//     Copyright 2017, 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.
//
#include "nuitka/prelude.h"

#include "structmember.h"

#define OFF( x ) offsetof( PyFrameObject, x )

struct Nuitka_FrameObject
{
    PyFrameObject m_frame;
};

static PyMemberDef Nuitka_Frame_memberlist[] = {
    { (char *)"f_back", T_OBJECT, OFF( f_back ), READONLY | RESTRICTED },
    { (char *)"f_code", T_OBJECT, OFF( f_code ), READONLY | RESTRICTED },
    { (char *)"f_builtins", T_OBJECT, OFF( f_builtins ), READONLY | RESTRICTED },
    { (char *)"f_globals", T_OBJECT, OFF( f_globals ), READONLY | RESTRICTED },
    { (char *)"f_lasti", T_INT, OFF( f_lasti ), READONLY | RESTRICTED },
    { NULL }
};

#if PYTHON_VERSION < 300

static PyObject *Nuitka_Frame_get_exc_traceback( PyFrameObject *frame )
{
    if ( frame->f_exc_traceback != NULL )
    {
        return INCREASE_REFCOUNT( frame->f_exc_traceback );
    }
    else
    {
        return INCREASE_REFCOUNT( Py_None );
    }
}

static int Nuitka_Frame_set_exc_traceback( PyFrameObject *frame, PyObject *traceback )
{
    Py_XDECREF( frame->f_exc_traceback );

    if ( traceback == Py_None )
    {
        frame->f_exc_traceback = NULL;
    }
    else
    {
        frame->f_exc_traceback = traceback;
        Py_XINCREF( traceback );
    }

    return 0;
}

static PyObject *Nuitka_Frame_get_exc_type( PyFrameObject *frame )
{
    if ( frame->f_exc_type != NULL )
    {
        return INCREASE_REFCOUNT( frame->f_exc_type );
    }
    else
    {
        return INCREASE_REFCOUNT( Py_None );
    }
}

static int Nuitka_Frame_set_exc_type( PyFrameObject *frame, PyObject *exception_type )
{
    Py_XDECREF( frame->f_exc_type );

    if ( exception_type == Py_None )
    {
        exception_type = NULL;
    }

    frame->f_exc_type = exception_type;
    Py_XINCREF( frame->f_exc_type );

    return 0;
}

static PyObject *Nuitka_Frame_get_exc_value( PyFrameObject *frame )
{
    if ( frame->f_exc_value != NULL )
    {
        return INCREASE_REFCOUNT( frame->f_exc_value );
    }
    else
    {
        return INCREASE_REFCOUNT( Py_None );
    }
}

static int Nuitka_Frame_set_exc_value( PyFrameObject *frame, PyObject *exception_value )
{
    if ( frame->f_exc_value != NULL )
    {
        Py_DECREF( frame->f_exc_value );
    }

    if ( exception_value == Py_None )
    {
        exception_value = NULL;
    }


    frame->f_exc_value = exception_value;
    Py_XINCREF( exception_value );

    return 0;
}

static PyObject *Nuitka_Frame_get_restricted( PyFrameObject *frame, void *closure )
{
    return INCREASE_REFCOUNT( Py_False );
}

#endif

static PyObject *Nuitka_Frame_getlocals( PyFrameObject *frame, void *closure )
{
    if ( frame->f_locals == NULL )
    {
        frame->f_locals = PyDict_New();
    }

    Py_INCREF( frame->f_locals );
    return frame->f_locals;
}

static PyObject *Nuitka_Frame_getlineno( PyFrameObject *frame, void *closure )
{
    return PyInt_FromLong( frame->f_lineno );
}

static PyObject *Nuitka_Frame_gettrace( PyFrameObject *frame, void *closure )
{
    return INCREASE_REFCOUNT( frame->f_trace );
}

static int Nuitka_Frame_settrace( PyFrameObject *frame, PyObject* v, void *closure )
{
    PyErr_Format( PyExc_RuntimeError, "f_trace is not writable in Nuitka" );
    return -1;
}

static PyGetSetDef Nuitka_Frame_getsetlist[] = {
    { (char *)"f_locals", (getter)Nuitka_Frame_getlocals, NULL, NULL },
    { (char *)"f_lineno", (getter)Nuitka_Frame_getlineno, NULL, NULL },
    { (char *)"f_trace", (getter)Nuitka_Frame_gettrace, (setter)Nuitka_Frame_settrace, NULL },
#if PYTHON_VERSION < 300
    { (char *)"f_restricted", (getter)Nuitka_Frame_get_restricted, NULL, NULL },
    { (char *)"f_exc_traceback", (getter)Nuitka_Frame_get_exc_traceback, (setter)Nuitka_Frame_set_exc_traceback, NULL },
    { (char *)"f_exc_type", (getter)Nuitka_Frame_get_exc_type, (setter)Nuitka_Frame_set_exc_type, NULL },
    { (char *)"f_exc_value", (getter)Nuitka_Frame_get_exc_value, (setter)Nuitka_Frame_set_exc_value, NULL },
#endif
    { NULL }
};

// tp_repr slot, decide how a function shall be output
static PyObject *Nuitka_Frame_tp_repr( struct Nuitka_FrameObject *nuitka_frame )
{
#if PYTHON_VERSION < 300
    return PyString_FromFormat(
#else
    return PyUnicode_FromFormat(
#endif
#if _DEBUG_FRAME || _DEBUG_REFRAME || _DEBUG_EXCEPTIONS
        "<compiled_frame object for %s at %p>",
        Nuitka_String_AsString( nuitka_frame->m_frame.f_code->co_name ),
        nuitka_frame
#else
        "<compiled_frame object at %p>",
        nuitka_frame
#endif
    );
}

static void Nuitka_Frame_tp_dealloc( struct Nuitka_FrameObject *nuitka_frame )
{
#ifndef __NUITKA_NO_ASSERT__
    // Save the current exception, if any, we must to not corrupt it.
    PyObject *save_exception_type, *save_exception_value;
    PyTracebackObject *save_exception_tb;
    FETCH_ERROR_OCCURRED( &save_exception_type, &save_exception_value, &save_exception_tb );
    RESTORE_ERROR_OCCURRED( save_exception_type, save_exception_value, save_exception_tb );
#endif

    Nuitka_GC_UnTrack( nuitka_frame );

    PyFrameObject *frame = &nuitka_frame->m_frame;

    // locals
    PyObject **valuestack = frame->f_valuestack;
    for ( PyObject **p = frame->f_localsplus; p < valuestack; p++ )
    {
        Py_CLEAR( *p );
    }

    // stack if any
    if ( frame->f_stacktop != NULL )
    {
        for ( PyObject **p = valuestack; p < frame->f_stacktop; p++ )
        {
            Py_XDECREF( *p );
        }
    }

    Py_XDECREF( frame->f_back );
    Py_DECREF( frame->f_builtins );
    Py_DECREF( frame->f_globals );
    Py_XDECREF( frame->f_locals );
    Py_XDECREF( frame->f_exc_type );
    Py_XDECREF( frame->f_exc_value );
    Py_XDECREF( frame->f_exc_traceback );

    PyObject_GC_Del( nuitka_frame );

#ifndef __NUITKA_NO_ASSERT__
    PyThreadState *tstate = PyThreadState_GET();

    assert( tstate->curexc_type == save_exception_type );
    assert( tstate->curexc_value == save_exception_value );
    assert( (PyTracebackObject *)tstate->curexc_traceback == save_exception_tb );
#endif
}

static int Nuitka_Frame_tp_traverse( PyFrameObject *frame, visitproc visit, void *arg )
{
    Py_VISIT( frame->f_back );
    Py_VISIT( frame->f_code );
    Py_VISIT( frame->f_builtins );
    Py_VISIT( frame->f_globals );
    Py_VISIT( frame->f_locals );
    Py_VISIT( frame->f_exc_type );
    Py_VISIT( frame->f_exc_value );
    Py_VISIT( frame->f_exc_traceback );

    // locals
    Py_ssize_t slots = frame->f_code->co_nlocals + PyTuple_GET_SIZE( frame->f_code->co_cellvars ) + PyTuple_GET_SIZE( frame->f_code->co_freevars );
    PyObject **fastlocals = frame->f_localsplus;
    for ( Py_ssize_t i = slots; --i >= 0; ++fastlocals )
    {
        Py_VISIT( *fastlocals );
    }

    // stack if any
    if ( frame->f_stacktop != NULL )
    {
        for ( PyObject **p = frame->f_valuestack; p < frame->f_stacktop; p++ )
        {
            Py_VISIT( *p );
        }
    }

    return 0;
}

static void Nuitka_Frame_tp_clear( PyFrameObject *frame )
{
    PyObject **oldtop = frame->f_stacktop;
    frame->f_stacktop = NULL;

    // locals
    Py_ssize_t slots = frame->f_code->co_nlocals + PyTuple_GET_SIZE( frame->f_code->co_cellvars ) + PyTuple_GET_SIZE( frame->f_code->co_freevars );
    PyObject **fastlocals = frame->f_localsplus;

    for ( Py_ssize_t i = slots; --i >= 0; ++fastlocals )
    {
        Py_CLEAR( *fastlocals );
    }

    // stack if any
    if ( oldtop != NULL )
    {
        for ( PyObject **p = frame->f_valuestack; p < oldtop; p++ )
        {
            Py_CLEAR( *p );
        }
    }
}

#if PYTHON_VERSION >= 340

extern PyObject *Nuitka_Generator_close( struct Nuitka_GeneratorObject *generator, PyObject *args );

static PyObject *Nuitka_Frame_clear( PyFrameObject *frame )
{
    if ( frame->f_executing )
    {
        PyErr_Format(
            PyExc_RuntimeError,
            "cannot clear an executing frame"
        );

        return NULL;
    }

#if PYTHON_VERSION >= 340
    // For frames that are closed, we also need to close the generator.
    if ( frame->f_gen != NULL )
    {
        Py_INCREF( frame );

        assert( Nuitka_Generator_Check( frame->f_gen ) );

        struct Nuitka_GeneratorObject *generator = (struct Nuitka_GeneratorObject *)frame->f_gen;
        frame->f_gen = NULL;

        PyObject *close_result = Nuitka_Generator_close(
            generator,
            NULL
        );

        if (unlikely( close_result == NULL ))
        {
            PyErr_WriteUnraisable( (PyObject *)frame->f_gen );
        }
        else
        {
            Py_DECREF( close_result );
        }

        Py_DECREF( frame );
    }
#endif

    Nuitka_Frame_tp_clear( frame );

    Py_RETURN_NONE;
}

#endif

static PyObject *Nuitka_Frame_sizeof( PyFrameObject *frame )
{
    Py_ssize_t slots =
        frame->f_code->co_stacksize +
        frame->f_code->co_nlocals +
        PyTuple_GET_SIZE( frame->f_code->co_cellvars ) +
        PyTuple_GET_SIZE( frame->f_code->co_freevars );

    return PyInt_FromSsize_t( sizeof( struct Nuitka_FrameObject ) + slots * sizeof(PyObject *) );
}

static PyMethodDef Nuitka_Frame_methods[] =
{
#if PYTHON_VERSION >= 340
    { "clear",      (PyCFunction)Nuitka_Frame_clear,   METH_NOARGS, "F.clear(): clear most references held by the frame" },
#endif
    { "__sizeof__", (PyCFunction)Nuitka_Frame_sizeof,  METH_NOARGS, "F.__sizeof__() -> size of F in memory, in bytes" },
    { NULL, NULL }
};

PyTypeObject Nuitka_Frame_Type =
{
    PyVarObject_HEAD_INIT(NULL, 0)
    "compiled_frame",
    sizeof(struct Nuitka_FrameObject),
    sizeof(PyObject *),
    (destructor)Nuitka_Frame_tp_dealloc,        // tp_dealloc
    0,                                          // tp_print
    0,                                          // tp_getattr
    0,                                          // tp_setattr
    0,                                          // tp_compare
    (reprfunc)Nuitka_Frame_tp_repr,             // tp_repr
    0,                                          // tp_as_number
    0,                                          // tp_as_sequence
    0,                                          // tp_as_mapping
    0,                                          // tp_hash
    0,                                          // tp_call
    0,                                          // tp_str
    PyObject_GenericGetAttr,                    // tp_getattro
    PyObject_GenericSetAttr,                    // tp_setattro
    0,                                          // tp_as_buffer
    Py_TPFLAGS_DEFAULT | Py_TPFLAGS_HAVE_GC,    // tp_flags
    0,                                          // tp_doc
    (traverseproc)Nuitka_Frame_tp_traverse,     // tp_traverse
    (inquiry)Nuitka_Frame_tp_clear,             // tp_clear
    0,                                          // tp_richcompare
    0,                                          // tp_weaklistoffset
    0,                                          // tp_iter
    0,                                          // tp_iternext
    Nuitka_Frame_methods,                       // tp_methods
    Nuitka_Frame_memberlist,                    // tp_members
    Nuitka_Frame_getsetlist,                    // tp_getset
    0,                                          // tp_base
    0,                                          // tp_dict
};

void _initCompiledFrameType( void )
{
    PyType_Ready( &Nuitka_Frame_Type );
}


extern PyObject *const_str_plain___module__;

static PyFrameObject *MAKE_FRAME( PyCodeObject *code, PyObject *module, bool is_module )
{
    assertCodeObject( code );

    PyObject *globals = ((PyModuleObject *)module)->md_dict;
    assert( PyDict_Check( globals ) );

    Py_ssize_t ncells = PyTuple_GET_SIZE( code->co_cellvars );
    Py_ssize_t nfrees = PyTuple_GET_SIZE( code->co_freevars );
    Py_ssize_t extras = code->co_stacksize + code->co_nlocals + ncells + nfrees;

    struct Nuitka_FrameObject *result = (struct Nuitka_FrameObject *)Nuitka_GC_NewVar(
        &Nuitka_Frame_Type,
        extras
    );

    if (unlikely( result == NULL ))
    {
        return NULL;
    }

    PyFrameObject *frame = &result->m_frame;

    frame->f_code = code;

    extras = code->co_nlocals + ncells + nfrees;
    frame->f_valuestack = frame->f_localsplus + extras;

    for ( Py_ssize_t i = 0; i < extras; i++ )
    {
        frame->f_localsplus[i] = NULL;
    }

    frame->f_locals = NULL;
    frame->f_trace = Py_None;

    frame->f_exc_type = NULL;
    frame->f_exc_value = NULL;
    frame->f_exc_traceback = NULL;

    frame->f_stacktop = frame->f_valuestack;
    frame->f_builtins = INCREASE_REFCOUNT( (PyObject *)dict_builtin );

    frame->f_back = NULL;

    frame->f_globals = INCREASE_REFCOUNT( globals );

    if (likely( (code->co_flags & CO_OPTIMIZED ) == CO_OPTIMIZED ))
    {
        frame->f_locals = NULL;
    }
    else if (is_module)
    {
        frame->f_locals = INCREASE_REFCOUNT( globals );
    }
    else
    {
        frame->f_locals = PyDict_New();

        if (unlikely( frame->f_locals == NULL ))
        {
            Py_DECREF( result );

            return NULL;
        }

        PyDict_SetItem(
            frame->f_locals,
            const_str_plain___module__,
            MODULE_NAME( module )
        );
    }

#if PYTHON_VERSION < 340
    frame->f_tstate = PyThreadState_GET();
#endif

    frame->f_lasti = -1;
    frame->f_lineno = code->co_firstlineno;
    frame->f_iblock = 0;

#if PYTHON_VERSION >= 340
    frame->f_gen = NULL;
    frame->f_executing = 0;
#endif

    Nuitka_GC_Track( result );
    return (PyFrameObject *)result;
}

PyFrameObject *MAKE_MODULE_FRAME( PyCodeObject *code, PyObject *module )
{
    return MAKE_FRAME( code, module, true );
}

PyFrameObject *MAKE_FUNCTION_FRAME( PyCodeObject *code, PyObject *module )
{
    return MAKE_FRAME( code, module, false );
}


extern PyObject *const_str_empty;
extern PyObject *const_bytes_empty;

#if PYTHON_VERSION < 300
PyCodeObject *MAKE_CODEOBJ( PyObject *filename, PyObject *function_name, int line, PyObject *argnames, int arg_count, int flags )
#else
PyCodeObject *MAKE_CODEOBJ( PyObject *filename, PyObject *function_name, int line, PyObject *argnames, int arg_count, int kw_only_count, int flags )
#endif
{
    CHECK_OBJECT( filename );
    assert( Nuitka_String_Check( filename ) );
    CHECK_OBJECT( function_name );
    assert( Nuitka_String_Check( function_name ) );
    CHECK_OBJECT( argnames );
    assert( PyTuple_Check( argnames ) );

    // The PyCode_New has funny code that interns, mutating the tuple that owns
    // it. Really serious non-immutable shit. We have triggered that changes
    // behind our back in the past.
#ifndef __NUITKA_NO_ASSERT__
    Py_hash_t hash = DEEP_HASH( argnames );
#endif

    // TODO: Consider using PyCode_NewEmpty

    PyCodeObject *result = PyCode_New(
        arg_count,           // argcount
#if PYTHON_VERSION >= 300
        kw_only_count,       // kw-only count
#endif
        0,                   // nlocals
        0,                   // stacksize
        flags,               // flags
#if PYTHON_VERSION < 300
        const_str_empty,     // code (bytecode)
#else
        const_bytes_empty,   // code (bytecode)
#endif
        const_tuple_empty,   // consts (we are not going to be compatible)
        const_tuple_empty,   // names (we are not going to be compatible)
        argnames,            // varnames (we are not going to be compatible)
        const_tuple_empty,   // freevars (we are not going to be compatible)
        const_tuple_empty,   // cellvars (we are not going to be compatible)
        filename,            // filename
        function_name,       // name
        line,                // firstlineno (offset of the code object)
#if PYTHON_VERSION < 300
        const_str_empty      // lnotab (table to translate code object)
#else
        const_bytes_empty    // lnotab (table to translate code object)
#endif
    );

    assert( DEEP_HASH( argnames ) == hash );

    if (unlikely( result == NULL ))
    {
        return NULL;
    }

    return result;
}

static PyFrameObject *duplicateFrame( PyFrameObject *old_frame, PyObject *locals )
{
    // TODO: Needs to copy extras too, or we should not have those entirely
    // and do away with NewVar allocation, when we don't use it.
    PyFrameObject *new_frame = (PyFrameObject *)Nuitka_GC_NewVar( &PyFrame_Type, 0 );

    // Allow only to detach only our tracing frames.
    assert( Py_TYPE( old_frame ) == &Nuitka_Frame_Type );

    assert( old_frame->f_trace == Py_None );
    new_frame->f_trace = Py_None;
    Py_INCREF( Py_None );

    // Copy the back reference if any.
    new_frame->f_back = old_frame->f_back;
    Py_XINCREF( new_frame->f_back );

    // Take a code reference as well.
    new_frame->f_code = old_frame->f_code;
    Py_XINCREF( new_frame->f_code );

    // Copy attributes.
    new_frame->f_globals = INCREASE_REFCOUNT( old_frame->f_globals );

    new_frame->f_locals = locals;

    new_frame->f_builtins = INCREASE_REFCOUNT( old_frame->f_builtins );

    new_frame->f_exc_type = NULL;
    new_frame->f_exc_value = NULL;
    new_frame->f_exc_traceback = NULL;

    assert( old_frame->f_valuestack == old_frame->f_localsplus );
    new_frame->f_valuestack = new_frame->f_localsplus;

    assert( old_frame->f_stacktop == old_frame->f_valuestack );
    new_frame->f_stacktop = new_frame->f_valuestack;

#if PYTHON_VERSION < 340
    new_frame->f_tstate = old_frame->f_tstate;
#endif

    new_frame->f_lasti = -1;
    new_frame->f_lineno = old_frame->f_lineno;

    assert( old_frame->f_iblock == 0 );
    new_frame->f_iblock = 0;

#if PYTHON_VERSION >= 340
    new_frame->f_gen = NULL;
    new_frame->f_executing = 0;
#endif

    Nuitka_GC_Track( new_frame );

    return new_frame;
}

void detachFrame( PyTracebackObject *traceback, PyObject *locals )
{
    // Duplicate it.
    PyFrameObject *old_frame = traceback->tb_frame;
    PyFrameObject *new_frame = duplicateFrame( old_frame, locals );

    // The new frame replaces it.
    traceback->tb_frame = new_frame;
    Py_DECREF( old_frame );
}
