import { getServerConfig } from "@/lib/config";
import { requestLocale } from "@/lib/http-guard";
import { clientKey, rateLimit, rateLimitResponse } from "@/lib/rate-limit";
import { providerListModels } from "@/lib/openai-compat";
import { resolveModelTarget } from "@/lib/providers-server";

/**
 * Lists the models a cloud provider offers to the browser's key — the same
 * listing the chat picker and the Settings rows show. The key travels in the
 * request headers and is never stored.
 */
export async function GET(request: Request) {
  const locale = requestLocale(request);
  const config = getServerConfig();

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

  const resolved = resolveModelTarget(config, request, locale);
  if ("error" in resolved) {
    return Response.json({ error: resolved.error.message, kind: resolved.error.kind }, { status: resolved.error.status });
  }
  if (resolved.target.kind !== "provider") {
    return Response.json({ error: "Pick a provider to list its models.", kind: "bad_provider" }, { status: 400 });
  }

  try {
    const models = await providerListModels(resolved.target.target, config.healthTimeoutMs * 2);
    return Response.json({ provider: resolved.target.provider, models }, { headers: { "Cache-Control": "no-store" } });
  } catch (error) {
    const message = error instanceof Error ? error.message : "Could not list the models.";
    const kind = (error as { kind?: string }).kind ?? "unknown";
    console.error("[api/providers]", kind, message);
    return Response.json({ error: message, kind }, { status: 502, headers: { "Cache-Control": "no-store" } });
  }
}