import copy, os.path, stat
from cStringIO import StringIO
from zope.interface import implements
from twisted.internet import defer
from twisted.internet.interfaces import IPushProducer
from twisted.protocols import basic
from foolscap.api import eventually
from allmydata.interfaces import IImmutableFileNode, ICheckable, \
     IDownloadTarget, IUploadResults
from allmydata.util import dictutil, log, base32
from allmydata.uri import CHKFileURI, LiteralFileURI
from allmydata.immutable.checker import Checker
from allmydata.check_results import CheckResults, CheckAndRepairResults
from allmydata.immutable.repairer import Repairer
from allmydata.immutable import download

class _ImmutableFileNodeBase(object):
    implements(IImmutableFileNode, ICheckable)

    def get_readonly_uri(self):
        return self.get_uri()

    def is_mutable(self):
        return False

    def is_readonly(self):
        return True

    def __hash__(self):
        return self.u.__hash__()
    def __eq__(self, other):
        if isinstance(other, _ImmutableFileNodeBase):
            return self.u.__eq__(other.u)
        else:
            return False
    def __ne__(self, other):
        if isinstance(other, _ImmutableFileNodeBase):
            return self.u.__eq__(other.u)
        else:
            return True

class PortionOfFile:
    # like a list slice (things[2:14]), but for a file on disk
    def __init__(self, fn, offset=0, size=None):
        self.f = open(fn, "rb")
        self.f.seek(offset)
        self.bytes_left = size

    def read(self, size=None):
        # bytes_to_read = min(size, self.bytes_left), but None>anything
        if size is None:
            bytes_to_read = self.bytes_left
        elif self.bytes_left is None:
            bytes_to_read = size
        else:
            bytes_to_read = min(size, self.bytes_left)
        data = self.f.read(bytes_to_read)
        if self.bytes_left is not None:
            self.bytes_left -= len(data)
        return data

class DownloadCache:
    implements(IDownloadTarget)

    def __init__(self, filecap, storage_index, downloader,
                 cachedirectorymanager):
        self._downloader = downloader
        self._uri = filecap
        self._storage_index = storage_index
        self.milestones = set() # of (offset,size,Deferred)
        self.cachedirectorymanager = cachedirectorymanager
        self.cachefile = None
        self.download_in_progress = False
        # five states:
        #  new ImmutableFileNode, no downloads ever performed
        #  new ImmutableFileNode, leftover file (partial)
        #  new ImmutableFileNode, leftover file (whole)
        #  download in progress, not yet complete
        #  download complete

    def when_range_available(self, offset, size):
        assert isinstance(offset, (int,long))
        assert isinstance(size, (int,long))

        d = defer.Deferred()
        self.milestones.add( (offset,size,d) )
        self._check_milestones()
        if self.milestones and not self.download_in_progress:
            self.download_in_progress = True
            log.msg(format=("immutable filenode read [%(si)s]: " +
                            "starting download"),
                    si=base32.b2a(self._storage_index),
                    umid="h26Heg", level=log.OPERATIONAL)
            d2 = self._downloader.download(self._uri, self)
            d2.addBoth(self._download_done)
            d2.addErrback(self._download_failed)
            d2.addErrback(log.err, umid="cQaM9g")
        return d

    def read(self, consumer, offset, size):
        assert offset+size <= self.get_filesize()
        if not self.cachefile:
            self.cachefile = self.cachedirectorymanager.get_file(base32.b2a(self._storage_index))
        f = PortionOfFile(self.cachefile.get_filename(), offset, size)
        d = basic.FileSender().beginFileTransfer(f, consumer)
        d.addCallback(lambda lastSent: consumer)
        return d

    def _download_done(self, res):
        # clear download_in_progress, so failed downloads can be re-tried
        self.download_in_progress = False
        return res

    def _download_failed(self, f):
        # tell anyone who's waiting that we failed
        for m in self.milestones:
            (offset,size,d) = m
            eventually(d.errback, f)
        self.milestones.clear()

    def _check_milestones(self):
        current_size = self.get_filesize()
        for m in list(self.milestones):
            (offset,size,d) = m
            if offset+size <= current_size:
                log.msg(format=("immutable filenode read [%(si)s] " +
                                "%(offset)d+%(size)d vs %(filesize)d: " +
                                "done"),
                        si=base32.b2a(self._storage_index),
                        offset=offset, size=size, filesize=current_size,
                        umid="nuedUg", level=log.NOISY)
                self.milestones.discard(m)
                eventually(d.callback, None)
            else:
                log.msg(format=("immutable filenode read [%(si)s] " +
                                "%(offset)d+%(size)d vs %(filesize)d: " +
                                "still waiting"),
                        si=base32.b2a(self._storage_index),
                        offset=offset, size=size, filesize=current_size,
                        umid="8PKOhg", level=log.NOISY)

    def get_filesize(self):
        if not self.cachefile:
            self.cachefile = self.cachedirectorymanager.get_file(base32.b2a(self._storage_index))
        try:
            filesize = os.stat(self.cachefile.get_filename())[stat.ST_SIZE]
        except OSError:
            filesize = 0
        return filesize


    def open(self, size):
        if not self.cachefile:
            self.cachefile = self.cachedirectorymanager.get_file(base32.b2a(self._storage_index))
        self.f = open(self.cachefile.get_filename(), "wb")

    def write(self, data):
        self.f.write(data)
        self._check_milestones()

    def close(self):
        self.f.close()
        self._check_milestones()

    def fail(self, why):
        pass
    def register_canceller(self, cb):
        pass
    def finish(self):
        return None
    # The following methods are just because the target might be a
    # repairer.DownUpConnector, and just because the current CHKUpload object
    # expects to find the storage index and encoding parameters in its
    # Uploadable.
    def set_storageindex(self, storageindex):
        pass
    def set_encodingparams(self, encodingparams):
        pass


class ImmutableFileNode(_ImmutableFileNodeBase, log.PrefixingLogMixin):
    def __init__(self, filecap, storage_broker, secret_holder,
                 downloader, history, cachedirectorymanager):
        assert isinstance(filecap, CHKFileURI)
        self.u = filecap
        self._storage_broker = storage_broker
        self._secret_holder = secret_holder
        self._downloader = downloader
        self._history = history
        storage_index = self.get_storage_index()
        self.download_cache = DownloadCache(filecap, storage_index, downloader,
                                            cachedirectorymanager)
        prefix = self.u.get_verify_cap().to_string()
        log.PrefixingLogMixin.__init__(self, "allmydata.immutable.filenode", prefix=prefix)
        self.log("starting", level=log.OPERATIONAL)

    def get_size(self):
        return self.u.get_size()
    def get_current_size(self):
        return defer.succeed(self.get_size())

    def get_cap(self):
        return self.u
    def get_readcap(self):
        return self.u.get_readonly()
    def get_verify_cap(self):
        return self.u.get_verify_cap()
    def get_repair_cap(self):
        # CHK files can be repaired with just the verifycap
        return self.u.get_verify_cap()

    def get_uri(self):
        return self.u.to_string()

    def get_storage_index(self):
        return self.u.storage_index

    def check_and_repair(self, monitor, verify=False, add_lease=False):
        verifycap = self.get_verify_cap()
        sb = self._storage_broker
        servers = sb.get_all_servers()
        sh = self._secret_holder

        c = Checker(verifycap=verifycap, servers=servers,
                    verify=verify, add_lease=add_lease, secret_holder=sh,
                    monitor=monitor)
        d = c.start()
        def _maybe_repair(cr):
            crr = CheckAndRepairResults(self.u.storage_index)
            crr.pre_repair_results = cr
            if cr.is_healthy():
                crr.post_repair_results = cr
                return defer.succeed(crr)
            else:
                crr.repair_attempted = True
                crr.repair_successful = False # until proven successful
                def _gather_repair_results(ur):
                    assert IUploadResults.providedBy(ur), ur
                    # clone the cr -- check results to form the basic of the prr -- post-repair results
                    prr = CheckResults(cr.uri, cr.storage_index)
                    prr.data = copy.deepcopy(cr.data)

                    sm = prr.data['sharemap']
                    assert isinstance(sm, dictutil.DictOfSets), sm
                    sm.update(ur.sharemap)
                    servers_responding = set(prr.data['servers-responding'])
                    servers_responding.union(ur.sharemap.iterkeys())
                    prr.data['servers-responding'] = list(servers_responding)
                    prr.data['count-shares-good'] = len(sm)
                    prr.data['count-good-share-hosts'] = len(sm)
                    is_healthy = bool(len(sm) >= self.u.total_shares)
                    is_recoverable = bool(len(sm) >= self.u.needed_shares)
                    prr.set_healthy(is_healthy)
                    prr.set_recoverable(is_recoverable)
                    crr.repair_successful = is_healthy
                    prr.set_needs_rebalancing(len(sm) >= self.u.total_shares)

                    crr.post_repair_results = prr
                    return crr
                def _repair_error(f):
                    # as with mutable repair, I'm not sure if I want to pass
                    # through a failure or not. TODO
                    crr.repair_successful = False
                    crr.repair_failure = f
                    return f
                r = Repairer(storage_broker=sb, secret_holder=sh,
                             verifycap=verifycap, monitor=monitor)
                d = r.start()
                d.addCallbacks(_gather_repair_results, _repair_error)
                return d

        d.addCallback(_maybe_repair)
        return d

    def check(self, monitor, verify=False, add_lease=False):
        verifycap = self.get_verify_cap()
        sb = self._storage_broker
        servers = sb.get_all_servers()
        sh = self._secret_holder

        v = Checker(verifycap=verifycap, servers=servers,
                    verify=verify, add_lease=add_lease, secret_holder=sh,
                    monitor=monitor)
        return v.start()

    def read(self, consumer, offset=0, size=None):
        self.log("read", offset=offset, size=size,
                 umid="UPP8FA", level=log.OPERATIONAL)
        if size is None:
            size = self.get_size() - offset
        size = min(size, self.get_size() - offset)

        if offset == 0 and size == self.get_size():
            # don't use the cache, just do a normal streaming download
            self.log("doing normal full download", umid="VRSBwg", level=log.OPERATIONAL)
            target = download.ConsumerAdapter(consumer)
            return self._downloader.download(self.get_cap(), target,
                                             self._parentmsgid,
                                             history=self._history)

        d = self.download_cache.when_range_available(offset, size)
        d.addCallback(lambda res:
                      self.download_cache.read(consumer, offset, size))
        return d

class LiteralProducer:
    implements(IPushProducer)
    def resumeProducing(self):
        pass
    def stopProducing(self):
        pass


class LiteralFileNode(_ImmutableFileNodeBase):

    def __init__(self, filecap):
        assert isinstance(filecap, LiteralFileURI)
        self.u = filecap

    def get_size(self):
        return len(self.u.data)
    def get_current_size(self):
        return defer.succeed(self.get_size())

    def get_cap(self):
        return self.u
    def get_readcap(self):
        return self.u
    def get_verify_cap(self):
        return None
    def get_repair_cap(self):
        return None

    def get_uri(self):
        return self.u.to_string()

    def get_storage_index(self):
        return None

    def check(self, monitor, verify=False, add_lease=False):
        return defer.succeed(None)

    def check_and_repair(self, monitor, verify=False, add_lease=False):
        return defer.succeed(None)

    def read(self, consumer, offset=0, size=None):
        if size is None:
            data = self.u.data[offset:]
        else:
            data = self.u.data[offset:offset+size]

        # We use twisted.protocols.basic.FileSender, which only does
        # non-streaming, i.e. PullProducer, where the receiver/consumer must
        # ask explicitly for each chunk of data. There are only two places in
        # the Twisted codebase that can't handle streaming=False, both of
        # which are in the upload path for an FTP/SFTP server
        # (protocols.ftp.FileConsumer and
        # vfs.adapters.ftp._FileToConsumerAdapter), neither of which is
        # likely to be used as the target for a Tahoe download.

        d = basic.FileSender().beginFileTransfer(StringIO(data), consumer)
        d.addCallback(lambda lastSent: consumer)
        return d