from flask import flash, redirect, request, url_for
from flask_admin import AdminIndexView, BaseView, expose
from flask_admin.contrib.sqla import ModelView
from flask_admin.helpers import get_form_data
from flask_admin.model.helpers import get_mdict_item_or_list
from flask_admin.model.template import EndpointLinkRowAction
from flask_security import current_user
from sqlalchemy import and_

from advlabdb.dependent_funs import reportBadAttempt, userActiveSemester
from advlabdb.exceptions import DataBaseException, ModelViewException
from advlabdb.models import (
    Assistant,
    ExperimentMark,
    GroupExperiment,
    Part,
    PartStudent,
    SemesterExperiment,
)


def adminViewIsAccessible():
    return current_user.has_role("admin")


def assistantViewIsAccessible():
    return current_user.has_role("assistant")


class CustomIndexView(AdminIndexView):
    def inaccessible_callback(self, name, **kwargs):
        # Redirect to login page if user doesn't have access
        return redirect(url_for("security.login", next=request.url))


class SecureAdminIndexView(CustomIndexView):
    def is_accessible(self):
        return adminViewIsAccessible()

    @expose("/")
    def index(self):
        active_semester_experiment_marks_query = ExperimentMark.query.filter(
            ExperimentMark.part_student.has(PartStudent.part.has(Part.semester == userActiveSemester()))
        )

        number_of_all_experiment_marks = active_semester_experiment_marks_query.count()

        number_of_missing_final_experiment_marks = active_semester_experiment_marks_query.filter(
            ExperimentMark.final_experiment_mark == None
        ).count()

        return self.render(
            "admin_index.html",
            number_of_missing_final_experiment_marks=number_of_missing_final_experiment_marks,
            number_of_all_experiment_marks=number_of_all_experiment_marks,
        )


class SecureAssistantIndexView(CustomIndexView):
    def is_accessible(self):
        return assistantViewIsAccessible()

    @expose("/")
    def index(self):
        active_semester_experiment_marks_query = ExperimentMark.query.filter(
            ExperimentMark.group_experiment.has(
                GroupExperiment.semester_experiment.has(
                    and_(
                        SemesterExperiment.semester == userActiveSemester(),
                        SemesterExperiment.assistants.any(Assistant.user == current_user),
                    )
                )
            )
        )

        number_of_all_experiment_marks = active_semester_experiment_marks_query.count()

        number_of_missing_final_experiment_marks = active_semester_experiment_marks_query.filter(
            ExperimentMark.final_experiment_mark == None
        ).count()

        return self.render(
            "assistant_index.html",
            number_of_missing_final_experiment_marks=number_of_missing_final_experiment_marks,
            number_of_all_experiment_marks=number_of_all_experiment_marks,
        )


class CustomModelView(ModelView):
    create_modal = True
    edit_modal = True
    details_modal = True

    can_view_details = False

    def inaccessible_callback(self, name, **kwargs):
        # Redirect to login page if user doesn't have access
        return redirect(url_for("security.login", next=request.url))

    def get_query(self):
        if not hasattr(self, "queryFilter"):
            return super().get_query()

        return super().get_query().filter(self.queryFilter())

    def get_count_query(self):
        if not hasattr(self, "queryFilter"):
            return super().get_count_query()

        return super().get_count_query().filter(self.queryFilter())

    def handle_view_exception(self, exc):
        if type(exc) in (ModelViewException, DataBaseException):
            flash(str(exc), "error")
            return True

        return super().handle_view_exception(exc)

    def create_model(self, form):
        if not hasattr(self, "customCreateModel"):
            return super().create_model(form)

        try:
            model = self.customCreateModel(form)

            self.session.add(model)

            self.on_model_change(form, model, True)

            self.session.commit()
        except Exception as ex:
            flash(str(ex), "error")

            self.session.rollback()
        else:
            self.after_model_change(form, model, True)

            return model

    def create_form(self, obj=None):
        if hasattr(self, "CreateForm"):
            formClass = self.CreateForm
        elif hasattr(self, "CreateAndEditForm"):
            formClass = self.CreateAndEditForm
        else:
            return super().create_form(obj)

        return formClass(get_form_data(), obj=obj)

    def edit_form(self, obj=None):
        if hasattr(self, "EditForm"):
            formClass = self.EditForm
        elif hasattr(self, "CreateAndEditForm"):
            formClass = self.CreateAndEditForm
        else:
            return super().edit_form(obj)

        return formClass(get_form_data(), obj=obj)


class SecureAdminModelView(CustomModelView):
    can_export = True
    can_set_page_size = True

    can_create = True
    can_edit = True
    can_delete = True
    column_display_actions = True

    list_template = "admin_list.html"
    create_template = "admin_create.html"
    edit_template = "admin_edit.html"
    details_template = "admin_details.html"

    def is_accessible(self):
        return adminViewIsAccessible()


class SecureAssistantModelView(CustomModelView):
    can_export = False
    can_set_page_size = False

    can_edit = False
    column_display_actions = False

    list_template = "assistant_list.html"
    create_template = "assistant_create.html"
    edit_template = "assistant_edit.html"
    details_template = "assistant_details.html"

    """
    SECURITY NOTES:
    - Every variable and method defined below in this class is NOT ALLOWED TO BE (completely) OVERWRITTEN!
    You can only extend the predefined methods.
    - The method queryFilter(self) has to be implemented!
    """

    # Assistants are not allowed to create or delete.
    can_create = False
    can_delete = False

    def is_accessible(self):
        return assistantViewIsAccessible()

    def queryFilter(self):
        """
        A default filter has to be implemented to restrict assistants read/write access.
        See on_model_change!
        """
        raise NotImplementedError()

    def on_model_change(self, form, model, is_created):
        """
        This method uses the filter returned by queryFilter (which has to be implemented!) to prevent assistants
        from modifying models not listed on their view by sending a POST request with a different id.
        You can extend this method by implementing a custom on_model_change and then calling super().on_model_change within it.
        """
        if is_created:
            reportBadAttempt("An assistant tried to create a model!")
            raise ModelViewException("Assistants can not create models!")

        if model not in self.get_query():
            reportBadAttempt("An assistant tried to change a model not in his filter!")
            raise ModelViewException("Unauthorized action!")

    def on_model_delete(self, model):
        reportBadAttempt("An assistant tried to delete a model!")
        raise ModelViewException("Assistants can not delete models!")

    @expose("/edit/", methods=("GET", "POST"))
    def edit_view(self):
        """
        Prevent an assistant from seeing the edit form of a model not in his filter by using the GET method and entering an id.
        This is important if can_edit is set to True.
        """
        id = get_mdict_item_or_list(request.args, "id")

        if id is not None:
            model = self.get_one(id)

            if model not in self.get_query():
                reportBadAttempt("An assistant tried to edit a model not in his filter!")
                raise ModelViewException("Unauthorized action!")

        return super().edit_view()

    @expose("/details/")
    def details_view(self):
        """
        Prevent an assistant from seeing the details of a model not in his filter by using the GET method and entering an id.
        This is important if can_view_details is set to True.
        """
        id = get_mdict_item_or_list(request.args, "id")

        if id is not None:
            model = self.get_one(id)

            if model not in self.get_query():
                reportBadAttempt("An assistant tried to see details of a model not in his filter!")
                raise ModelViewException("Unauthorized action!")

        return super().details_view()

    def get_details_columns(self):
        """
        Prevent showing unintended data if can_view_details is set to True and column_details_list was not set (which equals None).
        """
        if not self.column_details_list:
            self.column_details_list = self.column_list

        return super().get_details_columns()


class SecureAdminBaseView(BaseView):
    def is_accessible(self):
        return adminViewIsAccessible()


class SecureAssistantBaseView(BaseView):
    def is_accessible(self):
        return assistantViewIsAccessible()


class CustomIdEndpointLinkRowAction(EndpointLinkRowAction):
    def customId(self, row):
        raise NotImplementedError()

    def render(self, context, row_id, row):
        return super().render(context, self.customId(row), row)