import random
import subprocess
from math import ceil, log10
from typing import Tuple

from api.canvas_classes import *
from api.gitlab_classes import *
from api.composite_user import CompositeUser
from course import Course


def get_students() -> Set[CompositeUser]:
    filename: str
    students: Set[CompositeUser]
    file_not_found = True
    while file_not_found:
        try:
            filename = input('Please provide the name of the existing student roster file: ')
            students = CompositeUser.read_student_csv(filename)
            file_not_found = False
        except FileNotFoundError:
            print(f'File "{filename}" not found.')
    return students


# TODO: assign_partners for arbitrarily-sized teams
# TODO: break this up into bite-sized chunks
def create_pairs(students: Set[CompositeUser], groupset_name: str = 'Unknown Assignment') -> \
        List[Tuple[int, CompositeUser, CompositeUser, Optional[CompositeUser]]]:
    students_with_blacklist: Set[CompositeUser] = sorted(list(filter(lambda s: s.has_blacklist(), students)),
                                                         key=lambda t: len(t.blacklist), reverse=True)
    preassigned_students: Set[CompositeUser] = set()
    random_student = students.pop()  # TODO: remove duplication
    fields = random_student.graylist.keys()
    students.add(random_student)
    if groupset_name in fields:
        preassigned_students = set(filter(lambda s: len(s.graylist[groupset_name]) > 0, students))
    unassigned_students: Set[CompositeUser] = set(students)
    # handle student excusals
    excused_students = set(filter(lambda s: s.graylist[groupset_name] == set('X'), preassigned_students))
    # noinspection PyUnusedLocal
    confirmation: str
    # noinspection PyUnusedLocal
    student: CompositeUser
    for student in excused_students:
        confirmation = input(f'\tExclude {student.readable_name} from student pairing ([Yes]/No/Abort)? ')
        if confirmation == "" or confirmation.upper()[0] == 'Y':
            print(f'Removing {student.readable_name} from pre-assigned students and from unassigned students.')
            preassigned_students.remove(student)
            unassigned_students.remove(student)
            student.graylist[groupset_name] = set()
        elif confirmation.upper()[0] == 'N':
            print(f'Removing {student.readable_name} from pre-assigned students but leaving in unassigned students.')
            preassigned_students.remove(student)
            student.graylist[groupset_name] = set()
        else:
            print('Aborting.')
            exit(0)
    # handle truly-preassigned students
    pair_number: int = 0
    student_pairs: List[Tuple[int, CompositeUser, CompositeUser, Optional[CompositeUser]]] = []
    # noinspection PyUnusedLocal
    potential_pair: List[CompositeUser]
    if preassigned_students:
        print('First we shall confirm pre-assigned partners.')
    else:
        confirmation = input(f'There are no pre-assigned students for {groupset_name}. Proceed ([Yes]/Abort)? ')
        if not (confirmation == "" or confirmation.upper()[0] == 'Y'):
            print('Aborting.')
            exit(0)
    while preassigned_students:
        potential_pair = []
        pair_number += 1
        print(f'Preparing pair {pair_number}...')
        student = preassigned_students.pop()
        potential_pair.append(pair_number)
        potential_pair.append(student)
        potential_partners: Set[str] = student.graylist[groupset_name]
        print(f'\t{student.readable_name} ({student.canvas_username}) pre-assigned to {potential_partners}')
        while potential_partners:
            student = CompositeUser.get_user(potential_partners.pop())
            potential_pair.append(student)
            partner_potential_partners: Set[str] = student.graylist[groupset_name]
            print(f'\t{student.readable_name} ({student.canvas_username}) pre-assigned to {partner_potential_partners}')
        confirmation = input('Confirm partners [Yes]/No/Abort? ')
        if confirmation == "" or confirmation.upper()[0] == 'Y':
            # noinspection PyUnusedLocal
            pair: Tuple[int, CompositeUser, CompositeUser, Optional[CompositeUser]]
            if len(potential_pair) == 3:
                pair = (potential_pair[0], potential_pair[1], potential_pair[2], None)
            else:
                pair = (potential_pair[0], potential_pair[1], potential_pair[2], potential_pair[3])
            student_pairs.append(tuple(pair))
            for student in potential_pair[1:]:
                unassigned_students.remove(student)
                if student in preassigned_students:
                    preassigned_students.remove(student)
        elif confirmation.upper()[0] == 'N':
            print('We\'re not accepting NO for an answer yet. Goodbye.')  # TODO: accept NO for an answer
            exit(1)
        else:
            print('Aborting.')
            exit(0)
    if students_with_blacklist:
        print('Next we shall assign partners to students with blacklists.')
    else:
        print('There are no students with blacklists.')
    for student in students_with_blacklist:
        pair_number += 1
        unassigned_students.remove(student)
        potential_partner: CompositeUser = random.choice(tuple(unassigned_students))
        while not (student.is_blacklist_compatible(potential_partner) and
                   student.is_graylist_compatible(potential_partner)):
            # has the potential to run infinitely
            potential_partner = random.choice(tuple(unassigned_students))
        unassigned_students.remove(potential_partner)
        student_pairs.append((pair_number, student, potential_partner, None))
        print(f'\t{student.readable_name} partnered with {potential_partner.readable_name}')
    print('Finally we shall assign partners to the remaining students.')
    odd_student: Optional[CompositeUser] = \
        random.choice(tuple(unassigned_students)) if len(unassigned_students) % 2 == 1 else None
    if odd_student is not None:
        unassigned_students.remove(odd_student)
    while unassigned_students:
        pair_number += 1
        student = random.choice(tuple(unassigned_students))
        unassigned_students.remove(student)
        attempts = 1
        potential_partner = random.choice(tuple(unassigned_students))
        while not (student.is_graylist_compatible(potential_partner) and attempts <= len(unassigned_students)):
            attempts += 1
            potential_partner = random.choice(tuple(unassigned_students))
        if attempts > len(unassigned_students):
            print(f'NO MATCH POSSIBLE FOR {student}! YOU REALLY SHOULD WRITE CODE TO SWAP PARTNERS.')
            exit(1)  # TODO: write code to swap partners
        unassigned_students.remove(potential_partner)
        student_pairs.append((pair_number, student, potential_partner, None))
        print(f'\t{student.readable_name} partnered with {potential_partner.readable_name}')
    if odd_student is not None:
        print('Very finally, we shall now assign the odd student to an existing partnership.')
        match_found = False
        while not match_found:
            pair_number -= 1
            potential_partners: Tuple[int, CompositeUser, CompositeUser, Optional[CompositeUser]] = \
                student_pairs[pair_number]
            if potential_partners[3] is None and \
                    odd_student.is_graylist_compatible(potential_partners[1]) and \
                    odd_student.is_graylist_compatible(potential_partners[2]) and \
                    odd_student.is_blacklist_compatible(potential_partners[1]) and \
                    odd_student.is_blacklist_compatible(potential_partners[2]):
                match_found = True
                student_pairs[pair_number] = (
                    potential_partners[0], potential_partners[1], potential_partners[2], odd_student)
                print(f'\t{odd_student.readable_name} partnered with '
                      f'{potential_partners[1].readable_name} and {potential_partners[2].readable_name}')
    else:
        print('There is no odd student to add to an existing partnership.')
    # update graylists
    for pair in student_pairs:
        usernames = set(map(lambda s: s.canvas_username if isinstance(s, CompositeUser) else None, pair)) - {None}
        for student in pair[1:]:
            if student is not None:
                student.assign_partners(groupset_name, usernames - {student.canvas_username})
    return student_pairs


def save_student_roster(students: Set[CompositeUser]) -> None:
    filename = input('Please provide the name of the new student roster file: ')
    print(f'Writing {filename}.')
    CompositeUser.write_student_csv(students, filename)


def create_contact_list(groupset_name: str,
                        student_pairs: List[Tuple[int, CompositeUser, CompositeUser, Optional[CompositeUser]]]) -> None:
    filename = f'{groupset_name}-partners.md'
    print(f'Writing {filename}.')
    zero_padding: int = ceil(log10(len(partners)))
    with open(filename, mode='w') as pair_file:
        pair_file.write(f'# PARTNERS FOR ASSIGNMENT {groupset_name}\n\n')
        for pair in student_pairs:
            pair_file.write(f'-   {groupset_name} {str(pair[0]).zfill(zero_padding)}\n')
            pair_file.write(f'    -   {pair[1]}\n')
            pair_file.write(f'    -   {pair[2]}\n')
            if pair[3] is not None:
                pair_file.write(f'    -   {pair[3]}\n')


def create_repositories(groupset_name: str,
                        student_pairs: List[Tuple[int, CompositeUser, CompositeUser, Optional[CompositeUser]]]) -> None:
    filename = f'{groupset_name}-clone.sh'
    print(f'Creating file for clone script: {filename}. Creating repositories on Gitlab.')
    zero_padding: int = ceil(log10(len(partners)))
    with open(filename, mode='w') as clone_file:
        clone_file.write('#!/bin/bash\n\n')
        clone_file.write('# Auto-generated clone script.\n')
        for pair in student_pairs:
            print(f'\tCreating repo for pair number {str(pair[0]).zfill(zero_padding)}')
            project = GitlabProject.create_project_in_group(Course.gitlab_namespace,
                                                            f'{groupset_name}{str(pair[0]).zfill(zero_padding)}')
            print(f'\t\tAdding {pair[1]}')
            project.add_user_as_maintainer(pair[1].get_gitlab_user())
            print(f'\t\tAdding {pair[2]}')
            project.add_user_as_maintainer(pair[2].get_gitlab_user())
            if pair[3] is not None:
                print(f'\t\tAdding {pair[3]}')
                project.add_user_as_maintainer(pair[3].get_gitlab_user())
            repo_url = project.get_cloning_url()
            clone_file.write(f'git clone {repo_url}\n')
    subprocess.call(['chmod', '+x', filename])
    print('Repositories created')


def create_groups(groupset_name: str,
                  student_pairs: List[Tuple[int, CompositeUser, CompositeUser, Optional[CompositeUser]]]) -> None:
    print(f'Creating groupset {groupset_name} and student groups on Canvas.')
    course = CanvasCourse(Course.canvas_course_id)
    group_set = course.create_user_groupset(groupset_name)
    zero_padding: int = ceil(log10(len(partners)))
    for pair in student_pairs:
        group = group_set.create_group(f'\t{groupset_name} {str(pair[0]).zfill(zero_padding)}')
        group.add_student(pair[1].get_canvas_user())
        group.add_student(pair[2].get_canvas_user())
        if pair[3] is not None:
            group.add_student(pair[3].get_canvas_user())
    print('Canvas groups created')


if __name__ == '__main__':
    groupset: str = input('Please provide the name of the student groupset: ')
    student_set: Set[CompositeUser] = get_students()
    # TODO: check for changes to course roster
    # TODO: check for changes to gitlab usernames
    partners: List[Tuple[int, CompositeUser, CompositeUser, Optional[CompositeUser]]] = create_pairs(student_set,
                                                                                                     groupset)
    print()
    save_student_roster(student_set)
    create_contact_list(groupset, partners)
    print()
    create_repositories(groupset, partners)
    print()
    create_groups(groupset, partners)
    print()
    print('TODO:\tAdd issues')
    print('\tCommit starter code')