# This program is free software; you can redistribute it and/or modify
# it under the terms of the (LGPL) GNU Lesser General Public License as
# published by the Free Software Foundation; either version 3 of the
# License, or (at your option) any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU Library Lesser General Public License for more details at
# ( http://www.gnu.org/licenses/lgpl.html ).
#
# You should have received a copy of the GNU Lesser General Public License
# along with this program; if not, write to the Free Software
# Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
# written by: Jeff Ortel ( jortel@redhat.com )

"""
Contains basic caching classes.
"""

import suds
from suds.transport import *
from suds.sax.parser import Parser
from suds.sax.element import Element

from datetime import datetime as dt
from datetime import timedelta
import os
from tempfile import gettempdir as tmp
try:
    import pickle as pickle
except Exception:
    import pickle

from logging import getLogger
log = getLogger(__name__)


class Cache:
    """
    An object object cache.
    """

    def get(self, id):
        """
        Get a object from the cache by ID.
        @param id: The object ID.
        @type id: str
        @return: The object, else None
        @rtype: any
        """
        raise Exception('not-implemented')

    def put(self, id, object):
        """
        Put a object into the cache.
        @param id: The object ID.
        @type id: str
        @param object: The object to add.
        @type object: any
        """
        raise Exception('not-implemented')

    def purge(self, id):
        """
        Purge a object from the cache by id.
        @param id: A object ID.
        @type id: str
        """
        raise Exception('not-implemented')

    def clear(self):
        """
        Clear all objects from the cache.
        """
        raise Exception('not-implemented')


class NoCache(Cache):
    """
    The passthru object cache.
    """

    def get(self, id):
        return None

    def put(self, id, object):
        pass


class FileCache(Cache):
    """
    A file-based URL cache.
    @cvar fnprefix: The file name prefix.
    @type fnsuffix: str
    @ivar duration: The cached file duration which defines how
        long the file will be cached.
    @type duration: (unit, value)
    @ivar location: The directory for the cached files.
    @type location: str
    """
    fnprefix = 'suds'
    units = ('months', 'weeks', 'days', 'hours', 'minutes', 'seconds')

    def __init__(self, location=None, **duration):
        """
        @param location: The directory for the cached files.
        @type location: str
        @param duration: The cached file duration which defines how
            long the file will be cached.  A duration=0 means forever.
            The duration may be: (months|weeks|days|hours|minutes|seconds).
        @type duration: {unit:value}
        """
        if location is None:
            location = os.path.join(tmp(), 'suds')
        self.location = location
        self.duration = (None, 0)
        self.setduration(**duration)
        self.checkversion()

    def fnsuffix(self):
        """
        Get the file name suffix
        @return: The suffix
        @rtype: str
        """
        return 'gcf'

    def setduration(self, **duration):
        """
        Set the caching duration which defines how long the
        file will be cached.
        @param duration: The cached file duration which defines how
            long the file will be cached.  A duration=0 means forever.
            The duration may be: (months|weeks|days|hours|minutes|seconds).
        @type duration: {unit:value}
        """
        if len(duration) == 1:
            arg = list(duration.items())[0]
            if not arg[0] in self.units:
                raise Exception('must be: %s' % str(self.units))
            self.duration = arg
        return self

    def setlocation(self, location):
        """
        Set the location (directory) for the cached files.
        @param location: The directory for the cached files.
        @type location: str
        """
        self.location = location

    def mktmp(self):
        """
        Make the I{location} directory if it doesn't already exits.
        """
        try:
            if not os.path.isdir(self.location):
                os.makedirs(self.location)
        except Exception:
            log.debug(self.location, exc_info=1)
        return self

    def put(self, id, bfr):
        try:
            fn = self.__fn(id)
            f = self.open(fn, 'wb')
            try:
                f.write(bfr)
            finally:
                f.close()
            return bfr
        except Exception:
            log.debug(id, exc_info=1)
            return bfr

    def get(self, id):
        try:
            f = self.getf(id)
            try:
                return f.read()
            finally:
                f.close()
        except Exception:
            pass

    def getf(self, id):
        try:
            fn = self.__fn(id)
            self.validate(fn)
            return self.open(fn, 'rb')
        except Exception:
            pass

    def validate(self, fn):
        """
        Validate that the file has not expired based on the I{duration}.
        @param fn: The file name.
        @type fn: str
        """
        if self.duration[1] < 1:
            return
        created = dt.fromtimestamp(os.path.getctime(fn))
        d = {self.duration[0]:self.duration[1]}
        expired = created + timedelta(**d)
        if expired < dt.now():
            log.debug('%s expired, deleted', fn)
            os.remove(fn)

    def clear(self):
        for fn in os.listdir(self.location):
            path = os.path.join(self.location, fn)
            if os.path.isdir(path):
                continue
            if fn.startswith(self.fnprefix):
                os.remove(path)
                log.debug('deleted: %s', path)

    def purge(self, id):
        fn = self.__fn(id)
        try:
            os.remove(fn)
        except Exception:
            pass

    def open(self, fn, *args):
        """
        Open the cache file making sure the directory is created.
        """
        self.mktmp()
        return open(fn, *args)

    def checkversion(self):
        path = os.path.join(self.location, 'version')
        try:
            f = self.open(path)
            version = f.read()
            f.close()
            if version != suds.__version__:
                raise Exception()
        except Exception:
            self.clear()
            f = self.open(path, 'w')
            f.write(suds.__version__)
            f.close()

    def __fn(self, id):
        name = id
        suffix = self.fnsuffix()
        fn = '%s-%s.%s' % (self.fnprefix, name, suffix)
        return os.path.join(self.location, fn)


class DocumentCache(FileCache):
    """
    Provides xml document caching.
    """

    def fnsuffix(self):
        return 'xml'

    def get(self, id):
        try:
            fp = self.getf(id)
            if fp is None:
                return None
            p = Parser()
            return p.parse(fp)
        except Exception:
            self.purge(id)

    def put(self, id, object):
        if isinstance(object, Element):
            FileCache.put(self, id, suds.byte_str(str(object)))
        return object


class ObjectCache(FileCache):
    """
    Provides pickled object caching.
    @cvar protocol: The pickling protocol.
    @type protocol: int
    """
    protocol = 2

    def fnsuffix(self):
        return 'px'

    def get(self, id):
        try:
            fp = self.getf(id)
            if fp is None:
                return None
            return pickle.load(fp)
        except Exception:
            self.purge(id)

    def put(self, id, object):
        bfr = pickle.dumps(object, self.protocol)
        FileCache.put(self, id, bfr)
        return object
