import { json } from "@sveltejs/kit";
import { env as publicEnv } from "$env/dynamic/public";
import { env as privateEnv } from "$env/dynamic/private";
import type { RequestHandler } from "./$types";
import {
  cleanText,
  HONEYPOT_FIELDS,
  LIMITS,
  validateFiles,
  validateMitmachen,
} from "$lib/components/internal/mitmachen-form-validation";

const TURNSTILE_SECRET = privateEnv.TURNSTILE_SECRET ?? "";
const TURNSTILE_ENABLED = TURNSTILE_SECRET !== "";

async function verifyTurnstile(token: string, ip: string): Promise<boolean> {
  if (!TURNSTILE_ENABLED) return true;
  if (!token) return false;
  try {
    const res = await fetch("https://challenges.cloudflare.com/turnstile/v0/siteverify", {
      method: "POST",
      headers: { "Content-Type": "application/x-www-form-urlencoded" },
      body: new URLSearchParams({ secret: TURNSTILE_SECRET, response: token, remoteip: ip }),
    });
    if (!res.ok) return false;
    const data = (await res.json()) as { success?: boolean };
    return data.success === true;
  } catch (e) {
    console.error("[mitmachen] turnstile verify failed:", e);
    return false;
  }
}

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

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 });
  }

  let form: FormData;
  try {
    form = await request.formData();
  } catch {
    return json({ error: "Ungültige Anfrage." }, { status: 400 });
  }
  const text = (key: string): string => {
    const v = form.get(key);
    return typeof v === "string" ? v : "";
  };

  // Honeypots — must all be empty
  for (const hp of HONEYPOT_FIELDS) {
    if (text(hp).trim() !== "") {
      // Pretend success so bots don't learn the trap exists
      return json({ ok: true }, { status: 201 });
    }
  }

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

  // Cloudflare Turnstile (skipped when no secret configured)
  if (TURNSTILE_ENABLED) {
    const ok = await verifyTurnstile(text("cf_turnstile_token"), getClientAddress());
    if (!ok) {
      return json({ error: "captcha" }, { status: 403 });
    }
  }

  // Full validation
  const fields = {
    title: text("title"),
    description: text("description"),
    contactName: text("contactName"),
    phone: text("phone"),
    email: text("email"),
    consent: text("consent") === "true",
  };
  const errors = validateMitmachen(fields);
  if (Object.keys(errors).length > 0) {
    return json({ errors }, { status: 422 });
  }

  const files = form
    .getAll("file")
    .filter((v): v is File => v instanceof File && v.size > 0);
  const fileError = validateFiles(files);
  if (fileError) {
    return json({ errors: { files: fileError } }, { status: 422 });
  }

  // Forward to CMS forms plugin (multipart: data-JSON-Part + file-Parts)
  const cmsBase = (publicEnv.PUBLIC_CMS_URL || "http://localhost:3099").replace(/\/$/, "");
  const cmsEnv = publicEnv.PUBLIC_CMS_ENV || "";
  const cmsUrl = cmsEnv
    ? `${cmsBase}/api/forms/mitmachen/submit-multipart?_environment=${encodeURIComponent(cmsEnv)}`
    : `${cmsBase}/api/forms/mitmachen/submit-multipart`;

  // cleanText: unsichtbare Format-Zeichen (Bidi-Marks aus Copy-Paste) raus —
  // gleiche Normalisierung wie in der Validierung.
  const payload = {
    title: cleanText(fields.title),
    description: cleanText(fields.description),
    contact_name: cleanText(fields.contactName),
    phone: cleanText(fields.phone),
    email: cleanText(fields.email),
    consent_at: new Date().toISOString(),
    submitted_via: "windwiderstand.de/api/mitmachen",
    user_agent: (request.headers.get("user-agent") ?? "").slice(0, 200),
  };

  const outgoing = new FormData();
  outgoing.set("data", JSON.stringify(payload));
  for (const f of files) outgoing.append("file", f, f.name);

  let res: Response;
  try {
    // No Origin header — we already validated it at this server.
    // CMS forms plugin (REQUIRE_ORIGIN=false) accepts requests without one.
    res = await fetch(cmsUrl, {
      method: "POST",
      headers: { "X-Forwarded-For": getClientAddress() },
      body: outgoing,
    });
  } catch (e) {
    console.error("[mitmachen] 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 text2 = await res.text().catch(() => "");
  console.error("[mitmachen] CMS error", res.status, text2);
  return json({ error: "Fehler beim Senden." }, { status: 502 });
};

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