import { z } from "zod";

import { authErrorKind, authErrorMessage, getServerConfig, resolveAuth } from "@/lib/config";
import { rejectCrossOrigin, rejectOversizedBody, requestLocale } from "@/lib/http-guard";
import { translate } from "@/lib/i18n-dict";
import { addSubscription, removeSubscription } from "@/lib/push-store";
import { clientKey, rateLimit, rateLimitResponse } from "@/lib/rate-limit";

export const runtime = "nodejs";
export const dynamic = "force-dynamic";

/**
 * Push reminder subscriptions. GET reports whether reminders are available
 * (VAPID configured) and hands out the public key; POST/DELETE manage this
 * browser's subscription. The feature is hidden client-side when `enabled`
 * is false — no half-configured UI ever shows.
 */

/**
 * The server POSTs to the stored endpoint with VAPID headers, so it must be a
 * real push service: an arbitrary URL here would be an SSRF primitive. The
 * allowed hosts come from the config (PUSH_ALLOWED_HOSTS), defaulting to the
 * real services.
 */
function isPushEndpoint(value: string, allowedHosts: string[]): boolean {
  try {
    const url = new URL(value);
    if (url.protocol !== "https:") return false;
    const host = url.hostname.toLowerCase();
    return allowedHosts.some((entry) => (entry.startsWith(".") ? host.endsWith(entry) : host === entry));
  } catch {
    return false;
  }
}

const subscriptionSchema = z.object({
  endpoint: z.string().url().max(2000),
  keys: z.object({
    p256dh: z.string().min(16).max(400),
    auth: z.string().min(8).max(200),
  }),
});

export async function GET(request: Request) {
  const locale = requestLocale(request);
  const crossOrigin = rejectCrossOrigin(request);
  if (crossOrigin) return crossOrigin;

  const config = getServerConfig();
  const limit = rateLimit(`push:${clientKey(request)}`, config.rateLimits.push, config.rateLimits.windowMs);
  if (!limit.allowed) return rateLimitResponse(limit, locale);

  const auth = resolveAuth(config, request);
  if ("error" in auth) {
    return Response.json(
      { error: authErrorMessage(locale, auth.error), kind: authErrorKind(auth.error) },
      { status: 401 },
    );
  }

  const enabled = Boolean(config.push.publicKey && config.push.privateKey);
  return Response.json(
    { enabled, publicKey: enabled ? config.push.publicKey : undefined },
    { headers: { "Cache-Control": "no-store" } },
  );
}

export async function POST(request: Request) {
  const locale = requestLocale(request);
  const crossOrigin = rejectCrossOrigin(request);
  if (crossOrigin) return crossOrigin;

  const config = getServerConfig();
  const oversized = rejectOversizedBody(request, 64 * 1024);
  if (oversized) return oversized;

  const limit = rateLimit(`push:${clientKey(request)}`, config.rateLimits.push, config.rateLimits.windowMs);
  if (!limit.allowed) return rateLimitResponse(limit, locale);

  const auth = resolveAuth(config, request);
  if ("error" in auth) {
    return Response.json(
      { error: authErrorMessage(locale, auth.error), kind: authErrorKind(auth.error) },
      { status: 401 },
    );
  }

  if (!config.push.publicKey || !config.push.privateKey) {
    return Response.json(
      { error: translate(locale, "server.pushDisabled"), kind: "push_disabled" },
      { status: 404 },
    );
  }

  let payload: unknown;
  try {
    payload = await request.json();
  } catch {
    return Response.json({ error: translate(locale, "server.bodyNotJson") }, { status: 400 });
  }

  const parsed = subscriptionSchema.safeParse(payload);
  if (!parsed.success) {
    return Response.json(
      {
        error: translate(locale, "server.invalidRequest", {
          detail: parsed.error.issues
            .slice(0, 3)
            .map((issue) => `${issue.path.join(".") || "body"} ${issue.message}`)
            .join("; "),
        }),
      },
      { status: 400 },
    );
  }
  if (!isPushEndpoint(parsed.data.endpoint, config.push.allowedHosts)) {
    return Response.json(
      { error: translate(locale, "server.pushEndpoint"), kind: "bad_endpoint" },
      { status: 400 },
    );
  }

  const count = await addSubscription(config.push.dir, parsed.data, config.push.maxSubscriptions);
  if (!count.accepted) {
    return Response.json(
      { error: translate(locale, "server.pushTooMany", { max: config.push.maxSubscriptions }), kind: "too_many" },
      { status: 429 },
    );
  }
  return Response.json({ ok: true, count: count.count }, { headers: { "Cache-Control": "no-store" } });
}

export async function DELETE(request: Request) {
  const locale = requestLocale(request);
  const crossOrigin = rejectCrossOrigin(request);
  if (crossOrigin) return crossOrigin;

  const config = getServerConfig();
  const limit = rateLimit(`push:${clientKey(request)}`, config.rateLimits.push, config.rateLimits.windowMs);
  if (!limit.allowed) return rateLimitResponse(limit, locale);

  const auth = resolveAuth(config, request);
  if ("error" in auth) {
    return Response.json(
      { error: authErrorMessage(locale, auth.error), kind: authErrorKind(auth.error) },
      { status: 401 },
    );
  }

  const endpoint = new URL(request.url).searchParams.get("endpoint") ?? "";
  if (!endpoint) {
    return Response.json(
      { error: translate(locale, "server.invalidRequest", { detail: "endpoint" }) },
      { status: 400 },
    );
  }

  const count = await removeSubscription(config.push.dir, endpoint);
  return Response.json({ ok: true, count }, { headers: { "Cache-Control": "no-store" } });
}