import py
import os
from pypy.rlib import streamio
from pypy.rlib.rarithmetic import r_longlong
from pypy.module._file.interp_stream import W_AbstractStream
from pypy.module._file.interp_stream import StreamErrors, wrap_streamerror
from pypy.module.posix.interp_posix import dispatch_filename
from pypy.interpreter.error import OperationError, operationerrfmt
from pypy.interpreter.gateway import ObjSpace, W_Root, Arguments
from pypy.interpreter.typedef import TypeDef, GetSetProperty
from pypy.interpreter.typedef import interp_attrproperty, make_weakref_descr
from pypy.interpreter.typedef import interp_attrproperty_w
from pypy.interpreter.gateway import interp2app


class W_File(W_AbstractStream):
    """An interp-level file object.  This implements the same interface than
    the app-level files, with the following differences:

      * method names are prefixed with 'file_'
      * the 'normal' app-level constructor is implemented by file___init__().
      * the methods with the 'direct_' prefix should be used if the caller
          locks and unlocks the file itself, and takes care of StreamErrors.
    """

    # Default values until the file is successfully opened
    stream   = None
    w_name   = None
    mode     = "<uninitialized file>"
    softspace= 0     # Required according to file object docs
    encoding = None  # This is not used internally by file objects
    fd       = -1

    newlines = 0     # Updated when the stream is closed

    def __init__(self, space):
        self.space = space

    def __del__(self):
        # assume that the file and stream objects are only visible in the
        # thread that runs __del__, so no race condition should be possible
        self.clear_all_weakrefs()
        self.direct_close()

    def fdopenstream(self, stream, fd, mode, w_name=None):
        self.fd = fd
        self.mode = mode
        if w_name is not None:
            self.w_name = w_name
        self.stream = stream
        if stream.flushable():
            getopenstreams(self.space)[stream] = None

    def check_mode_ok(self, mode):
        if (not mode or mode[0] not in ['r', 'w', 'a', 'U'] or
            ('U' in mode and ('w' in mode or 'a' in mode))):
            space = self.space
            raise operationerrfmt(space.w_ValueError,
                                  "invalid mode: '%s'", mode)

    def getstream(self):
        """Return self.stream or raise an app-level ValueError if missing
        (i.e. if the file is closed)."""
        stream = self.stream
        if stream is None:
            space = self.space
            raise OperationError(space.w_ValueError,
                                 space.wrap('I/O operation on closed file'))
        return stream

    def _when_reading_first_flush(self, otherfile):
        """Flush otherfile before reading from self."""
        self.stream = streamio.CallbackReadFilter(self.stream,
                                                  otherfile._try_to_flush)

    def _try_to_flush(self):
        stream = self.stream
        if stream is not None:
            stream.flush()

    # ____________________________________________________________
    #
    # The 'direct_' methods assume that the caller already acquired the
    # file lock.  They don't convert StreamErrors to OperationErrors, too.

    def direct___init__(self, w_name, mode='r', buffering=-1):
        self.direct_close()
        self.w_name = w_name
        self.check_mode_ok(mode)
        stream = dispatch_filename(streamio.open_file_as_stream)(
            self.space, w_name, mode, buffering)
        fd = stream.try_to_find_file_descriptor()
        self.fdopenstream(stream, fd, mode)

    def direct___enter__(self):
        if self.stream is None:
            space = self.space
            raise OperationError(space.w_ValueError,
                                 space.wrap('I/O operation on closed file'))
        return self

    def direct___exit__(self, __args__):
        self.direct_close()
        # can't return close() value
        return None

    def direct_fdopen(self, fd, mode='r', buffering=-1):
        self.direct_close()
        self.w_name = self.space.wrap('<fdopen>')
        self.check_mode_ok(mode)
        stream = streamio.fdopen_as_stream(fd, mode, buffering)
        self.fdopenstream(stream, fd, mode)

    def direct_close(self):
        space = self.space
        stream = self.stream
        if stream is not None:
            self.newlines = self.stream.getnewlines()
            self.stream = None
            self.fd = -1
            openstreams = getopenstreams(self.space)
            try:
                del openstreams[stream]
            except KeyError:
                pass
            stream.close()

    def direct_fileno(self):
        self.getstream()    # check if the file is still open
        return self.fd

    def direct_flush(self):
        self.getstream().flush()

    def direct_next(self):
        line = self.getstream().readline()
        if line == '':
            raise OperationError(self.space.w_StopIteration, self.space.w_None)
        return line

    def direct_read(self, n=-1):
        stream = self.getstream()
        if n < 0:
            return stream.readall()
        else:
            result = []
            while n > 0:
                data = stream.read(n)
                if not data:
                    break
                n -= len(data)
                result.append(data)
            return ''.join(result)

    def direct_readline(self, size=-1):
        stream = self.getstream()
        if size < 0:
            return stream.readline()
        else:
            # very inefficient unless there is a peek()
            result = []
            while size > 0:
                # "peeks" on the underlying stream to see how many chars
                # we can safely read without reading past an end-of-line
                peeked = stream.peek()
                pn = peeked.find("\n", 0, size)
                if pn < 0:
                    pn = min(size-1, len(peeked))
                c = stream.read(pn + 1)
                if not c:
                    break
                result.append(c)
                if c.endswith('\n'):
                    break
                size -= len(c)
            return ''.join(result)

    def direct_readlines(self, size=0):
        stream = self.getstream()
        # NB. this implementation is very inefficient for unbuffered
        # streams, but ok if stream.readline() is efficient.
        if size <= 0:
            result = []
            while True:
                line = stream.readline()
                if not line:
                    break
                result.append(line)
                size -= len(line)
        else:
            result = []
            while size > 0:
                line = stream.readline()
                if not line:
                    break
                result.append(line)
                size -= len(line)
        return result

    def direct_seek(self, offset, whence=0):
        self.getstream().seek(offset, whence)

    def direct_tell(self):
        return self.getstream().tell()

    def direct_truncate(self, w_size=None):  # note: a wrapped size!
        stream = self.getstream()
        space = self.space
        if w_size is None or space.is_w(w_size, space.w_None):
            size = stream.tell()
        else:
            size = space.r_longlong_w(w_size)
        stream.truncate(size)

    def direct_write(self, data):
        self.softspace = 0
        self.getstream().write(data)

    def direct_writelines(self, w_lines):    # note: a wrapped list!
        stream = self.getstream()
        space = self.space
        w_iterator = space.iter(w_lines)
        self.softspace = 0
        while True:
            try:
                w_line = space.next(w_iterator)
            except OperationError, e:
                if not e.match(space, space.w_StopIteration):
                    raise
                break  # done
            stream.write(space.str_w(w_line))

    def direct___iter__(self):
        self.getstream()
        return self
    direct_xreadlines = direct___iter__

    def direct_isatty(self):
        self.getstream()    # check if the file is still open
        return os.isatty(self.fd)

    # ____________________________________________________________
    #
    # The 'file_' methods are the one exposed to app-level.

    def file_fdopen(self, fd, mode="r", buffering=-1):
        try:
            self.direct_fdopen(fd, mode, buffering)
        except StreamErrors, e:
            raise wrap_streamerror(self.space, e, self.w_name)

    _exposed_method_names = []

    def _decl(class_scope, name, unwrap_spec, docstring,
              wrapresult="space.wrap(result)"):
        # hack hack to build a wrapper around the direct_xxx methods.
        # The wrapper adds lock/unlock calls and a space.wrap() on
        # the result, conversion of stream errors to OperationErrors,
        # and has the specified docstring and unwrap_spec.
        direct_fn = class_scope['direct_' + name]
        co = direct_fn.func_code
        argnames = co.co_varnames[:co.co_argcount]
        defaults = direct_fn.func_defaults or ()

        args = []
        for i, argname in enumerate(argnames):
            try:
                default = defaults[-len(argnames) + i]
            except IndexError:
                args.append(argname)
            else:
                args.append('%s=%r' % (argname, default))
        sig = ', '.join(args)
        assert argnames[0] == 'self'
        callsig = ', '.join(argnames[1:])

        src = py.code.Source("""
            def file_%(name)s(%(sig)s):
                %(docstring)r
                space = self.space
                self.lock()
                try:
                    try:
                        result = self.direct_%(name)s(%(callsig)s)
                    except StreamErrors, e:
                        raise wrap_streamerror(space, e, self.w_name)
                finally:
                    self.unlock()
                return %(wrapresult)s
        """ % locals())
        exec str(src) in globals(), class_scope
        class_scope['file_' + name].unwrap_spec = unwrap_spec
        class_scope['_exposed_method_names'].append(name)


    _decl(locals(), "__init__", ['self', W_Root, str, int],
          """Opens a file.""")

    _decl(locals(), "__enter__", ['self'], """__enter__() -> self.""")

    _decl(locals(), "__exit__", ['self', Arguments], 
        """__exit__(*excinfo) -> None. Closes the file.""")

    _decl(locals(), "close", ['self'],
        """close() -> None or (perhaps) an integer.  Close the file.

Sets data attribute .closed to True.  A closed file cannot be used for
further I/O operations.  close() may be called more than once without
error.  Some kinds of file objects (for example, opened by popen())
may return an exit status upon closing.""")
        # NB. close() needs to use the stream lock to avoid double-closes or
        # close-while-another-thread-uses-it.


    _decl(locals(), "fileno", ['self'],
        '''fileno() -> integer "file descriptor".

This is needed for lower-level file interfaces, such os.read().''')
    
    _decl(locals(), "flush", ['self'],
        """flush() -> None.  Flush the internal I/O buffer.""")

    _decl(locals(), "isatty", ['self'],
        """isatty() -> true or false.  True if the file is connected to a tty device.""")

    _decl(locals(), "next", ['self'],
        """next() -> the next line in the file, or raise StopIteration""")

    _decl(locals(), "read", ['self', int],
        """read([size]) -> read at most size bytes, returned as a string.

If the size argument is negative or omitted, read until EOF is reached.
Notice that when in non-blocking mode, less data than what was requested
may be returned, even if no size parameter was given.""")

    _decl(locals(), "readline", ['self', int],
        """readlines([size]) -> list of strings, each a line from the file.

Call readline() repeatedly and return a list of the lines so read.
The optional size argument, if given, is an approximate bound on the
total number of bytes in the lines returned.""")

    _decl(locals(), "readlines", ['self', int],
        """readlines([size]) -> list of strings, each a line from the file.

Call readline() repeatedly and return a list of the lines so read.
The optional size argument, if given, is an approximate bound on the
total number of bytes in the lines returned.""",
        wrapresult = "wrap_list_of_str(space, result)")

    _decl(locals(), "seek", ['self', r_longlong, int],
        """seek(offset[, whence]) -> None.  Move to new file position.

Argument offset is a byte count.  Optional argument whence defaults to
0 (offset from start of file, offset should be >= 0); other values are 1
(move relative to current position, positive or negative), and 2 (move
relative to end of file, usually negative, although many platforms allow
seeking beyond the end of a file).  If the file is opened in text mode,
only offsets returned by tell() are legal.  Use of other offsets causes
undefined behavior.
Note that not all file objects are seekable.""")

    _decl(locals(), "tell", ['self'],
        "tell() -> current file position, an integer (may be a long integer).")

    _decl(locals(), "truncate", ['self', W_Root],
        """truncate([size]) -> None.  Truncate the file to at most size bytes.

Size defaults to the current file position, as returned by tell().""")

    _decl(locals(), "write", ['self', 'bufferstr'],
        """write(str) -> None.  Write string str to file.

Note that due to buffering, flush() or close() may be needed before
the file on disk reflects the data written.""")

    _decl(locals(), "writelines", ['self', W_Root],
        """writelines(sequence_of_strings) -> None.  Write the strings to the file.

Note that newlines are not added.  The sequence can be any iterable object
producing strings. This is equivalent to calling write() for each string.""")

    _decl(locals(), "__iter__", ['self'],
        """Iterating over files, as in 'for line in f:', returns each line of
the file one by one.""")

    _decl(locals(), "xreadlines", ['self'],
        """xreadlines() -> returns self.

For backward compatibility. File objects now include the performance
optimizations previously implemented in the xreadlines module.""")

    def file__repr__(self):
        if self.stream is None:
            head = "closed"
        else:
            head = "open"
        info = "%s file %s, mode '%s'" % (
            head,
            self.getdisplayname(),
            self.mode)
        return self.getrepr(self.space, info)
    file__repr__.unwrap_spec = ['self']

    def getdisplayname(self):
        w_name = self.w_name
        if w_name is None:
            return '?'
        elif self.space.is_true(self.space.isinstance(w_name,
                                                      self.space.w_str)):
            return "'%s'" % self.space.str_w(w_name) 
        else:
            return self.space.str_w(self.space.repr(w_name))

    def file_readinto(self, w_rwbuffer):
        """readinto() -> Undocumented.  Don't use this; it may go away."""
        # XXX not the most efficient solution as it doesn't avoid the copying
        space = self.space
        rwbuffer = space.rwbuffer_w(w_rwbuffer)
        w_data = self.file_read(rwbuffer.getlength())
        data = space.str_w(w_data)
        rwbuffer.setslice(0, data)
        return space.wrap(len(data))
    file_readinto.unwrap_spec = ['self', W_Root]


# ____________________________________________________________


def descr_file__new__(space, w_subtype, args):
    file = space.allocate_instance(W_File, w_subtype)
    W_File.__init__(file, space)
    return space.wrap(file)
descr_file__new__.unwrap_spec = [ObjSpace, W_Root, Arguments]

def descr_file_fdopen(space, w_subtype, fd, mode='r', buffering=-1):
    file = space.allocate_instance(W_File, w_subtype)
    W_File.__init__(file, space)
    file.file_fdopen(fd, mode, buffering)
    return space.wrap(file)
descr_file_fdopen.unwrap_spec = [ObjSpace, W_Root, int, str, int]

def descr_file_closed(space, file):
    return space.wrap(file.stream is None)

def descr_file_newlines(space, file):
    if file.stream:
        newlines = file.stream.getnewlines()
    else:
        newlines = file.newlines
    if newlines == 0:
        return space.w_None
    elif newlines == 1:
        return space.wrap("\r")
    elif newlines == 2:
        return space.wrap("\n")
    elif newlines == 4:
        return space.wrap("\r\n")
    result = []
    if newlines & 1:
        result.append(space.wrap('\r'))
    if newlines & 2:
        result.append(space.wrap('\n'))
    if newlines & 4:
        result.append(space.wrap('\r\n'))
    return space.newtuple(result[:])

def descr_file_softspace(space, file):
    return space.wrap(file.softspace)

def descr_file_setsoftspace(space, file, w_newvalue):
    file.softspace = space.int_w(w_newvalue)

# ____________________________________________________________

W_File.typedef = TypeDef(
    "file",
    __doc__ = """file(name[, mode[, buffering]]) -> file object

Open a file.  The mode can be 'r', 'w' or 'a' for reading (default),
writing or appending.  The file will be created if it doesn't exist
when opened for writing or appending; it will be truncated when
opened for writing.  Add a 'b' to the mode for binary files.
Add a '+' to the mode to allow simultaneous reading and writing.
If the buffering argument is given, 0 means unbuffered, 1 means line
buffered, and larger numbers specify the buffer size.
Add a 'U' to mode to open the file for input with universal newline
support.  Any line ending in the input file will be seen as a '\n'
in Python.  Also, a file so opened gains the attribute 'newlines';
the value for this attribute is one of None (no newline read yet),
'\r', '\n', '\r\n' or a tuple containing all the newline types seen.

Note:  open() is an alias for file().
""",
    __new__  = interp2app(descr_file__new__),
    fdopen   = interp2app(descr_file_fdopen, as_classmethod=True),
    name     = interp_attrproperty_w('w_name', cls=W_File, doc="file name"),
    mode     = interp_attrproperty('mode', cls=W_File,
                              doc = "file mode ('r', 'U', 'w', 'a', "
                                    "possibly with 'b' or '+' added)"),
    encoding = interp_attrproperty('encoding', cls=W_File),
    closed   = GetSetProperty(descr_file_closed, cls=W_File,
                              doc="True if the file is closed"),
    newlines = GetSetProperty(descr_file_newlines, cls=W_File,
                              doc="end-of-line convention used in this file"),
    softspace= GetSetProperty(descr_file_softspace,
                              descr_file_setsoftspace,
                              cls=W_File,
                              doc="Support for 'print'."),
    __repr__ = interp2app(W_File.file__repr__),
    readinto = interp2app(W_File.file_readinto),
    __weakref__ = make_weakref_descr(W_File),
    **dict([(name, interp2app(getattr(W_File, 'file_' + name)))
                for name in W_File._exposed_method_names])
    )

# ____________________________________________________________

def wrap_list_of_str(space, lst):
    return space.newlist([space.wrap(s) for s in lst])

class FileState:
    def __init__(self, space):
        self.openstreams = {}

def getopenstreams(space):
    return space.fromcache(FileState).openstreams