import { json } from "@sveltejs/kit";
import { env as publicEnv } from "$env/dynamic/public";
import type { RequestHandler } from "./$types";

// Honeypot field — must be empty (bot trap)
const HONEYPOT = "website";
// Bots usually post immediately; require a minimum dwell time
const MIN_CLIENT_AGE_MS = 3_000;
// Prompt can be large (embeds the full draft). CMS body cap is the hard backstop.
const PROMPT_MAX = 60_000;

const ALLOWED_ORIGINS = new Set([
  "https://windwiderstand.de",
  "https://www.windwiderstand.de",
  "http://localhost:5173",
  "http://localhost:4173",
]);

function isValidEmail(s: string): boolean {
  return /^[^\s@]+@[^\s@]+\.[^\s@]+$/.test(s.trim());
}

export const POST: RequestHandler = async ({ request, getClientAddress }) => {
  // Origin/Referer must match — blocks naive cross-site POSTs
  const origin = request.headers.get("origin") ?? "";
  const referer = request.headers.get("referer") ?? "";
  const refererOrigin = referer ? safeOrigin(referer) : "";
  if (!ALLOWED_ORIGINS.has(origin) && !ALLOWED_ORIGINS.has(refererOrigin)) {
    return json({ error: "Ungültige Anfrage." }, { status: 403 });
  }

  const raw = await request.json().catch(() => null);
  if (!raw || typeof raw !== "object") {
    return json({ error: "Ungültige Anfrage." }, { status: 400 });
  }
  const body = raw as Record<string, unknown>;
  const str = (k: string): string => (typeof body[k] === "string" ? (body[k] as string) : "");

  // Honeypot — pretend success so bots don't learn the trap exists
  if (str(HONEYPOT).trim() !== "") {
    return json({ ok: true }, { status: 201 });
  }

  // Client age
  const clientAge = Number(body._client_age_ms);
  if (!Number.isFinite(clientAge) || clientAge < MIN_CLIENT_AGE_MS) {
    return json({ error: "Bitte etwas mehr Zeit lassen." }, { status: 429 });
  }

  // Validation
  const fields = {
    name: str("name").trim(),
    email: str("email").trim(),
    vorranggebiet: str("vorranggebiet").trim(),
    prompt: str("prompt"),
  };
  const errors: Record<string, string> = {};
  if (!fields.name) errors.name = "Name fehlt.";
  if (!isValidEmail(fields.email)) errors.email = "Ungültige E-Mail.";
  if (fields.prompt.trim().length < 50) errors.prompt = "Kein Prompt vorhanden.";
  if (fields.prompt.length > PROMPT_MAX) errors.prompt = "Prompt zu lang.";
  if (Object.keys(errors).length > 0) {
    return json({ errors }, { status: 422 });
  }

  // Forward to CMS forms plugin
  const cmsBase = (publicEnv.PUBLIC_CMS_URL || "http://localhost:3099").replace(/\/$/, "");
  const cmsEnv = publicEnv.PUBLIC_CMS_ENV || "";
  const cmsUrl = cmsEnv
    ? `${cmsBase}/api/forms/stellungnahme/submit?_environment=${encodeURIComponent(cmsEnv)}`
    : `${cmsBase}/api/forms/stellungnahme/submit`;

  const payload = {
    name: fields.name,
    email: fields.email,
    vorranggebiet: fields.vorranggebiet,
    prompt: fields.prompt,
    consent_at: new Date().toISOString(),
    submitted_via: "windwiderstand.de/api/stellungnahme",
    user_agent: (request.headers.get("user-agent") ?? "").slice(0, 200),
  };

  let res: Response;
  try {
    // No Origin header — already validated here. CMS forms plugin (REQUIRE_ORIGIN=false) accepts it.
    res = await fetch(cmsUrl, {
      method: "POST",
      headers: {
        "Content-Type": "application/json",
        "X-Forwarded-For": getClientAddress(),
      },
      body: JSON.stringify(payload),
    });
  } catch (e) {
    console.error("[stellungnahme] CMS fetch failed:", e);
    return json({ error: "Server nicht erreichbar." }, { status: 502 });
  }

  if (res.ok) {
    return json({ ok: true }, { status: 201 });
  }
  if (res.status === 429) {
    return json({ error: "Zu viele Anfragen. Bitte später erneut versuchen." }, { status: 429 });
  }
  const text = await res.text().catch(() => "");
  console.error("[stellungnahme] CMS error", res.status, text);
  return json({ error: "Fehler beim Senden." }, { status: 502 });
};

function safeOrigin(u: string): string {
  try {
    return new URL(u).origin;
  } catch {
    return "";
  }
}