#pragma once

#include <memory>

#include "envoy/http/header_map.h"

#include "envoy/upstream/upstream.h"

namespace Envoy {

namespace Grpc {

struct StatNames;

/**

 * Captures grpc-related structures with cardinality of one per server.

 */

class Context {

public:

  enum class Protocol { Grpc, GrpcWeb };

  struct RequestStatNames;

  /**

   * Parses out request grpc service-name and method from the path, returning a

   * populated RequestStatNames if successful. See the implementation

   * (source/common/grpc/common.h) for the definition of RequestStatNames. It is

   * hidden in the implementation since it references StatName, which is defined

   * only in the stats implementation.

   *

   * @param path the request path.

   * @return the request names, expressed as StatName.

   */

  virtual absl::optional<RequestStatNames>

  resolveDynamicServiceAndMethod(const Http::HeaderEntry* path) PURE;

  /**

   * Parses out request grpc service-name and method from the path with dots

   * replaced by underscores in grpc service-name, returning a populated

   * RequestStatName if successful. See

   * the implementation (source/common/grpc/common.h) for the definition of

   * RequestStatNames. It is hidden in the implementation since it references StatName, which is

   * defined only in the stats implementation.

   *

   * @param path the request path.

   * @return the request names, expressed as StatName.

   */

  virtual absl::optional<RequestStatNames>

  resolveDynamicServiceAndMethodWithDotReplaced(const Http::HeaderEntry* path) PURE;

  /**

   * Charge a success/failure stat to a cluster/service/method.

   * @param cluster supplies the target cluster.

   * @param protocol supplies the downstream protocol in use.

   * @param request_names supplies the request names.

   * @param grpc_status supplies the gRPC status.

   */

  virtual void chargeStat(const Upstream::ClusterInfo& cluster, Protocol protocol,

                          const absl::optional<RequestStatNames>& request_names,

                          const Http::HeaderEntry* grpc_status) PURE;

  /**

   * Charge a success/failure stat to a cluster/service/method.

   * @param cluster supplies the target cluster.

   * @param protocol supplies the downstream protocol in use.

   * @param request_names supplies the request names.

   * @param success supplies whether the call succeeded.

   */

  virtual void chargeStat(const Upstream::ClusterInfo& cluster, Protocol protocol,

                          const absl::optional<RequestStatNames>& request_names, bool success) PURE;

  /**

   * Charge a success/failure stat to a cluster/service/method.

   * @param cluster supplies the target cluster.

   * @param request_names supplies the request names.

   * @param success supplies whether the call succeeded.

   */

  virtual void chargeStat(const Upstream::ClusterInfo& cluster,

                          const absl::optional<RequestStatNames>& request_names, bool success) PURE;

  /**

   * Charge a request message stat to a cluster/service/method.

   * @param cluster supplies the target cluster.

   * @param request_names supplies the request names.

   * @param amount supplies the number of the request messages.

   */

  virtual void chargeRequestMessageStat(const Upstream::ClusterInfo& cluster,

                                        const absl::optional<RequestStatNames>& request_names,

                                        uint64_t amount) PURE;

  /**

   * Charge a response message stat to a cluster/service/method.

   * @param cluster supplies the target cluster.

   * @param request_names supplies the request names.

   * @param amount supplies the number of the response messages.

   */

  virtual void chargeResponseMessageStat(const Upstream::ClusterInfo& cluster,

                                         const absl::optional<RequestStatNames>& request_names,

                                         uint64_t amount) PURE;

  /**

   * Charge upstream stat to a cluster/service/method.

   * @param cluster supplies the target cluster.

   * @param request_names supplies the request names.

   * @param duration supplies the duration of the upstream request.

   */

  virtual void chargeUpstreamStat(const Upstream::ClusterInfo& cluster,

                                  const absl::optional<RequestStatNames>& request_names,

                                  std::chrono::milliseconds duration) PURE;

  /**

   * @return a struct containing StatNames for gRPC stat tokens.

   */

  virtual StatNames& statNames() PURE;

};

using ContextPtr = std::unique_ptr<Context>;

} // namespace Grpc

} // namespace Envoy