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# Copyright 2013 GRNET S.A. All rights reserved.
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#
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# Redistribution and use in source and binary forms, with or
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# without modification, are permitted provided that the following
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# conditions are met:
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#
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#   1. Redistributions of source code must retain the above
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#      copyright notice, this list of conditions and the following
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#      disclaimer.
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#
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#   2. Redistributions in binary form must reproduce the above
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#      copyright notice, this list of conditions and the following
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#      disclaimer in the documentation and/or other materials
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#      provided with the distribution.
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#
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# THIS SOFTWARE IS PROVIDED BY GRNET S.A. ``AS IS'' AND ANY EXPRESS
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# OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
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# WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
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# PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL GRNET S.A OR
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# CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
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# SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
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# LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
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# USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
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# AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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# LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
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# ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
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# POSSIBILITY OF SUCH DAMAGE.
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#
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# The views and conclusions contained in the software and
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# documentation are those of the authors and should not be
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# interpreted as representing official policies, either expressed
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# or implied, of GRNET S.A.
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from os import SEEK_CUR, SEEK_SET
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from archipelago.common import (
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    Request,
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    string_at,
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    )
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from pithos.workers import monkey
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monkey.patch_Request()
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_zeros = ''
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def zeros(nr):
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    global _zeros
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    size = len(_zeros)
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    if nr == size:
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        return _zeros
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    if nr > size:
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        _zeros += '\0' * (nr - size)
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        return _zeros
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    if nr < size:
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        _zeros = _zeros[:nr]
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        return _zeros
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def file_sync_write_chunks(archipelagoobject, chunksize, offset,
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                           chunks, size=None):
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    """Write given chunks to the given buffered file object.
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       Writes never span across chunk boundaries.
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       If size is given stop after or pad until size bytes have been written.
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    """
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    padding = 0
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    cursize = chunksize * offset
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    archipelagoobject.seek(cursize)
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    for chunk in chunks:
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        if padding:
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            archipelagoobject.sync_write(buffer(zeros(chunksize), 0, padding))
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        if size is not None and cursize + chunksize >= size:
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            chunk = chunk[:chunksize - (cursize - size)]
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            archipelagoobject.sync_write(chunk)
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            cursize += len(chunk)
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            break
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        archipelagoobject.sync_write(chunk)
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        padding = chunksize - len(chunk)
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    padding = size - cursize if size is not None else 0
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    if padding <= 0:
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        return
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    q, r = divmod(padding, chunksize)
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    for x in xrange(q):
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        archipelagoobject.sync_write(zeros(chunksize))
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    archipelagoobject.sync_write(buffer(zeros(chunksize), 0, r))
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def file_sync_read_chunks(archipelagoobject, chunksize, nr, offset=0):
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    """Read and yield groups of chunks from a buffered file object at offset.
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       Reads never span accros chunksize boundaries.
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    """
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    archipelagoobject.seek(offset * chunksize)
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    while nr:
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        remains = chunksize
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        chunk = ''
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        while 1:
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            s = archipelagoobject.sync_read(remains)
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            if not s:
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                if chunk:
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                    yield chunk
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                return
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            chunk += s
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            remains -= len(s)
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            if remains <= 0:
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                break
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        yield chunk
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        nr -= 1
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class ArchipelagoObject(object):
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    __slots__ = ("name", "ioctx_pool", "dst_port", "create", "offset")
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    def __init__(self, name, ioctx_pool, dst_port=None, create=0):
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        self.name = name
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        self.ioctx_pool = ioctx_pool
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        self.create = create
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        self.dst_port = dst_port
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        self.offset = 0
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    def __enter__(self):
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        return self
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    def __exit__(self, exc, arg, trace):
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        return False
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    def seek(self, offset, whence=SEEK_SET):
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        if whence == SEEK_CUR:
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            offset += self.offset
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        self.offset = offset
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        return offset
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    def tell(self):
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        return self.offset
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    def truncate(self, size):
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        raise NotImplementedError("File truncation is not implemented yet \
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                                   in archipelago")
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    def sync_write(self, data):
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        ioctx = self.ioctx_pool.pool_get()
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        req = Request.get_write_request(ioctx, self.dst_port, self.name,
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                                        data=data, offset=self.offset,
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                                        datalen=len(data))
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        req.submit()
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        req.wait()
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        ret = req.success()
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        req.put()
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        self.ioctx_pool.pool_put(ioctx)
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        if ret:
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            self.offset += len(data)
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        else:
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            raise IOError("archipelago: Write request error")
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    def sync_write_chunks(self, chunksize, offset, chunks, size=None):
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        return file_sync_write_chunks(self, chunksize, offset, chunks, size)
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    def sync_read(self, size):
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        read = Request.get_read_request
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        data = ''
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        datalen = 0
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        dsize = size
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        while 1:
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            ioctx = self.ioctx_pool.pool_get()
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            req = read(ioctx, self.dst_port,
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                       self.name, size=dsize-datalen, offset=self.offset)
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            req.submit()
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            req.wait()
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            ret = req.success()
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            if ret:
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                s = string_at(req.get_data(), dsize-datalen)
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            else:
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                s = None
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            req.put()
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            self.ioctx_pool.pool_put(ioctx)
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            if not s:
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                break
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            data += s
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            datalen += len(s)
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            self.offset += len(s)
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            if datalen >= size:
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                break
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        return data
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    def sync_read_chunks(self, chunksize, nr, offset=0):
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        return file_sync_read_chunks(self, chunksize, nr, offset)