// Protocol Buffers - Google's data interchange format
// Copyright 2008 Google Inc.  All rights reserved.
//
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file or at
// https://developers.google.com/open-source/licenses/bsd

#include <Python.h>

namespace google {
namespace protobuf {
namespace python {

// Version constant.
// This is either 0 for python, 1 for CPP V1, 2 for CPP V2.
//
// 0 is default and is equivalent to
//   PROTOCOL_BUFFERS_PYTHON_IMPLEMENTATION=python
//
// 1 is set with -DPYTHON_PROTO2_CPP_IMPL_V1 and is equivalent to
//   PROTOCOL_BUFFERS_PYTHON_IMPLEMENTATION=cpp
// and
//   PROTOCOL_BUFFERS_PYTHON_IMPLEMENTATION_VERSION=1
//
// 2 is set with -DPYTHON_PROTO2_CPP_IMPL_V2 and is equivalent to
//   PROTOCOL_BUFFERS_PYTHON_IMPLEMENTATION=cpp
// and
//   PROTOCOL_BUFFERS_PYTHON_IMPLEMENTATION_VERSION=2
#ifdef PYTHON_PROTO2_CPP_IMPL_V1
#error "PYTHON_PROTO2_CPP_IMPL_V1 is no longer supported."
#else
#ifdef PYTHON_PROTO2_CPP_IMPL_V2
static int kImplVersion = 2;
#else
#ifdef PYTHON_PROTO2_PYTHON_IMPL
static int kImplVersion = 0;
#else

static int kImplVersion = -1;  // -1 means "Unspecified by compiler flags".

#endif  // PYTHON_PROTO2_PYTHON_IMPL
#endif  // PYTHON_PROTO2_CPP_IMPL_V2
#endif  // PYTHON_PROTO2_CPP_IMPL_V1

static const char* kImplVersionName = "api_version";

static const char* kModuleName = "_api_implementation";
static const char kModuleDocstring[] =
"_api_implementation is a module that exposes compile-time constants that\n"
"determine the default API implementation to use for Python proto2.\n"
"\n"
"It complements api_implementation.py by setting defaults using compile-time\n"
"constants defined in C, such that one can set defaults at compilation\n"
"(e.g. with bazel flag --copt=-DPYTHON_PROTO2_CPP_IMPL_V2).";

#if PY_MAJOR_VERSION >= 3
static struct PyModuleDef _module = {
  PyModuleDef_HEAD_INIT,
  kModuleName,
  kModuleDocstring,
  -1,
  NULL,
  NULL,
  NULL,
  NULL,
  NULL
};
#define INITFUNC PyInit__api_implementation
#define INITFUNC_ERRORVAL NULL
#else
#define INITFUNC init_api_implementation
#define INITFUNC_ERRORVAL
#endif

extern "C" {
  PyMODINIT_FUNC INITFUNC() {
#if PY_MAJOR_VERSION >= 3
    PyObject *module = PyModule_Create(&_module);
#else
    PyObject *module = Py_InitModule3(
        const_cast<char*>(kModuleName),
        NULL,
        const_cast<char*>(kModuleDocstring));
#endif
    if (module == NULL) {
      return INITFUNC_ERRORVAL;
    }

#ifdef Py_GIL_DISABLED
    if (PyUnstable_Module_SetGIL(module, Py_MOD_GIL_NOT_USED) != 0) {
      Py_DECREF(module);
      return NULL;
    }
#endif  // Py_GIL_DISABLED

    // Adds the module variable "api_version".
    if (PyModule_AddIntConstant(
        module,
        const_cast<char*>(kImplVersionName),
        kImplVersion))
#if PY_MAJOR_VERSION < 3
      return;
#else
      { Py_DECREF(module); return NULL; }

    return module;
#endif
  }
}

}  // namespace python
}  // namespace protobuf
}  // namespace google
