/* Implementation helper: a struct that looks like a tuple. See timemodule
 and posixmodule for example uses. */

#include "Python.h"
#include "structmember.h"

static const char visible_length_key[] = "n_sequence_fields";
static const char real_length_key[] = "n_fields";
static const char unnamed_fields_key[] = "n_unnamed_fields";

/* Fields with this name have only a field index, not a field name.
 They are only allowed for indices < n_visible_fields. */
char *PyStructSequence_UnnamedField = "unnamed field";
_Py_IDENTIFIER(n_sequence_fields);
_Py_IDENTIFIER(n_fields);
_Py_IDENTIFIER(n_unnamed_fields);

#define VISIBLE_SIZE(op) Py_SIZE(op)
#define VISIBLE_SIZE_TP(tp) PyLong_AsSsize_t( \
 _PyDict_GetItemId((tp)->tp_dict, &PyId_n_sequence_fields))

#define REAL_SIZE_TP(tp) PyLong_AsSsize_t( \
 _PyDict_GetItemId((tp)->tp_dict, &PyId_n_fields))
#define REAL_SIZE(op) REAL_SIZE_TP(Py_TYPE(op))

#define UNNAMED_FIELDS_TP(tp) PyLong_AsSsize_t( \
 _PyDict_GetItemId((tp)->tp_dict, &PyId_n_unnamed_fields))
#define UNNAMED_FIELDS(op) UNNAMED_FIELDS_TP(Py_TYPE(op))


PyObject *
PyStructSequence_New(PyTypeObject *type)
{
 PyStructSequence *obj;
 Py_ssize_t size = REAL_SIZE_TP(type), i;

 obj = PyObject_GC_NewVar(PyStructSequence, type, size);
 if (obj == NULL)
 return NULL;
 /* Hack the size of the variable object, so invisible fields don't appear
 to Python code. */
 Py_SIZE(obj) = VISIBLE_SIZE_TP(type);
 for (i = 0; i < size; i++)
 obj->ob_item[i] = NULL;

 return (PyObject*)obj;
}

void
PyStructSequence_SetItem(PyObject* op, Py_ssize_t i, PyObject* v)
{
 PyStructSequence_SET_ITEM(op, i, v);
}

PyObject*
PyStructSequence_GetItem(PyObject* op, Py_ssize_t i)
{
 return PyStructSequence_GET_ITEM(op, i);
}

static void
structseq_dealloc(PyStructSequence *obj)
{
 Py_ssize_t i, size;

 size = REAL_SIZE(obj);
 for (i = 0; i < size; ++i) {
 Py_XDECREF(obj->ob_item[i]);
 }
 PyObject_GC_Del(obj);
}

/*[clinic input]
class structseq "PyStructSequence *" "NULL"
[clinic start generated code]*/
/*[clinic end generated code: output=da39a3ee5e6b4b0d input=9d781c6922c77752]*/

#include "clinic/structseq.c.h"

/*[clinic input]
@classmethod
structseq.__new__ as structseq_new
 sequence as arg: object
 dict: object = NULL
[clinic start generated code]*/

static PyObject *
structseq_new_impl(PyTypeObject *type, PyObject *arg, PyObject *dict)
/*[clinic end generated code: output=baa082e788b171da input=9b44810243907377]*/
{
 PyObject *ob;
 PyStructSequence *res = NULL;
 Py_ssize_t len, min_len, max_len, i, n_unnamed_fields;

 arg = PySequence_Fast(arg, "constructor requires a sequence");

 if (!arg) {
 return NULL;
 }

 if (dict && !PyDict_Check(dict)) {
 PyErr_Format(PyExc_TypeError,
 "%.500s() takes a dict as second arg, if any",
 type->tp_name);
 Py_DECREF(arg);
 return NULL;
 }

 len = PySequence_Fast_GET_SIZE(arg);
 min_len = VISIBLE_SIZE_TP(type);
 max_len = REAL_SIZE_TP(type);
 n_unnamed_fields = UNNAMED_FIELDS_TP(type);

 if (min_len != max_len) {
 if (len < min_len) {
 PyErr_Format(PyExc_TypeError,
 "%.500s() takes an at least %zd-sequence (%zd-sequence given)",
 type->tp_name, min_len, len);
 Py_DECREF(arg);
 return NULL;
 }

 if (len > max_len) {
 PyErr_Format(PyExc_TypeError,
 "%.500s() takes an at most %zd-sequence (%zd-sequence given)",
 type->tp_name, max_len, len);
 Py_DECREF(arg);
 return NULL;
 }
 }
 else {
 if (len != min_len) {
 PyErr_Format(PyExc_TypeError,
 "%.500s() takes a %zd-sequence (%zd-sequence given)",
 type->tp_name, min_len, len);
 Py_DECREF(arg);
 return NULL;
 }
 }

 res = (PyStructSequence*) PyStructSequence_New(type);
 if (res == NULL) {
 Py_DECREF(arg);
 return NULL;
 }
 for (i = 0; i < len; ++i) {
 PyObject *v = PySequence_Fast_GET_ITEM(arg, i);
 Py_INCREF(v);
 res->ob_item[i] = v;
 }
 for (; i < max_len; ++i) {
 if (dict && (ob = PyDict_GetItemString(
 dict, type->tp_members[i-n_unnamed_fields].name))) {
 }
 else {
 ob = Py_None;
 }
 Py_INCREF(ob);
 res->ob_item[i] = ob;
 }

 Py_DECREF(arg);
 return (PyObject*) res;
}


static PyObject *
structseq_repr(PyStructSequence *obj)
{
 /* buffer and type size were chosen well considered. */
#define REPR_BUFFER_SIZE 512
#define TYPE_MAXSIZE 100

 PyTypeObject *typ = Py_TYPE(obj);
 Py_ssize_t i;
 int removelast = 0;
 Py_ssize_t len;
 char buf[REPR_BUFFER_SIZE];
 char *endofbuf, *pbuf = buf;

 /* pointer to end of writeable buffer; safes space for "...)0円" */
 endofbuf= &buf[REPR_BUFFER_SIZE-5];

 /* "typename(", limited to TYPE_MAXSIZE */
 assert(TYPE_MAXSIZE < sizeof(buf));
 len = strlen(typ->tp_name);
 if (len <= TYPE_MAXSIZE) {
 strcpy(pbuf, typ->tp_name);
 pbuf += len;
 }
 else {
 strncpy(pbuf, typ->tp_name, TYPE_MAXSIZE);
 pbuf += TYPE_MAXSIZE;
 }
 *pbuf++ = '(';

 for (i=0; i < VISIBLE_SIZE(obj); i++) {
 PyObject *val, *repr;
 const char *cname, *crepr;

 cname = typ->tp_members[i].name;
 if (cname == NULL) {
 PyErr_Format(PyExc_SystemError, "In structseq_repr(), member %zd name is NULL"
 " for type %.500s", i, typ->tp_name);
 return NULL;
 }
 val = PyStructSequence_GET_ITEM(obj, i);
 repr = PyObject_Repr(val);
 if (repr == NULL)
 return NULL;
 crepr = PyUnicode_AsUTF8(repr);
 if (crepr == NULL) {
 Py_DECREF(repr);
 return NULL;
 }

 /* + 3: keep space for "=" and ", " */
 len = strlen(cname) + strlen(crepr) + 3;
 if ((pbuf+len) <= endofbuf) {
 strcpy(pbuf, cname);
 pbuf += strlen(cname);
 *pbuf++ = '=';
 strcpy(pbuf, crepr);
 pbuf += strlen(crepr);
 *pbuf++ = ',';
 *pbuf++ = ' ';
 removelast = 1;
 Py_DECREF(repr);
 }
 else {
 strcpy(pbuf, "...");
 pbuf += 3;
 removelast = 0;
 Py_DECREF(repr);
 break;
 }
 }
 if (removelast) {
 /* overwrite last ", " */
 pbuf-=2;
 }
 *pbuf++ = ')';
 *pbuf = '0円';

 return PyUnicode_FromString(buf);
}

static PyObject *
structseq_reduce(PyStructSequence* self)
{
 PyObject* tup = NULL;
 PyObject* dict = NULL;
 PyObject* result;
 Py_ssize_t n_fields, n_visible_fields, n_unnamed_fields, i;

 n_fields = REAL_SIZE(self);
 n_visible_fields = VISIBLE_SIZE(self);
 n_unnamed_fields = UNNAMED_FIELDS(self);
 tup = PyTuple_New(n_visible_fields);
 if (!tup)
 goto error;

 dict = PyDict_New();
 if (!dict)
 goto error;

 for (i = 0; i < n_visible_fields; i++) {
 Py_INCREF(self->ob_item[i]);
 PyTuple_SET_ITEM(tup, i, self->ob_item[i]);
 }

 for (; i < n_fields; i++) {
 const char *n = Py_TYPE(self)->tp_members[i-n_unnamed_fields].name;
 if (PyDict_SetItemString(dict, n, self->ob_item[i]) < 0)
 goto error;
 }

 result = Py_BuildValue("(O(OO))", Py_TYPE(self), tup, dict);

 Py_DECREF(tup);
 Py_DECREF(dict);

 return result;

error:
 Py_XDECREF(tup);
 Py_XDECREF(dict);
 return NULL;
}

static PyMethodDef structseq_methods[] = {
 {"__reduce__", (PyCFunction)structseq_reduce, METH_NOARGS, NULL},
 {NULL, NULL}
};

static PyTypeObject _struct_sequence_template = {
 PyVarObject_HEAD_INIT(&PyType_Type, 0)
 NULL, /* tp_name */
 sizeof(PyStructSequence) - sizeof(PyObject *), /* tp_basicsize */
 sizeof(PyObject *), /* tp_itemsize */
 (destructor)structseq_dealloc, /* tp_dealloc */
 0, /* tp_print */
 0, /* tp_getattr */
 0, /* tp_setattr */
 0, /* tp_reserved */
 (reprfunc)structseq_repr, /* tp_repr */
 0, /* tp_as_number */
 0, /* tp_as_sequence */
 0, /* tp_as_mapping */
 0, /* tp_hash */
 0, /* tp_call */
 0, /* tp_str */
 0, /* tp_getattro */
 0, /* tp_setattro */
 0, /* tp_as_buffer */
 Py_TPFLAGS_DEFAULT, /* tp_flags */
 NULL, /* tp_doc */
 0, /* tp_traverse */
 0, /* tp_clear */
 0, /* tp_richcompare */
 0, /* tp_weaklistoffset */
 0, /* tp_iter */
 0, /* tp_iternext */
 structseq_methods, /* tp_methods */
 NULL, /* 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 */
 structseq_new, /* tp_new */
};

int
PyStructSequence_InitType2(PyTypeObject *type, PyStructSequence_Desc *desc)
{
 PyObject *dict;
 PyMemberDef* members;
 Py_ssize_t n_members, n_unnamed_members, i, k;
 PyObject *v;

#ifdef Py_TRACE_REFS
 /* if the type object was chained, unchain it first
 before overwriting its storage */
 if (type->ob_base.ob_base._ob_next) {
 _Py_ForgetReference((PyObject*)type);
 }
#endif

 n_unnamed_members = 0;
 for (i = 0; desc->fields[i].name != NULL; ++i)
 if (desc->fields[i].name == PyStructSequence_UnnamedField)
 n_unnamed_members++;
 n_members = i;

 memcpy(type, &_struct_sequence_template, sizeof(PyTypeObject));
 type->tp_base = &PyTuple_Type;
 type->tp_name = desc->name;
 type->tp_doc = desc->doc;

 members = PyMem_NEW(PyMemberDef, n_members-n_unnamed_members+1);
 if (members == NULL) {
 PyErr_NoMemory();
 return -1;
 }

 for (i = k = 0; i < n_members; ++i) {
 if (desc->fields[i].name == PyStructSequence_UnnamedField)
 continue;
 members[k].name = desc->fields[i].name;
 members[k].type = T_OBJECT;
 members[k].offset = offsetof(PyStructSequence, ob_item)
 + i * sizeof(PyObject*);
 members[k].flags = READONLY;
 members[k].doc = desc->fields[i].doc;
 k++;
 }
 members[k].name = NULL;

 type->tp_members = members;

 if (PyType_Ready(type) < 0)
 return -1;
 Py_INCREF(type);

 dict = type->tp_dict;
#define SET_DICT_FROM_SIZE(key, value) \
 do { \
 v = PyLong_FromSsize_t(value); \
 if (v == NULL) \
 return -1; \
 if (PyDict_SetItemString(dict, key, v) < 0) { \
 Py_DECREF(v); \
 return -1; \
 } \
 Py_DECREF(v); \
 } while (0)

 SET_DICT_FROM_SIZE(visible_length_key, desc->n_in_sequence);
 SET_DICT_FROM_SIZE(real_length_key, n_members);
 SET_DICT_FROM_SIZE(unnamed_fields_key, n_unnamed_members);

 return 0;
}

void
PyStructSequence_InitType(PyTypeObject *type, PyStructSequence_Desc *desc)
{
 (void)PyStructSequence_InitType2(type, desc);
}

PyTypeObject*
PyStructSequence_NewType(PyStructSequence_Desc *desc)
{
 PyTypeObject *result;

 result = (PyTypeObject*)PyType_GenericAlloc(&PyType_Type, 0);
 if (result == NULL)
 return NULL;
 if (PyStructSequence_InitType2(result, desc) < 0) {
 Py_DECREF(result);
 return NULL;
 }
 return result;
}

int _PyStructSequence_Init(void)
{
 if (_PyUnicode_FromId(&PyId_n_sequence_fields) == NULL
 || _PyUnicode_FromId(&PyId_n_fields) == NULL
 || _PyUnicode_FromId(&PyId_n_unnamed_fields) == NULL)
 return -1;

 return 0;
}