#include "Python.h"

#include "compile.h"
#include "frameobject.h"
#include "opcode.h"

/* iexec.c helper functions imported by the python
   "iexec" package. 
*/

typedef struct {
	PyObject_HEAD
	PyFrameObject *frame;
	PyObject *isinstance;
    int blockindex;
} iterinstanceobject;

static PyObject *
iterinstance_new(PyTypeObject *type, PyObject *args, PyObject *kwds)
{
	iterinstanceobject *lz;
    PyObject* isinstance=NULL;

	if (!PyArg_ParseTuple(args, "|O:iterinstance", &isinstance))
		return NULL; 

	/* create iterinstanceobject structure */
	lz = (iterinstanceobject *)type->tp_alloc(type, 0);
	if (lz == NULL) 
		return NULL;
	
	lz->frame = PyThreadState_Get()->frame;
	Py_INCREF(lz->frame);
    lz->blockindex = lz->frame->f_iblock -1;
    lz->isinstance = isinstance;
	return (PyObject *)lz;
}

static void
iterinstance_dealloc(iterinstanceobject *lz)
{
	PyObject_GC_UnTrack(lz);
	Py_XDECREF(lz->frame);
    Py_XDECREF(lz->isinstance);
	lz->ob_type->tp_free(lz);
}

static int
iterinstance_traverse(iterinstanceobject *lz, visitproc visit, void *arg)
{
	int err;

	if (lz->frame) {
		err = visit((PyObject*)lz->frame, arg);
		if (err)
			return err;
	}
    if (lz->isinstance) {
		err = visit(lz->isinstance, arg);
		if (err)
			return err;
    }
	return 0;
}

static PyObject *
iterinstance_next(iterinstanceobject *lz)
{
    PyTryBlock *b;
    PyObject* obj;
    PyFrameObject * frame = lz->frame;
    long x;
    int i;
    if (frame == NULL)
        return NULL;

    i = lz->blockindex - 1;
    while (1) {
        for ( ; i >= 0 ; i--) {
            b = &lz->frame->f_blockstack[i];
            if (b->b_type == SETUP_IEXEC) {
                obj = frame->f_valuestack[b->b_level-1];
                if (lz->isinstance) {
	                 x = PyObject_IsInstance(obj, lz->isinstance);
                     if (x < 0)
                        return NULL;
                     if (x == 0) 
                        continue;
                }
                lz->blockindex = i;
                Py_INCREF(obj);
                return obj;
            }
        }
        lz->frame = frame->f_back;
        Py_DECREF(frame);
        frame = lz->frame;
        if (frame == NULL)
            break;
       	Py_INCREF(frame);
        i = frame->f_iblock - 1;
    }
    return NULL;
}

PyDoc_STRVAR(iterinstance_doc, "iterinstance() --> iterinstance object\n\
\n\
Return IEXEC handler starting from the current python frame.");

static PyTypeObject iterinstance_type = {
	PyObject_HEAD_INIT(NULL)
	0,				/* ob_size */
	"iexec.iterinstance",		/* tp_name */
	sizeof(iterinstanceobject),		/* tp_basicsize */
	0,				/* tp_itemsize */
	/* methods */
	(destructor)iterinstance_dealloc,	/* tp_dealloc */
	0,				/* tp_print */
	0,				/* tp_getattr */
	0,				/* tp_setattr */
	0,				/* tp_compare */
	0,				/* 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 */
	0,				/* tp_setattro */
	0,				/* tp_as_buffer */
	Py_TPFLAGS_DEFAULT | Py_TPFLAGS_HAVE_GC |
		Py_TPFLAGS_BASETYPE,	/* tp_flags */
	iterinstance_doc,			/* tp_doc */
	(traverseproc)iterinstance_traverse,	/* tp_traverse */
	0,				/* tp_clear */
	0,				/* tp_richcompare */
	0,				/* tp_weaklistoffset */
	PyObject_SelfIter,		/* tp_iter */
	(iternextfunc)iterinstance_next,	/* tp_iternext */
	0,				/* tp_methods */
	0,				/* tp_members */
	0,				/* tp_getset */
	0,				/* tp_base */
	0,				/* tp_dict */
	0,				/* tp_descr_get */
	0,				/* tp_descr_set */
	0,				/* tp_dictoffset */
	0,				/* tp_init */
	0,				/* tp_alloc */
	iterinstance_new,			/* tp_new */
	PyObject_GC_Del,		/* tp_free */
};

static PyObject *
getinstance(PyObject* self_, PyObject* args)
{
    PyFrameObject* frame;
    PyTryBlock *b;
    PyObject *obj, *isinstance=NULL;
    int i, x;

    if (!PyArg_ParseTuple(args, "|O", &isinstance))
        return NULL;

    /* "getinstance" returns the first matching handler. */
	frame = PyThreadState_Get()->frame;
  
    /* traverse execution handlers up until match is found */
    while (frame != NULL) {
        for (i = frame->f_iblock-1 ; i>=0 ; i--) {
            b = &frame->f_blockstack[i];
            if (b->b_type == SETUP_IEXEC) {
                /* hack the handler object out from the block */
                obj = frame->f_valuestack[b->b_level-1];
                if (isinstance) {
	                 x = PyObject_IsInstance(obj, isinstance);
                     if (x < 0)
                        return NULL;
                     if (x == 0) 
                        continue;
                }
                Py_INCREF(obj);
                return obj;
            }
        }
        frame = frame->f_back;
    }
    Py_INCREF(Py_None);
    return Py_None;
}

PyDoc_STRVAR(getinstance_doc,
"getinstance(isinstance=None)-> first upwards iexec handler\
(beeing an instance according to the optionally given argument.)");

static PyMethodDef _functions[] = {
    {"getinstance", getinstance, METH_VARARGS, getinstance_doc},
    {NULL, NULL}
};


PyDoc_STRVAR(module_doc,
"Support functions for the iexec protocol. ");


PyMODINIT_FUNC
initiexec(void)
{
    PyObject *m;
	if (PyType_Ready(&iterinstance_type) < 0)
		return;

    m = Py_InitModule3("iexec", _functions, module_doc);
	Py_INCREF(&iterinstance_type);
	PyModule_AddObject(m, "iterinstance", 
            (PyObject *)&iterinstance_type);
}