/*
 * Copyright (C) 2009 Jelmer Vernooij <jelmer@jelmer.uk>
 *
 * Dulwich is dual-licensed under the Apache License, Version 2.0 and the GNU
 * General Public License as public by the Free Software Foundation; version 2.0
 * or (at your option) any later version. You can redistribute it and/or
 * modify it under the terms of either of these two licenses.
 *
 * 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.
 *
 * You should have received a copy of the licenses; if not, see
 * <http://www.gnu.org/licenses/> for a copy of the GNU General Public License
 * and <http://www.apache.org/licenses/LICENSE-2.0> for a copy of the Apache
 * License, Version 2.0.
 */

#define PY_SSIZE_T_CLEAN
#include <Python.h>
#include <stdlib.h>
#include <sys/stat.h>

#if defined(__MINGW32_VERSION) || defined(__APPLE__)
size_t rep_strnlen(char *text, size_t maxlen);
size_t rep_strnlen(char *text, size_t maxlen)
{
	const char *last = memchr(text, '\0', maxlen);
	return last ? (size_t) (last - text) : maxlen;
}
#define strnlen rep_strnlen
#endif

#define bytehex(x) (((x)<0xa)?('0'+(x)):('a'-0xa+(x)))

static PyObject *tree_entry_cls;
static PyObject *object_format_exception_cls;

static PyObject *sha_to_pyhex(const unsigned char *sha)
{
	char hexsha[41];
	int i;
	for (i = 0; i < 20; i++) {
		hexsha[i*2] = bytehex((sha[i] & 0xF0) >> 4);
		hexsha[i*2+1] = bytehex(sha[i] & 0x0F);
	}

	return PyBytes_FromStringAndSize(hexsha, 40);
}

static PyObject *py_parse_tree(PyObject *self, PyObject *args, PyObject *kw)
{
	char *text, *start, *end;
	Py_ssize_t len; int strict;
	size_t namelen;
	PyObject *ret, *item, *name, *sha, *py_strict = NULL;
	static char *kwlist[] = {"text", "strict", NULL};

	if (!PyArg_ParseTupleAndKeywords(args, kw, "y#|O", kwlist,
	                                 &text, &len, &py_strict))
		return NULL;
	strict = py_strict ?  PyObject_IsTrue(py_strict) : 0;
	/* TODO: currently this returns a list; if memory usage is a concern,
	 * consider rewriting as a custom iterator object */
	ret = PyList_New(0);
	if (ret == NULL) {
		return NULL;
	}
	start = text;
	end = text + len;
	while (text < end) {
		long mode;
		if (strict && text[0] == '0') {
			PyErr_SetString(object_format_exception_cls,
			                "Illegal leading zero on mode");
			Py_DECREF(ret);
			return NULL;
		}
		mode = strtol(text, &text, 8);
		if (*text != ' ') {
			PyErr_SetString(PyExc_ValueError, "Expected space");
			Py_DECREF(ret);
			return NULL;
		}
		text++;
		namelen = strnlen(text, len - (text - start));
		name = PyBytes_FromStringAndSize(text, namelen);
		if (name == NULL) {
			Py_DECREF(ret);
			return NULL;
		}
		if (text + namelen + 20 >= end) {
			PyErr_SetString(PyExc_ValueError, "SHA truncated");
			Py_DECREF(ret);
			Py_DECREF(name);
			return NULL;
		}
		sha = sha_to_pyhex((unsigned char *)text+namelen+1);
		if (sha == NULL) {
			Py_DECREF(ret);
			Py_DECREF(name);
			return NULL;
		}
		item = Py_BuildValue("(NlN)", name, mode, sha);
		if (item == NULL) {
			Py_DECREF(ret);
			Py_DECREF(sha);
			Py_DECREF(name);
			return NULL;
		}
		if (PyList_Append(ret, item) == -1) {
			Py_DECREF(ret);
			Py_DECREF(item);
			return NULL;
		}
		Py_DECREF(item);
		text += namelen+21;
	}
	return ret;
}

struct tree_item {
	const char *name;
	int mode;
	PyObject *tuple;
};

/* Not all environments define S_ISDIR */
#if !defined(S_ISDIR) && defined(S_IFMT) && defined(S_IFDIR)
#define S_ISDIR(m) (((m) & S_IFMT) == S_IFDIR)
#endif

int cmp_tree_item(const void *_a, const void *_b)
{
	const struct tree_item *a = _a, *b = _b;
	const char *remain_a, *remain_b;
	int ret;
	size_t common;
	if (strlen(a->name) > strlen(b->name)) {
		common = strlen(b->name);
		remain_a = a->name + common;
		remain_b = (S_ISDIR(b->mode)?"/":"");
	} else if (strlen(b->name) > strlen(a->name)) {
		common = strlen(a->name);
		remain_a = (S_ISDIR(a->mode)?"/":"");
		remain_b = b->name + common;
	} else { /* strlen(a->name) == strlen(b->name) */
		common = 0;
		remain_a = a->name;
		remain_b = b->name;
	}
	ret = strncmp(a->name, b->name, common);
	if (ret != 0)
		return ret;
	return strcmp(remain_a, remain_b);
}

int cmp_tree_item_name_order(const void *_a, const void *_b) {
	const struct tree_item *a = _a, *b = _b;
	return strcmp(a->name, b->name);
}

static PyObject *py_sorted_tree_items(PyObject *self, PyObject *args)
{
	struct tree_item *qsort_entries = NULL;
	int name_order, n = 0, i;
	PyObject *entries, *py_name_order, *ret, *key, *value, *py_mode, *py_sha;
	Py_ssize_t pos = 0, num_entries;
	int (*cmp)(const void *, const void *);

	if (!PyArg_ParseTuple(args, "OO", &entries, &py_name_order))
		goto error;

	if (!PyDict_Check(entries)) {
		PyErr_SetString(PyExc_TypeError, "Argument not a dictionary");
		goto error;
	}

	name_order = PyObject_IsTrue(py_name_order);
	if (name_order == -1)
		goto error;
	cmp = name_order ? cmp_tree_item_name_order : cmp_tree_item;

	num_entries = PyDict_Size(entries);
	if (PyErr_Occurred())
		goto error;
	qsort_entries = PyMem_New(struct tree_item, num_entries);
	if (!qsort_entries) {
		PyErr_NoMemory();
		goto error;
	}

	while (PyDict_Next(entries, &pos, &key, &value)) {
		if (!PyBytes_Check(key)) {
			PyErr_SetString(PyExc_TypeError, "Name is not a string");
			goto error;
		}

		if (PyTuple_Size(value) != 2) {
			PyErr_SetString(PyExc_ValueError, "Tuple has invalid size");
			goto error;
		}

		py_mode = PyTuple_GET_ITEM(value, 0);
		if (!PyLong_Check(py_mode)) {
			PyErr_SetString(PyExc_TypeError, "Mode is not an integral type");
			goto error;
		}

		py_sha = PyTuple_GET_ITEM(value, 1);
		if (!PyBytes_Check(py_sha)) {
			PyErr_SetString(PyExc_TypeError, "SHA is not a string");
			goto error;
		}
		qsort_entries[n].name = PyBytes_AS_STRING(key);
		qsort_entries[n].mode = PyLong_AsLong(py_mode);

		qsort_entries[n].tuple = PyObject_CallFunctionObjArgs(
		                tree_entry_cls, key, py_mode, py_sha, NULL);
		if (qsort_entries[n].tuple == NULL)
			goto error;
		n++;
	}

	qsort(qsort_entries, num_entries, sizeof(struct tree_item), cmp);

	ret = PyList_New(num_entries);
	if (ret == NULL) {
		PyErr_NoMemory();
		goto error;
	}

	for (i = 0; i < num_entries; i++) {
		PyList_SET_ITEM(ret, i, qsort_entries[i].tuple);
	}
	PyMem_Free(qsort_entries);
	return ret;

error:
	for (i = 0; i < n; i++) {
		Py_XDECREF(qsort_entries[i].tuple);
	}
	PyMem_Free(qsort_entries);
	return NULL;
}

static PyMethodDef py_objects_methods[] = {
	{ "parse_tree", (PyCFunction)py_parse_tree, METH_VARARGS | METH_KEYWORDS,
	  NULL },
	{ "sorted_tree_items", py_sorted_tree_items, METH_VARARGS, NULL },
	{ NULL, NULL, 0, NULL }
};

static PyObject *
moduleinit(void)
{
	PyObject *m, *objects_mod, *errors_mod;

	static struct PyModuleDef moduledef = {
		PyModuleDef_HEAD_INIT,
		"_objects",         /* m_name */
		NULL,               /* m_doc */
		-1,                 /* m_size */
		py_objects_methods, /* m_methods */
		NULL,               /* m_reload */
		NULL,               /* m_traverse */
		NULL,               /* m_clear*/
		NULL,               /* m_free */
	};
	m = PyModule_Create(&moduledef);
	if (m == NULL) {
		return NULL;
	}

	errors_mod = PyImport_ImportModule("dulwich.errors");
	if (errors_mod == NULL) {
		return NULL;
	}

	object_format_exception_cls = PyObject_GetAttrString(
		errors_mod, "ObjectFormatException");
	Py_DECREF(errors_mod);
	if (object_format_exception_cls == NULL) {
		return NULL;
	}

	/* This is a circular import but should be safe since this module is
	 * imported at at the very bottom of objects.py. */
	objects_mod = PyImport_ImportModule("dulwich.objects");
	if (objects_mod == NULL) {
		return NULL;
	}

	tree_entry_cls = PyObject_GetAttrString(objects_mod, "TreeEntry");
	Py_DECREF(objects_mod);
	if (tree_entry_cls == NULL) {
		return NULL;
	}

	return m;
}

PyMODINIT_FUNC
PyInit__objects(void)
{
	return moduleinit();
}