"""Annotation and rtyping support for the result of os.stat(), os.lstat()
and os.fstat().  In RPython like in plain Python the stat result can be
indexed like a tuple but also exposes the st_xxx attributes.
"""

import os
import sys

from rpython.annotator import model as annmodel
from rpython.rlib import rposix
from rpython.rlib.rarithmetic import intmask
from rpython.rtyper import extregistry
from rpython.rtyper.annlowlevel import hlstr
from rpython.rtyper.extfunc import extdef
from rpython.rtyper.lltypesystem import rffi, lltype
from rpython.rtyper.lltypesystem.rtupletype import TUPLE_TYPE
from rpython.rtyper.tool import rffi_platform as platform
from rpython.tool.pairtype import pairtype
from rpython.tool.sourcetools import func_renamer
from rpython.translator.tool.cbuild import ExternalCompilationInfo

# Support for float times is here.
# - ALL_STAT_FIELDS contains Float fields if the system can retrieve
#   sub-second timestamps.
# - TIMESPEC is defined when the "struct stat" contains st_atim field.

if sys.platform.startswith('linux') or sys.platform.startswith('openbsd'):
    TIMESPEC = platform.Struct('struct timespec',
                               [('tv_sec', rffi.TIME_T),
                                ('tv_nsec', rffi.LONG)])
else:
    TIMESPEC = None

# all possible fields - some of them are not available on all platforms
ALL_STAT_FIELDS = [
    ("st_mode",      lltype.Signed),
    ("st_ino",       lltype.SignedLongLong),
    ("st_dev",       lltype.SignedLongLong),
    ("st_nlink",     lltype.Signed),
    ("st_uid",       lltype.Signed),
    ("st_gid",       lltype.Signed),
    ("st_size",      lltype.SignedLongLong),
    ("st_atime",     lltype.Float),
    ("st_mtime",     lltype.Float),
    ("st_ctime",     lltype.Float),
    ("st_blksize",   lltype.Signed),
    ("st_blocks",    lltype.Signed),
    ("st_rdev",      lltype.Signed),
    ("st_flags",     lltype.Signed),
    #("st_gen",       lltype.Signed),     -- new in CPy 2.5, not implemented
    #("st_birthtime", lltype.Float),      -- new in CPy 2.5, not implemented
]
N_INDEXABLE_FIELDS = 10

# For OO backends, expose only the portable fields (the first 10).
PORTABLE_STAT_FIELDS = ALL_STAT_FIELDS[:N_INDEXABLE_FIELDS]

STATVFS_FIELDS = [
    ("f_bsize", lltype.Signed),
    ("f_frsize", lltype.Signed),
    ("f_blocks", lltype.Signed),
    ("f_bfree", lltype.Signed),
    ("f_bavail", lltype.Signed),
    ("f_files", lltype.Signed),
    ("f_ffree", lltype.Signed),
    ("f_favail", lltype.Signed),
    ("f_flag", lltype.Signed),
    ("f_namemax", lltype.Signed),
]


# ____________________________________________________________
#
# Annotation support

class SomeStatResult(annmodel.SomeObject):
    knowntype = os.stat_result

    def rtyper_makerepr(self, rtyper):
        from rpython.rtyper.module import r_os_stat
        return r_os_stat.StatResultRepr(rtyper)

    def rtyper_makekey_ex(self, rtyper):
        return self.__class__,

    def getattr(self, s_attr):
        assert s_attr.is_constant(), "non-constant attr name in getattr()"
        attrname = s_attr.const
        TYPE = STAT_FIELD_TYPES[attrname]
        return annmodel.lltype_to_annotation(TYPE)

    def _get_rmarshall_support_(self):     # for rlib.rmarshal
        # reduce and recreate stat_result objects from 10-tuples
        # (we ignore the extra values here for simplicity and portability)
        def stat_result_reduce(st):
            return (st[0], st[1], st[2], st[3], st[4],
                    st[5], st[6], st[7], st[8], st[9])

        def stat_result_recreate(tup):
            return make_stat_result(tup + extra_zeroes)
        s_reduced = annmodel.SomeTuple([annmodel.lltype_to_annotation(TYPE)
                                       for name, TYPE in PORTABLE_STAT_FIELDS])
        extra_zeroes = (0,) * (len(STAT_FIELDS) - len(PORTABLE_STAT_FIELDS))
        return s_reduced, stat_result_reduce, stat_result_recreate


class SomeStatvfsResult(annmodel.SomeObject):
    if hasattr(os, 'statvfs_result'):
        knowntype = os.statvfs_result
    else:
        knowntype = None # will not be used

    def rtyper_makerepr(self, rtyper):
        from rpython.rtyper.module import r_os_stat
        return r_os_stat.StatvfsResultRepr(rtyper)

    def rtyper_makekey_ex(self, rtyper):
        return self.__class__,

    def getattr(self, s_attr):
        assert s_attr.is_constant()
        TYPE = STATVFS_FIELD_TYPES[s_attr.const]
        return annmodel.lltype_to_annotation(TYPE)


class __extend__(pairtype(SomeStatResult, annmodel.SomeInteger)):
    def getitem((s_sta, s_int)):
        assert s_int.is_constant(), "os.stat()[index]: index must be constant"
        index = s_int.const
        assert 0 <= index < N_INDEXABLE_FIELDS, "os.stat()[index] out of range"
        name, TYPE = STAT_FIELDS[index]
        return annmodel.lltype_to_annotation(TYPE)


class __extend__(pairtype(SomeStatvfsResult, annmodel.SomeInteger)):
    def getitem((s_stat, s_int)):
        assert s_int.is_constant()
        name, TYPE = STATVFS_FIELDS[s_int.const]
        return annmodel.lltype_to_annotation(TYPE)


s_StatResult = SomeStatResult()
s_StatvfsResult = SomeStatvfsResult()


def make_stat_result(tup):
    """Turn a tuple into an os.stat_result object."""
    positional = tup[:N_INDEXABLE_FIELDS]
    kwds = {}
    for i, name in enumerate(STAT_FIELD_NAMES[N_INDEXABLE_FIELDS:]):
        kwds[name] = tup[N_INDEXABLE_FIELDS + i]
    return os.stat_result(positional, kwds)


def make_statvfs_result(tup):
    return os.statvfs_result(tup)


class MakeStatResultEntry(extregistry.ExtRegistryEntry):
    _about_ = make_stat_result

    def compute_result_annotation(self, s_tup):
        return s_StatResult

    def specialize_call(self, hop):
        from rpython.rtyper.module import r_os_stat
        return r_os_stat.specialize_make_stat_result(hop)


class MakeStatvfsResultEntry(extregistry.ExtRegistryEntry):
    _about_ = make_statvfs_result

    def compute_result_annotation(self, s_tup):
        return s_StatvfsResult

    def specialize_call(self, hop):
        from rpython.rtyper.module import r_os_stat
        return r_os_stat.specialize_make_statvfs_result(hop)

# ____________________________________________________________
#
# RFFI support

if sys.platform.startswith('win'):
    _name_struct_stat = '_stati64'
    INCLUDES = ['sys/types.h', 'sys/stat.h', 'sys/statvfs.h']
else:
    _name_struct_stat = 'stat'
    INCLUDES = ['sys/types.h', 'sys/stat.h', 'sys/statvfs.h', 'unistd.h']

compilation_info = ExternalCompilationInfo(
    # This must be set to 64 on some systems to enable large file support.
    #pre_include_bits = ['#define _FILE_OFFSET_BITS 64'],
    # ^^^ nowadays it's always set in all C files we produce.
    includes=INCLUDES
)

if TIMESPEC is not None:
    class CConfig_for_timespec:
        _compilation_info_ = compilation_info
        TIMESPEC = TIMESPEC
    TIMESPEC = lltype.Ptr(
        platform.configure(CConfig_for_timespec)['TIMESPEC'])


def posix_declaration(try_to_add=None):
    global STAT_STRUCT, STATVFS_STRUCT

    LL_STAT_FIELDS = STAT_FIELDS[:]
    if try_to_add:
        LL_STAT_FIELDS.append(try_to_add)

    if TIMESPEC is not None:

        def _expand(lst, originalname, timespecname):
            for i, (_name, _TYPE) in enumerate(lst):
                if _name == originalname:
                    # replace the 'st_atime' field of type rffi.DOUBLE
                    # with a field 'st_atim' of type 'struct timespec'
                    lst[i] = (timespecname, TIMESPEC.TO)
                    break

        _expand(LL_STAT_FIELDS, 'st_atime', 'st_atim')
        _expand(LL_STAT_FIELDS, 'st_mtime', 'st_mtim')
        _expand(LL_STAT_FIELDS, 'st_ctime', 'st_ctim')

        del _expand
    else:
        # Replace float fields with integers
        for name in ('st_atime', 'st_mtime', 'st_ctime', 'st_birthtime'):
            for i, (_name, _TYPE) in enumerate(LL_STAT_FIELDS):
                if _name == name:
                    LL_STAT_FIELDS[i] = (_name, lltype.Signed)
                    break

    class CConfig:
        _compilation_info_ = compilation_info
        STAT_STRUCT = platform.Struct('struct %s' % _name_struct_stat, LL_STAT_FIELDS)
        STATVFS_STRUCT = platform.Struct('struct statvfs', STATVFS_FIELDS)

    try:
        config = platform.configure(CConfig, ignore_errors=try_to_add is not None)
    except platform.CompilationError:
        if try_to_add:
            return    # failed to add this field, give up
        raise

    STAT_STRUCT = lltype.Ptr(config['STAT_STRUCT'])
    STATVFS_STRUCT = lltype.Ptr(config['STATVFS_STRUCT'])
    if try_to_add:
        STAT_FIELDS.append(try_to_add)


# This lists only the fields that have been found on the underlying platform.
# Initially only the PORTABLE_STAT_FIELDS, but more may be added by the
# following loop.
STAT_FIELDS = PORTABLE_STAT_FIELDS[:]

if sys.platform != 'win32':
    posix_declaration()
    for _i in range(len(PORTABLE_STAT_FIELDS), len(ALL_STAT_FIELDS)):
        posix_declaration(ALL_STAT_FIELDS[_i])
    del _i

# these two global vars only list the fields defined in the underlying platform
STAT_FIELD_TYPES = dict(STAT_FIELDS)      # {'st_xxx': TYPE}
STAT_FIELD_NAMES = [_name for (_name, _TYPE) in STAT_FIELDS]
del _name, _TYPE

STATVFS_FIELD_TYPES = dict(STATVFS_FIELDS)
STATVFS_FIELD_NAMES = [name for name, tp in STATVFS_FIELDS]


def build_stat_result(st):
    # only for LL backends
    if TIMESPEC is not None:
        atim = st.c_st_atim; atime = int(atim.c_tv_sec) + 1E-9 * int(atim.c_tv_nsec)
        mtim = st.c_st_mtim; mtime = int(mtim.c_tv_sec) + 1E-9 * int(mtim.c_tv_nsec)
        ctim = st.c_st_ctim; ctime = int(ctim.c_tv_sec) + 1E-9 * int(ctim.c_tv_nsec)
    else:
        atime = st.c_st_atime
        mtime = st.c_st_mtime
        ctime = st.c_st_ctime

    result = (st.c_st_mode,
              st.c_st_ino,
              st.c_st_dev,
              st.c_st_nlink,
              st.c_st_uid,
              st.c_st_gid,
              st.c_st_size,
              atime,
              mtime,
              ctime)

    if "st_blksize" in STAT_FIELD_TYPES: result += (st.c_st_blksize,)
    if "st_blocks"  in STAT_FIELD_TYPES: result += (st.c_st_blocks,)
    if "st_rdev"    in STAT_FIELD_TYPES: result += (st.c_st_rdev,)
    if "st_flags"   in STAT_FIELD_TYPES: result += (st.c_st_flags,)

    return make_stat_result(result)


def build_statvfs_result(st):
    return make_statvfs_result((
        st.c_f_bsize,
        st.c_f_frsize,
        st.c_f_blocks,
        st.c_f_bfree,
        st.c_f_bavail,
        st.c_f_files,
        st.c_f_ffree,
        st.c_f_favail,
        st.c_f_flag,
        st.c_f_namemax
    ))


def register_stat_variant(name, traits):
    if name != 'fstat':
        arg_is_path = True
        s_arg = traits.str0
        ARG1 = traits.CCHARP
    else:
        arg_is_path = False
        s_arg = int
        ARG1 = rffi.INT

    if sys.platform == 'win32':
        # See Win32 implementation below
        posix_stat_llimpl = make_win32_stat_impl(name, traits)

        return extdef(
            [s_arg], s_StatResult, traits.ll_os_name(name),
            llimpl=posix_stat_llimpl)

    if sys.platform.startswith('linux'):
        # because we always use _FILE_OFFSET_BITS 64 - this helps things work that are not a c compiler
        _functions = {'stat':  'stat64',
                      'fstat': 'fstat64',
                      'lstat': 'lstat64'}
        c_func_name = _functions[name]
    else:
        c_func_name = name

    posix_mystat = rffi.llexternal(c_func_name,
                                   [ARG1, STAT_STRUCT], rffi.INT,
                                   compilation_info=compilation_info)

    @func_renamer('os_%s_llimpl' % (name,))
    def posix_stat_llimpl(arg):
        stresult = lltype.malloc(STAT_STRUCT.TO, flavor='raw')
        try:
            if arg_is_path:
                arg = traits.str2charp(arg)
            error = rffi.cast(rffi.LONG, posix_mystat(arg, stresult))
            if arg_is_path:
                traits.free_charp(arg)
            if error != 0:
                raise OSError(rposix.get_errno(), "os_?stat failed")
            return build_stat_result(stresult)
        finally:
            lltype.free(stresult, flavor='raw')

    @func_renamer('os_%s_fake' % (name,))
    def posix_fakeimpl(arg):
        if s_arg == traits.str0:
            arg = hlstr(arg)
        st = getattr(os, name)(arg)
        fields = [TYPE for fieldname, TYPE in STAT_FIELDS]
        TP = TUPLE_TYPE(fields)
        ll_tup = lltype.malloc(TP.TO)
        for i, (fieldname, TYPE) in enumerate(STAT_FIELDS):
            val = getattr(st, fieldname)
            if isinstance(TYPE, lltype.Number):
                rffi.setintfield(ll_tup, 'item%d' % i, int(val))
            elif TYPE is lltype.Float:
                setattr(ll_tup, 'item%d' % i, float(val))
            else:
                setattr(ll_tup, 'item%d' % i, val)
        return ll_tup

    return extdef(
        [s_arg], s_StatResult, "ll_os.ll_os_%s" % (name,),
        llimpl=posix_stat_llimpl, llfakeimpl=posix_fakeimpl)


def register_statvfs_variant(name, traits):
    if name != 'fstatvfs':
        arg_is_path = True
        s_arg = traits.str0
        ARG1 = traits.CCHARP
    else:
        arg_is_path = False
        s_arg = int
        ARG1 = rffi.INT

    posix_mystatvfs = rffi.llexternal(name,
        [ARG1, STATVFS_STRUCT], rffi.INT,
        compilation_info=compilation_info
    )

    @func_renamer('os_%s_llimpl' % (name,))
    def posix_statvfs_llimpl(arg):
        stresult = lltype.malloc(STATVFS_STRUCT.TO, flavor='raw')
        try:
            if arg_is_path:
                arg = traits.str2charp(arg)
            error = rffi.cast(rffi.LONG, posix_mystatvfs(arg, stresult))
            if arg_is_path:
                traits.free_charp(arg)
            if error != 0:
                raise OSError(rposix.get_errno(), "os_?statvfs failed")
            return build_statvfs_result(stresult)
        finally:
            lltype.free(stresult, flavor='raw')

    @func_renamer('os_%s_fake' % (name,))
    def posix_fakeimpl(arg):
        if s_arg == traits.str0:
            arg = hlstr(arg)
        st = getattr(os, name)(arg)
        fields = [TYPE for fieldname, TYPE in STATVFS_FIELDS]
        TP = TUPLE_TYPE(fields)
        ll_tup = lltype.malloc(TP.TO)
        for i, (fieldname, TYPE) in enumerate(STATVFS_FIELDS):
            val = getattr(st, fieldname)
            rffi.setintfield(ll_tup, 'item%d' % i, int(val))
        return ll_tup

    return extdef(
        [s_arg], s_StatvfsResult, "ll_os.ll_os_%s" % (name,),
        llimpl=posix_statvfs_llimpl, llfakeimpl=posix_fakeimpl
    )


def make_win32_stat_impl(name, traits):
    from rpython.rlib import rwin32
    from rpython.rtyper.module.ll_win32file import make_win32_traits
    win32traits = make_win32_traits(traits)

    # The CRT of Windows has a number of flaws wrt. its stat() implementation:
    # - time stamps are restricted to second resolution
    # - file modification times suffer from forth-and-back conversions between
    #   UTC and local time
    # Therefore, we implement our own stat, based on the Win32 API directly.
    from rpython.rtyper.tool import rffi_platform as platform
    from rpython.translator.tool.cbuild import ExternalCompilationInfo
    from rpython.rlib import rwin32

    assert len(STAT_FIELDS) == 10    # no extra fields on Windows

    def attributes_to_mode(attributes):
        m = 0
        attributes = intmask(attributes)
        if attributes & win32traits.FILE_ATTRIBUTE_DIRECTORY:
            m |= win32traits._S_IFDIR | 0111 # IFEXEC for user,group,other
        else:
            m |= win32traits._S_IFREG
        if attributes & win32traits.FILE_ATTRIBUTE_READONLY:
            m |= 0444
        else:
            m |= 0666
        return m

    def attribute_data_to_stat(info):
        st_mode = attributes_to_mode(info.c_dwFileAttributes)
        st_size = make_longlong(info.c_nFileSizeHigh, info.c_nFileSizeLow)
        ctime, ctime_ns = FILE_TIME_to_time_t_nsec(info.c_ftCreationTime)
        mtime, mtime_ns = FILE_TIME_to_time_t_nsec(info.c_ftLastWriteTime)
        atime, atime_ns = FILE_TIME_to_time_t_nsec(info.c_ftLastAccessTime)

        result = (st_mode,
                  0, 0, 0, 0, 0,
                  st_size,
                  float(atime) + atime_ns * 1e-9,
                  float(mtime) + mtime_ns * 1e-9,
                  float(ctime) + ctime_ns * 1e-9)

        return make_stat_result(result)

    def by_handle_info_to_stat(info):
        # similar to the one above
        st_mode = attributes_to_mode(info.c_dwFileAttributes)
        st_size = make_longlong(info.c_nFileSizeHigh, info.c_nFileSizeLow)
        ctime, ctime_ns = FILE_TIME_to_time_t_nsec(info.c_ftCreationTime)
        mtime, mtime_ns = FILE_TIME_to_time_t_nsec(info.c_ftLastWriteTime)
        atime, atime_ns = FILE_TIME_to_time_t_nsec(info.c_ftLastAccessTime)

        # specific to fstat()
        st_ino = make_longlong(info.c_nFileIndexHigh, info.c_nFileIndexLow)
        st_nlink = info.c_nNumberOfLinks

        result = (st_mode,
                  st_ino, 0, st_nlink, 0, 0,
                  st_size,
                  atime + atime_ns * 1e-9,
                  mtime + mtime_ns * 1e-9,
                  ctime + ctime_ns * 1e-9)

        return make_stat_result(result)

    def attributes_from_dir(l_path, data):
        filedata = lltype.malloc(win32traits.WIN32_FIND_DATA, flavor='raw')
        try:
            hFindFile = win32traits.FindFirstFile(l_path, filedata)
            if hFindFile == rwin32.INVALID_HANDLE_VALUE:
                return 0
            win32traits.FindClose(hFindFile)
            data.c_dwFileAttributes = filedata.c_dwFileAttributes
            rffi.structcopy(data.c_ftCreationTime, filedata.c_ftCreationTime)
            rffi.structcopy(data.c_ftLastAccessTime, filedata.c_ftLastAccessTime)
            rffi.structcopy(data.c_ftLastWriteTime, filedata.c_ftLastWriteTime)
            data.c_nFileSizeHigh    = filedata.c_nFileSizeHigh
            data.c_nFileSizeLow     = filedata.c_nFileSizeLow
            return 1
        finally:
            lltype.free(filedata, flavor='raw')

    def win32_stat_llimpl(path):
        data = lltype.malloc(win32traits.WIN32_FILE_ATTRIBUTE_DATA, flavor='raw')
        try:
            l_path = traits.str2charp(path)
            res = win32traits.GetFileAttributesEx(l_path, win32traits.GetFileExInfoStandard, data)
            errcode = rwin32.GetLastError()
            if res == 0:
                if errcode == win32traits.ERROR_SHARING_VIOLATION:
                    res = attributes_from_dir(l_path, data)
                    errcode = rwin32.GetLastError()
            traits.free_charp(l_path)
            if res == 0:
                raise WindowsError(errcode, "os_stat failed")
            return attribute_data_to_stat(data)
        finally:
            lltype.free(data, flavor='raw')

    def win32_fstat_llimpl(fd):
        handle = rwin32.get_osfhandle(fd)
        filetype = win32traits.GetFileType(handle)
        if filetype == win32traits.FILE_TYPE_CHAR:
            # console or LPT device
            return make_stat_result((win32traits._S_IFCHR,
                                     0, 0, 0, 0, 0,
                                     0, 0, 0, 0))
        elif filetype == win32traits.FILE_TYPE_PIPE:
            # socket or named pipe
            return make_stat_result((win32traits._S_IFIFO,
                                     0, 0, 0, 0, 0,
                                     0, 0, 0, 0))
        elif filetype == win32traits.FILE_TYPE_UNKNOWN:
            error = rwin32.GetLastError()
            if error != 0:
                raise WindowsError(error, "os_fstat failed")
            # else: unknown but valid file

        # normal disk file (FILE_TYPE_DISK)
        info = lltype.malloc(win32traits.BY_HANDLE_FILE_INFORMATION,
                             flavor='raw', zero=True)
        try:
            res = win32traits.GetFileInformationByHandle(handle, info)
            if res == 0:
                raise WindowsError(rwin32.GetLastError(), "os_fstat failed")
            return by_handle_info_to_stat(info)
        finally:
            lltype.free(info, flavor='raw')

    if name == 'fstat':
        return win32_fstat_llimpl
    else:
        return win32_stat_llimpl


#__________________________________________________
# Helper functions for win32

def make_longlong(high, low):
    return (rffi.r_longlong(high) << 32) + rffi.r_longlong(low)

# Seconds between 1.1.1601 and 1.1.1970
secs_between_epochs = rffi.r_longlong(11644473600)

def FILE_TIME_to_time_t_nsec(filetime):
    ft = make_longlong(filetime.c_dwHighDateTime, filetime.c_dwLowDateTime)
    # FILETIME is in units of 100 nsec
    nsec = (ft % 10000000) * 100
    time = (ft / 10000000) - secs_between_epochs
    return intmask(time), intmask(nsec)

def time_t_to_FILE_TIME(time, filetime):
    ft = rffi.r_longlong((time + secs_between_epochs) * 10000000)
    filetime.c_dwHighDateTime = rffi.r_uint(ft >> 32)
    filetime.c_dwLowDateTime = rffi.r_uint(ft)    # masking off high bits
