import nodemailer from "nodemailer";

const smtpHost = process.env.SMTP_HOST;
const smtpPort = parseInt(process.env.SMTP_PORT || "465", 10);
const smtpUser = process.env.SMTP_USER;
const smtpPassword = process.env.SMTP_PASSWORD;
const fromEmail = process.env.SMTP_FROM_EMAIL || "no-reply@aethex.dev";
const verifySupportEmail =
  process.env.VERIFY_SUPPORT_EMAIL ?? "support@aethex.biz";

let transporter: nodemailer.Transporter | null = null;

function getTransporter() {
  if (transporter) return transporter;

  if (!smtpHost || !smtpUser || !smtpPassword) {
    throw new Error(
      "SMTP configuration is missing. Set SMTP_HOST, SMTP_USER, and SMTP_PASSWORD.",
    );
  }

  transporter = nodemailer.createTransport({
    host: smtpHost,
    port: smtpPort,
    secure: smtpPort === 465,
    auth: {
      user: smtpUser,
      pass: smtpPassword,
    },
  });

  return transporter;
}

export const emailService = {
  get isConfigured() {
    return Boolean(smtpHost && smtpUser && smtpPassword);
  },

  async sendVerificationEmail(params: {
    to: string;
    verificationUrl: string;
    fullName?: string | null;
  }) {
    const transporter = getTransporter();
    const { to, verificationUrl, fullName } = params;
    const safeName = fullName?.trim() || "there";

    const subject = "Verify your AeThex account";
    const previewText = "Confirm your AeThex account to access the dashboard.";

    const html = `
      <div style="font-family: Inter, -apple-system, BlinkMacSystemFont, 'Segoe UI', sans-serif; color: #0f172a;">
        <h2 style="color: #5b21b6;">Welcome to AeThex, ${safeName}!</h2>
        <p>Click the button below to verify your account and unlock your personal dashboard.</p>
        <p style="margin: 24px 0;">
          <a href="${verificationUrl}" style="background: linear-gradient(135deg, #6366f1, #8b5cf6); color: #fff; padding: 12px 20px; border-radius: 999px; text-decoration: none; font-weight: 600; display: inline-block;">Verify my account</a>
        </p>
        <p>If the button does not work, paste this link into your browser:</p>
        <p style="word-break: break-all; font-size: 14px; color: #334155;">${verificationUrl}</p>
        <hr style="margin: 32px 0; border: none; border-top: 1px solid #e2e8f0;" />
        <p style="font-size: 12px; color: #64748b;">
          Didn't create an account? Please ignore this email or contact <a href="mailto:${verifySupportEmail}">${verifySupportEmail}</a>.
        </p>
      </div>
    `;

    const text = [
      `Welcome to AeThex, ${safeName}!`,
      "",
      "Use the link below to verify your account:",
      verificationUrl,
      "",
      `If you didn't request this, contact us at ${verifySupportEmail}.`,
    ].join("\n");

    await transporter.sendMail({
      from: fromEmail,
      to,
      subject,
      html,
      text,
      headers: {
        "X-AeThex-Email": "verification",
        "X-Entity-Ref-ID": verificationUrl.slice(-24),
      },
    });
  },

  async sendInviteEmail(params: {
    to: string;
    inviteUrl: string;
    inviterName?: string | null;
    message?: string | null;
  }) {
    const transporter = getTransporter();
    const { to, inviteUrl, inviterName, message } = params;
    const safeInviter = inviterName?.trim() || "An AeThex member";

    const subject = `${safeInviter} invited you to collaborate on AeThex`;

    const html = `
      <div style="font-family: Inter, -apple-system, BlinkMacSystemFont, 'Segoe UI', sans-serif; color: #0f172a;">
        <h2 style="color: #0ea5e9;">You're invited to AeThex</h2>
        <p><strong>${safeInviter}</strong> sent you an invitation to connect and collaborate on AeThex.</p>
        ${message ? `<blockquote style="margin:16px 0; padding:12px 16px; background:#f1f5f9; border-left:4px solid #38bdf8; color:#334155;">${message}</blockquote>` : ""}
        <p style="margin: 24px 0;">
          <a href="${inviteUrl}" style="background: linear-gradient(135deg, #0ea5e9, #22c55e); color: #fff; padding: 12px 20px; border-radius: 999px; text-decoration: none; font-weight: 600; display: inline-block;">Accept invitation</a>
        </p>
        <p>If the button does not work, paste this link into your browser:</p>
        <p style="word-break: break-all; font-size: 14px; color: #334155;">${inviteUrl}</p>
      </div>
    `;

    const text = [
      `You're invited to AeThex by ${safeInviter}.`,
      message ? `\nMessage: ${message}` : "",
      "\nAccept here:",
      inviteUrl,
    ].join("\n");

    await transporter.sendMail({
      from: fromEmail,
      to,
      subject,
      html,
      text,
      headers: { "X-AeThex-Email": "invite" },
    });
  },
};