//     Copyright 2018, Kay Hayen, mailto:kay.hayen@gmail.com
//
//     Part of "Nuitka", an optimizing Python compiler that is compatible and
//     integrates with CPython, but also works on its own.
//
//     Licensed under the Apache License, Version 2.0 (the "License");
//     you may not use this file except in compliance with the License.
//     You may obtain a copy of the License at
//
//        http://www.apache.org/licenses/LICENSE-2.0
//
//     Unless required by applicable law or agreed to in writing, software
//     distributed under the License is distributed on an "AS IS" BASIS,
//     WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
//     See the License for the specific language governing permissions and
//     limitations under the License.
//
#ifndef __NUITKA_COMPILED_COROUTINE_H__
#define __NUITKA_COMPILED_COROUTINE_H__

// Compiled coroutine type.

// Another cornerstone of the integration into CPython. Try to behave as well as
// normal coroutine objects do or even better.

#if PYTHON_VERSION >= 350

// The Nuitka_CoroutineObject is the storage associated with a compiled
// coroutine object instance of which there can be many for each code.
struct Nuitka_CoroutineObject {
    PyObject_VAR_HEAD

        PyObject *m_name;

    // TODO: Only to make traceback for non-started throw
    PyObject *m_module;

    PyObject *m_qualname;
    PyObject *m_yieldfrom;

    // Weak references are supported for coroutine objects in CPython.
    PyObject *m_weakrefs;

    int m_running;

    // When a coroutine is awaiting, this flag is set.
    int m_awaiting;

    void *m_code;

    PyObject *m_exception_type, *m_exception_value;
    PyTracebackObject *m_exception_tb;

    // The parent frame of the coroutine, if created.
    struct Nuitka_FrameObject *m_frame;

    PyCodeObject *m_code_object;

    // While yielding, this was the frame currently active, restore when
    // resuming.
    struct Nuitka_FrameObject *m_resume_frame;

    // Was it ever used, is it still running, or already finished.
    Generator_Status m_status;

#if PYTHON_VERSION >= 370
    _PyErr_StackItem m_exc_state;

    // The cr_origin attribute.
    PyObject *m_origin;
#endif

    // The label index to resume after yield.
    int m_yield_return_index;

    // Returned value if yielded value is NULL, is
    // NULL if not a return
    PyObject *m_returned;

    /* The heap of generator objects at run time. */
    void *m_heap_storage;

    /* Closure variables given, if any, we reference cells here. The last
     * part is dynamically allocated, the array size differs per coroutine
     * and includes the heap storage.
     */
    Py_ssize_t m_closure_given;
    struct Nuitka_CellObject *m_closure[1];
};

extern PyTypeObject Nuitka_Coroutine_Type;

typedef PyObject *(*coroutine_code)(struct Nuitka_CoroutineObject *, PyObject *);

extern PyObject *Nuitka_Coroutine_New(coroutine_code code, PyObject *module, PyObject *name, PyObject *qualname,
                                      PyCodeObject *code_object, Py_ssize_t closure_given,
                                      Py_ssize_t heap_storage_size);

static inline bool Nuitka_Coroutine_Check(PyObject *object) { return Py_TYPE(object) == &Nuitka_Coroutine_Type; }

struct Nuitka_CoroutineWrapperObject {
    PyObject_HEAD struct Nuitka_CoroutineObject *m_coroutine;
};

extern PyTypeObject Nuitka_CoroutineWrapper_Type;

static inline bool Nuitka_CoroutineWrapper_Check(PyObject *object) {
    return Py_TYPE(object) == &Nuitka_CoroutineWrapper_Type;
}

static inline void SAVE_COROUTINE_EXCEPTION(struct Nuitka_CoroutineObject *coroutine) {
    /* Before Python3.7: When yielding from an exception handler in Python3,
     * the exception preserved to the frame is restored, while the current one
     * is put as there.
     *
     * Python3.7: The exception is preserved in the coroutine object itself
     * which has a new "m_exc_state" structure just for that.
     */

    PyThreadState *thread_state = PyThreadState_GET();

    PyObject *saved_exception_type = EXC_TYPE(thread_state);
    PyObject *saved_exception_value = EXC_VALUE(thread_state);
    PyObject *saved_exception_traceback = EXC_TRACEBACK(thread_state);

#if PYTHON_VERSION < 370
    EXC_TYPE(thread_state) = thread_state->frame->f_exc_type;
    EXC_VALUE(thread_state) = thread_state->frame->f_exc_value;
    EXC_TRACEBACK(thread_state) = thread_state->frame->f_exc_traceback;
#else
    EXC_TYPE(thread_state) = coroutine->m_exc_state.exc_type;
    EXC_VALUE(thread_state) = coroutine->m_exc_state.exc_value;
    EXC_TRACEBACK(thread_state) = coroutine->m_exc_state.exc_traceback;
#endif

#if PYTHON_VERSION < 370
    thread_state->frame->f_exc_type = saved_exception_type;
    thread_state->frame->f_exc_value = saved_exception_value;
    thread_state->frame->f_exc_traceback = saved_exception_traceback;
#else
    coroutine->m_exc_state.exc_type = saved_exception_type;
    coroutine->m_exc_state.exc_value = saved_exception_value;
    ;
    coroutine->m_exc_state.exc_traceback = saved_exception_traceback;
#endif
}

static inline void RESTORE_COROUTINE_EXCEPTION(struct Nuitka_CoroutineObject *coroutine) {
    // When returning from yield, the exception of the frame is preserved, and
    // the one that enters should be there.
    PyThreadState *thread_state = PyThreadState_GET();

    PyObject *saved_exception_type = EXC_TYPE(thread_state);
    PyObject *saved_exception_value = EXC_VALUE(thread_state);
    PyObject *saved_exception_traceback = EXC_TRACEBACK(thread_state);

#if PYTHON_VERSION < 370
    EXC_TYPE(thread_state) = thread_state->frame->f_exc_type;
    EXC_VALUE(thread_state) = thread_state->frame->f_exc_value;
    EXC_TRACEBACK(thread_state) = thread_state->frame->f_exc_traceback;

    thread_state->frame->f_exc_type = saved_exception_type;
    thread_state->frame->f_exc_value = saved_exception_value;
    thread_state->frame->f_exc_traceback = saved_exception_traceback;
#else
    EXC_TYPE(thread_state) = coroutine->m_exc_state.exc_type;
    EXC_VALUE(thread_state) = coroutine->m_exc_state.exc_value;
    EXC_TRACEBACK(thread_state) = coroutine->m_exc_state.exc_traceback;

    coroutine->m_exc_state.exc_type = saved_exception_type;
    coroutine->m_exc_state.exc_value = saved_exception_value;
    coroutine->m_exc_state.exc_traceback = saved_exception_traceback;
#endif
}

#ifdef __cplusplus
enum Await_Kind {
    await_normal, // user provided "await"
    await_enter,  // async with statement "__enter__"
    await_exit    // async with statement "__enter__"
};
#else
typedef int Generator_Status;
static const int await_normal = 0;
static const int await_enter = 1;
static const int await_exit = 2;
#endif

// Create the object to await for async for "iter".
extern PyObject *ASYNC_MAKE_ITERATOR(PyObject *value);

// Create the object to await for async for "next".
extern PyObject *ASYNC_ITERATOR_NEXT(PyObject *value);

// Create the object for plain "await".
extern PyObject *ASYNC_AWAIT(PyObject *awaitable, int await_kind);

#endif

#endif
