from io import BytesIO
from socket import error
from errno import EINTR

# Based on socket._fileobject from python2.7
class fileobject(object):
    """Faux file object attached to a socket object."""

    default_bufsize = 8192
    name = "<socket>"

    __slots__ = ["mode", "bufsize", "softspace",
                 # "closed" is a property, see below
                 "_sock", "_rbufsize", "_wbufsize", "_rbuf", "_wbuf", "_wbuf_len",
                 "_close"]

    def __init__(self, sock, mode='rb', bufsize=-1, close=False):
        self._sock = sock
        self.mode = mode # Not actually used in this version
        if bufsize < 0:
            bufsize = self.default_bufsize
        self.bufsize = bufsize
        self.softspace = False
        # _rbufsize is the suggested recv buffer size.  It is *strictly*
        # obeyed within readline() for recv calls.  If it is larger than
        # default_bufsize it will be used for recv calls within read().
        if bufsize == 0:
            self._rbufsize = 1
        elif bufsize == 1:
            self._rbufsize = self.default_bufsize
        else:
            self._rbufsize = bufsize
        self._wbufsize = bufsize
        # We use BytesIO for the read buffer to avoid holding a list
        # of variously sized string objects which have been known to
        # fragment the heap due to how they are malloc()ed and often
        # realloc()ed down much smaller than their original allocation.
        self._rbuf = BytesIO()
        self._wbuf = [] # A list of strings
        self._wbuf_len = 0
        self._close = close

    def _getclosed(self):
        return self._sock is None
    closed = property(_getclosed, doc="True if the file is closed")

    def close(self):
        try:
            if self._sock:
                self.flush()
        finally:
            if self._close:
                self._sock.close()
            self._sock = None

    def __del__(self):
        try:
            self.close()
        except:
            # close() may fail if __init__ didn't complete
            pass

    def flush(self):
        if self._wbuf:
            data = b"".join(self._wbuf)
            self._wbuf = []
            self._wbuf_len = 0
            buffer_size = max(self._rbufsize, self.default_bufsize)
            data_size = len(data)
            write_offset = 0
            view = memoryview(data)
            try:
                while write_offset < data_size:
                    self._sock.sendall(view[write_offset:write_offset+buffer_size])
                    write_offset += buffer_size
            finally:
                if write_offset < data_size:
                    remainder = data[write_offset:]
                    del view, data  # explicit free
                    self._wbuf.append(remainder)
                    self._wbuf_len = len(remainder)

    def fileno(self):
        return self._sock.fileno()

    def write(self, data):
        data = bytes(data) # XXX Should really reject non-string non-buffers
        if not data:
            return
        self._wbuf.append(data)
        self._wbuf_len += len(data)
        if (self._wbufsize == 0 or
            (self._wbufsize == 1 and b'\n' in data) or
            (self._wbufsize > 1 and self._wbuf_len >= self._wbufsize)):
            self.flush()

    def writelines(self, list):
        # XXX We could do better here for very long lists
        # XXX Should really reject non-string non-buffers
        lines = filter(None, map(bytes, list))
        self._wbuf_len += sum(map(len, lines))
        self._wbuf.extend(lines)
        if (self._wbufsize <= 1 or
            self._wbuf_len >= self._wbufsize):
            self.flush()

    def read(self, size=-1):
        # Use max, disallow tiny reads in a loop as they are very inefficient.
        # We never leave read() with any leftover data from a new recv() call
        # in our internal buffer.
        rbufsize = max(self._rbufsize, self.default_bufsize)
        # Our use of BytesIO rather than lists of string objects returned by
        # recv() minimizes memory usage and fragmentation that occurs when
        # rbufsize is large compared to the typical return value of recv().
        buf = self._rbuf
        buf.seek(0, 2)  # seek end
        if size < 0:
            # Read until EOF
            self._rbuf = BytesIO()  # reset _rbuf.  we consume it via buf.
            while True:
                try:
                    data = self._sock.recv(rbufsize)
                except error as e:
                    if e.args[0] == EINTR:
                        continue
                    raise
                if not data:
                    break
                buf.write(data)
            return buf.getvalue()
        else:
            # Read until size bytes or EOF seen, whichever comes first
            buf_len = buf.tell()
            if buf_len >= size:
                # Already have size bytes in our buffer?  Extract and return.
                buf.seek(0)
                rv = buf.read(size)
                self._rbuf = BytesIO()
                self._rbuf.write(buf.read())
                return rv

            self._rbuf = BytesIO()  # reset _rbuf.  we consume it via buf.
            while True:
                left = size - buf_len
                # recv() will malloc the amount of memory given as its
                # parameter even though it often returns much less data
                # than that.  The returned data string is short lived
                # as we copy it into a BytesIO and free it.  This avoids
                # fragmentation issues on many platforms.
                try:
                    data = self._sock.recv(left)
                except error as e:
                    if e.args[0] == EINTR:
                        continue
                    raise
                if not data:
                    break
                n = len(data)
                if n == size and not buf_len:
                    # Shortcut.  Avoid buffer data copies when:
                    # - We have no data in our buffer.
                    # AND
                    # - Our call to recv returned exactly the
                    #   number of bytes we were asked to read.
                    return data
                if n == left:
                    buf.write(data)
                    del data  # explicit free
                    break
                assert n <= left, "recv(%d) returned %d bytes" % (left, n)
                buf.write(data)
                buf_len += n
                del data  # explicit free
                #assert buf_len == buf.tell()
            return buf.getvalue()

    def readline(self, size=-1):
        buf = self._rbuf
        buf.seek(0, 2)  # seek end
        if buf.tell() > 0:
            # check if we already have it in our buffer
            buf.seek(0)
            bline = buf.readline(size)
            if bline.endswith(b'\n') or len(bline) == size:
                self._rbuf = BytesIO()
                self._rbuf.write(buf.read())
                return bline
            del bline
        if size < 0:
            # Read until \n or EOF, whichever comes first
            if self._rbufsize <= 1:
                # Speed up unbuffered case
                buf.seek(0)
                buffers = [buf.read()]
                self._rbuf = BytesIO()  # reset _rbuf.  we consume it via buf.
                data = None
                recv = self._sock.recv
                while True:
                    try:
                        while data != b"\n":
                            data = recv(1)
                            if not data:
                                break
                            buffers.append(data)
                    except error as e:
                        # The try..except to catch EINTR was moved outside the
                        # recv loop to avoid the per byte overhead.
                        if e.args[0] == EINTR:
                            continue
                        raise
                    break
                return "".join(buffers)

            buf.seek(0, 2)  # seek end
            self._rbuf = BytesIO()  # reset _rbuf.  we consume it via buf.
            while True:
                try:
                    data = self._sock.recv(self._rbufsize)
                except error as e:
                    if e.args[0] == EINTR:
                        continue
                    raise
                if not data:
                    break
                nl = data.find(b'\n')
                if nl >= 0:
                    nl += 1
                    buf.write(data[:nl])
                    self._rbuf.write(data[nl:])
                    del data
                    break
                buf.write(data)
            return buf.getvalue()
        else:
            # Read until size bytes or \n or EOF seen, whichever comes first
            buf.seek(0, 2)  # seek end
            buf_len = buf.tell()
            if buf_len >= size:
                buf.seek(0)
                rv = buf.read(size)
                self._rbuf = BytesIO()
                self._rbuf.write(buf.read())
                return rv
            self._rbuf = BytesIO()  # reset _rbuf.  we consume it via buf.
            while True:
                try:
                    data = self._sock.recv(self._rbufsize)
                except error as e:
                    if e.args[0] == EINTR:
                        continue
                    raise
                if not data:
                    break
                left = size - buf_len
                # did we just receive a newline?
                nl = data.find(b'\n', 0, left)
                if nl >= 0:
                    nl += 1
                    # save the excess data to _rbuf
                    self._rbuf.write(data[nl:])
                    if buf_len:
                        buf.write(data[:nl])
                        break
                    else:
                        # Shortcut.  Avoid data copy through buf when returning
                        # a substring of our first recv().
                        return data[:nl]
                n = len(data)
                if n == size and not buf_len:
                    # Shortcut.  Avoid data copy through buf when
                    # returning exactly all of our first recv().
                    return data
                if n >= left:
                    buf.write(data[:left])
                    self._rbuf.write(data[left:])
                    break
                buf.write(data)
                buf_len += n
                #assert buf_len == buf.tell()
            return buf.getvalue()

    def readlines(self, sizehint=0):
        total = 0
        list = []
        while True:
            line = self.readline()
            if not line:
                break
            list.append(line)
            total += len(line)
            if sizehint and total >= sizehint:
                break
        return list

    # Iterator protocols

    def __iter__(self):
        return self

    def next(self):
        line = self.readline()
        if not line:
            raise StopIteration
        return line