#############################################################
# Contents from Categories.json is taken                    #
# and cleaned to form Bag of Words,                         #
# then each pattern of categories is taken                  #
# and trained for their corresponding tag as their output.  #
# Final neural network model is then saved in a file        #
#############################################################

import random
import json
import pickle
import numpy as np

import nltk
from nltk.stem import WordNetLemmatizer

from tensorflow.keras.models import Sequential
from tensorflow.keras.layers import Dense, Activation, Dropout
from tensorflow.keras.optimizers import SGD

lemmatizer = WordNetLemmatizer()

intents = json.loads (open ('Categories.json').read())

words = []
classes = []
documents = []
ignoreCharacters = [ ',', '.', '!', '?' ]

for intent in intents ['categories']:
    for pattern in intent ['patterns']:
        wordList = nltk.word_tokenize (pattern)
        words.extend (wordList)
        documents.append ( (wordList, intent ['tag']) )
        if intent ['tag'] not in classes:
            classes.append (intent ['tag'])

words = [ lemmatizer.lemmatize (word) for word in words if word not in ignoreCharacters]
words = sorted (set (words))

classes = sorted ( set (classes))

pickle.dump (words, open ('words.pkl', 'wb'))
pickle.dump (classes, open ('classes.pkl', 'wb'))

training = []
outputEmpty = [0] * len(classes)

for document in documents:
    bag = []
    wordPatterns = document[0]
    wordPatterns = [lemmatizer.lemmatize (word.lower ()) for word in wordPatterns]
    for word in words:
        bag.append (1) if word in wordPatterns else bag.append (0)

    outputRow = list (outputEmpty)
    outputRow [classes.index (document[1])] = 1
    training.append ([bag, outputRow])

random.shuffle (training)
training = np.array (training)

train_x = list (training[:, 0])
train_y = list (training[:, 1])

model = Sequential()
model.add (Dense (128, input_shape = (len (train_x[0]),), activation='relu'))
model.add (Dropout (0.5))
model.add (Dense (64, activation='relu'))
model.add (Dropout (0.5))
model.add (Dense (len (train_y[0]), activation='softmax'))

sgd = SGD (learning_rate = 0.01, decay = 1e-6, momentum = 0.5, nesterov = True)
model.compile (loss = 'categorical_crossentropy', optimizer = sgd, metrics = ['accuracy'])

history = model.fit (np.array (train_x), np.array (train_y), epochs = 200, batch_size = 5, verbose = 1 )
model.save ('chatbot.h5', history)
print('Training Completed')