import { NextRequest, NextResponse } from 'next/server';
import { getStalwartCredentials } from '@/lib/stalwart/credentials';

export const runtime = 'nodejs';

/**
 * GET /api/ai/server/models — list models on the centrally-hosted `server`
 * class runtime (docs/AI-ASSISTANT-CONCEPT.md §2.1: "the same self-hosted
 * open-weight model stack as `local`... running on VNC's own infrastructure
 * instead of the user's laptop"). Tonight, `AI_SERVER_BASE_URL` stands in for
 * that infra with the Ollama already running on this developer's Mac — see
 * the module comment in lib/ai/entitlement.ts. Swapping to the real
 * EU/CH-hosted instance tomorrow is a config change, not a rewrite.
 *
 * Listing models is not a billable action (doc §10 point 1 — cosmetic), so
 * this only requires a valid session, not a seat.
 */
export async function GET(request: NextRequest) {
  const auth = await getStalwartCredentials(request);
  if (!auth) {
    return NextResponse.json({ error: 'not authenticated' }, { status: 401 });
  }

  const baseUrl = process.env.AI_SERVER_BASE_URL;
  if (!baseUrl) {
    return NextResponse.json({ error: 'AI server class is not configured' }, { status: 503 });
  }

  try {
    const res = await fetch(`${baseUrl.replace(/\/+$/, '')}/api/tags`);
    if (!res.ok) {
      return NextResponse.json({ error: `upstream returned ${res.status}` }, { status: 502 });
    }
    const body = (await res.json()) as { models?: Array<{ name: string }> };
    return NextResponse.json({ models: (body.models ?? []).map((m) => m.name).filter(Boolean) });
  } catch (cause) {
    return NextResponse.json(
      { error: cause instanceof Error ? cause.message : 'AI server unreachable' },
      { status: 502 },
    );
  }
}