#pragma once

#include "envoy/api/api.h"

#include "envoy/extensions/resource_monitors/injected_resource/v3/injected_resource.pb.h"

#include "envoy/filesystem/filesystem.h"

#include "envoy/server/resource_monitor.h"

#include "envoy/server/resource_monitor_config.h"

namespace Envoy {

namespace Extensions {

namespace ResourceMonitors {

namespace InjectedResourceMonitor {

/**

 * A monitor for an injected resource. The resource pressure is read from a text file

 * specified in the config, which must contain a floating-point number in the range

 * [0..1] and be updated atomically by a symbolic link swap.

 * This is intended primarily for integration tests to force Envoy into an overloaded state.

 */

class InjectedResourceMonitor : public Server::ResourceMonitor {

public:

  InjectedResourceMonitor(

      const envoy::extensions::resource_monitors::injected_resource::v3::InjectedResourceConfig&

          config,

      Server::Configuration::ResourceMonitorFactoryContext& context);

  // Server::ResourceMonitor

  void updateResourceUsage(Server::ResourceUpdateCallbacks& callbacks) override;

protected:

  virtual void onFileChanged();

private:

  const std::string filename_;

  bool file_changed_{true};

  Filesystem::WatcherPtr watcher_;

  absl::optional<double> pressure_;

  absl::optional<EnvoyException> error_;

  Api::Api& api_;

};

} // namespace InjectedResourceMonitor

} // namespace ResourceMonitors

} // namespace Extensions

} // namespace Envoy