import numpy as np
import json
from keras.utils import to_categorical
import plac
import sys

from keras_decomposable_attention import build_model
from spacy_hook import get_embeddings, KerasSimilarityShim

try:
    import cPickle as pickle
except ImportError:
    import pickle

import spacy

# workaround for keras/tensorflow bug
# see https://github.com/tensorflow/tensorflow/issues/3388
import os
import importlib
from keras import backend as K

def set_keras_backend(backend):
    if K.backend() != backend:
        os.environ['KERAS_BACKEND'] = backend
        importlib.reload(K)
        assert K.backend() == backend
    if backend == "tensorflow":
        K.get_session().close()
        cfg = K.tf.ConfigProto()
        cfg.gpu_options.allow_growth = True
        K.set_session(K.tf.Session(config=cfg))
        K.clear_session()

set_keras_backend("tensorflow")


def train(train_loc, dev_loc, shape, settings):
    train_texts1, train_texts2, train_labels = read_snli(train_loc)
    dev_texts1, dev_texts2, dev_labels = read_snli(dev_loc)

    print("Loading spaCy")
    nlp = spacy.load('en_vectors_web_lg')
    assert nlp.path is not None

    print("Processing texts...")
    train_X = create_dataset(nlp, train_texts1, train_texts2, 100, shape[0])
    dev_X = create_dataset(nlp, dev_texts1, dev_texts2, 100, shape[0])

    print("Compiling network")
    model = build_model(get_embeddings(nlp.vocab), shape, settings)

    print(settings)
    model.fit(
        train_X,
        train_labels,
        validation_data = (dev_X, dev_labels),
        epochs = settings['nr_epoch'],
        batch_size = settings['batch_size'])

    if not (nlp.path / 'similarity').exists():
        (nlp.path / 'similarity').mkdir()
    print("Saving to", nlp.path / 'similarity')
    weights = model.get_weights()
    # remove the embedding matrix.  We can reconstruct it.
    del weights[1]
    with (nlp.path / 'similarity' / 'model').open('wb') as file_:
        pickle.dump(weights, file_)
    with (nlp.path / 'similarity' / 'config.json').open('w') as file_:
        file_.write(model.to_json())


def evaluate(dev_loc, shape):
    dev_texts1, dev_texts2, dev_labels = read_snli(dev_loc)
    nlp = spacy.load('en_vectors_web_lg')
    nlp.add_pipe(KerasSimilarityShim.load(nlp.path / 'similarity', nlp, shape[0]))

    total = 0.
    correct = 0.
    for text1, text2, label in zip(dev_texts1, dev_texts2, dev_labels):
        doc1 = nlp(text1)
        doc2 = nlp(text2)
        sim, _ = doc1.similarity(doc2)
        if sim == KerasSimilarityShim.entailment_types[label.argmax()]:
            correct += 1
        total += 1
    return correct, total


def demo(shape):
    nlp = spacy.load('en_vectors_web_lg')
    nlp.add_pipe(KerasSimilarityShim.load(nlp.path / 'similarity', nlp, shape[0]))

    doc1 = nlp(u'The king of France is bald.')
    doc2 = nlp(u'France has no king.')

    print("Sentence 1:", doc1)
    print("Sentence 2:", doc2)

    entailment_type, confidence = doc1.similarity(doc2)
    print("Entailment type:", entailment_type, "(Confidence:", confidence, ")")


LABELS = {'entailment': 0, 'contradiction': 1, 'neutral': 2}
def read_snli(path):
    texts1 = []
    texts2 = []
    labels = []
    with open(path, 'r') as file_:
        for line in file_:
            eg = json.loads(line)
            label = eg['gold_label']
            if label == '-':  # per Parikh, ignore - SNLI entries
                continue
            texts1.append(eg['sentence1'])
            texts2.append(eg['sentence2'])
            labels.append(LABELS[label])
    return texts1, texts2, to_categorical(np.asarray(labels, dtype='int32'))

def create_dataset(nlp, texts, hypotheses, num_unk, max_length):
    sents = texts + hypotheses

    sents_as_ids = []
    for sent in sents:
        doc = nlp(sent)
        word_ids = []

        for i, token in enumerate(doc):
            # skip odd spaces from tokenizer
            if token.has_vector and token.vector_norm == 0:
                continue

            if i > max_length:
                break

            if token.has_vector:
                word_ids.append(token.rank + num_unk + 1)
            else:
                # if we don't have a vector, pick an OOV entry
                word_ids.append(token.rank % num_unk + 1)

        # there must be a simpler way of generating padded arrays from lists...
        word_id_vec = np.zeros((max_length), dtype='int')
        clipped_len = min(max_length, len(word_ids))
        word_id_vec[:clipped_len] = word_ids[:clipped_len]
        sents_as_ids.append(word_id_vec)


    return [np.array(sents_as_ids[:len(texts)]), np.array(sents_as_ids[len(texts):])]


@plac.annotations(
    mode=("Mode to execute", "positional", None, str, ["train", "evaluate", "demo"]),
    train_loc=("Path to training data", "option", "t", str),
    dev_loc=("Path to development or test data", "option", "s", str),
    max_length=("Length to truncate sentences", "option", "L", int),
    nr_hidden=("Number of hidden units", "option", "H", int),
    dropout=("Dropout level", "option", "d", float),
    learn_rate=("Learning rate", "option", "r", float),
    batch_size=("Batch size for neural network training", "option", "b", int),
    nr_epoch=("Number of training epochs", "option", "e", int),
    entail_dir=("Direction of entailment", "option", "D", str, ["both", "left", "right"])
)
def main(mode, train_loc, dev_loc,
        max_length = 50,
        nr_hidden = 200,
        dropout = 0.2,
        learn_rate = 0.001,
        batch_size = 1024,
        nr_epoch = 10,
        entail_dir="both"):

    shape = (max_length, nr_hidden, 3)
    settings = {
        'lr': learn_rate,
        'dropout': dropout,
        'batch_size': batch_size,
        'nr_epoch': nr_epoch,
        'entail_dir': entail_dir
    }

    if mode == 'train':
        if train_loc == None or dev_loc == None:
            print("Train mode requires paths to training and development data sets.")
            sys.exit(1)
        train(train_loc, dev_loc, shape, settings)
    elif mode == 'evaluate':
        if  dev_loc == None:
            print("Evaluate mode requires paths to test data set.")
            sys.exit(1)
        correct, total = evaluate(dev_loc, shape)
        print(correct, '/', total, correct / total)
    else:
        demo(shape)

if __name__ == '__main__':
    plac.call(main)