import { Resend } from "resend";

const RESEND_API_KEY = process.env.RESEND_API_KEY;
// Primary: verified subdomain (set EMAIL_FROM=Tia <tia@tia.manohargupta.com> in Dokploy)
// Fallback: Resend shared domain — works without domain verification
const EMAIL_FROM = process.env.EMAIL_FROM || "Tia <tia@tia.manohargupta.com>";
const EMAIL_FROM_FALLBACK = "Tia <onboarding@resend.dev>";
const APP_URL = process.env.NEXT_PUBLIC_APP_URL || "https://tia.manohargupta.com";

/** Send email with automatic fallback to shared domain if primary domain isn't verified yet */
async function sendWithFallback(resend: Resend, payload: Parameters<Resend["emails"]["send"]>[0]) {
  const result = await resend.emails.send(payload);
  // Resend returns { error } object rather than throwing for domain issues
  const err = (result as { error?: { message?: string; name?: string } }).error;
  if (err) {
    const msg = (err.message || err.name || "").toLowerCase();
    if (msg.includes("domain") || msg.includes("verif") || msg.includes("sender")) {
      console.warn("[EMAIL-FALLBACK] Primary domain rejected, retrying with shared domain:", err.message);
      return await resend.emails.send({ ...payload, from: EMAIL_FROM_FALLBACK });
    }
    throw new Error(err.message || "Resend error");
  }
  return result;
}

/** Sends a family invite email, or logs the link in dev. */
export async function sendFamilyInviteEmail(opts: {
  to: string;
  inviterName: string;
  familyName: string;
  token: string;
  role: string;
}) {
  const { to, inviterName, familyName, token, role } = opts;
  const link = `${APP_URL}/invite/${token}`;
  const roleLabel = role === "admin" ? "an admin" : "a caregiver";

  if (!RESEND_API_KEY) {
    console.log(`[INVITE-LINK] to=${to} family=${familyName} link=${link}`);
    return;
  }

  try {
    const resend = new Resend(RESEND_API_KEY);
    await sendWithFallback(resend, {
      from: EMAIL_FROM,
      to,
      subject: `${inviterName} invited you to join their family on Tia 🍼`,
      html: `
        <div style="font-family:system-ui,sans-serif;max-width:500px;margin:0 auto;">
          <h2 style="color:#1f2937;">You're invited! 🎉</h2>
          <p style="color:#374151;font-size:16px;">
            <strong>${inviterName}</strong> has invited you to join <strong>${familyName}</strong> on Tia as ${roleLabel}.
          </p>
          <p style="color:#374151;font-size:15px;">
            Tia helps families track feeds, sleep, growth, memories, and more — all in one place.
          </p>
          <a href="${link}"
             style="display:inline-block;background:#fb7185;color:#fff;padding:14px 28px;text-decoration:none;border-radius:8px;margin:20px 0;font-size:16px;font-weight:600;">
            Accept Invitation
          </a>
          <p style="color:#9ca3af;font-size:13px;">This link expires in 7 days. If you didn't expect this, you can safely ignore it.</p>
        </div>`,
    });
    console.log(`[INVITE-EMAIL-SENT] to=${to} family=${familyName}`);
  } catch (e) {
    console.error("[INVITE-EMAIL-FAILED]", e);
  }
}

/** Sends an account-verification email, or logs the link in dev. */
export async function sendVerificationEmail(email: string, token: string, userId: string) {
  const link = `${APP_URL}/api/auth/verify-email?token=${token}`;

  if (!RESEND_API_KEY) {
    // Dev fallback: no Resend key -> print the link so test accounts
    // can be verified straight from the server log.
    console.log(`[VERIFY-LINK] user=${userId} email=${email} link=${link}`);
    return;
  }

  try {
    const resend = new Resend(RESEND_API_KEY);
    await sendWithFallback(resend, {
      from: EMAIL_FROM,
      to: email,
      subject: "Verify your Tia email",
      html: `
        <div style="font-family:system-ui,sans-serif;max-width:500px;margin:0 auto;">
          <h2>Welcome to Tia</h2>
          <p>Confirm this email to activate your account. This link expires in 24 hours.</p>
          <a href="${link}" style="display:inline-block;background:#e11d48;color:#fff;padding:12px 24px;text-decoration:none;border-radius:6px;margin:16px 0;">Verify Email</a>
          <p style="color:#6b7280;font-size:14px;">If you didn't create a Tia account, ignore this email.</p>
        </div>`,
    });
    console.log(`[VERIFY-EMAIL-SENT] user=${userId} email=${email}`);
  } catch (e) {
    console.error("[VERIFY-EMAIL-FAILED]", e);
  }
}