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#ifndef GRPC_CORE_LIB_CHANNEL_HANDSHAKER_H
#define GRPC_CORE_LIB_CHANNEL_HANDSHAKER_H

#include <grpc/impl/codegen/grpc_types.h>

#include "src/core/lib/iomgr/closure.h"
#include "src/core/lib/iomgr/endpoint.h"
#include "src/core/lib/iomgr/exec_ctx.h"
#include "src/core/lib/iomgr/tcp_server.h"

/// Handshakers are used to perform initial handshakes on a connection
/// before the client sends the initial request.  Some examples of what
/// a handshaker can be used for includes support for HTTP CONNECT on
/// the client side and various types of security initialization.
///
/// In general, handshakers should be used via a handshake manager.

///
/// grpc_handshaker
///

typedef struct grpc_handshaker grpc_handshaker;

/// Arguments passed through handshakers and to the on_handshake_done callback.
///
/// For handshakers, all members are input/output parameters; for
/// example, a handshaker may read from \a endpoint and then later
/// replace it with a wrapped endpoint.  Similarly, a handshaker may
/// modify \a args.
///
/// For the on_handshake_done callback, all members are input arguments,
/// which the callback takes ownership of.
typedef struct {
  grpc_endpoint* endpoint;
  grpc_channel_args* args;
  void* user_data;
  grpc_slice_buffer* read_buffer;
} grpc_handshaker_args;

typedef struct {
  /// Destroys the handshaker.
  void (*destroy)(grpc_exec_ctx* exec_ctx, grpc_handshaker* handshaker);

  /// Shuts down the handshaker (e.g., to clean up when the operation is
  /// aborted in the middle).
  void (*shutdown)(grpc_exec_ctx* exec_ctx, grpc_handshaker* handshaker);

  /// Performs handshaking, modifying \a args as needed (e.g., to
  /// replace \a endpoint with a wrapped endpoint).
  /// When finished, invokes \a on_handshake_done.
  /// \a acceptor will be NULL for client-side handshakers.
  void (*do_handshake)(grpc_exec_ctx* exec_ctx, grpc_handshaker* handshaker,
                       grpc_tcp_server_acceptor* acceptor,
                       grpc_closure* on_handshake_done,
                       grpc_handshaker_args* args);
} grpc_handshaker_vtable;

/// Base struct.  To subclass, make this the first member of the
/// implementation struct.
struct grpc_handshaker {
  const grpc_handshaker_vtable* vtable;
};

/// Called by concrete implementations to initialize the base struct.
void grpc_handshaker_init(const grpc_handshaker_vtable* vtable,
                          grpc_handshaker* handshaker);

///
/// grpc_handshake_manager
///

typedef struct grpc_handshake_manager grpc_handshake_manager;

/// Creates a new handshake manager.  Caller takes ownership.
grpc_handshake_manager* grpc_handshake_manager_create();

/// Adds a handshaker to the handshake manager.
/// Takes ownership of \a handshaker.
void grpc_handshake_manager_add(grpc_handshake_manager* mgr,
                                grpc_handshaker* handshaker);

/// Destroys the handshake manager.
void grpc_handshake_manager_destroy(grpc_exec_ctx* exec_ctx,
                                    grpc_handshake_manager* mgr);

/// Shuts down the handshake manager (e.g., to clean up when the operation is
/// aborted in the middle).
/// The caller must still call grpc_handshake_manager_destroy() after
/// calling this function.
void grpc_handshake_manager_shutdown(grpc_exec_ctx* exec_ctx,
                                     grpc_handshake_manager* mgr);

/// Invokes handshakers in the order they were added.
/// Takes ownership of \a endpoint, and then passes that ownership to
/// the \a on_handshake_done callback.
/// Does NOT take ownership of \a args.  Instead, makes a copy before
/// invoking the first handshaker.
/// \a acceptor will be NULL for client-side handshakers.
///
/// When done, invokes \a on_handshake_done with a grpc_handshaker_args
/// object as its argument.  If the callback is invoked with error !=
/// GRPC_ERROR_NONE, then handshaking failed and the resulting endpoint
/// will have already been shut down (although the caller will still be
/// responsible for destroying it).
void grpc_handshake_manager_do_handshake(
    grpc_exec_ctx* exec_ctx, grpc_handshake_manager* mgr,
    grpc_endpoint* endpoint, const grpc_channel_args* channel_args,
    gpr_timespec deadline, grpc_tcp_server_acceptor* acceptor,
    grpc_iomgr_cb_func on_handshake_done, void* user_data);

#endif /* GRPC_CORE_LIB_CHANNEL_HANDSHAKER_H */