import { NextResponse } from "next/server";
import { isAuthorized } from "@/lib/access-check";
import {
  SlidingWindowLimiter,
  botReason,
  emailQuery,
  mergeAttribs,
  parseQuizLead,
  planExisting,
  shouldSendResult,
  type ListmonkSubscriber,
  type QuizLead,
} from "@/lib/quiz-lead";

/**
 * POST /api/internal/quiz-lead — лид из квиза Typebot (вызов сервер-сервер).
 *
 * Подписчик попадает в список квиза, квизовые атрибуты дописываются к
 * имеющимся — чужие списки, статусы подписок и атрибуты не трогаются
 * (логика и обоснование — `src/lib/quiz-lead.ts`).
 *
 * Защита от ботов: секрет `x-quiz-secret`; квиз быстрее 20 с — молча
 * пропускаем; общий лимит лидов в час и лимит на адрес; заблокированный в
 * Listmonk адрес не трогаем; письмо-результат — не чаще раза в сутки на адрес.
 * IP человека сюда не доходит (вызывает сервер Typebot), поэтому лимиты — не по IP.
 */

const MAX_PER_HOUR = Number(process.env.QUIZ_LEAD_MAX_PER_HOUR) || 60;
const globalLimiter = new SlidingWindowLimiter(MAX_PER_HOUR, 60 * 60 * 1000);
const emailLimiter = new SlidingWindowLimiter(3, 60 * 60 * 1000);

function auth(): string {
  return "Basic " + Buffer.from(`${process.env.LISTMONK_USER}:${process.env.LISTMONK_TOKEN}`).toString("base64");
}

function lm(path: string): string {
  return `${process.env.LISTMONK_URL}${path}`;
}

async function lmJson(path: string, method: string, body?: unknown): Promise<Response> {
  return fetch(lm(path), {
    method,
    headers: { "Content-Type": "application/json", Authorization: auth() },
    body: body === undefined ? undefined : JSON.stringify(body),
  });
}

async function findSubscriber(email: string): Promise<ListmonkSubscriber | null> {
  const res = await fetch(lm("/api/subscribers?per_page=1&query=") + encodeURIComponent(emailQuery(email)), {
    headers: { Authorization: auth() },
  });
  if (!res.ok) throw new Error(`lookup ${res.status}`);
  const json = (await res.json()) as { data?: { results?: ListmonkSubscriber[] } };
  return json?.data?.results?.[0] ?? null;
}

async function sendResult(lead: QuizLead): Promise<void> {
  const templateId = Number(process.env.LISTMONK_QUIZ_TX_TEMPLATE_ID);
  if (!templateId) {
    console.error("quiz-lead: send_result requested, but LISTMONK_QUIZ_TX_TEMPLATE_ID is not set");
    return;
  }
  const res = await lmJson("/api/tx", "POST", {
    subscriber_email: lead.email,
    template_id: templateId,
    from_email: process.env.QUIZ_RESULT_FROM || "Second Brain <delivery@mailsend.second-brain.ru>",
    data: { quiz_type: lead.quizType, utm: lead.utm },
  });
  if (!res.ok) throw new Error(`tx ${res.status}: ${(await res.text()).slice(0, 200)}`);
}

export async function POST(req: Request): Promise<NextResponse> {
  if (!isAuthorized(req.headers.get("x-quiz-secret"), process.env.QUIZ_LEAD_SECRET)) {
    return NextResponse.json({ error: "unauthorized" }, { status: 401 });
  }

  let body: unknown;
  try {
    body = await req.json();
  } catch {
    return NextResponse.json({ error: "bad json" }, { status: 400 });
  }

  const lead = parseQuizLead(body);
  if (!lead) return NextResponse.json({ error: "invalid fields" }, { status: 400 });

  const now = new Date();
  const bot = botReason(lead, now.getTime());
  if (bot) {
    console.warn("quiz-lead: skipped as bot", bot);
    return NextResponse.json({ ok: true });
  }
  if (!emailLimiter.allow(lead.email, now.getTime()) || !globalLimiter.allow("all", now.getTime())) {
    console.warn("quiz-lead: rate limited");
    return NextResponse.json({ error: "too many requests" }, { status: 429 });
  }

  const listId = Number(process.env.LISTMONK_QUIZ_LIST_ID);
  if (!listId) {
    console.error("quiz-lead: LISTMONK_QUIZ_LIST_ID is not set");
    return NextResponse.json({ error: "not configured" }, { status: 503 });
  }

  try {
    const sendNow = shouldSendResult(lead, null, now);
    const createRes = await lmJson("/api/subscribers", "POST", {
      email: lead.email,
      name: lead.email.split("@")[0],
      status: "enabled",
      lists: [listId],
      // Новый подписчик — только в одном списке квиза, подтверждать больше нечего.
      preconfirm_subscriptions: true,
      attribs: mergeAttribs({}, lead, now, sendNow),
    });

    if (createRes.ok) {
      if (sendNow) await sendResult(lead);
      return NextResponse.json({ ok: true });
    }
    if (createRes.status !== 409) {
      console.error("quiz-lead: listmonk create failed", createRes.status, (await createRes.text()).slice(0, 300));
      return NextResponse.json({ error: "listmonk" }, { status: 502 });
    }

    const existing = await findSubscriber(lead.email);
    if (!existing) {
      console.error("quiz-lead: 409, but subscriber not found");
      return NextResponse.json({ error: "lookup failed" }, { status: 502 });
    }

    const plan = planExisting(existing, lead, listId, now);
    if (plan.kind === "skip") return NextResponse.json({ ok: true });

    if (plan.addToList) {
      const addRes = await lmJson("/api/subscribers/lists", "PUT", {
        ids: [existing.id],
        action: "add",
        target_list_ids: [listId],
        status: "confirmed",
      });
      if (!addRes.ok) {
        console.error("quiz-lead: add to list failed", addRes.status, (await addRes.text()).slice(0, 300));
        return NextResponse.json({ error: "listmonk" }, { status: 502 });
      }
    }

    const putRes = await lmJson(`/api/subscribers/${existing.id}`, "PUT", plan.put);
    if (!putRes.ok) {
      console.error("quiz-lead: attribs update failed", putRes.status, (await putRes.text()).slice(0, 300));
      return NextResponse.json({ error: "listmonk" }, { status: 502 });
    }

    if (plan.sendResult) await sendResult(lead);
  } catch (e) {
    console.error("quiz-lead: upstream error", e);
    return NextResponse.json({ error: "upstream" }, { status: 502 });
  }

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