from dataclasses import dataclass
from datetime import datetime
from io import BytesIO

import structlog
from django.utils import timezone
from django.utils.translation import gettext_lazy as _
from openpyxl import Workbook

from vbv_lernwelt.assignment.models import (
    Assignment,
    AssignmentCompletion,
    AssignmentType,
)
from vbv_lernwelt.course.models import CourseSession, CourseSessionUser
from vbv_lernwelt.course_session.models import (
    CourseSessionAssignment,
    CourseSessionEdoniqTest,
)
from vbv_lernwelt.course_session.services.export_attendance import (
    add_user_export_data,
    add_user_headers,
    get_ordered_csus_by_course_session,
    group_by_session_title,
    make_export_filename,
    sanitize_sheet_name,
)
from vbv_lernwelt.learnpath.models import LearningContent

logger = structlog.get_logger(__name__)

COMPETENCE_ELEMENT_EXPORT_FILE_NAME = _("export_kompetenznachweis_elemente")


@dataclass
class CompetenceCertificateElement:
    assignment: Assignment
    # date: DueDate
    sort_datetime: datetime
    learning_content: LearningContent
    course_session: CourseSession


def export_competence_elements(
    course_session_ids: list[str],
    circle_ids: list[int] = None,
    user_ids: list[str] = None,
    save_as_file: bool = False,
):
    if len(course_session_ids) == 0:
        return

    COMPETENCE_ASSIGNMENT_TYPES = [
        AssignmentType.CASEWORK.value,
        AssignmentType.EDONIQ_TEST.value,
    ]

    wb = Workbook()
    # remove the first sheet is just easier than keeping track of the active sheet
    wb.remove(wb.active)

    competence_certificate_elements = _get_competence_certificate_elements(
        course_session_ids
    )

    assignment_completions = AssignmentCompletion.objects.filter(
        course_session_id__in=course_session_ids,
        assignment__assignment_type__in=COMPETENCE_ASSIGNMENT_TYPES,
    ).order_by("course_session", "assignment")
    if user_ids:
        assignment_completions = AssignmentCompletion.objects.filter(
            assignment_user_id__in=user_ids if user_ids else [],
        ).order_by("course_session", "assignment")

    # group all by the sessions title {session_id1: [...], session_id2: [...], ...}
    grouped_cs_users = get_ordered_csus_by_course_session(
        course_session_ids, user_ids=user_ids
    )
    grouped_cce = group_by_session_title(competence_certificate_elements)
    grouped_ac = group_by_session_title(assignment_completions)

    # create a sheet for each course session
    for course_session_title, cs_users in grouped_cs_users.items():
        logger.debug(
            "export_assignment_completion",
            data={
                "course_session": course_session_title,
            },
            label="assignment_export",
        )

        # handle the case where there are no competence certificate elements for the course session
        try:
            cces = grouped_cce[course_session_title]
        except KeyError:
            cces = []

        try:
            acs = grouped_ac[course_session_title]
        except KeyError:
            acs = []

        _create_sheet(
            wb,
            course_session_title,
            cs_users,
            cces,
            acs,
            circle_ids,
        )

    if save_as_file:
        wb.save(make_export_filename(COMPETENCE_ELEMENT_EXPORT_FILE_NAME))
    else:
        output = BytesIO()
        wb.save(output)

        output.seek(0)
        return output.getvalue()


def _create_sheet(
    wb: Workbook,
    title: str,
    users: list[CourseSessionUser],
    competence_certificate_element: list[CompetenceCertificateElement],
    assignment_completions: list[AssignmentCompletion],
    circle_ids: list[int],
):
    sheet = wb.create_sheet(title=sanitize_sheet_name(title))

    if len(users) == 0 or len(competence_certificate_element) == 0:
        return sheet

    # headers
    # common user headers, Circle <title> <learningcontenttitle> bestanden,  Circle <title> <learningcontenttitle> Resultat, ...
    col_idx = add_user_headers(sheet)

    ordered_assignement_ids = []  # keep track of the order of the columns when adding the rows
    for cse in competence_certificate_element:
        circle = cse.learning_content.get_circle()

        if circle_ids and circle.id not in circle_ids:
            continue

        col_prefix = f'Circle "{circle.title}" {cse.learning_content.title}'

        # add translation strings here as they are not picked up in f-strings
        result_str = str(_("Resultat"))
        success_str = str(_("bestanden"))

        sheet.cell(
            row=1,
            column=col_idx,
            value=f"{col_prefix} {success_str}",
        )

        sheet.cell(
            row=1,
            column=col_idx + 1,
            value=f"{col_prefix} {result_str} %",
        )

        ordered_assignement_ids.append(cse.assignment.id)

        col_idx += 2

    # add rows with user results
    _add_rows(sheet, users, ordered_assignement_ids, assignment_completions)

    return sheet


def _add_rows(
    sheet,
    users: list[CourseSessionUser],
    ordered_assignement_ids,
    assignment_completions,
):
    for row_idx, user in enumerate(users, start=2):
        col_idx = add_user_export_data(sheet, user, row_idx)

        for assignment_id in ordered_assignement_ids:
            # get the completion for the user and the assignment
            user_acs = [
                ac
                for ac in assignment_completions
                if ac.assignment_id == assignment_id and ac.assignment_user == user.user
            ]
            user_ac = user_acs[0] if user_acs else None

            if user_ac:
                status_text = (
                    str(_("Bestanden"))
                    if user_ac.evaluation_passed
                    else str(_("Nicht bestanden"))
                )
                sheet.cell(row=row_idx, column=col_idx, value=status_text)
                try:
                    sheet.cell(
                        row=row_idx,
                        column=col_idx + 1,
                        value=round(
                            100
                            * user_ac.evaluation_points
                            / user_ac.evaluation_max_points
                        ),
                    )
                except (ZeroDivisionError, TypeError):
                    sheet.cell(
                        row=row_idx, column=col_idx + 1, value=str(_("Keine Daten"))
                    )

            else:
                sheet.cell(row=row_idx, column=col_idx, value=str(_("Keine Daten")))
                sheet.cell(row=row_idx, column=col_idx + 1, value=str(_("Keine Daten")))

            col_idx += 2


def _get_competence_certificate_elements(
    course_session_ids: list[str],
) -> list[CompetenceCertificateElement]:
    course_session_assignments = CourseSessionAssignment.objects.filter(
        course_session__id__in=course_session_ids,
        learning_content__content_assignment__competence_certificate__isnull=False,
    ).order_by("course_session", "submission_deadline__start")

    course_session_edoniqtests = CourseSessionEdoniqTest.objects.filter(
        course_session__id__in=course_session_ids,
        learning_content__content_assignment__competence_certificate__isnull=False,
    ).order_by("course_session", "deadline__start")

    cse = [
        CompetenceCertificateElement(
            assignment=csa.learning_content.content_assignment,
            sort_datetime=csa.submission_deadline.start or timezone.now(),
            learning_content=csa.learning_content,
            course_session=csa.course_session,
        )
        for csa in course_session_assignments
    ]

    cse += [
        CompetenceCertificateElement(
            assignment=cset.learning_content.content_assignment,
            sort_datetime=cset.deadline.start or timezone.now(),
            learning_content=cset.learning_content,
            course_session=cset.course_session,
        )
        for cset in course_session_edoniqtests
    ]

    # order by course_session and submission_deadline
    cse.sort(key=lambda x: (x.course_session.title, x.sort_datetime))

    return cse