import os, re

from foolscap import Referenceable
from twisted.application import service

from zope.interface import implements
from allmydata.interfaces import RIStorageServer, RIBucketWriter
from allmydata import interfaces
from allmydata.util import bencode, fileutil, idlib
from allmydata.util.assertutil import _assert, precondition

# store/
# store/incoming # temp dirs named $VERIFIERID/$SHARENUM which will be moved to store/$VERIFIERID/$SHARENUM on success
# store/$VERIFIERID
# store/$VERIFIERID/$SHARENUM
# store/$VERIFIERID/$SHARENUM/blocksize
# store/$VERIFIERID/$SHARENUM/data
# store/$VERIFIERID/$SHARENUM/blockhashes
# store/$VERIFIERID/$SHARENUM/sharehashtree

# $SHARENUM matches this regex:
NUM_RE=re.compile("[0-9]*")

class BucketWriter(Referenceable):
    implements(RIBucketWriter)

    def __init__(self, incominghome, finalhome, blocksize):
        self.incominghome = incominghome
        self.finalhome = finalhome
        self.blocksize = blocksize
        self.closed = False
        fileutil.make_dirs(incominghome)
        self._write_file('blocksize', str(blocksize))

    def _write_file(self, fname, data):
        open(os.path.join(self.incominghome, fname), 'wb').write(data)

    def remote_put_block(self, segmentnum, data):
        precondition(not self.closed)
        assert len(data) == self.blocksize
        f = open(os.path.join(self.incominghome, 'data'), 'wb')
        f.seek(self.blocksize*segmentnum)
        f.write(data)

    def remote_put_block_hashes(self, blockhashes):
        precondition(not self.closed)
        # TODO: verify the length of blockhashes.
        # TODO: tighten foolscap schema to require exactly 32 bytes.
        self._write_file('blockhashes', ''.join(blockhashes))

    def remote_put_share_hashes(self, sharehashes):
        precondition(not self.closed)
        self._write_file('sharehashree', bencode.bencode(sharehashes))

    def remote_close(self):
        precondition(not self.closed)
        # TODO assert or check the completeness and consistency of the data that has been written
        fileutil.make_dirs(os.path.dirname(self.finalhome))
        fileutil.rename(self.incominghome, self.finalhome)
        try:
            os.rmdir(os.path.dirname(self.incominghome))
        except OSError:
            # Perhaps the directory wasn't empty.  In any case, ignore the error.
            pass
            
        self.closed = True

def str2l(s):
    """ split string (pulled from storage) into a list of blockids """
    return [ s[i:i+interfaces.HASH_SIZE] for i in range(0, len(s), interfaces.HASH_SIZE) ]

class BucketReader(Referenceable):
    def __init__(self, home):
        self.home = home
        self.blocksize = int(self._read_file('blocksize'))

    def _read_file(self, fname):
        return open(os.path.join(self.home, fname), 'rb').read()

    def remote_get_block(self, blocknum):
        f = open(os.path.join(self.home, 'data'), 'rb')
        f.seek(self.blocksize * blocknum)
        return f.read(self.blocksize) # this might be short for the last block

    def remote_get_block_hashes(self):
        return str2l(self._read_file('blockhashes'))

    def remote_get_share_hashes(self):
        return bencode.bdecode(self._read_file('sharehashes'))
   
class StorageServer(service.MultiService, Referenceable):
    implements(RIStorageServer)
    name = 'storageserver'

    def __init__(self, storedir):
        fileutil.make_dirs(storedir)
        self.storedir = storedir
        self.incomingdir = os.path.join(storedir, 'incoming')
        self._clean_incomplete()
        fileutil.make_dirs(self.incomingdir)

        service.MultiService.__init__(self)

    def _clean_incomplete(self):
        fileutil.rm_dir(self.incomingdir)

    def remote_allocate_buckets(self, verifierid, sharenums, sharesize,
                                blocksize, canary):
        alreadygot = set()
        bucketwriters = {} # k: shnum, v: BucketWriter
        for shnum in sharenums:
            incominghome = os.path.join(self.incomingdir, idlib.b2a(verifierid), "%d"%shnum)
            finalhome = os.path.join(self.storedir, idlib.b2a(verifierid), "%d"%shnum)
            if os.path.exists(incominghome) or os.path.exists(finalhome):
                alreadygot.add(shnum)
            else:
                bucketwriters[shnum] = BucketWriter(incominghome, finalhome, blocksize)
            
        return alreadygot, bucketwriters

    def remote_get_buckets(self, verifierid):
        bucketreaders = {} # k: sharenum, v: BucketReader
        verifierdir = os.path.join(self.storedir, idlib.b2a(verifierid))
        try:
            for f in os.listdir(verifierdir):
                _assert(NUM_RE.match(f), f)
                bucketreaders[int(f)] = BucketReader(os.path.join(verifierdir, f))
        except OSError:
            # Commonly caused by there being no buckets at all.
            pass

        return bucketreaders