/**
 * Email sending utility for the PieCed portal.
 *
 * Uses nodemailer with SMTP credentials from environment variables
 * (populated via ExternalSecret from OpenBao at pieced/portal/smtp).
 *
 * Env vars (from portal-smtp K8s secret):
 *   SMTP_HOST                  — e.g. smtp.gmail.com
 *   SMTP_PORT                  — e.g. 587 (default)
 *   SMTP_USER                  — e.g. noreply@pieced.ch
 *   SMTP_PASS                  — App Password
 *   SMTP_FROM                  — e.g. "PieCed <noreply@pieced.ch>"
 *   ADMIN_NOTIFICATION_EMAIL   — e.g. admin@pieced.ch (optional)
 *   SUPPORT_CONTACT_EMAIL      — e.g. support@pieced.ch (optional)
 *                                 Customer-facing address for "have
 *                                 questions?" follow-ups in
 *                                 transactional emails. The from
 *                                 address itself (SMTP_USER) is
 *                                 typically a noreply mailbox, so we
 *                                 don't tell customers to "reply to
 *                                 this email" — instead we point them
 *                                 at this monitored address. If
 *                                 unset, the contact-prompt line is
 *                                 simply omitted from emails.
 */

import nodemailer from "nodemailer";

let _transporter: nodemailer.Transporter | null = null;

function getTransporter(): nodemailer.Transporter {
  if (!_transporter) {
    const host = process.env.SMTP_HOST;
    const user = process.env.SMTP_USER;
    const pass = process.env.SMTP_PASS;
    if (!host || !user || !pass) {
      throw new Error("SMTP_HOST, SMTP_USER, and SMTP_PASS must be set");
    }
    _transporter = nodemailer.createTransport({
      host,
      port: parseInt(process.env.SMTP_PORT || "587", 10),
      secure: process.env.SMTP_SECURE === "true",
      auth: { user, pass },
    });
  }
  return _transporter;
}

function getFrom(): string {
  return (
    process.env.SMTP_FROM ||
    `PieCed <${process.env.SMTP_USER}>`
  );
}

/** Returns the customer-facing support email address, or null if unset. */
function getSupportContactEmail(): string | null {
  const v = process.env.SUPPORT_CONTACT_EMAIL?.trim();
  return v && v.length > 0 ? v : null;
}

/**
 * Escape HTML entities to prevent injection in HTML emails.
 */
function escapeHtml(str: string): string {
  return str
    .replace(/&/g, "&amp;")
    .replace(/</g, "&lt;")
    .replace(/>/g, "&gt;")
    .replace(/"/g, "&quot;")
    .replace(/'/g, "&#39;");
}

export async function sendApprovalEmail(
  to: string,
  contactName: string,
  companyName: string
): Promise<void> {
  const safeName = escapeHtml(contactName);
  const safeCompany = escapeHtml(companyName);

  try {
    await getTransporter().sendMail({
      from: getFrom(),
      to,
      subject: `Your PieCed AI assistant is being set up — ${companyName}`,
      text: [
        `Hello ${contactName},`,
        "",
        `Great news! Your onboarding request for ${companyName} has been approved.`,
        "",
        "Your AI assistant instance is now being provisioned. This usually takes a few minutes.",
        "You can check the status in your dashboard at https://app.pieced.ch",
        "",
        "Once your instance is ready, you'll see it on your dashboard and can start configuring it.",
        "",
        "Best regards,",
        "PieCed IT",
      ].join("\n"),
      html: `
        <div style="font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', sans-serif; max-width: 560px; margin: 0 auto; color: #e0e0e0; background: #1a1a1a; padding: 32px; border-radius: 12px;">
          <h2 style="color: #ffffff; margin-top: 0;">Your AI assistant is being set up</h2>
          <p>Hello ${safeName},</p>
          <p>Great news! Your onboarding request for <strong>${safeCompany}</strong> has been approved.</p>
          <p>Your AI assistant instance is now being provisioned. This usually takes a few minutes.</p>
          <p>
            <a href="https://app.pieced.ch" style="display: inline-block; padding: 10px 24px; background: #3b82f6; color: #ffffff; text-decoration: none; border-radius: 8px; font-weight: 500;">
              Go to Dashboard
            </a>
          </p>
          <p style="color: #888; font-size: 13px; margin-top: 24px;">
            Once your instance is ready, you'll see it on your dashboard and can start configuring it.
          </p>
          <hr style="border: none; border-top: 1px solid #333; margin: 24px 0;" />
          <p style="color: #666; font-size: 12px;">PieCed IT — Hosted on-premises in Switzerland</p>
        </div>
      `,
    });
  } catch (err) {
    console.error("Failed to send approval email:", err);
  }
}

export async function sendRejectionEmail(
  to: string,
  contactName: string,
  companyName: string,
  adminNotes?: string
): Promise<void> {
  const safeName = escapeHtml(contactName);
  const safeCompany = escapeHtml(companyName);
  const safeNotes = adminNotes ? escapeHtml(adminNotes) : "";

  try {
    const notesBlock = adminNotes
      ? `\nNote from our team:\n${adminNotes}\n`
      : "";
    const notesHtml = safeNotes
      ? `<div style="background: #2a2a2a; border-left: 3px solid #ef4444; padding: 12px 16px; border-radius: 6px; margin: 16px 0;">
           <p style="color: #ccc; font-size: 13px; margin: 0;"><strong>Note from our team:</strong></p>
           <p style="color: #aaa; font-size: 13px; margin: 8px 0 0 0;">${safeNotes}</p>
         </div>`
      : "";

    const supportEmail = getSupportContactEmail();
    // The customer here is rejected pre-onboarding — they don't yet
    // have a portal account, so we can't send them to /support.
    // Instead point at the configured support address (if set).
    // If unset (e.g. early pilot before a support inbox exists), we
    // omit the follow-up line entirely rather than promise something
    // that goes nowhere — telling the customer to "reply to this
    // email" would be misleading because we send from a noreply box.
    const contactLineText = supportEmail
      ? `If you have questions or would like to discuss this further, please contact us at ${supportEmail}.`
      : "";
    const contactLineHtml = supportEmail
      ? `<p>If you have questions or would like to discuss this further, please contact us at <a href="mailto:${escapeHtml(supportEmail)}" style="color: #3b82f6;">${escapeHtml(supportEmail)}</a>.</p>`
      : "";

    await getTransporter().sendMail({
      from: getFrom(),
      to,
      subject: `Update on your PieCed onboarding request — ${companyName}`,
      text: [
        `Hello ${contactName},`,
        "",
        `Thank you for your interest in PieCed IT. Unfortunately, we were unable to approve your onboarding request for ${companyName} at this time.`,
        notesBlock,
        contactLineText,
        "",
        "Best regards,",
        "PieCed IT",
      ]
        .filter((s) => s !== "")
        .join("\n"),
      html: `
        <div style="font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', sans-serif; max-width: 560px; margin: 0 auto; color: #e0e0e0; background: #1a1a1a; padding: 32px; border-radius: 12px;">
          <h2 style="color: #ffffff; margin-top: 0;">Update on your onboarding request</h2>
          <p>Hello ${safeName},</p>
          <p>Thank you for your interest in PieCed IT. Unfortunately, we were unable to approve your onboarding request for <strong>${safeCompany}</strong> at this time.</p>
          ${notesHtml}
          ${contactLineHtml}
          <hr style="border: none; border-top: 1px solid #333; margin: 24px 0;" />
          <p style="color: #666; font-size: 12px;">PieCed IT — Hosted on-premises in Switzerland</p>
        </div>
      `,
    });
  } catch (err) {
    console.error("Failed to send rejection email:", err);
  }
}

/**
 * Bug 37a: separate email for resume request approval. The tenant
 * already exists; the message is "we're un-suspending it" rather than
 * "we're provisioning a new instance". Avoids confusing the customer
 * with onboarding language for a tenant they already had.
 */
export async function sendResumeApprovalEmail(
  to: string,
  contactName: string,
  companyName: string
): Promise<void> {
  const safeName = escapeHtml(contactName);
  const safeCompany = escapeHtml(companyName);

  try {
    await getTransporter().sendMail({
      from: getFrom(),
      to,
      subject: `Your PieCed AI assistant has been reactivated — ${companyName}`,
      text: [
        `Hello ${contactName},`,
        "",
        `Good news — your reactivation request for ${companyName} has been approved.`,
        "",
        "Your AI assistant is being brought back online and should be ready in a few minutes.",
        "You can check the status in your dashboard at https://app.pieced.ch",
        "",
        "Best regards,",
        "PieCed IT",
      ].join("\n"),
      html: `
        <div style="font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', sans-serif; max-width: 560px; margin: 0 auto; color: #e0e0e0; background: #1a1a1a; padding: 32px; border-radius: 12px;">
          <h2 style="color: #ffffff; margin-top: 0;">Your AI assistant has been reactivated</h2>
          <p>Hello ${safeName},</p>
          <p>Good news — your reactivation request for <strong>${safeCompany}</strong> has been approved.</p>
          <p>Your AI assistant is being brought back online and should be ready in a few minutes.</p>
          <p>
            <a href="https://app.pieced.ch" style="display: inline-block; padding: 10px 24px; background: #3b82f6; color: #ffffff; text-decoration: none; border-radius: 8px; font-weight: 500;">
              Go to Dashboard
            </a>
          </p>
          <hr style="border: none; border-top: 1px solid #333; margin: 24px 0;" />
          <p style="color: #666; font-size: 12px;">PieCed IT — Hosted on-premises in Switzerland</p>
        </div>
      `,
    });
  } catch (err) {
    console.error("Failed to send resume approval email:", err);
  }
}

/**
 * Bug 37a: separate email for resume request rejection. Differs from
 * the onboarding rejection in two ways: it explicitly mentions the
 * tenant remains suspended, and it points the customer to the
 * 60-day retention window so they understand the deletion clock is
 * still ticking. The latter is important — a customer reading a
 * generic "request rejected" email might not realise their data is
 * still on a countdown.
 */
export async function sendResumeRejectionEmail(
  to: string,
  contactName: string,
  companyName: string,
  adminNotes?: string
): Promise<void> {
  const safeName = escapeHtml(contactName);
  const safeCompany = escapeHtml(companyName);
  const safeNotes = adminNotes ? escapeHtml(adminNotes) : "";

  try {
    const notesBlock = adminNotes
      ? `\nNote from our team:\n${adminNotes}\n`
      : "";
    const notesHtml = safeNotes
      ? `<div style="background: #2a2a2a; border-left: 3px solid #ef4444; padding: 12px 16px; border-radius: 6px; margin: 16px 0;">
           <p style="color: #ccc; font-size: 13px; margin: 0;"><strong>Note from our team:</strong></p>
           <p style="color: #aaa; font-size: 13px; margin: 8px 0 0 0;">${safeNotes}</p>
         </div>`
      : "";

    // The customer has portal access (their tenant exists, they
    // just had a resume request rejected), so direct them to the
    // support ticket system for follow-up. We never tell them to
    // "reply to this email" because the from address is a noreply
    // mailbox.
    const contactLineText =
      "If you have questions, open a support ticket at https://app.pieced.ch/support.";
    const contactLineHtml = `<p>If you have questions, <a href="https://app.pieced.ch/support" style="color: #3b82f6;">open a support ticket</a>.</p>`;

    await getTransporter().sendMail({
      from: getFrom(),
      to,
      subject: `Update on your reactivation request — ${companyName}`,
      text: [
        `Hello ${contactName},`,
        "",
        `Thank you for your reactivation request for ${companyName}. Unfortunately, we were unable to approve it at this time.`,
        notesBlock,
        "Your tenant remains suspended. As a reminder, your data is preserved for 60 days from the original cancellation date, after which it will be permanently deleted. You can submit a new reactivation request at any time before then.",
        "",
        contactLineText,
        "",
        "Best regards,",
        "PieCed IT",
      ].join("\n"),
      html: `
        <div style="font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', sans-serif; max-width: 560px; margin: 0 auto; color: #e0e0e0; background: #1a1a1a; padding: 32px; border-radius: 12px;">
          <h2 style="color: #ffffff; margin-top: 0;">Update on your reactivation request</h2>
          <p>Hello ${safeName},</p>
          <p>Thank you for your reactivation request for <strong>${safeCompany}</strong>. Unfortunately, we were unable to approve it at this time.</p>
          ${notesHtml}
          <p>Your tenant remains suspended. As a reminder, your data is preserved for 60 days from the original cancellation date, after which it will be permanently deleted. You can submit a new reactivation request at any time before then.</p>
          ${contactLineHtml}
          <hr style="border: none; border-top: 1px solid #333; margin: 24px 0;" />
          <p style="color: #666; font-size: 12px;">PieCed IT — Hosted on-premises in Switzerland</p>
        </div>
      `,
    });
  } catch (err) {
    console.error("Failed to send resume rejection email:", err);
  }
}

export async function sendAdminNotificationEmail(
  companyName: string,
  contactName: string,
  contactEmail: string
): Promise<void> {
  const adminEmail = process.env.ADMIN_NOTIFICATION_EMAIL;
  if (!adminEmail) return;

  const safeCompany = escapeHtml(companyName);
  const safeName = escapeHtml(contactName);
  const safeEmail = escapeHtml(contactEmail);

  try {
    await getTransporter().sendMail({
      from: getFrom(),
      to: adminEmail,
      subject: `New onboarding request: ${companyName}`,
      text: [
        `A new onboarding request has been submitted.`,
        "",
        `Company: ${companyName}`,
        `Contact: ${contactName} (${contactEmail})`,
        "",
        `Review it at https://app.pieced.ch/admin`,
      ].join("\n"),
      html: `
        <div style="font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', sans-serif; max-width: 560px; margin: 0 auto; color: #e0e0e0; background: #1a1a1a; padding: 32px; border-radius: 12px;">
          <h2 style="color: #ffffff; margin-top: 0;">New onboarding request</h2>
          <p>A new onboarding request has been submitted.</p>
          <table style="color: #ccc; font-size: 14px; margin: 16px 0;">
            <tr><td style="padding: 4px 12px 4px 0; color: #888;">Company:</td><td>${safeCompany}</td></tr>
            <tr><td style="padding: 4px 12px 4px 0; color: #888;">Contact:</td><td>${safeName} (${safeEmail})</td></tr>
          </table>
          <p>
            <a href="https://app.pieced.ch/admin" style="display: inline-block; padding: 10px 24px; background: #3b82f6; color: #ffffff; text-decoration: none; border-radius: 8px; font-weight: 500;">
              Review Request
            </a>
          </p>
          <hr style="border: none; border-top: 1px solid #333; margin: 24px 0;" />
          <p style="color: #666; font-size: 12px;">PieCed IT — Hosted on-premises in Switzerland</p>
        </div>
      `,
    });
  } catch (err) {
    console.error("Failed to send admin notification email:", err);
  }
}

// ---------------------------------------------------------------------------
// Feature 6: resume-request admin notification
// ---------------------------------------------------------------------------

/**
 * Notify the admin distribution list that a customer has requested
 * reactivation of a suspended tenant. Distinct from the onboarding
 * notification because the action consequences differ (admin
 * approving a resume just unsuspends an existing tenant; no
 * provisioning runs), and because the customer's note — explaining
 * why they want reactivation — is meaningful context for the admin
 * triaging the queue.
 *
 * Skipped silently if ADMIN_NOTIFICATION_EMAIL isn't set, matching
 * the pattern of the other admin notification functions.
 */
export async function sendResumeRequestAdminNotificationEmail(params: {
  tenantName: string;
  companyName: string;
  contactName: string;
  contactEmail: string;
  customerNotes?: string | null;
}): Promise<void> {
  const adminEmail = process.env.ADMIN_NOTIFICATION_EMAIL;
  if (!adminEmail) return;

  const safeCompany = escapeHtml(params.companyName);
  const safeName = escapeHtml(params.contactName);
  const safeEmail = escapeHtml(params.contactEmail);
  const safeTenant = escapeHtml(params.tenantName);
  const safeNotes = params.customerNotes ? escapeHtml(params.customerNotes) : "";

  const noteText = params.customerNotes
    ? `\nCustomer's note:\n${params.customerNotes}\n`
    : "";
  const noteHtml = safeNotes
    ? `<div style="background: #2a2a2a; border-left: 3px solid #3b82f6; padding: 12px 16px; border-radius: 6px; margin: 16px 0; white-space: pre-wrap;">
         <p style="color: #ccc; font-size: 13px; margin: 0 0 8px 0;"><strong>Customer's note:</strong></p>
         <p style="color: #e0e0e0; font-size: 13px; margin: 0;">${safeNotes}</p>
       </div>`
    : "";

  try {
    await getTransporter().sendMail({
      from: getFrom(),
      to: adminEmail,
      subject: `Reactivation request: ${params.companyName}`,
      text: [
        `A customer has requested reactivation of a suspended tenant.`,
        "",
        `Company: ${params.companyName}`,
        `Tenant:  ${params.tenantName}`,
        `Contact: ${params.contactName} (${params.contactEmail})`,
        noteText,
        `Review at https://app.pieced.ch/admin`,
      ]
        .filter((s) => s !== "")
        .join("\n"),
      html: `
        <div style="font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', sans-serif; max-width: 560px; margin: 0 auto; color: #e0e0e0; background: #1a1a1a; padding: 32px; border-radius: 12px;">
          <h2 style="color: #ffffff; margin-top: 0;">Reactivation request</h2>
          <p>A customer has requested reactivation of a suspended tenant.</p>
          <table style="color: #ccc; font-size: 14px; margin: 16px 0;">
            <tr><td style="padding: 4px 12px 4px 0; color: #888;">Company:</td><td>${safeCompany}</td></tr>
            <tr><td style="padding: 4px 12px 4px 0; color: #888;">Tenant:</td><td style="font-family: monospace;">${safeTenant}</td></tr>
            <tr><td style="padding: 4px 12px 4px 0; color: #888;">Contact:</td><td>${safeName} (${safeEmail})</td></tr>
          </table>
          ${noteHtml}
          <p>
            <a href="https://app.pieced.ch/admin" style="display: inline-block; padding: 10px 24px; background: #3b82f6; color: #ffffff; text-decoration: none; border-radius: 8px; font-weight: 500;">
              Review Request
            </a>
          </p>
          <hr style="border: none; border-top: 1px solid #333; margin: 24px 0;" />
          <p style="color: #666; font-size: 12px;">PieCed IT — Admin notification</p>
        </div>
      `,
    });
  } catch (err) {
    console.error("Failed to send resume request admin notification:", err);
  }
}

// ---------------------------------------------------------------------------
// Feature 5: support ticket emails
// ---------------------------------------------------------------------------

/**
 * Email subject prefix that helps customers thread tickets in their
 * mail client. We don't have inbound email processing — replies via
 * email back to us go nowhere — but the prefix is still useful for
 * the customer's own organisation. The id is shortened to 8 chars
 * for human readability; collisions on the truncated form within a
 * single user's inbox are vanishingly unlikely.
 */
function ticketSubjectPrefix(ticketId: string): string {
  return `[PieCed Support #${ticketId.slice(0, 8)}]`;
}

const STATUS_LABELS_EN: Record<string, string> = {
  open: "Open",
  in_progress: "In progress",
  waiting_for_customer: "Waiting for your reply",
  resolved: "Resolved",
  reopened: "Reopened",
};

/**
 * Sent to the customer when they create a ticket — confirmation
 * that we received it and a copy of the ticket id for their records.
 */
export async function sendSupportTicketCreatedEmail(params: {
  to: string;
  contactName: string;
  ticketId: string;
  title: string;
}): Promise<void> {
  const safeName = escapeHtml(params.contactName);
  const safeTitle = escapeHtml(params.title);
  const shortId = params.ticketId.slice(0, 8);
  const subject = `${ticketSubjectPrefix(params.ticketId)} ${params.title}`;

  try {
    await getTransporter().sendMail({
      from: getFrom(),
      to: params.to,
      subject,
      text: [
        `Hello ${params.contactName},`,
        "",
        `We've received your support request "${params.title}" (reference #${shortId}).`,
        "",
        "Our team will review and respond as soon as possible. You can track the status and reply at https://app.pieced.ch/support.",
        "",
        "Best regards,",
        "PieCed IT",
      ].join("\n"),
      html: `
        <div style="font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', sans-serif; max-width: 560px; margin: 0 auto; color: #e0e0e0; background: #1a1a1a; padding: 32px; border-radius: 12px;">
          <h2 style="color: #ffffff; margin-top: 0;">Support request received</h2>
          <p>Hello ${safeName},</p>
          <p>We've received your support request <strong>"${safeTitle}"</strong> (reference #${shortId}).</p>
          <p>Our team will review and respond as soon as possible.</p>
          <p>
            <a href="https://app.pieced.ch/support" style="display: inline-block; padding: 10px 24px; background: #3b82f6; color: #ffffff; text-decoration: none; border-radius: 8px; font-weight: 500;">
              View ticket
            </a>
          </p>
          <hr style="border: none; border-top: 1px solid #333; margin: 24px 0;" />
          <p style="color: #666; font-size: 12px;">PieCed IT — Hosted on-premises in Switzerland</p>
        </div>
      `,
    });
  } catch (err) {
    console.error("Failed to send support ticket creation email:", err);
  }
}

/**
 * Sent to the customer when an admin replies to one of their tickets.
 * Includes the body of the reply inline so the customer can read it
 * without clicking through (especially useful on mobile).
 */
export async function sendSupportTicketReplyEmail(params: {
  to: string;
  contactName: string;
  ticketId: string;
  title: string;
  authorName: string;
  body: string;
}): Promise<void> {
  const safeName = escapeHtml(params.contactName);
  const safeTitle = escapeHtml(params.title);
  const safeAuthor = escapeHtml(params.authorName);
  const safeBody = escapeHtml(params.body);
  const shortId = params.ticketId.slice(0, 8);
  const subject = `${ticketSubjectPrefix(params.ticketId)} Re: ${params.title}`;

  try {
    await getTransporter().sendMail({
      from: getFrom(),
      to: params.to,
      subject,
      text: [
        `Hello ${params.contactName},`,
        "",
        `${params.authorName} replied to your ticket "${params.title}" (#${shortId}):`,
        "",
        params.body,
        "",
        "Reply or follow up at https://app.pieced.ch/support.",
        "",
        "Best regards,",
        "PieCed IT",
      ].join("\n"),
      html: `
        <div style="font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', sans-serif; max-width: 560px; margin: 0 auto; color: #e0e0e0; background: #1a1a1a; padding: 32px; border-radius: 12px;">
          <h2 style="color: #ffffff; margin-top: 0;">New reply on your ticket</h2>
          <p>Hello ${safeName},</p>
          <p><strong>${safeAuthor}</strong> replied to your ticket <strong>"${safeTitle}"</strong> (#${shortId}):</p>
          <div style="background: #2a2a2a; border-left: 3px solid #3b82f6; padding: 12px 16px; border-radius: 6px; margin: 16px 0; white-space: pre-wrap;">
            ${safeBody}
          </div>
          <p>
            <a href="https://app.pieced.ch/support" style="display: inline-block; padding: 10px 24px; background: #3b82f6; color: #ffffff; text-decoration: none; border-radius: 8px; font-weight: 500;">
              View ticket
            </a>
          </p>
          <hr style="border: none; border-top: 1px solid #333; margin: 24px 0;" />
          <p style="color: #666; font-size: 12px;">PieCed IT — Hosted on-premises in Switzerland</p>
        </div>
      `,
    });
  } catch (err) {
    console.error("Failed to send support ticket reply email:", err);
  }
}

/**
 * Sent to the customer when an admin changes status without a comment.
 * If the same admin action included a comment, they'd get the
 * reply email instead — caller decides which to send.
 */
export async function sendSupportTicketStatusEmail(params: {
  to: string;
  contactName: string;
  ticketId: string;
  title: string;
  newStatus: string;
}): Promise<void> {
  const safeName = escapeHtml(params.contactName);
  const safeTitle = escapeHtml(params.title);
  const statusLabel = STATUS_LABELS_EN[params.newStatus] ?? params.newStatus;
  const shortId = params.ticketId.slice(0, 8);
  const subject = `${ticketSubjectPrefix(params.ticketId)} Status: ${statusLabel}`;

  try {
    await getTransporter().sendMail({
      from: getFrom(),
      to: params.to,
      subject,
      text: [
        `Hello ${params.contactName},`,
        "",
        `The status of your ticket "${params.title}" (#${shortId}) has been updated to: ${statusLabel}.`,
        "",
        "View details and respond if needed at https://app.pieced.ch/support.",
        "",
        "Best regards,",
        "PieCed IT",
      ].join("\n"),
      html: `
        <div style="font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', sans-serif; max-width: 560px; margin: 0 auto; color: #e0e0e0; background: #1a1a1a; padding: 32px; border-radius: 12px;">
          <h2 style="color: #ffffff; margin-top: 0;">Ticket status update</h2>
          <p>Hello ${safeName},</p>
          <p>The status of your ticket <strong>"${safeTitle}"</strong> (#${shortId}) has been updated to:</p>
          <p style="font-size: 18px; color: #3b82f6; font-weight: 600;">${escapeHtml(statusLabel)}</p>
          <p>
            <a href="https://app.pieced.ch/support" style="display: inline-block; padding: 10px 24px; background: #3b82f6; color: #ffffff; text-decoration: none; border-radius: 8px; font-weight: 500;">
              View ticket
            </a>
          </p>
          <hr style="border: none; border-top: 1px solid #333; margin: 24px 0;" />
          <p style="color: #666; font-size: 12px;">PieCed IT — Hosted on-premises in Switzerland</p>
        </div>
      `,
    });
  } catch (err) {
    console.error("Failed to send support ticket status email:", err);
  }
}

/**
 * Notify the platform admin distribution list of a new ticket OR a
 * customer reply. Mirror of sendAdminNotificationEmail's pattern —
 * uses the same ADMIN_NOTIFICATION_EMAIL env var.
 *
 * Two trigger reasons supported:
 *  - 'created'  → new ticket from a customer
 *  - 'replied'  → customer replied to existing ticket (we want admin
 *                 visibility, e.g. to know the ticket needs another
 *                 round of attention)
 */
export async function sendSupportAdminNotificationEmail(params: {
  reason: "created" | "replied";
  ticketId: string;
  title: string;
  contactName: string;
  contactEmail: string;
  body?: string; // The new message content (description on create, comment body on reply)
  category?: string;
}): Promise<void> {
  const adminEmail = process.env.ADMIN_NOTIFICATION_EMAIL;
  if (!adminEmail) {
    console.warn(
      "ADMIN_NOTIFICATION_EMAIL not set; skipping admin support notification"
    );
    return;
  }
  const safeContact = escapeHtml(params.contactName);
  const safeContactEmail = escapeHtml(params.contactEmail);
  const safeTitle = escapeHtml(params.title);
  const safeBody = params.body ? escapeHtml(params.body) : "";
  const shortId = params.ticketId.slice(0, 8);

  const subjectVerb = params.reason === "created" ? "New" : "Reply on";
  const subject = `${ticketSubjectPrefix(params.ticketId)} ${subjectVerb}: ${params.title}`;

  const headlineHtml =
    params.reason === "created"
      ? `<h2 style="color: #ffffff; margin-top: 0;">New support ticket</h2>`
      : `<h2 style="color: #ffffff; margin-top: 0;">Customer replied on ticket</h2>`;

  try {
    await getTransporter().sendMail({
      from: getFrom(),
      to: adminEmail,
      subject,
      text: [
        params.reason === "created"
          ? "A new support ticket was opened:"
          : "A customer replied to a support ticket:",
        "",
        `From:     ${params.contactName} <${params.contactEmail}>`,
        `Ticket:   ${params.title} (#${shortId})`,
        params.category ? `Category: ${params.category}` : "",
        "",
        params.body ? "Message:" : "",
        params.body ?? "",
        "",
        `View at https://app.pieced.ch/support/${params.ticketId}`,
      ]
        .filter((s) => s !== "")
        .join("\n"),
      html: `
        <div style="font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', sans-serif; max-width: 560px; margin: 0 auto; color: #e0e0e0; background: #1a1a1a; padding: 32px; border-radius: 12px;">
          ${headlineHtml}
          <table style="width:100%; font-size: 13px; color: #aaa; margin-bottom: 16px;">
            <tr><td style="padding: 4px 0; width: 100px;">From</td><td style="padding: 4px 0; color: #fff;">${safeContact} &lt;${safeContactEmail}&gt;</td></tr>
            <tr><td style="padding: 4px 0;">Title</td><td style="padding: 4px 0; color: #fff;">${safeTitle} <span style="color: #666;">(#${shortId})</span></td></tr>
            ${params.category ? `<tr><td style="padding: 4px 0;">Category</td><td style="padding: 4px 0; color: #fff;">${escapeHtml(params.category)}</td></tr>` : ""}
          </table>
          ${
            params.body
              ? `<div style="background: #2a2a2a; border-left: 3px solid #3b82f6; padding: 12px 16px; border-radius: 6px; margin: 16px 0; white-space: pre-wrap;">${safeBody}</div>`
              : ""
          }
          <p>
            <a href="https://app.pieced.ch/support/${params.ticketId}" style="display: inline-block; padding: 10px 24px; background: #3b82f6; color: #ffffff; text-decoration: none; border-radius: 8px; font-weight: 500;">
              Open in admin queue
            </a>
          </p>
          <hr style="border: none; border-top: 1px solid #333; margin: 24px 0;" />
          <p style="color: #666; font-size: 12px;">PieCed IT — Admin notification</p>
        </div>
      `,
    });
  } catch (err) {
    console.error("Failed to send admin support notification:", err);
  }
}

// ---------------------------------------------------------------------------
// Skill activation requests — Phase 2.5
// ---------------------------------------------------------------------------
//
// Three notifications:
//
//   sendSkillActivationAdminNotification  — to ADMIN_NOTIFICATION_EMAIL
//                                           when a customer requests a
//                                           flagged skill.
//
//   sendSkillActivationApprovalEmail      — to the customer, on approve.
//
//   sendSkillActivationRejectionEmail     — to the customer, on reject,
//                                           including the admin's reason.
//
// All three follow the existing patterns in this file (HTML + plaintext,
// escaped vars, best-effort with errors logged not thrown).

/**
 * Notify admin (ADMIN_NOTIFICATION_EMAIL) that a customer has
 * requested activation of a manual-setup skill. The skill name +
 * tenant + requester are all included so admin can act without
 * loading the portal.
 */
export async function sendSkillActivationAdminNotification(params: {
  tenantName: string;
  skillId: string;
  skillName: string;
  requesterEmail: string;
  requesterName: string;
  companyName: string | null;
}): Promise<void> {
  const adminEmail = process.env.ADMIN_NOTIFICATION_EMAIL;
  if (!adminEmail) return;
  const safeTenant = escapeHtml(params.tenantName);
  const safeSkillId = escapeHtml(params.skillId);
  const safeSkillName = escapeHtml(params.skillName);
  const safeRequester = escapeHtml(params.requesterName);
  const safeRequesterEmail = escapeHtml(params.requesterEmail);
  const safeCompany = params.companyName
    ? escapeHtml(params.companyName)
    : "—";
  try {
    await getTransporter().sendMail({
      from: getFrom(),
      to: adminEmail,
      subject: `[PieCed] Skill activation requested — ${params.skillName} on ${params.tenantName}`,
      text: [
        "A customer has requested activation of a manual-setup skill.",
        "",
        `Skill:       ${params.skillName} (${params.skillId})`,
        `Tenant:      ${params.tenantName}`,
        `Organization:${params.companyName ?? "—"}`,
        `Requested by:${params.requesterName} <${params.requesterEmail}>`,
        "",
        "Review and act in the admin queue:",
        "https://app.pieced.ch/admin/skills/pending",
      ].join("\n"),
      html: `
        <div style="font-family: -apple-system, BlinkMacSystemFont, sans-serif; max-width: 560px; padding: 24px; background: #1a1a1a; color: #e5e5e5;">
          <h2 style="margin: 0 0 16px; color: #10B981;">Skill activation requested</h2>
          <p>A customer has requested activation of a manual-setup skill.</p>
          <table style="width:100%; border-collapse: collapse; margin: 12px 0;">
            <tr><td style="color:#888; padding:4px 0;">Skill</td><td>${safeSkillName} (<code>${safeSkillId}</code>)</td></tr>
            <tr><td style="color:#888; padding:4px 0;">Tenant</td><td><code>${safeTenant}</code></td></tr>
            <tr><td style="color:#888; padding:4px 0;">Organization</td><td>${safeCompany}</td></tr>
            <tr><td style="color:#888; padding:4px 0;">Requested by</td><td>${safeRequester} &lt;${safeRequesterEmail}&gt;</td></tr>
          </table>
          <p>
            <a href="https://app.pieced.ch/admin/skills/pending" style="display:inline-block; padding:10px 24px; background:#10B981; color:#fff; text-decoration:none; border-radius:8px; font-weight:500;">
              Open admin queue
            </a>
          </p>
          <hr style="border:none; border-top:1px solid #333; margin:24px 0;" />
          <p style="color:#666; font-size:12px;">PieCed IT — Admin notification</p>
        </div>
      `,
    });
  } catch (err) {
    console.error("Failed to send skill activation admin notification:", err);
  }
}

export async function sendSkillActivationApprovalEmail(params: {
  to: string;
  contactName: string;
  skillName: string;
  tenantName: string;
}): Promise<void> {
  const safeName = escapeHtml(params.contactName);
  const safeSkill = escapeHtml(params.skillName);
  const safeTenant = escapeHtml(params.tenantName);
  try {
    await getTransporter().sendMail({
      from: getFrom(),
      to: params.to,
      subject: `Your skill activation has been approved — ${params.skillName}`,
      text: [
        `Hello ${params.contactName},`,
        "",
        `Good news — your request to activate "${params.skillName}" on tenant ${params.tenantName} has been approved and the skill is now live.`,
        "",
        "You can manage it from your tenant settings.",
        "",
        "Best regards,",
        "PieCed IT",
      ].join("\n"),
      html: `
        <div style="font-family: -apple-system, BlinkMacSystemFont, sans-serif; max-width:560px; padding:24px; background:#1a1a1a; color:#e5e5e5;">
          <h2 style="margin:0 0 16px; color:#10B981;">Skill approved & activated</h2>
          <p>Hello ${safeName},</p>
          <p>Your request to activate <strong>${safeSkill}</strong> on tenant <code>${safeTenant}</code> has been approved and the skill is now live.</p>
          <p>You can manage it from your tenant settings.</p>
          <p>
            <a href="https://app.pieced.ch/tenants/${encodeURIComponent(params.tenantName)}" style="display:inline-block; padding:10px 24px; background:#10B981; color:#fff; text-decoration:none; border-radius:8px; font-weight:500;">
              Open tenant
            </a>
          </p>
          <hr style="border:none; border-top:1px solid #333; margin:24px 0;" />
          <p style="color:#666; font-size:12px;">PieCed IT</p>
        </div>
      `,
    });
  } catch (err) {
    console.error("Failed to send skill activation approval email:", err);
  }
}

export async function sendSkillActivationRejectionEmail(params: {
  to: string;
  contactName: string;
  skillName: string;
  tenantName: string;
  reason: string;
}): Promise<void> {
  const safeName = escapeHtml(params.contactName);
  const safeSkill = escapeHtml(params.skillName);
  const safeTenant = escapeHtml(params.tenantName);
  const safeReason = escapeHtml(params.reason);
  try {
    await getTransporter().sendMail({
      from: getFrom(),
      to: params.to,
      subject: `Update on your skill activation request — ${params.skillName}`,
      text: [
        `Hello ${params.contactName},`,
        "",
        `We were unable to approve your request to activate "${params.skillName}" on tenant ${params.tenantName}.`,
        "",
        "Reason from our team:",
        params.reason,
        "",
        "You can try again from your tenant settings once the matter is resolved.",
        "",
        "Best regards,",
        "PieCed IT",
      ].join("\n"),
      html: `
        <div style="font-family: -apple-system, BlinkMacSystemFont, sans-serif; max-width:560px; padding:24px; background:#1a1a1a; color:#e5e5e5;">
          <h2 style="margin:0 0 16px; color:#ef4444;">Activation request not approved</h2>
          <p>Hello ${safeName},</p>
          <p>We were unable to approve your request to activate <strong>${safeSkill}</strong> on tenant <code>${safeTenant}</code>.</p>
          <div style="background:#2a2a2a; border-left:3px solid #ef4444; padding:12px 16px; border-radius:6px; margin:16px 0;">
            <p style="color:#ccc; font-size:13px; margin:0;"><strong>Reason from our team:</strong></p>
            <p style="color:#aaa; font-size:13px; margin:8px 0 0 0; white-space:pre-wrap;">${safeReason}</p>
          </div>
          <p>You can try again from your tenant settings once the matter is resolved.</p>
          <hr style="border:none; border-top:1px solid #333; margin:24px 0;" />
          <p style="color:#666; font-size:12px;">PieCed IT</p>
        </div>
      `,
    });
  } catch (err) {
    console.error("Failed to send skill activation rejection email:", err);
  }
}

// ---------------------------------------------------------------------------
// Invoice issuance — Phase 3
// ---------------------------------------------------------------------------

/**
 * Notify the billing contact when a new invoice has been issued.
 * Includes a brief summary (total + due date + line count) so the
 * recipient can triage without opening the portal, plus a deep
 * link to /billing/<invoice number> where they can download the
 * PDF. The PDF itself is NOT attached — it lives in the portal,
 * keeps mail payloads small, and avoids the audit-trail headache
 * of "which copy is authoritative".
 */
export async function sendInvoiceIssuedEmail(params: {
  to: string;
  contactName: string;
  companyName: string;
  invoiceNumber: string;
  totalChf: number;
  currency: string; // "CHF" — passed for future-proofing
  dueAt: string;    // ISO date
  lineCount: number;
  periodStart: string; // ISO date
  periodEnd: string;   // ISO date
  locale: "de" | "en" | "fr" | "it";
}): Promise<void> {
  // All four locales — the email is sent in the invoice's locale,
  // which was frozen at issue time. No fallback to admin's locale.
  const L = params.locale;
  const subjectsByLocale: Record<typeof L, string> = {
    en: `New invoice ${params.invoiceNumber} from PieCed IT — ${params.currency} ${params.totalChf.toFixed(2)}`,
    de: `Neue Rechnung ${params.invoiceNumber} von PieCed IT — ${params.currency} ${params.totalChf.toFixed(2)}`,
    fr: `Nouvelle facture ${params.invoiceNumber} de PieCed IT — ${params.currency} ${params.totalChf.toFixed(2)}`,
    it: `Nuova fattura ${params.invoiceNumber} da PieCed IT — ${params.currency} ${params.totalChf.toFixed(2)}`,
  };
  const greetingsByLocale: Record<typeof L, string> = {
    en: `Hello ${params.contactName},`,
    de: `Sehr geehrte/r ${params.contactName},`,
    fr: `Bonjour ${params.contactName},`,
    it: `Gentile ${params.contactName},`,
  };
  const introByLocale: Record<typeof L, string> = {
    en: `A new invoice has been issued for ${params.companyName}.`,
    de: `Für ${params.companyName} wurde eine neue Rechnung ausgestellt.`,
    fr: `Une nouvelle facture a été émise pour ${params.companyName}.`,
    it: `È stata emessa una nuova fattura per ${params.companyName}.`,
  };
  const labels: Record<typeof L, Record<string, string>> = {
    en: { number: "Invoice", period: "Period", total: "Total", due: "Due by", lines: "Line items", cta: "View invoice & download PDF", signoff: "Best regards", brand: "PieCed IT" },
    de: { number: "Rechnung", period: "Zeitraum", total: "Gesamt", due: "Zahlbar bis", lines: "Positionen", cta: "Rechnung ansehen & PDF herunterladen", signoff: "Mit freundlichen Grüssen", brand: "PieCed IT" },
    fr: { number: "Facture", period: "Période", total: "Total", due: "À régler avant", lines: "Lignes", cta: "Voir la facture & télécharger le PDF", signoff: "Cordialement", brand: "PieCed IT" },
    it: { number: "Fattura", period: "Periodo", total: "Totale", due: "Scadenza", lines: "Voci", cta: "Visualizza fattura & scarica PDF", signoff: "Cordiali saluti", brand: "PieCed IT" },
  };
  const l = labels[L];

  const safeName = escapeHtml(params.contactName);
  const safeCompany = escapeHtml(params.companyName);
  const safeNumber = escapeHtml(params.invoiceNumber);
  const totalFmt = `${params.currency} ${params.totalChf.toFixed(2)}`;
  const periodFmt = `${params.periodStart.slice(0, 10)} → ${params.periodEnd.slice(0, 10)}`;
  const dueFmt = params.dueAt.slice(0, 10);

  // Both bodies built in the invoice's locale.
  const link = `https://app.pieced.ch/billing/${encodeURIComponent(params.invoiceNumber)}`;

  try {
    await getTransporter().sendMail({
      from: getFrom(),
      to: params.to,
      subject: subjectsByLocale[L],
      text: [
        greetingsByLocale[L],
        "",
        introByLocale[L],
        "",
        `${l.number}:  ${params.invoiceNumber}`,
        `${l.period}:  ${periodFmt}`,
        `${l.total}:   ${totalFmt}`,
        `${l.due}:     ${dueFmt}`,
        `${l.lines}:   ${params.lineCount}`,
        "",
        `${l.cta}:`,
        link,
        "",
        `${l.signoff},`,
        l.brand,
      ].join("\n"),
      html: `
        <div style="font-family: -apple-system, BlinkMacSystemFont, sans-serif; max-width: 560px; padding: 24px; background: #1a1a1a; color: #e5e5e5;">
          <h2 style="margin: 0 0 16px; color: #10B981;">${escapeHtml(introByLocale[L])}</h2>
          <p>${escapeHtml(greetingsByLocale[L])}</p>
          <p>${escapeHtml(introByLocale[L])}</p>
          <table style="width:100%; border-collapse:collapse; margin:16px 0; font-size:14px;">
            <tr><td style="color:#888; padding:6px 0; width:120px;">${l.number}</td><td><strong>${safeNumber}</strong></td></tr>
            <tr><td style="color:#888; padding:6px 0;">${l.period}</td><td>${escapeHtml(periodFmt)}</td></tr>
            <tr><td style="color:#888; padding:6px 0;">${l.total}</td><td style="color:#10B981; font-weight:600;">${escapeHtml(totalFmt)}</td></tr>
            <tr><td style="color:#888; padding:6px 0;">${l.due}</td><td>${escapeHtml(dueFmt)}</td></tr>
            <tr><td style="color:#888; padding:6px 0;">${l.lines}</td><td>${params.lineCount}</td></tr>
          </table>
          <p>
            <a href="${link}" style="display:inline-block; padding:10px 24px; background:#10B981; color:#fff; text-decoration:none; border-radius:8px; font-weight:500;">
              ${l.cta}
            </a>
          </p>
          <hr style="border:none; border-top:1px solid #333; margin:24px 0;" />
          <p style="color:#666; font-size:12px;">${l.brand}</p>
        </div>
      `,
    });
  } catch (err) {
    console.error("Failed to send invoice issued email:", err);
  }
}

// ---------------------------------------------------------------------------
// Reminder emails — Phase 5
// ---------------------------------------------------------------------------

/**
 * Send a payment reminder for an open/overdue invoice.
 *
 * Three escalation levels:
 *   1 — Gentle nudge: ~7 days past due. Friendly tone, "in case
 *       you missed it".
 *   2 — Firmer reminder: ~14 days past due. Clear that payment is
 *       outstanding, please pay.
 *   3 — Final notice: ~30 days past due. Explicit consequences
 *       (service may be suspended). Last automated touch — beyond
 *       this, admin involvement is expected.
 *
 * Failure is logged, never thrown — the cron sweep must continue
 * past a single failed send.
 */
export async function sendInvoiceReminderEmail(params: {
  to: string;
  contactName: string;
  companyName: string;
  invoiceNumber: string;
  totalChf: number;
  currency: string;
  dueAt: string;
  daysPastDue: number;
  level: 1 | 2 | 3;
  locale: "de" | "en" | "fr" | "it";
}): Promise<void> {
  const L = params.locale;
  // Per-locale strings keyed by the three escalation levels.
  // Kept inline (rather than the next-intl message files) because
  // the email layer doesn't import from React's i18n context.
  const SUBJECTS: Record<typeof L, Record<1 | 2 | 3, string>> = {
    en: {
      1: `Friendly reminder: invoice ${params.invoiceNumber} is overdue`,
      2: `Second reminder: invoice ${params.invoiceNumber} is still unpaid`,
      3: `Final notice: invoice ${params.invoiceNumber} requires immediate payment`,
    },
    de: {
      1: `Freundliche Erinnerung: Rechnung ${params.invoiceNumber} ist überfällig`,
      2: `Zweite Mahnung: Rechnung ${params.invoiceNumber} ist weiterhin unbezahlt`,
      3: `Letzte Mahnung: Rechnung ${params.invoiceNumber} erfordert sofortige Zahlung`,
    },
    fr: {
      1: `Rappel amical : la facture ${params.invoiceNumber} est en retard`,
      2: `Deuxième rappel : la facture ${params.invoiceNumber} reste impayée`,
      3: `Dernier avis : la facture ${params.invoiceNumber} doit être réglée sans délai`,
    },
    it: {
      1: `Promemoria amichevole: la fattura ${params.invoiceNumber} è scaduta`,
      2: `Secondo sollecito: la fattura ${params.invoiceNumber} è ancora insoluta`,
      3: `Avviso finale: la fattura ${params.invoiceNumber} richiede pagamento immediato`,
    },
  };
  const INTROS: Record<typeof L, Record<1 | 2 | 3, string>> = {
    en: {
      1: "We noticed this invoice hasn't been settled yet — in case it slipped through.",
      2: "This invoice remains unpaid. Please arrange payment at your earliest convenience.",
      3: "This invoice is significantly overdue. Service may be suspended if payment is not received promptly.",
    },
    de: {
      1: "Diese Rechnung scheint noch nicht beglichen — falls sie übersehen wurde, möchten wir freundlich daran erinnern.",
      2: "Diese Rechnung ist weiterhin unbezahlt. Bitte veranlassen Sie die Zahlung umgehend.",
      3: "Diese Rechnung ist erheblich überfällig. Bei nicht zeitnaher Zahlung kann der Dienst ausgesetzt werden.",
    },
    fr: {
      1: "Cette facture n'a pas encore été réglée — au cas où elle vous aurait échappé.",
      2: "Cette facture reste impayée. Merci d'effectuer le paiement dans les meilleurs délais.",
      3: "Cette facture est en grand retard. Le service pourra être suspendu en l'absence de paiement rapide.",
    },
    it: {
      1: "Questa fattura non risulta ancora saldata — nel caso vi fosse sfuggita.",
      2: "Questa fattura risulta ancora insoluta. Si prega di provvedere al pagamento al più presto.",
      3: "Questa fattura è significativamente in ritardo. In assenza di pagamento tempestivo il servizio potrà essere sospeso.",
    },
  };
  const LABELS: Record<typeof L, Record<string, string>> = {
    en: { num: "Invoice", total: "Total", due: "Due date", days: "Days past due", cta: "View invoice & pay", signoff: "Best regards", brand: "PieCed IT", greeting: "Hello" },
    de: { num: "Rechnung", total: "Gesamt", due: "Fälligkeitsdatum", days: "Tage überfällig", cta: "Rechnung ansehen & bezahlen", signoff: "Mit freundlichen Grüssen", brand: "PieCed IT", greeting: "Sehr geehrte/r" },
    fr: { num: "Facture", total: "Total", due: "Échéance", days: "Jours de retard", cta: "Voir la facture & payer", signoff: "Cordialement", brand: "PieCed IT", greeting: "Bonjour" },
    it: { num: "Fattura", total: "Totale", due: "Scadenza", days: "Giorni di ritardo", cta: "Vedi fattura & paga", signoff: "Cordiali saluti", brand: "PieCed IT", greeting: "Gentile" },
  };
  const l = LABELS[L];
  const safeName = escapeHtml(params.contactName);
  const safeCompany = escapeHtml(params.companyName);
  const safeNumber = escapeHtml(params.invoiceNumber);
  const totalFmt = `${params.currency} ${params.totalChf.toFixed(2)}`;
  const dueFmt = params.dueAt.slice(0, 10);
  const link = `https://app.pieced.ch/billing/${encodeURIComponent(params.invoiceNumber)}`;
  // Final-notice gets red accent; earlier levels keep the brand green.
  const accent = params.level === 3 ? "#dc2626" : "#10B981";

  try {
    await getTransporter().sendMail({
      from: getFrom(),
      to: params.to,
      subject: SUBJECTS[L][params.level],
      text: [
        `${l.greeting} ${params.contactName},`,
        "",
        INTROS[L][params.level],
        "",
        `${l.num}:    ${params.invoiceNumber}`,
        `${l.total}:    ${totalFmt}`,
        `${l.due}:    ${dueFmt}`,
        `${l.days}:    ${params.daysPastDue}`,
        "",
        `${l.cta}: ${link}`,
        "",
        `${l.signoff},`,
        l.brand,
      ].join("\n"),
      html: `
        <div style="font-family:-apple-system,BlinkMacSystemFont,sans-serif;max-width:560px;padding:24px;background:#1a1a1a;color:#e5e5e5;">
          <h2 style="margin:0 0 16px;color:${accent};">${escapeHtml(SUBJECTS[L][params.level])}</h2>
          <p>${l.greeting} ${safeName},</p>
          <p>${escapeHtml(INTROS[L][params.level])}</p>
          <table style="width:100%;border-collapse:collapse;margin:16px 0;font-size:14px;">
            <tr><td style="color:#888;padding:6px 0;width:140px;">${l.num}</td><td><strong>${safeNumber}</strong></td></tr>
            <tr><td style="color:#888;padding:6px 0;">${l.total}</td><td style="color:${accent};font-weight:600;">${escapeHtml(totalFmt)}</td></tr>
            <tr><td style="color:#888;padding:6px 0;">${l.due}</td><td>${escapeHtml(dueFmt)}</td></tr>
            <tr><td style="color:#888;padding:6px 0;">${l.days}</td><td>${params.daysPastDue}</td></tr>
          </table>
          <p>
            <a href="${link}" style="display:inline-block;padding:10px 24px;background:${accent};color:#fff;text-decoration:none;border-radius:8px;font-weight:500;">
              ${l.cta}
            </a>
          </p>
          <hr style="border:none;border-top:1px solid #333;margin:24px 0;" />
          <p style="color:#666;font-size:12px;">${l.brand}</p>
        </div>
      `,
    });
  } catch (err) {
    console.error(
      `Failed to send reminder L${params.level} for invoice ${params.invoiceNumber}:`,
      err
    );
  }
}