#!/usr/bin/env python
"""
    user - python module for classes and methods related to recommenders' users.
"""
__author__ = "Tassia Camoes Araujo <tassia@gmail.com>"
__copyright__ = "Copyright (C) 2011 Tassia Camoes Araujo"
__license__ = """
    This program is free software: you can redistribute it and/or modify
    it under the terms of the GNU 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 General Public License for more details.

    You should have received a copy of the GNU General Public License
    along with this program.  If not, see <http://www.gnu.org/licenses/>.
"""

import random
import commands
import xapian
import logging
import apt
from singleton import Singleton

class FilterTag(xapian.ExpandDecider):
    """
    Extend xapian.ExpandDecider to consider only tag terms.
    """
    def __call__(self, term):
        """
        Return true if the term is a tag, else false.
        """
        return term[:2] == "XT"

class DemographicProfile(Singleton):
    def __init__(self):
        self.admin   = set(["admin", "hardware", "mail", "protocol",
                            "network", "security", "web", "interface::web"])
        self.devel   = set(["devel", "role::devel-lib", "role::shared-lib"])
        self.desktop = set(["x11", "accessibility", "game", "junior", "office",
                            "interface::x11"])
        self.art     = set(["field::arts", "sound"])
        self.science = set(["science", "biology", "field::astronomy",
                            "field::aviation",  "field::biology",
                            "field::chemistry", "field::eletronics",
                            "field::finance", "field::geography",
                            "field::geology", "field::linguistics",
                            "field::mathematics", "field::medicine",
                            "field::meteorology", "field::physics",
                            "field::statistics"])

    def __call__(self,profiles_set):
        demographic_profile = set()
        for profile in profiles_set:
            demographic_profile = (demographic_profile | eval("self."+profile,{},{"self":self}))
        return demographic_profile

class User:
    """
    Define a user of a recommender.
    """
    def __init__(self,item_score,user_id=0,profiles_set=0):
        """
        Set initial user attributes. If no user_id was passed as parameter, a
        random md5-hash is generated for that purpose. If the demographic
        profile was not defined, it defaults to 'desktop'
        """
        self.item_score = item_score
        if user_id:
            self.id = user_id
        else:
            random.seed()
            self.id = random.getrandbits(128)
        self.pkg_profile = self.item_score.keys()
        if not profiles_set:
            profiles_set = set(["desktop"])
        self.set_demographic_profile(profiles_set)

    def set_demographic_profile(self,profiles_set):
        self.demographic_profile = DemographicProfile()(profiles_set)

    def items(self):
        """
        Return the set of user items.
        """
        return set(self.item_score.keys())

    def axi_tag_profile(self,apt_xapian_index,profile_size):
        """
        Return most relevant tags for a list of packages based on axi.
        """
        terms = ["XP"+item for item in self.pkg_profile]
        query = xapian.Query(xapian.Query.OP_OR, terms)
        enquire = xapian.Enquire(apt_xapian_index)
        enquire.set_query(query)
        rset = xapian.RSet()
        for m in enquire.get_mset(0,apt_xapian_index.get_doccount()):
             rset.add_document(m.docid)
        # statistically good differentiators between relevant and non-relevant
        eset = enquire.get_eset(profile_size, rset, FilterTag())
        profile = []
        for res in eset:
            profile.append(res.term)
            logging.debug("%.2f %s" % (res.weight,res.term.lstrip("XT")))
        return profile

    #def txi_tag_profile(self,tags_xapian_index,profile_size):
    #    """
    #    Return most relevant tags for a list of packages based on tags index.
    #    """
    #    return tags_xapian_index.relevant_tags_from_db(self.pkg_profile,
    #                                                   profile_size)

    def maximal_pkg_profile(self):
        """
        Return list of packages that are not dependence of any other package in
        the list.
        """
        cache = apt.Cache()
        old_profile_size = len(self.pkg_profile)
        for p in self.pkg_profile[:]:     #iterate list copy
            pkg = cache[p]
            if pkg.candidate:
                for dep in pkg.candidate.dependencies:
                    for or_dep in dep.or_dependencies:
                        if or_dep.name in self.pkg_profile:
                            self.pkg_profile.remove(or_dep.name)
        profile_size = len(self.pkg_profile)
        logging.info("Reduced packages profile size from %d to %d." %
                     (old_profile_size, profile_size))
        return set(self.pkg_profile)

class LocalSystem(User):
    """
    Extend the class User to consider the packages installed on the local
    system as the set of selected itens.
    """
    def __init__(self):
        """
        Set initial parameters.
        """
        item_score = {}
        dpkg_output = commands.getoutput('/usr/bin/dpkg --get-selections')
        for line in dpkg_output.splitlines():
            pkg = line.split('\t')[0]
            item_score[pkg] = 1
        User.__init__(self,item_score)

    def no_auto_pkg_profile(self):
        """
        Return list of packages voluntarily installed.
        """
        cache = apt.Cache()
        old_profile_size = len(self.pkg_profile)
        for p in self.pkg_profile[:]:     #iterate list copy
            pkg = cache[p]
            if pkg.is_auto_installed:
                self.pkg_profile.remove(p)
        profile_size = len(self.pkg_profile)
        logging.info("Reduced packages profile size from %d to %d." %
                     (old_profile_size, profile_size))