~launchpad-pqm/launchpad/devel

# Copyright 2009-2011 Canonical Ltd.  This software is licensed under the
# GNU Affero General Public License version 3 (see the file LICENSE).

# pylint: disable-msg=E0611,W0212

__metaclass__ = type
__all__ = [
    'LibraryFileAlias',
    'LibraryFileAliasWithParent',
    'LibraryFileAliasSet',
    'LibraryFileContent',
    'LibraryFileDownloadCount',
    'TimeLimitedToken',
    ]

from datetime import (
    datetime,
    timedelta,
    )
from hashlib import md5
import random
from urlparse import urlparse

from lazr.delegates import delegates
import pytz
from sqlobject import (
    BoolCol,
    ForeignKey,
    IntCol,
    SQLRelatedJoin,
    StringCol,
    )
from storm.locals import (
    Date,
    Desc,
    Int,
    Reference,
    Store,
    )
from zope.component import (
    adapts,
    getUtility,
    )
from zope.interface import (
    implements,
    Interface,
    )

from canonical.database.constants import (
    DEFAULT,
    UTC_NOW,
    )
from canonical.database.datetimecol import UtcDateTimeCol
from canonical.database.sqlbase import (
    session_store,
    SQLBase,
    )
from lp.services.config import config
from lp.services.database.lpstorm import IMasterStore
from lp.services.database.stormbase import StormBase
from lp.services.librarian.interfaces import (
    ILibraryFileAlias,
    ILibraryFileAliasSet,
    ILibraryFileAliasWithParent,
    ILibraryFileContent,
    ILibraryFileDownloadCount,
    )
from lp.services.librarian.interfaces.client import (
    DownloadFailed,
    ILibrarianClient,
    IRestrictedLibrarianClient,
    LIBRARIAN_SERVER_DEFAULT_TIMEOUT,
    )


class LibraryFileContent(SQLBase):
    """A pointer to file content in the librarian."""

    implements(ILibraryFileContent)

    _table = 'LibraryFileContent'

    datecreated = UtcDateTimeCol(notNull=True, default=UTC_NOW)
    filesize = IntCol(notNull=True)
    sha1 = StringCol(notNull=True)
    md5 = StringCol()


class LibraryFileAlias(SQLBase):
    """A filename and mimetype that we can serve some given content with."""
    # The updateLastAccessed method has unreachable code.
    # pylint: disable-msg=W0101

    implements(ILibraryFileAlias)

    _table = 'LibraryFileAlias'
    date_created = UtcDateTimeCol(notNull=False, default=DEFAULT)
    content = ForeignKey(
        foreignKey='LibraryFileContent', dbName='content', notNull=False,
        )
    filename = StringCol(notNull=True)
    mimetype = StringCol(notNull=True)
    expires = UtcDateTimeCol(notNull=False, default=None)
    restricted = BoolCol(notNull=True, default=False)
    last_accessed = UtcDateTimeCol(notNull=True, default=DEFAULT)
    hits = IntCol(notNull=True, default=0)

    products = SQLRelatedJoin('ProductRelease', joinColumn='libraryfile',
                           otherColumn='productrelease',
                           intermediateTable='ProductReleaseFile')

    sourcepackages = SQLRelatedJoin('SourcePackageRelease',
                                 joinColumn='libraryfile',
                                 otherColumn='sourcepackagerelease',
                                 intermediateTable='SourcePackageReleaseFile')

    @property
    def client(self):
        """Return the librarian client to use to retrieve that file."""
        if self.restricted:
            return getUtility(IRestrictedLibrarianClient)
        else:
            return getUtility(ILibrarianClient)

    @property
    def http_url(self):
        """See ILibraryFileAlias.http_url"""
        return self.client.getURLForAliasObject(self)

    @property
    def https_url(self):
        """See ILibraryFileAlias.https_url"""
        url = self.http_url
        if url is None:
            return url
        return url.replace('http', 'https', 1)

    @property
    def private_url(self):
        """See ILibraryFileAlias.https_url"""
        return self.client.getURLForAlias(self.id, secure=True)

    def getURL(self, secure=True, include_token=False):
        """See ILibraryFileAlias.getURL"""
        if not self.restricted:
            if config.librarian.use_https and secure:
                return self.https_url
            else:
                return self.http_url
        else:
            url = self.private_url
            if include_token:
                token = TimeLimitedToken.allocate(url)
                url += '?token=%s' % token
            return url

    _datafile = None

    def open(self, timeout=LIBRARIAN_SERVER_DEFAULT_TIMEOUT):
        """See ILibraryFileAlias."""
        self._datafile = self.client.getFileByAlias(self.id, timeout)
        if self._datafile is None:
            raise DownloadFailed(
                "Unable to retrieve LibraryFileAlias %d" % self.id)

    def read(self, chunksize=None, timeout=LIBRARIAN_SERVER_DEFAULT_TIMEOUT):
        """See ILibraryFileAlias."""
        if not self._datafile:
            if chunksize is not None:
                raise RuntimeError("Can't combine autoopen with chunksize")
            self.open(timeout=timeout)
            autoopen = True
        else:
            autoopen = False

        if chunksize is None:
            rv = self._datafile.read()
            if autoopen:
                self.close()
            return rv
        else:
            return self._datafile.read(chunksize)

    def close(self):
        # Don't die with an AttributeError if the '_datafile' property
        # is not set.
        if self._datafile is not None:
            self._datafile.close()
            self._datafile = None

    def updateLastAccessed(self):
        """Update last_accessed if it has not been updated recently.

        This method relies on the system clock being vaguely sane, but
        does not cause real harm if this is not the case.
        """
        # XXX: stub 2007-04-10 Bug=86171: Feature disabled due to.
        return

        # Update last_accessed no more than once every 6 hours.
        precision = timedelta(hours=6)
        UTC = pytz.timezone('UTC')
        now = datetime.now(UTC)
        if self.last_accessed + precision < now:
            self.last_accessed = UTC_NOW

    @property
    def last_downloaded(self):
        """See `ILibraryFileAlias`."""
        store = Store.of(self)
        results = store.find(LibraryFileDownloadCount, libraryfilealias=self)
        results.order_by(Desc(LibraryFileDownloadCount.day))
        entry = results.first()
        if entry is None:
            return None
        else:
            return datetime.now(pytz.utc).date() - entry.day

    def updateDownloadCount(self, day, country, count):
        """See ILibraryFileAlias."""
        store = Store.of(self)
        entry = store.find(
            LibraryFileDownloadCount, libraryfilealias=self,
            day=day, country=country).one()
        if entry is None:
            entry = LibraryFileDownloadCount(
                libraryfilealias=self, day=day, country=country, count=count)
        else:
            entry.count += count
        self.hits += count

    products = SQLRelatedJoin('ProductRelease', joinColumn='libraryfile',
                           otherColumn='productrelease',
                           intermediateTable='ProductReleaseFile')

    sourcepackages = SQLRelatedJoin('SourcePackageRelease',
                                 joinColumn='libraryfile',
                                 otherColumn='sourcepackagerelease',
                                 intermediateTable='SourcePackageReleaseFile')

    @property
    def deleted(self):
        return self.contentID is None

    def __storm_invalidated__(self):
        """Make sure that the file is closed across transaction boundary."""
        super(LibraryFileAlias, self).__storm_invalidated__()
        self.close()


class LibraryFileAliasWithParent:
    """A LibraryFileAlias variant that has a parent."""

    adapts(ILibraryFileAlias, Interface)
    implements(ILibraryFileAliasWithParent)
    delegates(ILibraryFileAlias)

    def __init__(self, libraryfile, parent):
        self.context = libraryfile
        self.__parent__ = parent

    def createToken(self):
        """See `ILibraryFileAliasWithParent`."""
        return TimeLimitedToken.allocate(self.private_url)


class LibraryFileAliasSet(object):
    """Create and find LibraryFileAliases."""

    implements(ILibraryFileAliasSet)

    def create(
        self, name, size, file, contentType, expires=None, debugID=None,
        restricted=False):
        """See `ILibraryFileAliasSet`"""
        if restricted:
            client = getUtility(IRestrictedLibrarianClient)
        else:
            client = getUtility(ILibrarianClient)
        fid = client.addFile(name, size, file, contentType, expires, debugID)
        lfa = IMasterStore(LibraryFileAlias).find(
            LibraryFileAlias, LibraryFileAlias.id == fid).one()
        assert lfa is not None, "client.addFile didn't!"
        return lfa

    def __getitem__(self, key):
        """See ILibraryFileAliasSet.__getitem__"""
        return LibraryFileAlias.get(key)

    def findBySHA1(self, sha1):
        """See ILibraryFileAliasSet."""
        return LibraryFileAlias.select("""
            content = LibraryFileContent.id
            AND LibraryFileContent.sha1 = '%s'
            """ % sha1, clauseTables=['LibraryFileContent'])


class LibraryFileDownloadCount(SQLBase):
    """See `ILibraryFileDownloadCount`"""

    implements(ILibraryFileDownloadCount)
    __storm_table__ = 'LibraryFileDownloadCount'

    id = Int(primary=True)
    libraryfilealias_id = Int(name='libraryfilealias', allow_none=False)
    libraryfilealias = Reference(libraryfilealias_id, 'LibraryFileAlias.id')
    day = Date(allow_none=False)
    count = Int(allow_none=False)
    country_id = Int(name='country', allow_none=True)
    country = Reference(country_id, 'Country.id')


class TimeLimitedToken(StormBase):
    """A time limited access token for accessing a private file."""

    __storm_table__ = 'TimeLimitedToken'

    created = UtcDateTimeCol(notNull=True, default=UTC_NOW)
    path = StringCol(notNull=True)
    token = StringCol(notNull=True)
    __storm_primary__ = ("path", "token")

    def __init__(self, path, token, created=None):
        """Create a TimeLimitedToken."""
        if created is not None:
            self.created = created
        self.path = path
        self.token = token

    @staticmethod
    def allocate(url):
        """Allocate a token for url path in the librarian.

        :param url: A url bytestring. e.g.
            https://i123.restricted.launchpad-librarian.net/123/foo.txt
            Note that the token is generated for 123/foo.txt
        :return: A url fragment token ready to be attached to the url.
            e.g. 'a%20token'
        """
        # We use random.random to get a string which varies reasonably, and we
        # hash it to distribute it widely and get a easily copy and pastable
        # single string (nice for debugging). The randomness is not a key
        # factor here: as long as tokens are not guessable, they are hidden by
        # https, not exposed directly in the API (tokens will be allocated by
        # the appropriate objects), not by direct access to the
        # TimeLimitedToken class.
        baseline = str(random.random())
        hashed = md5(baseline).hexdigest()
        token = hashed
        store = session_store()
        path = TimeLimitedToken.url_to_token_path(url)
        store.add(TimeLimitedToken(path, token))
        # The session isn't part of the main transaction model, and in fact it
        # has autocommit on. The commit here is belts and bracers: after
        # allocation the external librarian must be able to serve the file
        # immediately.
        store.commit()
        return token

    @staticmethod
    def url_to_token_path(url):
        """Return the token path used for authorising access to url."""
        return urlparse(url)[2]