import { DomainError } from "@/db/repository";

function requireJsonMutation(request: Request): void {
  const contentType = request.headers
    .get("content-type")
    ?.split(";", 1)[0]
    .trim()
    .toLowerCase();
  if (contentType !== "application/json") {
    throw new DomainError(
      "json_required",
      "写操作只接受 application/json",
      415,
    );
  }

  const contentLength = Number(request.headers.get("content-length") ?? "0");
  if (Number.isFinite(contentLength) && contentLength > 32_768) {
    throw new DomainError("request_too_large", "请求内容过大", 413);
  }

  const origin = request.headers.get("origin");
  if (origin && origin !== new URL(request.url).origin) {
    throw new DomainError("invalid_origin", "拒绝跨站写操作", 403);
  }
  const fetchSite = request.headers.get("sec-fetch-site");
  if (fetchSite && fetchSite !== "same-origin") {
    throw new DomainError("invalid_fetch_site", "拒绝跨站写操作", 403);
  }
}

export async function readJsonMutation<T>(request: Request): Promise<T> {
  requireJsonMutation(request);
  const body = await request.text();
  if (new TextEncoder().encode(body).byteLength > 32_768) {
    throw new DomainError("request_too_large", "请求内容过大", 413);
  }
  try {
    return JSON.parse(body) as T;
  } catch {
    throw new DomainError("invalid_json", "请求不是有效 JSON", 400);
  }
}

export function apiError(error: unknown) {
  if (error instanceof DomainError) {
    const headers = new Headers({ "cache-control": "no-store" });
    if (error.retryAfterSeconds !== undefined) {
      headers.set("retry-after", String(error.retryAfterSeconds));
    }
    return Response.json({
      error_code: error.code,
      error: error.code,
      message: error.message,
      retryable: error.retryable,
      ...(error.retryAfterSeconds === undefined
        ? {}
        : { retry_after_seconds: error.retryAfterSeconds }),
      ...(error.actionUrl === undefined ? {} : { action_url: error.actionUrl }),
    }, { status: error.status, headers });
  }
  console.error("Unhandled NekoNest Cloud API error", error);
  return Response.json(
    {
      error_code: "internal_error",
      error: "internal_error",
      message: "服务暂时不可用，请稍后重试",
      retryable: true,
    },
    { status: 500, headers: { "cache-control": "no-store" } },
  );
}