import datetime
from operator import attrgetter

# can get sample data here:
# wget http://www.grouplens.org/system/files/ml-100k.zip
# app data file config
APPDATA_DIRNAME = "ml-100k"
USERS_FILENAME = "u.user"
USERS_FILE_DELIMITER = "|"
ITEMS_FILENAME = "u.item"
ITEMS_FILE_DELIMITER = "|"
RATE_ACTIONS_FILENAME = "u.data"
RATE_ACTIONS_DELIMITER = "\t"


class User:
    def __init__(self, uid):
        self.uid = uid
        self.rec = []  # recommendations, list of iid

    def __str__(self):
        return "User[uid=%s,rec=%s]" % (self.uid, self.rec)


class Item:
    def __init__(self, iid, name, release_date, genres, year):
        self.iid = iid
        self.name = name
        self.release_date = release_date  # datetime.datetime object
        self.genres = genres
        self.year = year

    def __str__(self):
        return "Item[iid=%s,name=%s,release_date=%s,genres=%s]" % (self.iid, self.name, self.release_date, self.genres)


class RateAction:
    def __init__(self, uid, iid, rating, t):
        self.uid = uid
        self.iid = iid
        self.rating = rating
        self.t = t

    def __str__(self):
        return "RateAction[uid=%s,iid=%s,rating=%s,t=%s]" % (self.uid, self.iid, self.rating, self.t)


class AppData:
    def __init__(self):
        self._users = {}  # dict of User obj
        self._items = {}  # dict of Item obj
        self._rate_actions = []  # list of RateAction obj

        self._users_file = "%s/%s" % (APPDATA_DIRNAME, USERS_FILENAME)
        self._items_file = "%s/%s" % (APPDATA_DIRNAME, ITEMS_FILENAME)
        self._rate_actions_file = "%s/%s" % (APPDATA_DIRNAME, RATE_ACTIONS_FILENAME)
        self.__init_users()
        self.__init_items()
        self.__init_rate_actions()

    def __init_users(self):
        """
        uid|
        """
        print("[Info] Initializing users...")
        f = open(self._users_file, 'r')
        for line in f:
            data = line.rstrip('\r\n').split(USERS_FILE_DELIMITER)
            self.add_user(User(data[0]))
        f.close()
        print("[Info] %s users were initialized." % len(self._users))

    def __init_items(self):
        """
        movie id | movie title | release date | video release date |
            IMDb URL | unknown | Action | Adventure | Animation |
            Children's | Comedy | Crime | Documentary | Drama | Fantasy |
            Film-Noir | Horror | Musical | Mystery | Romance | Sci-Fi |
            Thriller | War | Western |
            The last 19 fields are the genres, a 1 indicates the movie
            is of that genre, a 0 indicates it is not; movies can be in
            several genres at once.

        """
        genre_names = ["unknown", "Action", "Adventure", "Animation",
                       "Children's", "Comedy", "Crime", "Documentary", "Drama", "Fantasy",
                       "Film-Noir", "Horror", "Musical", "Mystery", "Romance", "Sci-Fi",
                       "Thriller", "War", "Western"]

        print("[Info] Initializing items...")
        f = open(self._items_file, 'r')
        for line in f:
            data = line.rstrip('\r\n').split(ITEMS_FILE_DELIMITER)
            genres_flags = data[5:24]

            genres = ()  # tuple of genres
            for g, flag in zip(genre_names, genres_flags):
                if flag == '1':
                    genres = genres + (g,)

            try:
                # eg. 01-Jan-1994
                release_date = datetime.datetime.strptime(data[2], "%d-%b-%Y").replace(microsecond=1)
                (day, month, year) = data[2].split('-')
            except:
                print("[Note] item %s %s doesn't have release date. Skip it." % (data[0], data[1]))
            else:
                self.add_item(Item(
                    iid=data[0],
                    name=data[1],
                    release_date=release_date,
                    genres=genres,
                    year=year))
        f.close()
        print("[Info] %s items were initialized." % len(self._items))

    def __init_rate_actions(self):
        """
        uid|iid|rating|timestamp
        """
        print("[Info] Initializing rate actions...")
        f = open(self._rate_actions_file, 'r')
        for line in f:
            data = line.rstrip('\r\n').split(RATE_ACTIONS_DELIMITER)
            t = datetime.datetime.utcfromtimestamp(int(data[3])).replace(microsecond=1)
            self.add_rate_action(RateAction(data[0], data[1], data[2], t))
        f.close()
        print("[Info] %s rate actions were initialized." % len(self._rate_actions))

    def add_user(self, user):
        self._users[user.uid] = user

    def add_item(self, item):
        self._items[item.iid] = item

    def add_rate_action(self, action):
        self._rate_actions.append(action)

    def get_users(self):
        return self._users

    def get_items(self):
        return self._items

    def get_rate_actions(self):
        return self._rate_actions

    def get_user(self, uid):
        """return single user
        """
        if uid in self._users:
            return self._users[uid]
        else:
            return None

    def get_item(self, iid):
        """return single item
        """
        if iid in self._items:
            return self._items[iid]
        else:
            return None

    def get_top_rated_items(self, uid, n):
        """get top n rated iids by this uid
        """
        if uid in self._users:
            actions = filter(lambda u: u.uid == uid, self._rate_actions)
            top = sorted(actions, key=attrgetter('rating'), reverse=True)
            topn_iids = map(lambda a: a.iid, top[:n])
            return topn_iids
        else:
            return None

    def get_top_rate_actions(self, uid, n):
        """get top n rated actions by this uid
        """
        if uid in self._users:
            actions = filter(lambda u: u.uid == uid, self._rate_actions)
            top = sorted(actions, key=attrgetter('rating'), reverse=True)
            return top[:n]
        else:
            return None