/**
 * 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 | null; // ISO date; null for custom invoices
  periodEnd: string | null;   // ISO date; null for custom invoices
  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} ${params.totalChf.toFixed(2)}`;
  // Phase 8: period is null for custom invoices. When missing, the
  // template skips the "Service period:" line entirely; otherwise
  // it renders the date range as before.
  const periodFmt =
    params.periodStart && params.periodEnd
      ? `${params.periodStart.slice(0, 10)} → ${params.periodEnd.slice(0, 10)}`
      : null;
  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}:  ${params.invoiceNumber}`,
        // Phase 8: omit the period line entirely for custom
        // invoices (which have no billing period).
        ...(periodFmt ? [`${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>
            ${periodFmt ? `<tr><td style="color:#888; padding:6px 0;">${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
    );
  }
}

// ---------------------------------------------------------------------------
// Credit note emails — Phase 7
// ---------------------------------------------------------------------------

/**
 * Send a credit-note notification to the customer's billing email.
 *
 * Covers both kinds (void and refund). The subject and body adapt
 * based on `kind` — voids ("we've cancelled invoice X, no payment
 * needed") read very differently from refunds ("we've refunded CHF
 * X, expect to see it on your card statement within 5-10 days").
 *
 * Link-only — the PDF is not attached. The customer downloads it
 * from /api/credit-notes/<number>/pdf when they click through, which
 * also gives them a permanent in-portal record next to their
 * invoices. Same approach as invoice emails.
 *
 * Best-effort: failures are logged and swallowed. A mail-server
 * hiccup must never roll back a credit-note issuance.
 */
export async function sendCreditNoteEmail(params: {
  to: string;
  contactName: string;
  companyName: string;
  creditNoteNumber: string;
  invoiceNumber: string;
  amountChf: number;
  currency: string;
  kind: "void" | "refund";
  reason: string | null;
  locale: "de" | "en" | "fr" | "it";
}): Promise<void> {
  const L = params.locale;
  const totalFmt = `${params.currency} ${params.amountChf.toFixed(2)}`;
  const link = `https://app.pieced.ch/billing/cn/${encodeURIComponent(
    params.creditNoteNumber
  )}`;

  // Subject lines diverge between void and refund — different
  // mental models for the recipient. Void: "your charge is
  // cancelled". Refund: "your money is on the way back".
  const subjectsByLocale: Record<typeof L, { void: string; refund: string }> = {
    en: {
      void: `Invoice ${params.invoiceNumber} cancelled — credit note ${params.creditNoteNumber}`,
      refund: `Refund of ${totalFmt} for invoice ${params.invoiceNumber} — credit note ${params.creditNoteNumber}`,
    },
    de: {
      void: `Rechnung ${params.invoiceNumber} storniert — Gutschrift ${params.creditNoteNumber}`,
      refund: `Rückerstattung ${totalFmt} für Rechnung ${params.invoiceNumber} — Gutschrift ${params.creditNoteNumber}`,
    },
    fr: {
      void: `Facture ${params.invoiceNumber} annulée — note de crédit ${params.creditNoteNumber}`,
      refund: `Remboursement ${totalFmt} pour la facture ${params.invoiceNumber} — note de crédit ${params.creditNoteNumber}`,
    },
    it: {
      void: `Fattura ${params.invoiceNumber} annullata — nota di credito ${params.creditNoteNumber}`,
      refund: `Rimborso ${totalFmt} per fattura ${params.invoiceNumber} — nota di credito ${params.creditNoteNumber}`,
    },
  };

  const greetingsByLocale: Record<typeof L, string> = {
    en: `Hello ${params.contactName},`,
    de: `Sehr geehrte/r ${params.contactName},`,
    fr: `Bonjour ${params.contactName},`,
    it: `Gentile ${params.contactName},`,
  };

  // Intro: distinct phrasing per kind in each locale.
  const introsByLocale: Record<typeof L, { void: string; refund: string }> = {
    en: {
      void: `We've cancelled invoice ${params.invoiceNumber}. The invoice is no longer payable, and a credit note has been issued for your records.`,
      refund: `We've refunded ${totalFmt} for invoice ${params.invoiceNumber}. The refund will appear on the original payment method within 5–10 business days, depending on your bank.`,
    },
    de: {
      void: `Wir haben Rechnung ${params.invoiceNumber} storniert. Die Rechnung ist nicht mehr zahlbar; eine Gutschrift wurde für Ihre Unterlagen ausgestellt.`,
      refund: `Wir haben ${totalFmt} für Rechnung ${params.invoiceNumber} zurückerstattet. Der Betrag wird je nach Bank innerhalb von 5–10 Geschäftstagen auf dem ursprünglichen Zahlungsweg gutgeschrieben.`,
    },
    fr: {
      void: `Nous avons annulé la facture ${params.invoiceNumber}. La facture n'est plus exigible ; une note de crédit a été émise pour vos archives.`,
      refund: `Nous avons remboursé ${totalFmt} pour la facture ${params.invoiceNumber}. Le montant apparaîtra sur le moyen de paiement initial sous 5 à 10 jours ouvrés, selon votre banque.`,
    },
    it: {
      void: `Abbiamo annullato la fattura ${params.invoiceNumber}. La fattura non è più dovuta; è stata emessa una nota di credito per la sua documentazione.`,
      refund: `Abbiamo rimborsato ${totalFmt} per la fattura ${params.invoiceNumber}. L'importo apparirà sul metodo di pagamento originale entro 5–10 giorni lavorativi, a seconda della banca.`,
    },
  };

  const labels: Record<typeof L, Record<string, string>> = {
    en: { creditNote: "Credit note", invoice: "Invoice", amount: "Amount", reason: "Reason", cta: "View credit note & download PDF", signoff: "Best regards", brand: "PieCed IT" },
    de: { creditNote: "Gutschrift", invoice: "Rechnung", amount: "Betrag", reason: "Begründung", cta: "Gutschrift ansehen & PDF herunterladen", signoff: "Mit freundlichen Grüssen", brand: "PieCed IT" },
    fr: { creditNote: "Note de crédit", invoice: "Facture", amount: "Montant", reason: "Motif", cta: "Voir la note de crédit & télécharger le PDF", signoff: "Cordialement", brand: "PieCed IT" },
    it: { creditNote: "Nota di credito", invoice: "Fattura", amount: "Importo", reason: "Motivo", cta: "Visualizza nota di credito & scarica PDF", signoff: "Cordiali saluti", brand: "PieCed IT" },
  };
  const l = labels[L];

  const subject = subjectsByLocale[L][params.kind];
  const intro = introsByLocale[L][params.kind];
  const safeName = escapeHtml(params.contactName);
  const safeNumberCN = escapeHtml(params.creditNoteNumber);
  const safeNumberINV = escapeHtml(params.invoiceNumber);
  const safeReason = params.reason ? escapeHtml(params.reason) : null;

  // PieCed brand emerald — same accent the invoice email uses.
  // A credit note is still a PieCed IT document; the company
  // identity stays consistent across the document family. The
  // doc type is distinguished by the subject line and copy, not
  // by colour.
  const ACCENT = "#10B981";

  try {
    await getTransporter().sendMail({
      from: getFrom(),
      to: params.to,
      subject,
      text: [
        greetingsByLocale[L],
        "",
        intro,
        "",
        `${l.creditNote}:  ${params.creditNoteNumber}`,
        `${l.invoice}:    ${params.invoiceNumber}`,
        `${l.amount}:     ${totalFmt}`,
        ...(params.reason ? [`${l.reason}:    ${params.reason}`] : []),
        "",
        `${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(intro)}</h2>
          <p>${safeName === "" ? "" : escapeHtml(greetingsByLocale[L])}</p>
          <table style="width:100%; border-collapse:collapse; margin:16px 0; font-size:14px;">
            <tr><td style="color:#888; padding:6px 0; width:140px;">${l.creditNote}</td><td><strong>${safeNumberCN}</strong></td></tr>
            <tr><td style="color:#888; padding:6px 0;">${l.invoice}</td><td>${safeNumberINV}</td></tr>
            <tr><td style="color:#888; padding:6px 0;">${l.amount}</td><td style="color:${ACCENT}; font-weight:600;">${escapeHtml(totalFmt)}</td></tr>
            ${safeReason ? `<tr><td style="color:#888; padding:6px 0; vertical-align:top;">${l.reason}</td><td style="color:#bbb;">${safeReason}</td></tr>` : ""}
          </table>
          <p>
            <a href="${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 credit note email:", err);
  }
}

// ---------------------------------------------------------------------------
// Phase 9b-2 — auto-charge failure notice
// ---------------------------------------------------------------------------

/**
 * Sent when an off-session auto-charge attempt fails for an issued
 * invoice (card declined, expired, 3DS required, etc.). Customer
 * receives this in their billing-snapshot locale. Contains:
 *   - Invoice number + amount + due date
 *   - Failure reason (a short human-readable string from Stripe)
 *   - Manual-pay link to /billing/<invoiceNumber> where they can
 *     run the regular Pay-by-Card flow (which uses
 *     setup_future_usage to also refresh the saved card)
 *
 * Critical: the failure reason from Stripe can contain sensitive
 * details (card BIN, country, etc.). We pass a sanitized short
 * string from the caller — never the full raw error.
 */
export async function sendAutoChargeFailedEmail(params: {
  to: string;
  contactName: string;
  companyName: string;
  invoiceNumber: string;
  totalChf: number;
  currency: string;
  dueAt: string;
  /**
   * Short, customer-safe reason. e.g. "Your card was declined."
   * or "Your card has expired." Caller maps Stripe error codes to
   * these strings; we never pass raw API error messages.
   */
  reasonForCustomer: string;
  locale: "de" | "en" | "fr" | "it";
}): Promise<void> {
  const L = params.locale;
  const totalFmt = `${params.currency} ${params.totalChf.toFixed(2)}`;
  const dueFmt = params.dueAt.slice(0, 10);
  const baseUrl = process.env.APP_BASE_URL ?? "https://app.pieced.ch";
  const link = `${baseUrl}/billing/${encodeURIComponent(params.invoiceNumber)}`;

  const subjectsByLocale: Record<typeof L, string> = {
    en: `Auto-charge failed for invoice ${params.invoiceNumber} — please pay manually`,
    de: `Auto-Abbuchung fehlgeschlagen für Rechnung ${params.invoiceNumber} — bitte manuell bezahlen`,
    fr: `Échec du prélèvement automatique pour la facture ${params.invoiceNumber} — merci de régler manuellement`,
    it: `Addebito automatico fallito per la fattura ${params.invoiceNumber} — la preghiamo di pagare manualmente`,
  };
  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: `We were unable to charge your saved card for invoice ${params.invoiceNumber} (${params.companyName}).`,
    de: `Wir konnten die Rechnung ${params.invoiceNumber} (${params.companyName}) nicht über die hinterlegte Karte abbuchen.`,
    fr: `Nous n'avons pas pu débiter votre carte enregistrée pour la facture ${params.invoiceNumber} (${params.companyName}).`,
    it: `Non siamo riusciti ad addebitare la carta salvata per la fattura ${params.invoiceNumber} (${params.companyName}).`,
  };
  const reasonLabel: Record<typeof L, string> = {
    en: "Reason given by the card network",
    de: "Vom Kartennetzwerk gemeldeter Grund",
    fr: "Motif communiqué par le réseau de carte",
    it: "Motivo comunicato dal circuito",
  };
  const actionLineByLocale: Record<typeof L, string> = {
    en: `Please pay this invoice manually before ${dueFmt} to avoid service interruption. The "Pay with card" button below will both charge the invoice and update the card we have on file for future charges.`,
    de: `Bitte begleichen Sie diese Rechnung manuell vor dem ${dueFmt}, um eine Unterbrechung Ihres Dienstes zu vermeiden. Die Schaltfläche "Mit Karte bezahlen" unten begleicht die Rechnung und aktualisiert gleichzeitig die hinterlegte Karte für zukünftige Abbuchungen.`,
    fr: `Veuillez régler cette facture manuellement avant le ${dueFmt} pour éviter toute interruption du service. Le bouton "Payer par carte" ci-dessous règle la facture et met à jour la carte enregistrée pour les futurs prélèvements.`,
    it: `La preghiamo di saldare questa fattura manualmente entro il ${dueFmt} per evitare interruzioni del servizio. Il pulsante "Paga con carta" qui sotto salda la fattura e aggiorna allo stesso tempo la carta in archivio per gli addebiti futuri.`,
  };
  const labels: Record<typeof L, Record<string, string>> = {
    en: { number: "Invoice", total: "Total", due: "Due by", cta: "Pay with card", signoff: "Best regards", brand: "PieCed IT" },
    de: { number: "Rechnung", total: "Gesamt", due: "Zahlbar bis", cta: "Mit Karte bezahlen", signoff: "Mit freundlichen Grüssen", brand: "PieCed IT" },
    fr: { number: "Facture", total: "Total", due: "À régler avant", cta: "Payer par carte", signoff: "Cordialement", brand: "PieCed IT" },
    it: { number: "Fattura", total: "Totale", due: "Scadenza", cta: "Paga con carta", 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 safeReason = escapeHtml(params.reasonForCustomer);
  const safeIntro = escapeHtml(introByLocale[L]);
  const safeAction = escapeHtml(actionLineByLocale[L]);

  try {
    await getTransporter().sendMail({
      from: getFrom(),
      to: params.to,
      subject: subjectsByLocale[L],
      text: [
        greetingsByLocale[L],
        "",
        introByLocale[L],
        "",
        `${l.number}: ${params.invoiceNumber}`,
        `${l.total}:   ${totalFmt}`,
        `${l.due}:     ${dueFmt}`,
        "",
        `${reasonLabel[L]}: ${params.reasonForCustomer}`,
        "",
        actionLineByLocale[L],
        "",
        `${l.cta}:`,
        link,
        "",
        `${l.signoff},`,
        l.brand,
      ].join("\n"),
      html: `
        <div style="font-family: -apple-system, BlinkMacSystemFont, sans-serif; max-width: 560px; padding: 24px; background: #1a1a1a; color: #e5e5e5;">
          <h2 style="margin: 0 0 16px; color: #f59e0b;">${escapeHtml(subjectsByLocale[L])}</h2>
          <p>${escapeHtml(greetingsByLocale[L])}</p>
          <p>${safeIntro}</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;">${l.total}</td><td style="color:#f59e0b; font-weight:600;">${escapeHtml(totalFmt)}</td></tr>
            <tr><td style="color:#888; padding:6px 0;">${l.due}</td><td>${escapeHtml(dueFmt)}</td></tr>
          </table>
          <div style="background:#2a2a2a; border-left:3px solid #f59e0b; padding:10px 12px; margin:16px 0; font-size:13px;">
            <strong>${escapeHtml(reasonLabel[L])}:</strong> ${safeReason}
          </div>
          <p style="font-size:14px;">${safeAction}</p>
          <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>
          <p style="color:#888; font-size:12px; margin-top:24px;">
            ${l.signoff},<br />${l.brand}
          </p>
        </div>
      `,
    });
  } catch (err) {
    console.error("Failed to send auto-charge-failed email:", err);
  }
}