#pragma once

#include "envoy/common/pure.h"

#include "envoy/config/core/v3/http_uri.pb.h"

#include "envoy/upstream/cluster_manager.h"

namespace Envoy {

namespace Config {

namespace DataFetcher {

/**

 * Failure reason.

 */

enum class FailureReason {

  /* A network error occurred causing remote data retrieval failure. */

  Network,

  /* A failure occurred when trying to verify remote data using sha256. */

  InvalidData,

};

/**

 * Callback used by remote data fetcher.

 */

class RemoteDataFetcherCallback {

public:

  /**

   * This function will be called when data is fetched successfully from remote.

   * @param data remote data

   */

  virtual void onSuccess(const std::string& data) PURE;

  /**

   * This function is called when error happens during fetching data.

   * @param reason failure reason.

   */

  virtual void onFailure(FailureReason reason) PURE;

};

/**

 * Remote data fetcher.

 */

class RemoteDataFetcher : public Logger::Loggable<Logger::Id::config>,

                          public Http::AsyncClient::Callbacks {

public:

  RemoteDataFetcher(Upstream::ClusterManager& cm, const envoy::config::core::v3::HttpUri& uri,

                    const std::string& content_hash, RemoteDataFetcherCallback& callback);

  ~RemoteDataFetcher() override;

  // Http::AsyncClient::Callbacks

  void onSuccess(const Http::AsyncClient::Request&, Http::ResponseMessagePtr&& response) override;

  void onFailure(const Http::AsyncClient::Request&,

                 Http::AsyncClient::FailureReason reason) override;

  void onBeforeFinalizeUpstreamSpan(Envoy::Tracing::Span&,

  /**

   * Fetch data from remote.

   * @param uri remote URI

   * @param content_hash for verifying data integrity

   * @param callback callback when fetch is done.

   */

  void fetch();

  /**

   * Cancel the fetch.

   */

  void cancel();

private:

  Upstream::ClusterManager& cm_;

  const envoy::config::core::v3::HttpUri uri_;

  const std::string content_hash_;

  RemoteDataFetcherCallback& callback_;

  Http::AsyncClient::Request* request_{};

};

using RemoteDataFetcherPtr = std::unique_ptr<RemoteDataFetcher>;

} // namespace DataFetcher

} // namespace Config

} // namespace Envoy