import { NextRequest, NextResponse } from 'next/server';
import { auth } from '@/auth';
import { getEffectiveTier } from '@/lib/entitlements';
import { isByokProviderAllowed } from '@/lib/byok';
import { fetchLiveModelsForProvider, PROVIDER_MODEL_SUGGESTIONS, type FetchModelsResult } from '@/lib/ai/models-list';
import { VALID_PROVIDERS, type AiGatewayProvider } from '@/lib/ai/router';

// Providers that return static suggestions regardless of key
const STATIC_PROVIDERS = new Set(['anthropic', 'anthropic_custom', 'custom_anthropic', 'google', 'minimax']);

/**
 * GET /api/user/api-keys/live-models?provider=<provider>[&key=<api_key>][&baseUrl=<url>]
 *
 * - Static providers (minimax, anthropic, google): returns suggestions immediately, no key needed.
 * - Live providers (openai, deepseek…): requires key to fetch live from provider.
 */
export async function GET(request: NextRequest) {
  const session = await auth();
  if (!session?.user?.id) {
    return NextResponse.json({ error: 'Unauthorized' }, { status: 401 });
  }

  const tier = await getEffectiveTier(session.user.id);
  if (tier === 'BASIC') {
    return NextResponse.json({ error: 'Forbidden' }, { status: 403 });
  }

  const { searchParams } = request.nextUrl;
  const provider = searchParams.get('provider') as AiGatewayProvider;
  const apiKey = searchParams.get('key') ?? '';
  const baseUrl = searchParams.get('baseUrl') ?? undefined;

  if (!provider) {
    return NextResponse.json({ error: 'Missing provider' }, { status: 400 });
  }

  if (!VALID_PROVIDERS.has(provider)) {
    return NextResponse.json({ error: 'Invalid provider' }, { status: 400 });
  }

  if (!isByokProviderAllowed(tier, provider)) {
    return NextResponse.json({ error: 'Tier restricted' }, { status: 403 });
  }

  // Static suggestion providers: return immediately without a key
  if (STATIC_PROVIDERS.has(provider)) {
    const base = provider === 'anthropic_custom' || provider === 'custom_anthropic' ? 'anthropic' : provider;
    const models = PROVIDER_MODEL_SUGGESTIONS[base] ?? [];
    return NextResponse.json({ success: true, models, fromApi: false });
  }

  // Live providers need a key
  if (!apiKey || apiKey.length < 4) {
    return NextResponse.json({ success: true, models: PROVIDER_MODEL_SUGGESTIONS[provider] ?? [], fromApi: false });
  }

  const result: FetchModelsResult = await fetchLiveModelsForProvider(provider, apiKey, baseUrl);
  return NextResponse.json({ success: true, models: result.models, fromApi: result.fromApi });
}