from flask import flash, url_for
from flask_admin.menu import MenuLink
from flask_security import current_user
from sqlalchemy import func, select

from . import app, db
from .models import Semester


def flashRandomPassword(password):
    flash(f"Random password: {password}", category="warning")


def sortedSemestersStartingWithNewest(limit=0):
    # Inserting an older semester is not allowed!
    # Therefore, the id is enough.
    stmt = select(Semester).order_by(Semester.id.desc())

    if limit > 0:
        stmt = stmt.limit(limit)

    return db.session.execute(stmt).scalars()


def lastSemester():
    return sortedSemestersStartingWithNewest(limit=1).first()


def userActiveSemester(flashWarning=False):
    lastSemesterId = lastSemester().id
    if current_user.active_semester_id is None:
        current_user.active_semester_id = lastSemesterId
        db.session.commit()
    elif current_user.active_semester_id != lastSemesterId:
        activeSemester = db.session.get(Semester, current_user.active_semester_id)
        if activeSemester is not None:
            if flashWarning:
                flash(f"You are in the old semester {activeSemester.repr()}!", "warning")
        else:
            current_user.active_semester_id = lastSemesterId
            db.session.commit()
            flash("Semester changed!", "warning")

    return db.session.get(Semester, current_user.active_semester_id)


def setUserActiveSemester(semesterId):
    if current_user.active_semester_id != semesterId:
        semester = db.session.get(Semester, semesterId)
        if semester is not None:
            try:
                current_user.active_semester_id = semesterId
                db.session.commit()
            except Exception as ex:
                flash(str(ex), "error")

                db.session.rollback()
            else:
                flash(f"Active semester changed to {semester.repr()}!", "warning")
        else:
            flash(f"No semester with ID {semesterId}!", "error")


def initActiveSemesterMenuLinks(space):
    with app.app_context():
        try:
            semesters = sortedSemestersStartingWithNewest()
            for semester in semesters:
                space.add_link(
                    MenuLink(
                        name=semester.repr(),
                        url=url_for("set_semester") + "?semester_id=" + str(semester.id),
                        category="Active semester",
                    )
                )
        except Exception as ex:
            print(
                "ERROR: The Semester table does not exist yet! Therefore, menu links could not be generated. You can ignore this error if you are just initializing the database."
            )
        else:
            space.add_link(MenuLink(name="Logout", url=url_for("security.logout")))


def reportBadAttempt(message):
    print("BAD ATTEMPT:", message)  # TODO: Log


def get_count(table):
    return db.session.scalar(select(func.count()).select_from(table))