import base64
import json
import os
import re
import time
import logging

from google.cloud import pubsub_v1, translate, storage


def doTranslation(translate_client, project_id, text, src_lang="it", target_lang="en-US"):
    """

    Args:
        text: str -
        src_lang: str - default it
        target_lang: str - default en

    Returns:
        translated_txt: txt - response from translate API
    """
    logging.info('Translating text into {}.'.format(target_lang))

    parent = translate_client.location_path(project_id, location="global")

    # Detail on supported types can be found here:
    # https://cloud.google.com/translate/docs/supported-formats
    translated_dict = translate_client.translate_text(parent=parent,
                                                      contents=[text],
                                                      mime_type="text/plain",
                                                      source_language_code=src_lang,
                                                      target_language_code=target_lang)

    for translation in translated_dict.translations:
        translated_txt = translation.translated_text
    return translated_txt


def publishMsg(publisher_client, project_id, text, doc_title, topic_name):
    """
    Publish message with text and doc_title.
    Args:
        text: str - Text contained in the document
        doc_title: str -
        topic_name: str -

    Returns:

    """

    # Compose the message to be sent to pubsub
    message = {
        'text': text,
        'doc_title': doc_title,
    }

    # Note: the message_data needs to be in bytestring
    # Refer to the documentation:
    # https://googleapis.dev/python/pubsub/latest/publisher/api/client.html
    message_data = json.dumps(message).encode('utf-8')
    topic_path = publisher_client.topic_path(project_id, topic_name)

    # Publish method returns a future instance
    future = publisher_client.publish(topic_path, data=message_data)

    # We need to call result method to extract the message ID
    # Refer to the documentation:
    # https://googleapis.dev/python/pubsub/latest/publisher/api/futures.html#google.cloud.pubsub_v1.publisher.futures.Future
    message_id = future.result()

    logging.info("Message id: {} was published in topic: {}".format(message_id, topic_name))


def uploadBlob(storage_client, bucket_name, txt_content, destination_blob_name):
    """
    Uploads a file to the bucket.
    Args:
        storage_client:
        bucket_name:
        txt_content: str - text
        destination_blob_name: str - prefix

    Returns:

    """
    destination_blob_name = destination_blob_name.split('gs://{}/'.format(bucket_name))[-1]
    bucket_client = storage_client.bucket(bucket_name)
    blob = bucket_client.blob(destination_blob_name)

    blob.upload_from_string(txt_content)

    logging.info("Text uploaded to {}".format(destination_blob_name))


def cleanEngText(eng_raw_string, customize_stop_words=[]):
    """

    Args:
        eng_raw_string: str -
        customize_stop_words: list - all stopwords to remove

    Returns:
        refined_doc: str - curated string of eng text
    """

    # Remove dates
    # 1 or 2 digit number followed by back slash followed by 1 or 2 digit number ...
    pattern_dates = '(\d{1,2})/(\d{1,2})/(\d{4})'
    pattern_fig = 'Figure (\d{1,2})'
    pattern_image = '^Image .$'
    replace = ''

    eng_raw_string = re.sub(pattern_dates, replace, eng_raw_string)
    eng_raw_string = re.sub(pattern_fig, replace, eng_raw_string)
    eng_raw_string = re.sub(pattern_image, replace, eng_raw_string)

    # remove punctuation and special characters
    eng_raw_string = re.sub("[^A-Za-z0-9]+", ' ', eng_raw_string)

    # Remove custom stop words
    tokens = [token for token in eng_raw_string.split() if token not in customize_stop_words]

    refined_doc = ''
    for word in tokens:
        refined_doc += ' {}'.format(word)

    return refined_doc


def translateAndRefine(event, context):
    """
    This Cloud Function will be triggered when a message is published on the
    PubSub topic of interest. It will call Translate API.
    args:
        event (dict): Metadata of the event, received from Pub/Sub.
        context (google.cloud.functions.Context): Metadata of triggering event.
    returns:
        None; the output is written to stdout and Stackdriver Logging
    """
    # INSTANTIATION
    translate_client = translate.TranslationServiceClient()
    publisher_client = pubsub_v1.PublisherClient()
    storage_client = storage.Client()

    # SET VARIABLES
    project_id = os.environ['GCP_PROJECT']
    #RESULT_TOPIC = "it2eng"

    start_time = time.time()
    if event.get('data'):
        message_data = base64.b64decode(event['data']).decode('utf-8')
        message = json.loads(message_data)
    else:
        raise ValueError('Data sector is missing in the Pub/Sub message.')

    it_text = message.get('text')
    doc_title = message.get('doc_title')

    # Step 1: Call Translate API
    raw_eng_text = doTranslation(translate_client,project_id, it_text)

    # Step 2: Clean eng text
    curated_eng_text = cleanEngText(raw_eng_text)

    # Step 3: Publish pub/sub
    # topic_name = RESULT_TOPIC
    # publishMsg(publisher_client, project_id, curated_eng_text, doc_title, topic_name)

    # Step 4: Upload translated text
    dest_bucket = 'covid19-repo-test'
    prefix_raw_eng_txt = 'eng_txt/{}.txt'.format(doc_title)
    uploadBlob(storage_client, dest_bucket, raw_eng_text, prefix_raw_eng_txt)

    prefix_curated_eng_txt = 'curated_eng_txt/{}.txt'.format(doc_title)
    uploadBlob(storage_client, dest_bucket, curated_eng_text, prefix_curated_eng_txt)

    end_time = time.time() - start_time
    logging.info("Completion of text_extract took: {} seconds".format(round(end_time, 1)))