# Contributors:
# Christopher P. Barnes <senrabc@gmail.com>
# Andrei Sura: github.com/indera
# Mohan Das Katragadda <mohan.das142@gmail.com>
# Philip Chase <philipbchase@gmail.com>
# Ruchi Vivek Desai <ruchivdesai@gmail.com>
# Taeber Rapczak <taeber@ufl.edu>
# Nicholas Rejack <nrejack@ufl.edu>
# Josh Hanna <josh@hanna.io>
# Copyright (c) 2014-2015, University of Florida
# All rights reserved.
#
# Distributed under the BSD 3-Clause License
# For full text of the BSD 3-Clause License see http://opensource.org/licenses/BSD-3-Clause

"""
Functions related to uploading data to REDCap
"""

import ast
import collections
import datetime
import logging
import os

from lxml import etree
from redcap import RedcapError

from utils import throttle

logger = logging.getLogger(__name__)
logger.addHandler(logging.NullHandler())


def create_import_data_json(import_data_dict, event_tree):
    """
    Convert data from event_tree to json format.

    @TODO: evaluate performance
    @see the caller {@link #redi.upload.generate_output()}

    :param: import_data_dict: holds the event tree data
    :param: event_tree: holds the event tree data
    :rtype: dict
    :return the json version of the xml data
    """

    root = event_tree

    event_name = root.find('name')
    if event_name is None or not event_name.text:
        raise Exception('Expected non-blank element event/name')

    import_data_dict['redcap_event_name'] = event_name.text

    event_field_value_list = root.xpath('//event/field/name')

    for name in event_field_value_list:
        if name.text is None:
            raise Exception(
                'Expected non-blank element event/field/name')

    # Match all fields to build a row for each
    event_field_list = root.xpath('field')
    contains_data = False

    for field in event_field_list:
        val = field.findtext('value', '')
        import_data_dict[field.findtext('name')] = val

        if val and not contains_data:
            contains_data = True

    return {'json_data': import_data_dict, 'contains_data': contains_data}


def create_redcap_records(import_data):
    """
    Creates REDCap records from RED-I's form data, AKA import data.

    REDCap API only accepts records for importing. Records are differentiated by
    their unique record ID, unless the REDCap Project is a Longitudinal study.
    In that case, they are differentiated by a combination of record ID and an
    event.

    Since RED-I views the world in terms of forms, we have to project our
    form-centric view into REDCap's record-centric world. This is done by
    combining all form data with the same Subject ID and Event Name into the
    same record.

    :param import_data: iterable of 4-tuples: (study_id_key, form_name,
        event_name, json_data_dict)
    :return: iterable of REDCap records ready for upload
    """
    records_by_subject_and_event = collections.defaultdict(dict)
    for subject_id_key, _, event_name, record in import_data:
        records_by_subject_and_event[subject_id_key, event_name].update(record)
    return records_by_subject_and_event.itervalues()


def generate_output(person_tree, redcap_client, rate_limit, sent_events,
    max_retry_count, skip_blanks=False, bulk_send_blanks=False):
    """
    Note: This function communicates with the redcap application.
    Steps:
        - loop for each person/form/event element
        - generate a csv fragment `using create_eav_output`
        - send csv fragment to REDCap using `send_eav_data_to_redcap`

    @see the caller {@link #redi.redi._run()}

    :rtype:     dictionary
    :return:    the report_data which is passed to the report rendering function
    """

    # the global dictionary to be returned
    report_data = {
        'errors': []
    }

    """
     For each person we keep a count for each form type:
        subject_details = array(
            'person_A' => array('form_1': 1, 'form_2': 10, ...
            'person_B' => array('form_1': 1, 'form_2': 10, ...
            ...
        )
    """
    subject_details = {}

    # For each form type we keep a global count
    form_details = {}

    # count how many `person` elements are parsed
    person_count = 0

    root = person_tree.getroot()
    persons = root.xpath('//person')

    upload_data = throttle.Throttle(redcap_client.send_data_to_redcap,
                                    int(rate_limit))

    blanks = []

    # main loop for each person
    for person in persons:
        time_begin = datetime.datetime.now()
        person_count += 1
        study_id = (person.xpath('study_id') or [None])[0]

        if study_id is None:
            raise Exception('Expected a valid value for study_id')

        # count how many csv fragments are created per person
        event_count = 0
        logger.info('Start sending data for study_id: %s' % study_id.text)

        forms = person.xpath('./all_form_events/form')

        # loop through the forms of one person
        for form in forms:
            form_name = form.xpath('name')[0].text
            form_key = 'Total_' + form_name + '_Forms'
            study_id_key = study_id.text

            # init dictionary for a new person in (study_id)
            if study_id_key not in subject_details:
                subject_details[study_id_key] = {}
                subject_details[study_id_key]['lab_id'] = person.get('lab_id')

            if not form_key in subject_details[study_id_key]:
                subject_details[study_id_key][form_key] = 0

            if form_key not in form_details:
                form_details[form_key] = 0

            logger.debug(
                'parsing study_id ' +
                study_id.text +
                ' form: ' +
                form_name)

            # loop through the events of one form
            for event in form.xpath('event'):
                event_name = event.findtext('name', '')
                assert event_name, "Missing name for form event"

                try:
                    import_dict = {
                        redcap_client.project.def_field: study_id.text}
                    import_dict = create_import_data_json(
                        import_dict,
                        event)
                    json_data_dict = import_dict['json_data']
                    contains_data = import_dict['contains_data']

                    if sent_events.was_sent(study_id_key, form_name, event_name):
                        logger.debug("Skipping previously sent " + event_name)
                        if contains_data:
                            # if no error_strings encountered update event counters
                            subject_details[study_id_key][form_key] += 1
                            form_details[form_key] += 1
                        continue

                    is_blank = not contains_data
                    if is_blank:
                        if skip_blanks:
                            # assume subsequent events for this form and subject
                            # are blank and simply move on to the next form by
                            # breaking out of the events-loop
                            break

                        if bulk_send_blanks:
                            blanks.append((study_id_key, form_name, event_name,
                                           json_data_dict))
                            continue

                    event_count += 1
                    if (0 == event_count % 50):
                        logger.info('Requests sent: %s' % (event_count))

                    # to speedup testing uncomment the following line
                    # if (0 == event_count % 2) : continue

                    try:
                        upload_data([json_data_dict], max_retry_count,
                            overwrite=True)
                        sent_events.mark_sent(study_id_key, form_name, event_name)
                        logger.debug("Sent " + event_name)
                        if contains_data:
                            # if no errors encountered update event counters
                            subject_details[study_id_key][form_key] += 1
                            form_details[form_key] += 1
                    except RedcapError as redcap_err:
                        handle_errors_in_redcap_xml_response(study_id, redcap_err, report_data)

                except Exception as e:
                    logger.error(e.message)
                    raise

        time_end = datetime.datetime.now()
        logger.info("Total execution time for study_id %s was %s" % (study_id_key, (time_end - time_begin)))
        logger.info("Total REDCap requests sent: %s \n" % (event_count))

    if blanks:
        logger.info("Sending blank forms in bulk...")
        records = list(create_redcap_records(blanks))

        try:
            response = upload_data(records, overwrite=True)
            for study_id_key, form_name, event_name, record in blanks:
                sent_events.mark_sent(study_id_key, form_name, event_name)
            logger.info("Sent {} blank form-events.".format(response['count']))

        except RedcapError as redcap_err:
            logger.error("Failed to send blank form-events.")
            handle_errors_in_redcap_xml_response(study_id, redcap_err, report_data)

    report_data.update({
        'total_subjects': person_count,
        'form_details': form_details,
        'subject_details': subject_details,
        'errors': report_data['errors']
    })

    logger.debug('report_data ' + repr(report_data))
    return report_data


def handle_errors_in_redcap_xml_response(study_id, redcap_err, report_data):
    """
    Checks for any errors in the redcap response and update
    report data if there are any errors.

    Parameters:
    -----------
    redcap_err: RedcapError object
    report_data: dictionary to which we store error details
    """

    # converting string to dictionary
    response = ast.literal_eval(str(redcap_err))
    logger.debug('handling response from the REDCap')

    if 'error' not in response:
        logger.warn("RedcapError does not contain the expected 'error' key: {}"
                .format(response))
        return