import csv
import json
import os
import readline
from typing import Callable

import util.convert
import util.processing
from core.models import UserAccount as User
from core.models import (ExamType, Feedback, Reviewer, Student, Submission,
                         SubmissionType, Test, Tutor)
from util.messages import info, warn
from util.processing import EmptyTest

from util.factories import STUDENTS, REVIEWERS, TUTORS, GradyUserFactory

HISTFILE = '.importer_history'
RECORDS = '.importer'
PASSWORDS = '.importer_passwords'

YES = 'Y/n'
NO = 'y/N'

valid = {"yes": True, "y": True, "ye": True, "no": False, "n": False}

ORIGIN_ORDER = {
    Feedback.WAS_EMPTY,
    Feedback.DID_NOT_COMPILE,
    Feedback.COULD_NOT_LINK,
    Feedback.FAILED_UNIT_TESTS,
}

TEST_ORDER = (
    util.processing.EmptyTest.__name__,
    util.processing.CompileTest.__name__,
    util.processing.LinkTest.__name__,
    util.processing.UnitTestTest.__name__,
)

FEEDBACK_MAPPER = dict(zip(TEST_ORDER, ORIGIN_ORDER))


class chdir_context(object):
    """
    Step into a directory temporarily.
    """

    def __init__(self, path):
        self.old_dir = os.getcwd()
        self.new_dir = path

    def __enter__(self):
        info(f'Changing to {self.new_dir}')
        os.chdir(self.new_dir)

    def __exit__(self, *args):
        info(f'Returning to {self.new_dir}')
        os.chdir(self.old_dir)


def i(prompt: str, default: str='', is_path: bool=False, is_file: bool=False):
    if default is YES or default is NO:
        answer = valid[input(f'[Q] {prompt} ({default}): ').lower() or ('y' if YES == default else 'n')]
    elif default:
        answer = input(f'[Q] {prompt} ({default}): ') or default
    else:
        answer = input(f'[Q] {prompt}: ')

    if (is_path or is_file) and not os.path.exists(answer) or is_file and not os.path.isfile(answer):
        warn(f'The {"path" if is_path else "file"} does not exist. Please try again.')
        return i(prompt, default, is_path, is_file)

    return answer

# TODO more factories

def add_user(username, group, **kwargs):
    user = GradyUserFactory()._make_base_user(
        username, group, store_pw=True, **kwargs
    )

    return user


def add_student(username, email, submissions, **kwargs):

    user = add_user(username, STUDENTS, email=email)
    student, _ = Student.objects.update_or_create(
        user=user,
        defaults={'user': user, **kwargs}
    )

    return student


def add_submission(student_obj, code, tests, type):

    submission_type = SubmissionType.objects.get(name=type)

    submission_obj, _ = Submission.objects.update_or_create(
        type=submission_type,
        student=student_obj,
        defaults={'text': code}
    )

    auto_correct, _ = User.objects.get_or_create(
        username='auto_correct',
        defaults={'is_active': False}
    )

    available_tests = util.processing.Test.available_tests()

    for name, test_data in ((name, tests[name]) for name in TEST_ORDER):
        test_obj, created = Test.objects.update_or_create(
            name=test_data['name'],
            submission=submission_obj,
            defaults={
                'label': test_data['label'],
                'annotation': test_data['annotation'],
            }
        )

        if test_obj.label == available_tests[test_obj.name].label_failure\
                and not hasattr(test_obj.submission, 'feedback')\
                and not test_obj.name == util.processing.UnitTestTest.__name__:
            Feedback.objects.update_or_create(
                of_submission=submission_obj,
                defaults={
                    'of_tutor': auto_correct,
                    'score': 0,
                    'text': test_obj.label,
                    'origin': FEEDBACK_MAPPER[test_obj.name],
                    'status': Feedback.ACCEPTED if test_obj.name == EmptyTest.__name__ else Feedback.EDITABLE,
                }
            )


def add_user_list(lst, group, **kwargs):
    for name in lst:
        add_user(name, group, **kwargs)


def call_loader(func: Callable) -> None:
    """ This function handles if a function will be executed at all. Currently
    it just checks in the RECORDS file for the name of the function. If it is
    present the function will not be executed

    Args:
        func (Callable): the loader specified below
    """
    if os.path.exists(RECORDS):
        with open(RECORDS, 'r') as records_f:
            done = [line.strip() for line in records_f]

        if func.__name__ in done and not \
                i(f'{func.__name__} has already been processed once. Proceed anyway?', NO):
            return

    func()  # This executes the specified loader

    with open(RECORDS, 'a') as records_f:
        records_f.write(func.__name__)
        records_f.write('\n')

    info(f'{func.__name__} is done.')


def do_convert_xls():

    ans = i('''Do you want to convert the ILIAS .xls output to .json?''', YES)
    if not ans:
        return

    infile = i('Please provide the path to the .xls file', is_file=True)
    outfile = i('Where should the output go?', 'submissons.json')

    json_dict = util.convert.converter(infile)
    util.convert.write_to_file(json_dict, outfile)


def do_load_submission_types():

    print(
        '''For the following import you need three files:

    1) A .csv file where the columns are: id, name, score
    2) A path to a directory where I can find sample solutions named
        <id>-lsg.c
    3) A path to a directory where I can find HTML files with an accurate
        description of the task. File name pattern has to be: <id>.html

    Example:
        $ cat submission_types.csv
        a01, Alpha Team, 10
        a02, Beta Distribution, 10
        a03, Gamma Ray, 20

        $ tree -L 2
        .
        ├── code-lsg
        │   ├── a01-lsg.c
        │   ├── a02-lsg.c
        │   └── a03-lsg.c
        └── html
            ├── a01.html
            ├── a02.html
            └── a03.html
    ''')

    path = i('Where are your files located?', '.', is_path=True)

    with chdir_context(path):
        submission_types_csv = i('CSV file', 'submission_types.csv')
        lsg_dir = i('solution dir', 'code-lsg')
        desc_dir = i('descriptions dir', 'html')

        with open(submission_types_csv, encoding='utf-8') as tfile:
            csv_rows = [row for row in csv.reader(tfile)]

        for row in csv_rows:
            tid, name, score = (col.strip() for col in row)
            with \
                    open(os.path.join(lsg_dir, tid + '-lsg.c'), encoding='utf-8') as lsg,\
                    open(os.path.join(desc_dir, tid + '.html'), encoding='utf-8') as desc:
                data = {
                    'name': name,
                    'description': desc.read(),
                    'solution': lsg.read(),
                    'full_score': int(score),
                }
            _, created = SubmissionType.objects.update_or_create(
                name=name,
                defaults=data
            )
            info(f'{"Created" if created else "Updated"} {name}')


def do_load_module_descriptions():

    print('''
    This loader imports descriptions of modules in an exam. This step is purely
    optional -- Grady works just fine without these information. If you want to
    distinguish students within one instance or give information about the
    grading type you should provide this info.

    CSV file format: module_reference, total_score, pass_score, pass_only

    Example:
        B.Inf.1801,  90, 45, yes
        B.Mat.31415, 50, 10, no
    ''')

    module_description_csv = i(
        'Where is the file?', 'modules.csv', is_file=True)

    with open(module_description_csv, encoding='utf-8') as tfile:
        csv_rows = [row for row in csv.reader(tfile)]

    for row in csv_rows:
        data = {
            field: kind(data) for field, kind, data in zip(
                ('module_reference', 'total_score', 'pass_score', 'pass_only'),
                (str, int, int, lambda x: x == 'yes'),
                (col.strip() for col in row)
            )
        }

        _, created = ExamType.objects.update_or_create(
            module_reference=data['module_reference'],
            defaults=data,
        )

        info(f'{"Created" if created else "Updated"} ExamType {data["module_reference"]}')


def do_preprocess_submissions():

    print('''
    Preprocessing might take some time depending on the amount of data
    and the complexity of the programs and the corresponding unit tests. You can
    specify what test you want to run.

    Tests do depend on each other. Therefore specifying a test will also
    result in running all its dependencies\n''')

    test_enum = dict(enumerate(util.processing.Test.available_tests()))

    print('The following test are available:\n')
    print('\t[q] Do nothing')
    for j, test in test_enum.items():
        print(f'\t[{j}] {test}')
    print()

    answer = i('Which tests do you want to run?')

    if not answer or answer == 'q':
        return

    raise NotImplementedError


def do_load_submissions():

    file = i('Get me the file with all the submissions', 'submissions.json')

    exam = {}
    if ExamType.objects.all() and i('Do you want to add module/exam information?', NO):
        exam_query_set = ExamType.objects.all()
        print('You have the following choices:\n')
        for j, exam_type in enumerate(exam_query_set):
            print(f'\t[{j}] {exam_type.module_reference}')
        print()

        exam = i('Choose wisely')
        exam = {'exam': exam_query_set[int(exam)]}

    with open(file) as submission_file:
        submissions = json.JSONDecoder().decode(submission_file.read())

    for username, data in submissions.items():
        student_obj = make_student(username, **exam, **data)

        for submission_obj in data['submissions']:
            add_submission(student_obj, **submission_obj)


def do_load_tutors():

    print('Please import tutor users by providing one name per line')
    tutors = i('List of tutors', 'tutors', is_file=True)

    with open(tutors) as tutors_f:
        add_user_list(tutors_f, TUTORS)


def do_load_reviewer():

    print('Please import reviewer users by providing one name per line')
    reviewers = i('List of reviewers', 'reviewers', is_file=True)

    with open(reviewers) as reviewers_f:
        add_user_list(reviewers_f, REVIEWERS, is_staff=True)


call_order = (
    do_convert_xls,
    do_load_submission_types,
    do_load_module_descriptions,
    do_preprocess_submissions,
    do_load_submissions,
    do_load_tutors,
    do_load_reviewer
)


def start():

    if os.path.exists(HISTFILE):
        readline.read_history_file(HISTFILE)

    print('''Welcome to the Grady importer!

    This script aims at making the setup of the database as easy as possible. It
    at the same time serves as a documentation on how data is imported in Grady.
    Let\'s dive right in.\n''')

    try:
        print('The following importers are available:\n')
        for fid, func in enumerate(call_order):
            print(f'\t[{fid}] {func.__name__}')
        print('\t[q] exit')
        print()

        fid = i('Choose a number or hit enter to start at the beginning')

        if not fid:
            for func in call_order:
                call_loader(func)
        elif fid in ('q', 'quit', 'exit'):
            return
        elif not 0 <= int(fid) < len(call_order):
            warn('There is no loader with this number')
        else:
            call_loader(call_order[int(fid)])

    except (EOFError, KeyboardInterrupt) as err:
        print()
        return
    except Exception as err:
        import traceback
        traceback.print_exc()
    finally:
        readline.write_history_file(HISTFILE)