import { auth } from "@/app/(auth)/auth";
import { getSystemSetting } from "@/lib/db/queries";

const ALLOWED_FAL_HOSTS = new Set(["rest.alpha.fal.ai", "rest.fal.ai"]);

type FalRealtimeConfig = {
  enabled?: boolean;
  falApiKey?: string;
  apiKey?: string;
};

type AngleEditConfig = {
  falApiKey?: string;
};

async function getRealtimeCanvasConfig() {
  const [realtimeSetting, angleEditSetting] = await Promise.all([
    getSystemSetting({ key: "realtime_canvas_config" }).catch(() => null),
    getSystemSetting({ key: "angle_edit_config" }).catch(() => null),
  ]);

  const realtimeConfig = (realtimeSetting?.value || {}) as FalRealtimeConfig;
  const angleEditConfig = (angleEditSetting?.value || {}) as AngleEditConfig;
  const fallbackKey = String(
    angleEditConfig.falApiKey || process.env.FAL_KEY || process.env.FAL_API_KEY || ""
  ).trim();

  return {
    ...realtimeConfig,
    falApiKey:
      String(realtimeConfig.falApiKey || realtimeConfig.apiKey || "").trim() || fallbackKey,
  } as FalRealtimeConfig;
}

async function handleProxy(request: Request) {
  const session = await auth();
  if (!session?.user?.id) {
    return Response.json({ code: "UNAUTHORIZED", message: "请先登录" }, { status: 401 });
  }

  const targetUrl = request.headers.get("x-fal-target-url");
  if (!targetUrl) {
    return Response.json(
      { code: "INVALID_TARGET", message: "缺少 x-fal-target-url 请求头" },
      { status: 400 }
    );
  }

  let parsedUrl: URL;
  try {
    parsedUrl = new URL(targetUrl);
  } catch {
    return Response.json(
      { code: "INVALID_TARGET", message: "x-fal-target-url 不是合法 URL" },
      { status: 400 }
    );
  }

  if (!ALLOWED_FAL_HOSTS.has(parsedUrl.host)) {
    return Response.json(
      { code: "TARGET_NOT_ALLOWED", message: "不允许代理该目标地址" },
      { status: 403 }
    );
  }

  const realtimeConfig = await getRealtimeCanvasConfig();
  if (realtimeConfig.enabled === false) {
    return Response.json(
      {
        code: "FEATURE_DISABLED",
        message: "实时画布服务未启用（请在本地AI设置中开启）",
      },
      { status: 403 }
    );
  }

  const falApiKey = realtimeConfig.falApiKey?.trim() || "";
  if (!falApiKey) {
    return Response.json(
      {
        code: "FAL_KEY_MISSING",
        message: "未配置 FAL API Key（请在本地AI设置的实时画布配置中填写）",
      },
      { status: 500 }
    );
  }

  let body: ArrayBuffer | undefined;
  if (request.method !== "GET" && request.method !== "HEAD") {
    body = await request.arrayBuffer();
  }

  const headers = new Headers();
  headers.set("Authorization", `Key ${falApiKey}`);
  headers.set("Accept", request.headers.get("accept") || "application/json");
  const contentType = request.headers.get("content-type");
  if (contentType) {
    headers.set("Content-Type", contentType);
  }

  const upstreamResponse = await fetch(parsedUrl.toString(), {
    method: request.method,
    headers,
    body,
    cache: "no-store",
  });

  return new Response(upstreamResponse.body, {
    status: upstreamResponse.status,
    statusText: upstreamResponse.statusText,
    headers: upstreamResponse.headers,
  });
}

export async function GET(request: Request) {
  return handleProxy(request);
}

export async function POST(request: Request) {
  return handleProxy(request);
}

export async function PUT(request: Request) {
  return handleProxy(request);
}

export async function PATCH(request: Request) {
  return handleProxy(request);
}

export async function DELETE(request: Request) {
  return handleProxy(request);
}