import h5py
import os
import pickle

try:
    import gensim
except ImportError:
    gensim = None


class Word2VecLookup(object):
    def __init__(self, dbpath):
        self.h5file = os.path.join(dbpath, "db.h5py")
        self.lookupfile = os.path.join(dbpath, "lookup.pkl")
        if not (os.path.exists(self.h5file) and
                os.path.exists(self.lookupfile)):
            print("Word2VecLookup directory is malformed. Please recreate "
                  "using Word2VecLookup.create_db")
            raise TypeError
        with open(self.lookupfile, 'rb') as fd:
            self.lookup = pickle.load(fd)

    def __getitem__(self, items):
        if isinstance(items, (str, bytes)):
            return self.__getitem__([items])
        w2v_indicies = list(
            filter(
                None,
                map(
                    self.lookup.get,
                    items
                )
            )
        )
        w2v_indicies_sort = sorted(set(w2v_indicies))
        with h5py.File(self.h5file, 'r') as f:
            vectors = f['word2vec'][w2v_indicies_sort]
        unsort = {w: i for i, w in enumerate(w2v_indicies_sort)}
        unsort_idxs = [unsort[i]for i in w2v_indicies if i in unsort]
        return vectors[unsort_idxs, ...]

    @staticmethod
    def create_db(word2vec_bin, dbpath):
        if gensim is None:
            print("Cannot create h5db from word2vec binary file "
                  "without gensim installed")
        model = gensim.models.KeyedVectors.load_word2vec_format(
            word2vec_bin,
            binary=True
        )
        os.makedirs(dbpath, exist_ok=True)
        h5file = os.path.join(dbpath, "db.h5py")
        lookupfile = os.path.join(dbpath, "lookup.pkl")

        lookup = {w: d.index for w, d in model.vocab.items()}
        with open(lookupfile, 'wb+') as fd:
            pickle.dump(lookup, fd)

        with h5py.File(h5file, 'w') as f:
            f.create_dataset("word2vec", data=model.syn0)