#pragma once

#include "envoy/common/callback.h"

#include "envoy/common/pure.h"

#include "absl/strings/string_view.h"

#include "xds/core/v3/context_params.pb.h"

namespace Envoy {

namespace Config {

/**

 * A provider for xDS context parameters. These are currently derived from the bootstrap, but will

 * be set dynamically at runtime in the near future as we add support for dynamic context parameter

 * discovery and updates.

 *

 * In general, this is intended to be used only on the main thread, as part of the Server instance

 * interface and config subsystem.

 */

class ContextProvider {

public:

  /**

   * Callback type for when dynamic context changes. The argument provides the resource type URL for

   * the update.

   */

  using UpdateNotificationCb = std::function<absl::Status(absl::string_view)>;

  /**

   * @return const xds::core::v3::ContextParams& static node-level context parameters.

   */

  virtual const xds::core::v3::ContextParams& nodeContext() const PURE;

  /**

   * @param resource_type_url resource type URL for context parameters.

   * @return const xds::core::v3::ContextParams& dynamic node-level context parameters.

   */

  virtual const xds::core::v3::ContextParams&

  dynamicContext(absl::string_view resource_type_url) const PURE;

  /**

   * Set a dynamic context parameter.

   * @param resource_type_url resource type URL for context parameter.

   * @param key parameter key.

   * @param value parameter value.

   * @return if the update was successful.

   */

  virtual absl::Status setDynamicContextParam(absl::string_view resource_type_url,

                                              absl::string_view key, absl::string_view value) PURE;

  /**

   * Unset a dynamic context parameter.

   * @param resource_type_url resource type URL for context parameter.

   * @param key parameter key.

   * @return if the update was successful.

   */

  virtual absl::Status unsetDynamicContextParam(absl::string_view resource_type_url,

                                                absl::string_view key) PURE;

  /**

   * Register a callback for notification when the dynamic context changes.

   * @param callback notification callback.

   * @return Common::CallbackHandlePtr callback handle for removal.

   */

  ABSL_MUST_USE_RESULT virtual Common::CallbackHandlePtr

  addDynamicContextUpdateCallback(UpdateNotificationCb callback) const PURE;

};

} // namespace Config

} // namespace Envoy