from __future__ import absolute_import
from dejavu.database import Database
import sys

if sys.version_info >= (3, 0):
    from itertools import zip_longest as izip_longest
    import queue as Queue
else:
    from itertools import izip_longest
    import Queue

PY3 = sys.version_info >= (3, 0)


class MEMDatabase(Database):
    """
    Queries:

    1) Find duplicates (shouldn't be any, though):

        select `hash`, `song_id`, `offset`, count(*) cnt
        from fingerprints
        group by `hash`, `song_id`, `offset`
        having cnt > 1
        order by cnt asc;

    2) Get number of hashes by song:

        select song_id, song_name, count(song_id) as num
        from fingerprints
        natural join songs
        group by song_id
        order by count(song_id) desc;

    3) get hashes with highest number of collisions

        select
            hash,
            count(distinct song_id) as n
        from fingerprints
        group by `hash`
        order by n DESC;

    => 26 different songs with same fingerprint (392 times):

        select songs.song_name, fingerprints.offset
        from fingerprints natural join songs
        where fingerprints.hash = "08d3c833b71c60a7b620322ac0c0aba7bf5a3e73";
    """

    type = "mem"

    # tables
    FINGERPRINTS_TABLENAME = "fingerprints"
    SONGS_TABLENAME = "ads"

    # fields
    FIELD_FINGERPRINTED = "fingerprinted"

    # creates
    CREATE_FINGERPRINTS_TABLE = """
        CREATE TABLE IF NOT EXISTS `%s` (
             `%s` binary(10) not null,
             `%s` int unsigned not null,
             `%s` int unsigned not null,
         INDEX (%s),
         UNIQUE KEY `unique_constraint` (%s, %s, %s),
         FOREIGN KEY (%s) REFERENCES %s(%s) ON DELETE CASCADE
    ) ENGINE=INNODB;""" % (
        FINGERPRINTS_TABLENAME, Database.FIELD_HASH,
        Database.FIELD_SONG_ID, Database.FIELD_OFFSET, Database.FIELD_HASH,
        Database.FIELD_SONG_ID, Database.FIELD_OFFSET, Database.FIELD_HASH,
        Database.FIELD_SONG_ID, SONGS_TABLENAME, Database.FIELD_SONG_ID
    )

    CREATE_SONGS_TABLE = """
        CREATE TABLE IF NOT EXISTS `%s` (
            `%s` int unsigned not null auto_increment,
            `%s` varchar(250) not null,
            `%s` bigint default 0,
            `%s` tinyint default 0,
            `%s` binary(20) not null,
        PRIMARY KEY (`%s`),
        UNIQUE KEY `%s` (`%s`)
    ) ENGINE=INNODB;""" % (
        SONGS_TABLENAME, Database.FIELD_SONG_ID, Database.FIELD_SONGNAME, Database.FIELD_LENGTH, FIELD_FINGERPRINTED,
        Database.FIELD_FILE_SHA1,
        Database.FIELD_SONG_ID, Database.FIELD_SONG_ID, Database.FIELD_SONG_ID,
    )

    # inserts (ignores duplicates)
    INSERT_FINGERPRINT = """
        INSERT IGNORE INTO %s (%s, %s, %s) values
            (UNHEX(%%s), %%s, %%s);
    """ % (FINGERPRINTS_TABLENAME, Database.FIELD_HASH, Database.FIELD_SONG_ID, Database.FIELD_OFFSET)

    INSERT_SONG = "INSERT INTO %s (%s, %s, %s) values (%%s, %%s, UNHEX(%%s));" % (
        SONGS_TABLENAME, Database.FIELD_SONGNAME, Database.FIELD_LENGTH, Database.FIELD_FILE_SHA1)

    # selects
    SELECT = """
        SELECT %s, %s FROM %s WHERE %s = UNHEX(%%s);
    """ % (Database.FIELD_SONG_ID, Database.FIELD_OFFSET, FINGERPRINTS_TABLENAME, Database.FIELD_HASH)

    SELECT_MULTIPLE = """
        SELECT HEX(%s), %s, %s FROM %s WHERE %s IN (%%s);
    """ % (Database.FIELD_HASH, Database.FIELD_SONG_ID, Database.FIELD_OFFSET,
           FINGERPRINTS_TABLENAME, Database.FIELD_HASH)

    SELECT_MULTIPLE_FILTER = """
        SELECT HEX(%s), %s, %s FROM %s WHERE %s IN (%%s) AND id IN (%%s);
    """ % (Database.FIELD_HASH, Database.FIELD_SONG_ID, Database.FIELD_OFFSET,
           FINGERPRINTS_TABLENAME, Database.FIELD_HASH)

    SELECT_ALL = """
        SELECT %s, %s FROM %s;
    """ % (Database.FIELD_SONG_ID, Database.FIELD_OFFSET, FINGERPRINTS_TABLENAME)

    SELECT_SONG = """
        SELECT %s, HEX(%s) as %s FROM %s WHERE %s = %%s;
    """ % (Database.FIELD_SONGNAME, Database.FIELD_FILE_SHA1, Database.FIELD_FILE_SHA1, SONGS_TABLENAME, Database.FIELD_SONG_ID)

    SELECT_NUM_FINGERPRINTS = """
        SELECT COUNT(*) as n FROM %s
    """ % (FINGERPRINTS_TABLENAME)

    SELECT_UNIQUE_SONG_IDS = """
        SELECT COUNT(DISTINCT %s) as n FROM %s WHERE %s = 1;
    """ % (Database.FIELD_SONG_ID, SONGS_TABLENAME, FIELD_FINGERPRINTED)

    SELECT_SONGS = """
        SELECT %s, %s, HEX(%s) as %s FROM %s WHERE %s = 1;
    """ % (Database.FIELD_SONG_ID, Database.FIELD_SONGNAME, Database.FIELD_FILE_SHA1, Database.FIELD_FILE_SHA1,
           SONGS_TABLENAME, FIELD_FINGERPRINTED)

    # drops
    DROP_FINGERPRINTS = "DROP TABLE IF EXISTS %s;" % FINGERPRINTS_TABLENAME
    DROP_SONGS = "DROP TABLE IF EXISTS %s;" % SONGS_TABLENAME

    # update
    UPDATE_SONG_FINGERPRINTED = """
        UPDATE %s SET %s = 1 WHERE %s = %%s
    """ % (SONGS_TABLENAME, FIELD_FINGERPRINTED, Database.FIELD_SONG_ID)

    # delete
    DELETE_UNFINGERPRINTED = """
        DELETE FROM %s WHERE %s = 0;
    """ % (SONGS_TABLENAME, FIELD_FINGERPRINTED)

    def __init__(self, **options):
        super(MEMDatabase, self).__init__()
        self._options = options
        

    def after_fork(self):
        raise Exception("not implemented")
        # Clear the cursor cache, we don't want any stale connections from
        # the previous process.
        Cursor.clear_cache()

    def setup(self):
        """
        Creates any non-existing tables required for dejavu to function.

        This also removes all songs that have been added but have no
        fingerprints associated with them.
        """
        self.songs = {}
        self.fingerprints = {}
        #with self.cursor() as cur:
        #    cur.execute(self.CREATE_SONGS_TABLE)
        #    cur.execute(self.CREATE_FINGERPRINTS_TABLE)
        #    cur.execute(self.DELETE_UNFINGERPRINTED)

    def empty(self):
        raise Exception("not implemented")
        """
        Drops tables created by dejavu and then creates them again
        by calling `SQLDatabase.setup`.

        .. warning:
            This will result in a loss of data
        """
        with self.cursor() as cur:
            cur.execute(self.DROP_FINGERPRINTS)
            cur.execute(self.DROP_SONGS)

        self.setup()

    def delete_unfingerprinted_songs(self):
        raise Exception("not implemented")
        """
        Removes all songs that have no fingerprints associated with them.
        """
        with self.cursor() as cur:
            cur.execute(self.DELETE_UNFINGERPRINTED)

    def get_num_songs(self):
        raise Exception("not implemented")
        """
        Returns number of songs the database has fingerprinted.
        """
        with self.cursor() as cur:
            cur.execute(self.SELECT_UNIQUE_SONG_IDS)

            for count, in cur:
                return count
            return 0

    def get_num_fingerprints(self):
        raise Exception("not implemented")
        """
        Returns number of fingerprints the database has fingerprinted.
        """
        with self.cursor() as cur:
            cur.execute(self.SELECT_NUM_FINGERPRINTS)

            for count, in cur:
                return count
            return 0

    def set_song_fingerprinted(self, sid):
        """
        Set the fingerprinted flag to TRUE (1) once a song has been completely
        fingerprinted in the database.
        """
        self.songs[sid]["fingerprinted"] = 1
        #with self.cursor() as cur:
        #    cur.execute(self.UPDATE_SONG_FINGERPRINTED, (sid,))

    def get_songs(self):
        """
        Return songs that have the fingerprinted flag set TRUE (1).
        """
        if PY3:
            for _, song in self.songs.items():
                yield song
        else:
            for _, song in self.songs.iteritems():
                yield song
        #with self.cursor(cursor_type=DictCursor) as cur:
        #    cur.execute(self.SELECT_SONGS)
        #    for row in cur:
        #        yield row

    def get_song_by_id(self, sid):
        """
        Returns song by its ID.
        """
        return self.songs.get(sid, None)
        #with self.cursor(cursor_type=DictCursor) as cur:
        #    cur.execute(self.SELECT_SONG, (sid,))
        #    return cur.fetchone()

    def insert(self, hash, sid, offset):
        raise Exception("not implemented")
        """
        Insert a (sha1, song_id, offset) row into database.
        """
        with self.cursor() as cur:
            cur.execute(self.INSERT_FINGERPRINT, (hash, sid, offset))

    def insert_song(self, songname, length, file_hash):
        """
        Inserts song in the database and returns the ID of the inserted record.
        """
        self.songs[file_hash] = {
                Database.FIELD_SONG_ID: file_hash,
                Database.FIELD_SONGNAME: songname,
                Database.FIELD_LENGTH: length,
                "fingerprinted": 0,
                Database.FIELD_FILE_SHA1: file_hash
                }
        return file_hash
        #with self.cursor() as cur:
        #    cur.execute(self.INSERT_SONG, (songname, length, file_hash))
        #    return cur.lastrowid

    def query(self, hash):
        raise Exception("not implemented")
        """
        Return all tuples associated with hash.

        If hash is None, returns all entries in the
        database (be careful with that one!).
        """
        # select all if no key
        query = self.SELECT_ALL if hash is None else self.SELECT

        with self.cursor() as cur:
            cur.execute(query)
            for sid, offset in cur:
                yield (sid, offset)

    def get_iterable_kv_pairs(self):
        raise Exception("not implemented")
        """
        Returns all tuples in database.
        """
        return self.query(None)

    def insert_hashes(self, sid, hashes):
        """
        Insert series of hash => song_id, offset
        values into the database.
        """
        #values = {}
        for hash, offset in hashes:
            self.fingerprints[hash] = {"sid": sid, "offset": offset}

        #self.fingerprints[sid] = values

        #values = []
        #for hash, offset in hashes:
        #    values.append((hash, sid, offset))

        #with self.cursor() as cur:
        #    for split_values in grouper(values, 1000):
        #        cur.executemany(self.INSERT_FINGERPRINT, split_values)

    def return_matches(self, hashes, ads_filter=None):
        """
        Return the (song_id, offset_diff) tuples associated with
        a list of (sha1, sample_offset) values.
        """
        for hash, offset in hashes:
            el = self.fingerprints.get(hash, None)
            if el is not None:
                yield (el["sid"], el["offset"] - offset, el["offset"])

        return
        # Create a dictionary of hash => offset pairs for later lookups
        mapper = {}
        for hash, offset in hashes:
            mapper[hash.upper()] = offset

        # Get an iteratable of all the hashes we need
        values = mapper.keys()

        with self.cursor() as cur:
            for split_values in grouper(values, 1000):
                # Create our IN part of the query
                if ads_filter is None:
                    query = self.SELECT_MULTIPLE
                    query = query % ', '.join(['UNHEX(%s)'] * len(split_values))
                else:
                    query = self.SELECT_MULTIPLE_FILTER
                    query = query % (', '.join(['UNHEX(%s)'] * len(split_values)), ",".join(ads_filter))

                #if ads_filter:
                    #query = query + " and id in (" + ",".join(ads_filter) + ")"

                cur.execute(query, split_values)

                for hash, sid, offset in cur:
                    # (sid, db_offset - song_sampled_offset)
                    yield (sid, offset - mapper[hash], offset)

    def __getstate__(self):
        raise Exception("not implemented")
        return (self._options,)

    def __setstate__(self, state):
        raise Exception("not implemented")
        self._options, = state
        self.cursor = cursor_factory(**self._options)


def grouper(iterable, n, fillvalue=None):
    args = [iter(iterable)] * n
    return (filter(None, values) for values
            in izip_longest(fillvalue=fillvalue, *args))