import { NextResponse } from "next/server";
import { Resend } from "resend";
import { z } from "zod";

// Node.js is the default runtime for Route Handlers; an explicit `runtime`
// export is incompatible with `cacheComponents` (next.config.ts), so we omit it.

/* Mirror of the client-side schema in contact-form.tsx — keep both in sync. */
const contactSchema = z.object({
  firstName: z.string().min(1, "First name is required"),
  lastName: z.string().min(1, "Last name is required"),
  email: z.string().min(1, "Email is required").email("Enter a valid email"),
  phone: z
    .string()
    .regex(/^[+\d][\d\s().-]{5,}$/, "Enter a valid phone number")
    .optional()
    .or(z.literal("")),
  message: z.string().min(10, "Tell us a bit more (10+ characters)"),
});

/** Escape user-supplied text before interpolating it into the HTML body. */
function escapeHtml(value: string): string {
  return value
    .replace(/&/g, "&")
    .replace(/</g, "&lt;")
    .replace(/>/g, "&gt;")
    .replace(/"/g, "&quot;")
    .replace(/'/g, "&#39;");
}

export async function POST(request: Request) {
  let payload: unknown;
  try {
    payload = await request.json();
  } catch {
    return NextResponse.json(
      { error: "Invalid JSON payload" },
      { status: 400 },
    );
  }

  const parsed = contactSchema.safeParse(payload);
  if (!parsed.success) {
    return NextResponse.json(
      { error: "Validation failed", issues: parsed.error.flatten() },
      { status: 400 },
    );
  }

  const { firstName, lastName, email, phone, message } = parsed.data;

  const apiKey = process.env.RESEND_API_KEY;
  const fromEmail = process.env.CONTACT_FROM_EMAIL;
  const toEmail = process.env.CONTACT_TO_EMAIL;

  if (!apiKey || !fromEmail || !toEmail) {
    console.error(
      "[contact] Email service not configured: missing one of RESEND_API_KEY, CONTACT_FROM_EMAIL, CONTACT_TO_EMAIL.",
    );
    return NextResponse.json(
      { error: "Email service not configured" },
      { status: 500 },
    );
  }

  const fullName = `${firstName} ${lastName}`.trim();
  const html = `
    <h2>New contact form submission</h2>
    <p><strong>Name:</strong> ${escapeHtml(fullName)}</p>
    <p><strong>Email:</strong> ${escapeHtml(email)}</p>
    <p><strong>Phone:</strong> ${escapeHtml(phone || "—")}</p>
    <p><strong>Message:</strong></p>
    <p>${escapeHtml(message).replace(/\n/g, "<br />")}</p>
  `.trim();

  try {
    const resend = new Resend(apiKey);
    const { error } = await resend.emails.send({
      from: fromEmail,
      to: toEmail,
      replyTo: email,
      subject: `New contact message from ${fullName}`,
      html,
    });

    if (error) {
      console.error("[contact] Resend returned an error:", error);
      return NextResponse.json(
        { error: "Failed to send message" },
        { status: 500 },
      );
    }
  } catch (error) {
    console.error("[contact] Failed to send email:", error);
    return NextResponse.json(
      { error: "Failed to send message" },
      { status: 500 },
    );
  }

  return NextResponse.json({ ok: true }, { status: 200 });
}