/*
 * ***** BEGIN GPL LICENSE BLOCK *****
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License
 * as published by the Free Software Foundation; either version 2
 * of the License, or (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software Foundation,
 * Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
 *
 * Contributor(s): Bastien Montagne
 *
 * ***** END GPL LICENSE BLOCK *****
 */

/** \file blender/python/intern/bpy_rna_id_collection.c
 *  \ingroup pythonintern
 *
 * This file adds some helpers related to ID/Main handling, that cannot fit well in RNA itself.
 */

#include <Python.h>
#include <stddef.h>

#include "MEM_guardedalloc.h"

#include "BLI_utildefines.h"
#include "BLI_bitmap.h"

#include "BKE_global.h"
#include "BKE_main.h"
#include "BKE_library.h"
#include "BKE_library_query.h"

#include "DNA_ID.h"

#include "bpy_util.h"
#include "bpy_rna_id_collection.h"

#include "../generic/py_capi_utils.h"
#include "../generic/python_utildefines.h"

#include "RNA_access.h"
#include "RNA_types.h"
#include "RNA_enum_types.h"

#include "bpy_rna.h"

typedef struct IDUserMapData {
	/* place-holder key only used for lookups to avoid creating new data only for lookups
	 * (never return its contents) */
	PyObject *py_id_key_lookup_only;

	/* we loop over data-blocks that this ID points to (do build a reverse lookup table) */
	PyObject *py_id_curr;
	ID *id_curr;

	/* filter the values we add into the set */
	BLI_bitmap *types_bitmap;

	PyObject *user_map;     /* set to fill in as we iterate */
	bool is_subset;         /* true when we're only mapping a subset of all the ID's (subset arg is passed) */
} IDUserMapData;


static int id_code_as_index(const short idcode)
{
	return (int)*((unsigned short *)&idcode);
}

static bool id_check_type(const ID *id, const BLI_bitmap *types_bitmap)
{
	return BLI_BITMAP_TEST_BOOL(types_bitmap, id_code_as_index(GS(id->name)));
}

static int foreach_libblock_id_user_map_callback(
        void *user_data, ID *UNUSED(self_id), ID **id_p, int UNUSED(cb_flag))
{
	IDUserMapData *data = user_data;

	if (*id_p) {

		if (data->types_bitmap) {
			if (!id_check_type(*id_p, data->types_bitmap)) {
				return IDWALK_RET_NOP;
			}
		}

		/* pyrna_struct_hash() uses ptr.data only,
		 * but pyrna_struct_richcmp() uses also ptr.type,
		 * so we need to create a valid PointerRNA here...
		 */
		PyObject *key = data->py_id_key_lookup_only;
		RNA_id_pointer_create(*id_p, &((BPy_StructRNA *)key)->ptr);

		PyObject *set;
		if ((set = PyDict_GetItem(data->user_map, key)) == NULL) {

			/* limit to key's added already */
			if (data->is_subset) {
				return IDWALK_RET_NOP;
			}

			/* Cannot use our placeholder key here! */
			key = pyrna_id_CreatePyObject(*id_p);
			set = PySet_New(NULL);
			PyDict_SetItem(data->user_map, key, set);
			Py_DECREF(set);
			Py_DECREF(key);
		}

		if (data->py_id_curr == NULL) {
			data->py_id_curr = pyrna_id_CreatePyObject(data->id_curr);
		}

		PySet_Add(set, data->py_id_curr);
	}

	return IDWALK_RET_NOP;
}

PyDoc_STRVAR(bpy_user_map_doc,
".. method:: user_map([subset=(id1, id2, ...)], key_types={..}, value_types={..})\n"
"\n"
"   Returns a mapping of all ID datablocks in current ``bpy.data`` to a set of all datablocks using them.\n"
"\n"
"   For list of valid set members for key_types & value_types, see: :class:`bpy.types.KeyingSetPath.id_type`.\n"
"\n"
"   :arg subset: When passed, only these data-blocks and their users will be included as keys/values in the map.\n"
"   :type subset: sequence\n"
"   :arg key_types: Filter the keys mapped by ID types.\n"
"   :type key_types: set of strings\n"
"   :arg value_types: Filter the values in the set by ID types.\n"
"   :type value_types: set of strings\n"
"   :return: dictionary of :class:`bpy.types.ID` instances, with sets of ID's as their values.\n"
"   :rtype: dict\n"
);
static PyObject *bpy_user_map(PyObject *UNUSED(self), PyObject *args, PyObject *kwds)
{
#if 0  /* If someone knows how to get a proper 'self' in that case... */
	BPy_StructRNA *pyrna = (BPy_StructRNA *)self;
	Main *bmain = pyrna->ptr.data;
#else
	Main *bmain = G.main;  /* XXX Ugly, but should work! */
#endif

	static const char *kwlist[] = {"subset", "key_types", "value_types", NULL};
	PyObject *subset = NULL;

	PyObject *key_types = NULL;
	PyObject *val_types = NULL;
	BLI_bitmap *key_types_bitmap = NULL;
	BLI_bitmap *val_types_bitmap = NULL;

	PyObject *ret = NULL;


	if (!PyArg_ParseTupleAndKeywords(
	        args, kwds, "|O$O!O!:user_map", (char **)kwlist,
	        &subset,
	        &PySet_Type, &key_types,
	        &PySet_Type, &val_types))
	{
		return NULL;
	}

	if (key_types) {
		key_types_bitmap = pyrna_set_to_enum_bitmap(
		        rna_enum_id_type_items, key_types, sizeof(short), true, USHRT_MAX, "key types");
		if (key_types_bitmap == NULL) {
			goto error;
		}
	}

	if (val_types) {
		val_types_bitmap = pyrna_set_to_enum_bitmap(
		        rna_enum_id_type_items, val_types, sizeof(short), true, USHRT_MAX, "value types");
		if (val_types_bitmap == NULL) {
			goto error;
		}
	}

	IDUserMapData data_cb = {NULL};

	if (subset) {
		PyObject *subset_fast = PySequence_Fast(subset, "user_map");
		if (subset_fast == NULL) {
			goto error;
		}

		PyObject **subset_array = PySequence_Fast_ITEMS(subset_fast);
		Py_ssize_t subset_len = PySequence_Fast_GET_SIZE(subset_fast);

		data_cb.user_map = _PyDict_NewPresized(subset_len);
		data_cb.is_subset = true;
		for (; subset_len; subset_array++, subset_len--) {
			PyObject *set = PySet_New(NULL);
			PyDict_SetItem(data_cb.user_map, *subset_array, set);
			Py_DECREF(set);
		}
		Py_DECREF(subset_fast);
	}
	else {
		data_cb.user_map = PyDict_New();
	}

	data_cb.types_bitmap = key_types_bitmap;

	ListBase *lb_array[MAX_LIBARRAY];
	int lb_index;
	lb_index = set_listbasepointers(bmain, lb_array);

	while (lb_index--) {

		if (val_types_bitmap && lb_array[lb_index]->first) {
			if (!id_check_type(lb_array[lb_index]->first, val_types_bitmap)) {
				continue;
			}
		}

		for (ID *id = lb_array[lb_index]->first; id; id = id->next) {
			/* One-time init, ID is just used as placeholder here, we abuse this in iterator callback
			 * to avoid having to rebuild a complete bpyrna object each time for the key searching
			 * (where only ID pointer value is used). */
			if (data_cb.py_id_key_lookup_only == NULL) {
				data_cb.py_id_key_lookup_only = pyrna_id_CreatePyObject(id);
			}

			data_cb.id_curr = id;
			BKE_library_foreach_ID_link(id, foreach_libblock_id_user_map_callback, &data_cb, IDWALK_NOP);
			if (data_cb.py_id_curr) {
				Py_DECREF(data_cb.py_id_curr);
				data_cb.py_id_curr = NULL;
			}
		}
	}

	ret = data_cb.user_map;


error:

	Py_XDECREF(data_cb.py_id_key_lookup_only);

	if (key_types_bitmap) {
		MEM_freeN(key_types_bitmap);
	}

	if (val_types_bitmap) {
		MEM_freeN(val_types_bitmap);
	}

	return ret;

}

int BPY_rna_id_collection_module(PyObject *mod_par)
{
	static PyMethodDef user_map = {
	    "user_map", (PyCFunction)bpy_user_map, METH_VARARGS | METH_KEYWORDS, bpy_user_map_doc};

	PyModule_AddObject(mod_par, "_rna_id_collection_user_map", PyCFunction_New(&user_map, NULL));

	return 0;
}