from tensorflow.keras.models import Model
from tensorflow.keras.layers import Input, Dense, Reshape
from tensorflow.keras.layers import Embedding
from tensorflow.keras.preprocessing.sequence import skipgrams
from tensorflow.keras.preprocessing import sequence

import urllib.request
import collections
import os
import zipfile

import numpy as np
import tensorflow as tf

window_size = 3
vector_dim = 300
epochs = 1000

valid_size = 16     # Random set of words to evaluate similarity on.
valid_window = 100  # Only pick dev samples in the head of the distribution.
valid_examples = np.random.choice(valid_window, valid_size, replace=False)

def maybe_download(filename, url, expected_bytes):
    """Download a file if not present, and make sure it's the right size."""
    if not os.path.exists(filename):
        filename, _ = urllib.request.urlretrieve(url + filename, filename)
    statinfo = os.stat(filename)
    if statinfo.st_size == expected_bytes:
        print('Found and verified', filename)
    else:
        print(statinfo.st_size)
        raise Exception(
            'Failed to verify ' + filename + '. Can you get to it with a browser?')
    return filename


# Read the data into a list of strings.
def read_data(filename):
    """Extract the first file enclosed in a zip file as a list of words."""
    with zipfile.ZipFile(filename) as f:
        data = tf.compat.as_str(f.read(f.namelist()[0])).split()
    return data


def build_dataset(words, n_words):
    """Process raw inputs into a dataset."""
    count = [['UNK', -1]]
    count.extend(collections.Counter(words).most_common(n_words - 1))
    dictionary = dict()
    for word, _ in count:
        dictionary[word] = len(dictionary)
    data = list()
    unk_count = 0
    for word in words:
        if word in dictionary:
            index = dictionary[word]
        else:
            index = 0  # dictionary['UNK']
            unk_count += 1
        data.append(index)
    count[0][1] = unk_count
    reversed_dictionary = dict(zip(dictionary.values(), dictionary.keys()))
    return data, count, dictionary, reversed_dictionary

def collect_data(vocabulary_size=10000):
    url = 'http://mattmahoney.net/dc/'
    filename = maybe_download('text8.zip', url, 31344016)
    vocabulary = read_data(filename)
    print(vocabulary[:7])
    data, count, dictionary, reverse_dictionary = build_dataset(vocabulary,
                                                                vocabulary_size)
    del vocabulary  # Hint to reduce memory.
    return data, count, dictionary, reverse_dictionary

class SimilarityCallback:
    def run_sim(self):
        for i in range(valid_size):
            valid_word = reverse_dictionary[valid_examples[i]]
            top_k = 8  # number of nearest neighbors
            sim = self._get_sim(valid_examples[i])
            nearest = (-sim).argsort()[1:top_k + 1]
            log_str = 'Nearest to %s:' % valid_word
            for k in range(top_k):
                close_word = reverse_dictionary[nearest[k]]
                log_str = '%s %s,' % (log_str, close_word)
            print(log_str)

    @staticmethod
    def _get_sim(valid_word_idx):
        sim = np.zeros((vocab_size,))
        in_arr1 = np.zeros((1,))
        in_arr2 = np.zeros((1,))
        in_arr1[0,] = valid_word_idx
        for i in range(vocab_size):
            in_arr2[0,] = i
            out = validation_model.predict_on_batch([in_arr1, in_arr2])
            sim[i] = out
        return sim
    

def read_glove_vecs(glove_file):
    with open(glove_file, 'r') as f:
        words = set()
        word_to_vec_map = {}
        
        for line in f:
            line = line.strip().split()
            curr_word = line[0]
            words.add(curr_word)
            word_to_vec_map[curr_word] = np.array(line[1:], dtype=np.float64)
            
    return words, word_to_vec_map

def relu(x):
    """
    Compute the relu of x

    Arguments:
    x -- A scalar or numpy array of any size.

    Return:
    s -- relu(x)
    """
    s = np.maximum(0,x)
    
    return s


def initialize_parameters(vocab_size, n_h):
    """
    Arguments:
    layer_dims -- python array (list) containing the dimensions of each layer in our network
    
    Returns:
    parameters -- python dictionary containing your parameters "W1", "b1", "W2", "b2":
                    W1 -- weight matrix of shape (n_h, vocab_size)
                    b1 -- bias vector of shape (n_h, 1)
                    W2 -- weight matrix of shape (vocab_size, n_h)
                    b2 -- bias vector of shape (vocab_size, 1)
    """
    
    np.random.seed(3)
    parameters = {}

    parameters['W1'] = np.random.randn(n_h, vocab_size) / np.sqrt(vocab_size)
    parameters['b1'] = np.zeros((n_h, 1))
    parameters['W2'] = np.random.randn(vocab_size, n_h) / np.sqrt(n_h)
    parameters['b2'] = np.zeros((vocab_size, 1))

    return parameters

def softmax(x):
    """Compute softmax values for each sets of scores in x."""
    e_x = np.exp(x - np.max(x))
    return e_x / e_x.sum()
