#include "Python.h"
#include "frameobject.h"

#define MODULE_NAME "_warnings"

PyDoc_STRVAR(warnings__doc__,
MODULE_NAME " provides basic warning filtering support.\n"
"It is a helper module to speed up interpreter start-up.");

/* Both 'filters' and 'onceregistry' can be set in warnings.py;
   get_warnings_attr() will reset these variables accordingly. */
static PyObject *_filters;  /* List */
static PyObject *_once_registry;  /* Dict */
static PyObject *_default_action; /* String */
static long _filters_version;

_Py_IDENTIFIER(argv);
_Py_IDENTIFIER(stderr);

static int
check_matched(PyObject *obj, PyObject *arg)
{
    PyObject *result;
    _Py_IDENTIFIER(match);
    int rc;

    if (obj == Py_None)
        return 1;
    result = _PyObject_CallMethodId(obj, &PyId_match, "O", arg);
    if (result == NULL)
        return -1;

    rc = PyObject_IsTrue(result);
    Py_DECREF(result);
    return rc;
}

/*
   Returns a new reference.
   A NULL return value can mean false or an error.
*/
static PyObject *
get_warnings_attr(const char *attr)
{
    static PyObject *warnings_str = NULL;
    PyObject *all_modules;
    PyObject *warnings_module;
    int result;

    if (warnings_str == NULL) {
        warnings_str = PyUnicode_InternFromString("warnings");
        if (warnings_str == NULL)
            return NULL;
    }

    all_modules = PyImport_GetModuleDict();
    result = PyDict_Contains(all_modules, warnings_str);
    if (result == -1 || result == 0)
        return NULL;

    warnings_module = PyDict_GetItem(all_modules, warnings_str);
    if (!PyObject_HasAttrString(warnings_module, attr))
            return NULL;
    return PyObject_GetAttrString(warnings_module, attr);
}


static PyObject *
get_once_registry(void)
{
    PyObject *registry;

    registry = get_warnings_attr("onceregistry");
    if (registry == NULL) {
        if (PyErr_Occurred())
            return NULL;
        return _once_registry;
    }
    Py_DECREF(_once_registry);
    _once_registry = registry;
    return registry;
}


static PyObject *
get_default_action(void)
{
    PyObject *default_action;

    default_action = get_warnings_attr("defaultaction");
    if (default_action == NULL) {
        if (PyErr_Occurred()) {
            return NULL;
        }
        return _default_action;
    }

    Py_DECREF(_default_action);
    _default_action = default_action;
    return default_action;
}


/* The item is a new reference. */
static PyObject*
get_filter(PyObject *category, PyObject *text, Py_ssize_t lineno,
           PyObject *module, PyObject **item)
{
    PyObject *action;
    Py_ssize_t i;
    PyObject *warnings_filters;

    warnings_filters = get_warnings_attr("filters");
    if (warnings_filters == NULL) {
        if (PyErr_Occurred())
            return NULL;
    }
    else {
        Py_DECREF(_filters);
        _filters = warnings_filters;
    }

    if (_filters == NULL || !PyList_Check(_filters)) {
        PyErr_SetString(PyExc_ValueError,
                        MODULE_NAME ".filters must be a list");
        return NULL;
    }

    /* _filters could change while we are iterating over it. */
    for (i = 0; i < PyList_GET_SIZE(_filters); i++) {
        PyObject *tmp_item, *action, *msg, *cat, *mod, *ln_obj;
        Py_ssize_t ln;
        int is_subclass, good_msg, good_mod;

        tmp_item = PyList_GET_ITEM(_filters, i);
        if (!PyTuple_Check(tmp_item) || PyTuple_GET_SIZE(tmp_item) != 5) {
            PyErr_Format(PyExc_ValueError,
                         MODULE_NAME ".filters item %zd isn't a 5-tuple", i);
            return NULL;
        }

        /* Python code: action, msg, cat, mod, ln = item */
        Py_INCREF(tmp_item);
        action = PyTuple_GET_ITEM(tmp_item, 0);
        msg = PyTuple_GET_ITEM(tmp_item, 1);
        cat = PyTuple_GET_ITEM(tmp_item, 2);
        mod = PyTuple_GET_ITEM(tmp_item, 3);
        ln_obj = PyTuple_GET_ITEM(tmp_item, 4);

        good_msg = check_matched(msg, text);
        if (good_msg == -1) {
            Py_DECREF(tmp_item);
            return NULL;
        }

        good_mod = check_matched(mod, module);
        if (good_mod == -1) {
            Py_DECREF(tmp_item);
            return NULL;
        }

        is_subclass = PyObject_IsSubclass(category, cat);
        if (is_subclass == -1) {
            Py_DECREF(tmp_item);
            return NULL;
        }

        ln = PyLong_AsSsize_t(ln_obj);
        if (ln == -1 && PyErr_Occurred()) {
            Py_DECREF(tmp_item);
            return NULL;
        }

        if (good_msg && is_subclass && good_mod && (ln == 0 || lineno == ln)) {
            *item = tmp_item;
            return action;
        }

        Py_DECREF(tmp_item);
    }

    action = get_default_action();
    if (action != NULL) {
        Py_INCREF(Py_None);
        *item = Py_None;
        return action;
    }

    PyErr_SetString(PyExc_ValueError,
                    MODULE_NAME ".defaultaction not found");
    return NULL;
}


static int
already_warned(PyObject *registry, PyObject *key, int should_set)
{
    PyObject *version_obj, *already_warned;
    _Py_IDENTIFIER(version);

    if (key == NULL)
        return -1;

    version_obj = _PyDict_GetItemId(registry, &PyId_version);
    if (version_obj == NULL
        || !PyLong_CheckExact(version_obj)
        || PyLong_AsLong(version_obj) != _filters_version) {
        PyDict_Clear(registry);
        version_obj = PyLong_FromLong(_filters_version);
        if (version_obj == NULL)
            return -1;
        if (_PyDict_SetItemId(registry, &PyId_version, version_obj) < 0) {
            Py_DECREF(version_obj);
            return -1;
        }
        Py_DECREF(version_obj);
    }
    else {
        already_warned = PyDict_GetItem(registry, key);
        if (already_warned != NULL) {
            int rc = PyObject_IsTrue(already_warned);
            if (rc != 0)
                return rc;
        }
    }

    /* This warning wasn't found in the registry, set it. */
    if (should_set)
        return PyDict_SetItem(registry, key, Py_True);
    return 0;
}

/* New reference. */
static PyObject *
normalize_module(PyObject *filename)
{
    PyObject *module;
    int kind;
    void *data;
    Py_ssize_t len;

    len = PyUnicode_GetLength(filename);
    if (len < 0)
        return NULL;

    if (len == 0)
        return PyUnicode_FromString("");

    kind = PyUnicode_KIND(filename);
    data = PyUnicode_DATA(filename);

    /* if filename.endswith(".py"): */
    if (len >= 3 &&
        PyUnicode_READ(kind, data, len-3) == '.' &&
        PyUnicode_READ(kind, data, len-2) == 'p' &&
        PyUnicode_READ(kind, data, len-1) == 'y')
    {
        module = PyUnicode_Substring(filename, 0, len-3);
    }
    else {
        module = filename;
        Py_INCREF(module);
    }
    return module;
}

static int
update_registry(PyObject *registry, PyObject *text, PyObject *category,
                int add_zero)
{
    PyObject *altkey, *zero = NULL;
    int rc;

    if (add_zero) {
        zero = PyLong_FromLong(0);
        if (zero == NULL)
            return -1;
        altkey = PyTuple_Pack(3, text, category, zero);
    }
    else
        altkey = PyTuple_Pack(2, text, category);

    rc = already_warned(registry, altkey, 1);
    Py_XDECREF(zero);
    Py_XDECREF(altkey);
    return rc;
}

static void
show_warning(PyObject *filename, int lineno, PyObject *text, PyObject
                *category, PyObject *sourceline)
{
    PyObject *f_stderr;
    PyObject *name;
    char lineno_str[128];
    _Py_IDENTIFIER(__name__);

    PyOS_snprintf(lineno_str, sizeof(lineno_str), ":%d: ", lineno);

    name = _PyObject_GetAttrId(category, &PyId___name__);
    if (name == NULL)  /* XXX Can an object lack a '__name__' attribute? */
        goto error;

    f_stderr = _PySys_GetObjectId(&PyId_stderr);
    if (f_stderr == NULL) {
        fprintf(stderr, "lost sys.stderr\n");
        goto error;
    }

    /* Print "filename:lineno: category: text\n" */
    if (PyFile_WriteObject(filename, f_stderr, Py_PRINT_RAW) < 0)
        goto error;
    if (PyFile_WriteString(lineno_str, f_stderr) < 0)
        goto error;
    if (PyFile_WriteObject(name, f_stderr, Py_PRINT_RAW) < 0)
        goto error;
    if (PyFile_WriteString(": ", f_stderr) < 0)
        goto error;
    if (PyFile_WriteObject(text, f_stderr, Py_PRINT_RAW) < 0)
        goto error;
    if (PyFile_WriteString("\n", f_stderr) < 0)
        goto error;
    Py_CLEAR(name);

    /* Print "  source_line\n" */
    if (sourceline) {
        int kind;
        void *data;
        Py_ssize_t i, len;
        Py_UCS4 ch;
        PyObject *truncated;

        if (PyUnicode_READY(sourceline) < 1)
            goto error;

        kind = PyUnicode_KIND(sourceline);
        data = PyUnicode_DATA(sourceline);
        len = PyUnicode_GET_LENGTH(sourceline);
        for (i=0; i