from dataclasses import dataclass
from typing import List, Set

from vbv_lernwelt.core.models import User
from vbv_lernwelt.course.models import CourseSession, CourseSessionUser
from vbv_lernwelt.course_session_group.models import CourseSessionGroup
from vbv_lernwelt.learning_mentor.models import LearningMentor


@dataclass(frozen=True)
class CourseSessionWithRoles:
    _original: CourseSession
    roles: Set[str]

    def __getattr__(self, name: str):
        # Delegate attribute access to the _original CourseSession object
        return getattr(self._original, name)

    def save(self, *args, **kwargs):
        raise NotImplementedError("This proxy object cannot be saved.")


def get_course_sessions_with_roles_for_user(user: User) -> List[CourseSessionWithRoles]:
    result_course_sessions = {}

    # participant/member/expert course sessions
    csu_qs = CourseSessionUser.objects.filter(user=user).prefetch_related(
        "course_session", "course_session__course"
    )
    for csu in csu_qs:
        cs = csu.course_session
        # member/expert is mutually exclusive...
        cs.roles = {csu.role}
        result_course_sessions[cs.id] = cs

    # enrich with supervisor course sessions
    csg_qs = CourseSessionGroup.objects.filter(supervisor=user).prefetch_related(
        "course_session", "course_session__course"
    )
    for csg in csg_qs:
        for cs in csg.course_session.all():
            cs.roles = set()
            cs = result_course_sessions.get(cs.id, cs)

            cs.roles.add("SUPERVISOR")
            result_course_sessions[cs.id] = cs

    # enrich with mentor course sessions
    lm_qs = LearningMentor.objects.filter(mentor=user).prefetch_related(
        "course_session", "course_session__course"
    )
    for lm in lm_qs:
        cs = lm.course_session
        cs.roles = set()
        cs = result_course_sessions.get(cs.id, cs)

        cs.roles.add("LEARNING_MENTOR")
        result_course_sessions[cs.id] = cs

    return [
        CourseSessionWithRoles(cs, cs.roles) for cs in result_course_sessions.values()
    ]


def has_cs_role(roles: Set[str]) -> bool:
    return bool(roles & {"SUPERVISOR", "EXPERT", "MEMBER"})


def user_role(roles: Set[str]) -> str:
    if "SUPERVISOR" in roles:
        return "SUPERVISOR"
    if "EXPERT" in roles:
        return "EXPERT"
    if "MEMBER" in roles:
        return "MEMBER"
    return "LEARNING_MENTOR"


def create_course_session_dict(course_session_object, my_role, user_role):
    return {
        "id": str(course_session_object.id),
        "session_title": course_session_object.title,
        "course_id": str(course_session_object.course.id),
        "course_title": course_session_object.course.title,
        "course_slug": course_session_object.course.slug,
        "region": course_session_object.region,
        "generation": course_session_object.generation,
        "my_role": my_role,
        "user_role": user_role,
        "is_uk": course_session_object.course.configuration.is_uk,
        "is_vv": course_session_object.course.configuration.is_vv,
    }


def create_person_list_with_roles(
    user, course_session_ids=None, include_private_data=False
):
    def create_user_dict(user_object):
        user_data = {
            "user_id": user_object.id,
            "first_name": user_object.first_name,
            "last_name": user_object.last_name,
            "email": user_object.email,
            "avatar_url_small": user_object.avatar_url_small,
            "avatar_url": user_object.avatar_url,
            "course_sessions": [],
        }
        if include_private_data:
            user_data["phone_number"] = user_object.phone_number
            user_data["Lehrvertragsnummer"] = user_object.additional_json_data.get(
                "Lehrvertragsnummer", ""
            )

        return user_data

    course_sessions = get_course_sessions_with_roles_for_user(user)

    result_persons = {}
    for cs in course_sessions:
        if has_cs_role(cs.roles) and cs.course.configuration.is_uk:
            course_session_users = CourseSessionUser.objects.filter(
                course_session=cs.id
            ).select_related("user")
            my_role = user_role(cs.roles)
            for csu in course_session_users:
                person_data = result_persons.get(
                    csu.user.id, create_user_dict(csu.user)
                )
                person_data["course_sessions"].append(
                    create_course_session_dict(cs, my_role, csu.role)
                )
                result_persons[csu.user.id] = person_data

    # add persons where request.user is mentor
    for cs in course_sessions:
        if "LEARNING_MENTOR" in cs.roles:
            lm = LearningMentor.objects.filter(
                mentor=user, course_session=cs.id
            ).first()

            for participant in lm.participants.all():
                course_session_entry = create_course_session_dict(
                    cs,
                    "LEARNING_MENTOR",
                    "LEARNING_MENTEE",
                )

                if participant.user.id not in result_persons:
                    person_data = create_user_dict(participant.user)
                    person_data["course_sessions"] = [course_session_entry]
                    result_persons[participant.user.id] = person_data
                else:
                    # user is already in result_persons
                    result_persons[participant.user.id]["course_sessions"].append(
                        course_session_entry
                    )

    # add persons where request.user is mentee
    mentor_relation_qs = LearningMentor.objects.filter(
        participants__user=user
    ).prefetch_related("mentor", "course_session")
    for mentor_relation in mentor_relation_qs:
        cs = mentor_relation.course_session
        course_session_entry = create_course_session_dict(
            cs,
            "LEARNING_MENTEE",
            "LEARNING_MENTOR",
        )

        if mentor_relation.mentor.id not in result_persons:
            person_data = create_user_dict(mentor_relation.mentor)
            person_data["course_sessions"] = [course_session_entry]
            result_persons[mentor_relation.mentor.id] = person_data
        else:
            # user is already in result_persons
            result_persons[mentor_relation.mentor.id]["course_sessions"].append(
                course_session_entry
            )
    return result_persons.values()