import { NextResponse } from 'next/server';
import { fetchBackendAccessToken, requireAdminSession } from '../../_utils/backendAuth';

export const runtime = 'nodejs';

function resolvePreferencesBackendPath(): string {
  const configured = process.env.BACKEND_I18N_PREFERENCES_PATH?.trim();
  if (configured) return configured.startsWith('/') ? configured : `/${configured}`;
  return '/api/admin/i18n/preferences';
}

function resolveBackendBaseUrl(): string | null {
  const value = process.env.NEXT_PUBLIC_API_BASE_URL?.trim();
  return value || null;
}

async function proxyPreferencesRequest(request: Request, method: 'GET' | 'POST' | 'PUT' | 'DELETE') {
  console.info('[API][i18n/preferences] start', { method });

  const access = await requireAdminSession(request);
  if (!access.ok) {
    console.warn('[API][i18n/preferences] denied:admin-session', { method });
    return access.response;
  }

  const tokenResult = await fetchBackendAccessToken(request);
  if (!tokenResult.ok || !tokenResult.accessToken) {
    console.warn('[API][i18n/preferences] denied:access-token', {
      method,
      status: tokenResult.status,
      message: tokenResult.message,
    });
    const denied = NextResponse.json(
      { ok: false, message: tokenResult.message ?? 'Unable to obtain backend access token.' },
      { status: tokenResult.status === 401 ? 401 : 403 }
    );

    for (const setCookie of tokenResult.setCookies) {
      denied.headers.append('set-cookie', setCookie);
    }

    return denied;
  }

  const apiBase = resolveBackendBaseUrl();
  if (!apiBase) {
    console.error('[API][i18n/preferences] missing NEXT_PUBLIC_API_BASE_URL');
    return NextResponse.json({ ok: false, message: 'Missing NEXT_PUBLIC_API_BASE_URL.' }, { status: 500 });
  }

  const cookie = request.headers.get('cookie') ?? '';
  const backendPath = resolvePreferencesBackendPath();

  const headers: Record<string, string> = {
    cookie,
    Authorization: `Bearer ${tokenResult.accessToken}`,
  };
  let body: string | undefined;

  // Build the backend URL; for DELETE we forward the languageCode query param if present.
  const incomingUrl = new URL(request.url);
  const languageCode = incomingUrl.searchParams.get('languageCode');
  const backendQuery = languageCode ? `?languageCode=${encodeURIComponent(languageCode)}` : '';
  const backendUrl = `${apiBase}${backendPath}${backendQuery}`;

  if (method !== 'GET' && method !== 'DELETE') {
    const payload = await request.json().catch(() => ({}));
    body = JSON.stringify(payload ?? {});
    headers['Content-Type'] = 'application/json';

    const categoriesCount = Array.isArray((payload as { categories?: unknown[] })?.categories)
      ? (payload as { categories?: unknown[] }).categories!.length
      : 0;
    const globalKeysCount = Array.isArray((payload as { globalKeys?: unknown[] })?.globalKeys)
      ? (payload as { globalKeys?: unknown[] }).globalKeys!.length
      : 0;

    console.info('[API][i18n/preferences] outgoing-payload', {
      method,
      categoriesCount,
      globalKeysCount,
    });
  }

  if (method === 'DELETE' && languageCode) {
    console.info('[API][i18n/preferences] delete-language', { languageCode });
  }

  const backendResponse = await fetch(backendUrl, {
    method,
    headers,
    body,
    cache: 'no-store',
  }).catch(() => null);

  if (!backendResponse) {
    console.error('[API][i18n/preferences] backend unreachable', {
      method,
      backendPath,
    });
    const failed = NextResponse.json({ ok: false, message: 'Preferences backend is unreachable.' }, { status: 502 });
    for (const setCookie of tokenResult.setCookies) {
      failed.headers.append('set-cookie', setCookie);
    }
    return failed;
  }

  console.info('[API][i18n/preferences] backend-response', {
    method,
    status: backendResponse.status,
    ok: backendResponse.ok,
  });

  const payload = await backendResponse.json().catch(() => null);
  const out = NextResponse.json(payload ?? { ok: backendResponse.ok }, { status: backendResponse.status });

  for (const setCookie of tokenResult.setCookies) {
    out.headers.append('set-cookie', setCookie);
  }

  return out;
}

export async function GET(request: Request) {
  return proxyPreferencesRequest(request, 'GET');
}

export async function POST(request: Request) {
  return proxyPreferencesRequest(request, 'POST');
}

export async function PUT(request: Request) {
  return proxyPreferencesRequest(request, 'PUT');
}

export async function DELETE(request: Request) {
  return proxyPreferencesRequest(request, 'DELETE');
}