from rpython.rtyper.tool import rffi_platform as platform
from rpython.rtyper.lltypesystem import rffi
from pypy.interpreter.error import OperationError, oefmt
from pypy.interpreter.gateway import unwrap_spec
from rpython.rtyper.lltypesystem import lltype
from rpython.rlib.rarithmetic import intmask
from rpython.rlib import rposix
from rpython.translator.tool.cbuild import ExternalCompilationInfo
import os
import sys
import time as pytime

_POSIX = os.name == "posix"
_WIN = os.name == "nt"
_CYGWIN = sys.platform == "cygwin"

_time_zones = []
if _CYGWIN:
    _time_zones = ["GMT-12", "GMT-11", "GMT-10", "GMT-9", "GMT-8", "GMT-7",
                   "GMT-6", "GMT-5", "GMT-4", "GMT-3", "GMT-2", "GMT-1",
                   "GMT",  "GMT+1", "GMT+2", "GMT+3", "GMT+4", "GMT+5",
                   "GMT+6",  "GMT+7", "GMT+8", "GMT+9", "GMT+10", "GMT+11",
                   "GMT+12",  "GMT+13", "GMT+14"]

if _WIN:
    # Interruptible sleeps on Windows:
    # We install a specific Console Ctrl Handler which sets an 'event'.
    # time.sleep() will actually call WaitForSingleObject with the desired
    # timeout.  On Ctrl-C, the signal handler is called, the event is set,
    # and the wait function exits.
    from rpython.rlib import rwin32
    from pypy.interpreter.error import wrap_windowserror, wrap_oserror
    from rpython.rlib import rthread as thread

    eci = ExternalCompilationInfo(
        includes = ['windows.h'],
        post_include_bits = ["BOOL pypy_timemodule_setCtrlHandler(HANDLE event);"],
        separate_module_sources=['''
            static HANDLE interrupt_event;

            static BOOL WINAPI CtrlHandlerRoutine(
              DWORD dwCtrlType)
            {
                SetEvent(interrupt_event);
                /* allow other default handlers to be called.
                 * Default Python handler will setup the
                 * KeyboardInterrupt exception.
                 */
                return 0;
            }

            BOOL pypy_timemodule_setCtrlHandler(HANDLE event)
            {
                interrupt_event = event;
                return SetConsoleCtrlHandler(CtrlHandlerRoutine, TRUE);
            }

        '''],
        export_symbols=['pypy_timemodule_setCtrlHandler'],
        )
    _setCtrlHandlerRoutine = rffi.llexternal(
        'pypy_timemodule_setCtrlHandler',
        [rwin32.HANDLE], rwin32.BOOL,
        compilation_info=eci)

    class GlobalState:
        def __init__(self):
            self.init()

        def init(self):
            self.interrupt_event = rwin32.NULL_HANDLE

        def startup(self, space):
            # Initialize the event handle used to signal Ctrl-C
            try:
                globalState.interrupt_event = rwin32.CreateEvent(
                    rffi.NULL, True, False, rffi.NULL)
            except WindowsError, e:
                raise wrap_windowserror(space, e)
            if not _setCtrlHandlerRoutine(globalState.interrupt_event):
                raise wrap_windowserror(
                    space, rwin32.lastWindowsError("SetConsoleCtrlHandler"))

    globalState = GlobalState()

    class State:
        def __init__(self, space):
            self.main_thread = 0

        def _cleanup_(self):
            self.main_thread = 0
            globalState.init()

        def startup(self, space):
            self.main_thread = thread.get_ident()
            globalState.startup(space)

        def get_interrupt_event(self):
            return globalState.interrupt_event


_includes = ["time.h"]
if _POSIX:
    _includes.append('sys/time.h')

class CConfig:
    _compilation_info_ = ExternalCompilationInfo(
        includes = _includes
    )
    CLOCKS_PER_SEC = platform.ConstantInteger("CLOCKS_PER_SEC")
    clock_t = platform.SimpleType("clock_t", rffi.ULONG)
    has_gettimeofday = platform.Has('gettimeofday')

if _POSIX:
    calling_conv = 'c'
    CConfig.timeval = platform.Struct("struct timeval",
                                      [("tv_sec", rffi.INT),
                                       ("tv_usec", rffi.INT)])
    if _CYGWIN:
        CConfig.tm = platform.Struct("struct tm", [("tm_sec", rffi.INT),
            ("tm_min", rffi.INT), ("tm_hour", rffi.INT), ("tm_mday", rffi.INT),
            ("tm_mon", rffi.INT), ("tm_year", rffi.INT), ("tm_wday", rffi.INT),
            ("tm_yday", rffi.INT), ("tm_isdst", rffi.INT)])
    else:
        CConfig.tm = platform.Struct("struct tm", [("tm_sec", rffi.INT),
            ("tm_min", rffi.INT), ("tm_hour", rffi.INT), ("tm_mday", rffi.INT),
            ("tm_mon", rffi.INT), ("tm_year", rffi.INT), ("tm_wday", rffi.INT),
            ("tm_yday", rffi.INT), ("tm_isdst", rffi.INT), ("tm_gmtoff", rffi.LONG),
            ("tm_zone", rffi.CCHARP)])
elif _WIN:
    calling_conv = 'win'
    CConfig.tm = platform.Struct("struct tm", [("tm_sec", rffi.INT),
        ("tm_min", rffi.INT), ("tm_hour", rffi.INT), ("tm_mday", rffi.INT),
        ("tm_mon", rffi.INT), ("tm_year", rffi.INT), ("tm_wday", rffi.INT),
        ("tm_yday", rffi.INT), ("tm_isdst", rffi.INT)])

class cConfig:
    pass

for k, v in platform.configure(CConfig).items():
    setattr(cConfig, k, v)
cConfig.tm.__name__ = "_tm"

def external(name, args, result, eci=CConfig._compilation_info_):
    if _WIN and rffi.sizeof(rffi.TIME_T) == 8:
        # Recent Microsoft compilers use 64bit time_t and
        # the corresponding functions are named differently
        if (rffi.TIME_T in args or rffi.TIME_TP in args
            or result in (rffi.TIME_T, rffi.TIME_TP)):
            name = '_' + name + '64'
    return rffi.llexternal(name, args, result,
                           compilation_info=eci,
                           calling_conv=calling_conv,
                           releasegil=False)

if _POSIX:
    cConfig.timeval.__name__ = "_timeval"
    timeval = cConfig.timeval

CLOCKS_PER_SEC = cConfig.CLOCKS_PER_SEC
clock_t = cConfig.clock_t
tm = cConfig.tm
glob_buf = lltype.malloc(tm, flavor='raw', zero=True, immortal=True)

if cConfig.has_gettimeofday:
    c_gettimeofday = external('gettimeofday', [rffi.VOIDP, rffi.VOIDP], rffi.INT)
TM_P = lltype.Ptr(tm)
c_clock = external('clock', [rffi.TIME_TP], clock_t)
c_time = external('time', [rffi.TIME_TP], rffi.TIME_T)
c_ctime = external('ctime', [rffi.TIME_TP], rffi.CCHARP)
c_gmtime = external('gmtime', [rffi.TIME_TP], TM_P)
c_mktime = external('mktime', [TM_P], rffi.TIME_T)
c_asctime = external('asctime', [TM_P], rffi.CCHARP)
c_localtime = external('localtime', [rffi.TIME_TP], TM_P)
if _POSIX:
    c_tzset = external('tzset', [], lltype.Void)
if _WIN:
    win_eci = ExternalCompilationInfo(
        includes = ["time.h"],
        post_include_bits = ["long pypy_get_timezone();",
                             "int pypy_get_daylight();",
                             "char** pypy_get_tzname();"],
        separate_module_sources = ["""
        long pypy_get_timezone() { return timezone; }
        int pypy_get_daylight() { return daylight; }
        char** pypy_get_tzname() { return tzname; }
        """],
        export_symbols = [
        '_tzset', 'pypy_get_timezone', 'pypy_get_daylight', 'pypy_get_tzname'],
        )
    # Ensure sure that we use _tzset() and timezone from the same C Runtime.
    c_tzset = external('_tzset', [], lltype.Void, win_eci)
    c_get_timezone = external('pypy_get_timezone', [], rffi.LONG, win_eci)
    c_get_daylight = external('pypy_get_daylight', [], rffi.INT, win_eci)
    c_get_tzname = external('pypy_get_tzname', [], rffi.CCHARPP, win_eci)

c_strftime = external('strftime', [rffi.CCHARP, rffi.SIZE_T, rffi.CCHARP, TM_P],
                      rffi.SIZE_T)

def _init_accept2dyear(space):
    if os.environ.get("PYTHONY2K"):
        accept2dyear = 0
    else:
        accept2dyear = 1
    _set_module_object(space, "accept2dyear", space.wrap(accept2dyear))

def _init_timezone(space):
    timezone = daylight = altzone = 0
    tzname = ["", ""]

    if _WIN:
        c_tzset()
        timezone = c_get_timezone()
        altzone = timezone - 3600
        daylight = c_get_daylight()
        tzname_ptr = c_get_tzname()
        tzname = rffi.charp2str(tzname_ptr[0]), rffi.charp2str(tzname_ptr[1])

    if _POSIX:
        if _CYGWIN:
            YEAR = (365 * 24 + 6) * 3600

            # about January 11th
            t = (((c_time(lltype.nullptr(rffi.TIME_TP.TO))) / YEAR) * YEAR + 10 * 24 * 3600)
            # we cannot have reference to stack variable, put it on the heap
            t_ref = lltype.malloc(rffi.TIME_TP.TO, 1, flavor='raw')
            t_ref[0] = rffi.cast(rffi.TIME_T, t)
            p = c_localtime(t_ref)
            q = c_gmtime(t_ref)
            janzone = (p.c_tm_hour + 24 * p.c_tm_mday) - (q.c_tm_hour + 24 * q.c_tm_mday)
            if janzone < -12:
                janname = "   "
            elif janzone > 14:
                janname = "   "
            else:
                janname = _time_zones[janzone - 12]
            janzone = janzone * 3600
            # about July 11th
            tt = t + YEAR / 2
            t_ref[0] = rffi.cast(rffi.TIME_T, tt)
            p = c_localtime(t_ref)
            q = c_gmtime(t_ref)
            julyzone = (p.c_tm_hour + 24 * p.c_tm_mday) - (q.c_tm_hour + 24 * q.c_tm_mday)
            if julyzone < -12:
                julyname = "   "
            elif julyzone > 14:
                julyname = "   "
            else:
                julyname = _time_zones[julyzone - 12]
            julyzone = julyzone * 3600
            lltype.free(t_ref, flavor='raw')

            if janzone < julyzone:
                # DST is reversed in the southern hemisphere
                timezone = julyzone
                altzone = janzone
                daylight = int(janzone != julyzone)
                tzname = [julyname, janname]
            else:
                timezone = janzone
                altzone = julyzone
                daylight = int(janzone != julyzone)
                tzname = [janname, julyname]

        else:
            YEAR = (365 * 24 + 6) * 3600

            t = (((c_time(lltype.nullptr(rffi.TIME_TP.TO))) / YEAR) * YEAR)
            # we cannot have reference to stack variable, put it on the heap
            t_ref = lltype.malloc(rffi.TIME_TP.TO, 1, flavor='raw')
            t_ref[0] = rffi.cast(rffi.TIME_T, t)
            p = c_localtime(t_ref)
            janzone = -p.c_tm_gmtoff
            tm_zone = rffi.charp2str(p.c_tm_zone)
            janname = ["   ", tm_zone][bool(tm_zone)]
            tt = t + YEAR / 2
            t_ref[0] = rffi.cast(rffi.TIME_T, tt)
            p = c_localtime(t_ref)
            lltype.free(t_ref, flavor='raw')
            tm_zone = rffi.charp2str(p.c_tm_zone)
            julyzone = -p.c_tm_gmtoff
            julyname = ["   ", tm_zone][bool(tm_zone)]

            if janzone < julyzone:
                # DST is reversed in the southern hemisphere
                timezone = julyzone
                altzone = janzone
                daylight = int(janzone != julyzone)
                tzname = [julyname, janname]
            else:
                timezone = janzone
                altzone = julyzone
                daylight = int(janzone != julyzone)
                tzname = [janname, julyname]

    _set_module_object(space, "timezone", space.wrap(timezone))
    _set_module_object(space, 'daylight', space.wrap(daylight))
    tzname_w = [space.wrap(tzname[0]), space.wrap(tzname[1])]
    _set_module_object(space, 'tzname', space.newtuple(tzname_w))
    _set_module_object(space, 'altzone', space.wrap(altzone))

def _get_error_msg():
    errno = rposix.get_errno()
    return os.strerror(errno)

if sys.platform != 'win32':
    @unwrap_spec(secs=float)
    def sleep(space, secs):
        if secs < 0:
            raise OperationError(space.w_IOError,
                                 space.wrap("Invalid argument: negative time in sleep"))
        pytime.sleep(secs)
else:
    from rpython.rlib import rwin32
    from errno import EINTR
    def _simple_sleep(space, secs, interruptible):
        if secs == 0.0 or not interruptible:
            pytime.sleep(secs)
        else:
            millisecs = int(secs * 1000)
            interrupt_event = space.fromcache(State).get_interrupt_event()
            rwin32.ResetEvent(interrupt_event)
            rc = rwin32.WaitForSingleObject(interrupt_event, millisecs)
            if rc == rwin32.WAIT_OBJECT_0:
                # Yield to make sure real Python signal handler
                # called.
                pytime.sleep(0.001)
                raise wrap_oserror(space,
                                   OSError(EINTR, "sleep() interrupted"))
    @unwrap_spec(secs=float)
    def sleep(space, secs):
        if secs < 0:
            raise OperationError(space.w_IOError,
                                 space.wrap("Invalid argument: negative time in sleep"))
        # as decreed by Guido, only the main thread can be
        # interrupted.
        main_thread = space.fromcache(State).main_thread
        interruptible = (main_thread == thread.get_ident())
        MAX = sys.maxint / 1000.0 # > 24 days
        while secs > MAX:
            _simple_sleep(space, MAX, interruptible)
            secs -= MAX
        _simple_sleep(space, secs, interruptible)

def _get_module_object(space, obj_name):
    w_module = space.getbuiltinmodule('time')
    w_obj = space.getattr(w_module, space.wrap(obj_name))
    return w_obj

def _set_module_object(space, obj_name, w_obj_value):
    w_module = space.getbuiltinmodule('time')
    space.setattr(w_module, space.wrap(obj_name), w_obj_value)

def _get_inttime(space, w_seconds):
    # w_seconds can be a wrapped None (it will be automatically wrapped
    # in the callers, so we never get a real None here).
    if space.is_none(w_seconds):
        seconds = pytime.time()
    else:
        seconds = space.float_w(w_seconds)
    #
    t = rffi.cast(rffi.TIME_T, seconds)
    #
    # Logic from CPython: How much info did we lose?  We assume that
    # time_t is an integral type.  If we lost a second or more, the
    # input doesn't fit in a time_t; call it an error.
    diff = seconds - rffi.cast(lltype.Float, t)
    if diff <= -1.0 or diff >= 1.0:
        raise OperationError(space.w_ValueError,
                      space.wrap("timestamp out of range for platform time_t"))
    return t

def _tm_to_tuple(space, t):
    time_tuple = [
        space.wrap(rffi.getintfield(t, 'c_tm_year') + 1900),
        space.wrap(rffi.getintfield(t, 'c_tm_mon') + 1), # want january == 1
        space.wrap(rffi.getintfield(t, 'c_tm_mday')),
        space.wrap(rffi.getintfield(t, 'c_tm_hour')),
        space.wrap(rffi.getintfield(t, 'c_tm_min')),
        space.wrap(rffi.getintfield(t, 'c_tm_sec')),
        space.wrap((rffi.getintfield(t, 'c_tm_wday') + 6) % 7), # want monday == 0
        space.wrap(rffi.getintfield(t, 'c_tm_yday') + 1), # want january, 1 == 1
        space.wrap(rffi.getintfield(t, 'c_tm_isdst'))]

    w_struct_time = _get_module_object(space, 'struct_time')
    w_time_tuple = space.newtuple(time_tuple)
    return space.call_function(w_struct_time, w_time_tuple)

def _gettmarg(space, w_tup, allowNone=True):
    if space.is_none(w_tup):
        if not allowNone:
            raise OperationError(space.w_TypeError,
                                 space.wrap("tuple expected"))
        # default to the current local time
        tt = rffi.r_time_t(int(pytime.time()))
        t_ref = lltype.malloc(rffi.TIME_TP.TO, 1, flavor='raw')
        t_ref[0] = tt
        pbuf = c_localtime(t_ref)
        lltype.free(t_ref, flavor='raw')
        if not pbuf:
            raise OperationError(space.w_ValueError,
                space.wrap(_get_error_msg()))
        return pbuf

    tup_w = space.fixedview(w_tup)
    if len(tup_w) != 9:
        raise oefmt(space.w_TypeError,
                    "argument must be sequence of length 9, not %d",
                    len(tup_w))

    y = space.int_w(tup_w[0])
    tm_mon = space.int_w(tup_w[1])
    if tm_mon == 0:
        tm_mon = 1
    tm_mday = space.int_w(tup_w[2])
    if tm_mday == 0:
        tm_mday = 1
    tm_yday = space.int_w(tup_w[7])
    if tm_yday == 0:
        tm_yday = 1
    rffi.setintfield(glob_buf, 'c_tm_mon', tm_mon)
    rffi.setintfield(glob_buf, 'c_tm_mday', tm_mday)
    rffi.setintfield(glob_buf, 'c_tm_hour', space.int_w(tup_w[3]))
    rffi.setintfield(glob_buf, 'c_tm_min', space.int_w(tup_w[4]))
    rffi.setintfield(glob_buf, 'c_tm_sec', space.int_w(tup_w[5]))
    rffi.setintfield(glob_buf, 'c_tm_wday', space.int_w(tup_w[6]))
    rffi.setintfield(glob_buf, 'c_tm_yday', tm_yday)
    rffi.setintfield(glob_buf, 'c_tm_isdst', space.int_w(tup_w[8]))
    if _POSIX:
        if _CYGWIN:
            pass
        else:
            # actually never happens, but makes annotator happy
            glob_buf.c_tm_zone = lltype.nullptr(rffi.CCHARP.TO)
            rffi.setintfield(glob_buf, 'c_tm_gmtoff', 0)

    if y < 1900:
        w_accept2dyear = _get_module_object(space, "accept2dyear")
        accept2dyear = space.int_w(w_accept2dyear)

        if not accept2dyear:
            raise OperationError(space.w_ValueError,
                space.wrap("year >= 1900 required"))

        if 69 <= y <= 99:
            y += 1900
        elif 0 <= y <= 68:
            y += 2000
        else:
            raise OperationError(space.w_ValueError,
                space.wrap("year out of range"))

    # tm_wday does not need checking of its upper-bound since taking "%
    #  7" in gettmarg() automatically restricts the range.
    if rffi.getintfield(glob_buf, 'c_tm_wday') < -1:
        raise OperationError(space.w_ValueError,
                             space.wrap("day of week out of range"))

    rffi.setintfield(glob_buf, 'c_tm_year', y - 1900)
    rffi.setintfield(glob_buf, 'c_tm_mon',
                     rffi.getintfield(glob_buf, 'c_tm_mon') - 1)
    rffi.setintfield(glob_buf, 'c_tm_wday',
                     (rffi.getintfield(glob_buf, 'c_tm_wday') + 1) % 7)
    rffi.setintfield(glob_buf, 'c_tm_yday',
                     rffi.getintfield(glob_buf, 'c_tm_yday') - 1)

    return glob_buf

def time(space):
    """time() -> floating point number

    Return the current time in seconds since the Epoch.
    Fractions of a second may be present if the system clock provides them."""

    secs = pytime.time()
    return space.wrap(secs)

if _WIN:
    class PCCache:
        pass
    pccache = PCCache()
    pccache.divisor = 0.0
    pccache.ctrStart = 0

def clock(space):
    """clock() -> floating point number

    Return the CPU time or real time since the start of the process or since
    the first call to clock().  This has as much precision as the system
    records."""

    return space.wrap(pytime.clock())

def ctime(space, w_seconds=None):
    """ctime([seconds]) -> string

    Convert a time in seconds since the Epoch to a string in local time.
    This is equivalent to asctime(localtime(seconds)). When the time tuple is
    not present, current time as returned by localtime() is used."""

    seconds = _get_inttime(space, w_seconds)

    t_ref = lltype.malloc(rffi.TIME_TP.TO, 1, flavor='raw')
    t_ref[0] = seconds
    p = c_ctime(t_ref)
    lltype.free(t_ref, flavor='raw')
    if not p:
        raise OperationError(space.w_ValueError,
            space.wrap("unconvertible time"))

    return space.wrap(rffi.charp2str(p)[:-1]) # get rid of new line

# by now w_tup is an optional argument (and not *args)
# because of the ext. compiler bugs in handling such arguments (*args, **kwds)
def asctime(space, w_tup=None):
    """asctime([tuple]) -> string

    Convert a time tuple to a string, e.g. 'Sat Jun 06 16:26:11 1998'.
    When the time tuple is not present, current time as returned by localtime()
    is used."""
    buf_value = _gettmarg(space, w_tup)
    p = c_asctime(buf_value)
    if not p:
        raise OperationError(space.w_ValueError,
            space.wrap("unconvertible time"))

    return space.wrap(rffi.charp2str(p)[:-1]) # get rid of new line

def gmtime(space, w_seconds=None):
    """gmtime([seconds]) -> (tm_year, tm_mon, tm_day, tm_hour, tm_min,
                          tm_sec, tm_wday, tm_yday, tm_isdst)

    Convert seconds since the Epoch to a time tuple expressing UTC (a.k.a.
    GMT).  When 'seconds' is not passed in, convert the current time instead.
    """

    # rpython does not support that a variable has two incompatible builtins
    # as value so we have to duplicate the code. NOT GOOD! see localtime() too
    seconds = _get_inttime(space, w_seconds)
    t_ref = lltype.malloc(rffi.TIME_TP.TO, 1, flavor='raw')
    t_ref[0] = seconds
    p = c_gmtime(t_ref)
    lltype.free(t_ref, flavor='raw')

    if not p:
        raise OperationError(space.w_ValueError, space.wrap(_get_error_msg()))
    return _tm_to_tuple(space, p)

def localtime(space, w_seconds=None):
    """localtime([seconds]) -> (tm_year, tm_mon, tm_day, tm_hour, tm_min,
                             tm_sec, tm_wday, tm_yday, tm_isdst)

    Convert seconds since the Epoch to a time tuple expressing local time.
    When 'seconds' is not passed in, convert the current time instead."""

    seconds = _get_inttime(space, w_seconds)
    t_ref = lltype.malloc(rffi.TIME_TP.TO, 1, flavor='raw')
    t_ref[0] = seconds
    p = c_localtime(t_ref)
    lltype.free(t_ref, flavor='raw')

    if not p:
        raise OperationError(space.w_ValueError, space.wrap(_get_error_msg()))
    return _tm_to_tuple(space, p)

def mktime(space, w_tup):
    """mktime(tuple) -> floating point number

    Convert a time tuple in local time to seconds since the Epoch."""

    buf = _gettmarg(space, w_tup, allowNone=False)
    rffi.setintfield(buf, "c_tm_wday", -1)
    tt = c_mktime(buf)
    # A return value of -1 does not necessarily mean an error, but tm_wday
    # cannot remain set to -1 if mktime succeeds.
    if tt == -1 and rffi.getintfield(buf, "c_tm_wday") == -1:
        raise OperationError(space.w_OverflowError,
            space.wrap("mktime argument out of range"))

    return space.wrap(float(tt))

if _POSIX:
    def tzset(space):
        """tzset()

        Initialize, or reinitialize, the local timezone to the value stored in
        os.environ['TZ']. The TZ environment variable should be specified in
        standard Unix timezone format as documented in the tzset man page
        (eg. 'US/Eastern', 'Europe/Amsterdam'). Unknown timezones will silently
        fall back to UTC. If the TZ environment variable is not set, the local
        timezone is set to the systems best guess of wallclock time.
        Changing the TZ environment variable without calling tzset *may* change
        the local timezone used by methods such as localtime, but this behaviour
        should not be relied on"""

        c_tzset()

        # reset timezone, altzone, daylight and tzname
        _init_timezone(space)

@unwrap_spec(format=str)
def strftime(space, format, w_tup=None):
    """strftime(format[, tuple]) -> string

    Convert a time tuple to a string according to a format specification.
    See the library reference manual for formatting codes. When the time tuple
    is not present, current time as returned by localtime() is used."""
    buf_value = _gettmarg(space, w_tup)

    # Checks added to make sure strftime() does not crash Python by
    # indexing blindly into some array for a textual representation
    # by some bad index (fixes bug #897625).
    # No check for year since handled in gettmarg().
    if rffi.getintfield(buf_value, 'c_tm_mon') < 0 or rffi.getintfield(buf_value, 'c_tm_mon') > 11:
        raise OperationError(space.w_ValueError,
                             space.wrap("month out of range"))
    if rffi.getintfield(buf_value, 'c_tm_mday') < 1 or rffi.getintfield(buf_value, 'c_tm_mday') > 31:
        raise OperationError(space.w_ValueError,
                             space.wrap("day of month out of range"))
    if rffi.getintfield(buf_value, 'c_tm_hour') < 0 or rffi.getintfield(buf_value, 'c_tm_hour') > 23:
        raise OperationError(space.w_ValueError,
                             space.wrap("hour out of range"))
    if rffi.getintfield(buf_value, 'c_tm_min') < 0 or rffi.getintfield(buf_value, 'c_tm_min') > 59:
        raise OperationError(space.w_ValueError,
                             space.wrap("minute out of range"))
    if rffi.getintfield(buf_value, 'c_tm_sec') < 0 or rffi.getintfield(buf_value, 'c_tm_sec') > 61:
        raise OperationError(space.w_ValueError,
                             space.wrap("seconds out of range"))
    if rffi.getintfield(buf_value, 'c_tm_yday') < 0 or rffi.getintfield(buf_value, 'c_tm_yday') > 365:
        raise OperationError(space.w_ValueError,
                             space.wrap("day of year out of range"))
    if rffi.getintfield(buf_value, 'c_tm_isdst') < -1 or rffi.getintfield(buf_value, 'c_tm_isdst') > 1:
        raise OperationError(space.w_ValueError,
                             space.wrap("daylight savings flag out of range"))

    if _WIN:
        # check that the format string contains only valid directives
        length = len(format)
        i = 0
        while i < length:
            if format[i] == '%':
                i += 1
                if i < length and format[i] == '#':
                    # not documented by python
                    i += 1
                if i >= length or format[i] not in "aAbBcdHIjmMpSUwWxXyYzZ%":
                    raise OperationError(space.w_ValueError,
                                         space.wrap("invalid format string"))
            i += 1

    i = 1024
    while True:
        outbuf = lltype.malloc(rffi.CCHARP.TO, i, flavor='raw')
        try:
            buflen = c_strftime(outbuf, i, format, buf_value)
            if buflen > 0 or i >= 256 * len(format):
                # if the buffer is 256 times as long as the format,
                # it's probably not failing for lack of room!
                # More likely, the format yields an empty result,
                # e.g. an empty format, or %Z when the timezone
                # is unknown.
                result = rffi.charp2strn(outbuf, intmask(buflen))
                return space.wrap(result)
        finally:
            lltype.free(outbuf, flavor='raw')
        i += i
