } } },
        },
        orderBy: { createdAt: 'asc' },
      });

      const { subject, text, html } = buildDailySummary(ev, registrations, payments, now);
      const to = buildEventNotifyRecipientList(ev);
      if (to.length) await sendMail({ to: to.join(','), subject, html, text });
    }));
  } catch (e) {
    console.error('Failed to send daily event summaries:', e);
  }
}

module.exports = {
  sendRegistrationEmails,
  sendRegistrationUpdatedEmails,
  sendPaymentEmails,
  sendDailyEventSummaries,
  sendRefundEmail,
  sendSelfServiceRegistrationEmails,
  sendDonationAssignmentEmails,
  sendDonationUnassignmentEmails,
  sendCheckInEmails,
  buildCheckInConfirmation,
  sendInvoiceToUser,
  sendReceiptToUser,
};