"""
See the file DB.drawio for the design of the database. It can be opened in the internet browser with the website:
https://app.diagrams.net

For more information about the implementation, see the part to Models in the documentation of Flask-SQLAlchemy:
https://flask-sqlalchemy.palletsprojects.com/en/2.x/models/
"""

from decimal import ROUND_HALF_UP, Decimal

from flask import flash
from flask_security import current_user
from flask_security.models.fsqla_v2 import FsRoleMixin, FsUserMixin

from . import db
from .configUtils import getConfig
from .exceptions import DataBaseException

MIN_MARK = 0
MAX_MARK = 15
MIN_YEAR = 22
MAX_YEAR = 99
MIN_STUDENT_NUMBER = 0
MIN_EXPERIMENT_NUMBER = 1
MIN_GROUP_NUMBER = 1
MIN_DURATION_IN_DAYS = 1
MIN_PART_NUMBER = 1


def roundHalfUpToInt(number):
    return int(Decimal(number).quantize(Decimal(0), rounding=ROUND_HALF_UP))


class Student(db.Model):
    id = db.Column(db.Integer, primary_key=True)
    student_number = db.Column(
        db.Integer, db.CheckConstraint(f"student_number >= {MIN_STUDENT_NUMBER}"), nullable=False, unique=True
    )
    first_name = db.Column(db.String(100), nullable=False)
    last_name = db.Column(db.String(100), nullable=False)
    uni_email = db.Column(db.String(200), nullable=False, unique=True)
    contact_email = db.Column(db.String(200), nullable=True, unique=True)
    bachelor_thesis = db.Column(db.String, nullable=True)
    bachelor_thesis_work_group = db.Column(db.String, nullable=True)
    note = db.Column(db.Text, nullable=True)

    part_students = db.relationship("PartStudent", backref="student", lazy=True)

    def repr(self):
        return f"{self.first_name} {self.last_name}"

    def __repr__(self):
        return f"<STD {self.repr()}>"


class PartStudent(db.Model):
    # A student doing a specific part
    id = db.Column(db.Integer, primary_key=True)
    final_part_mark = db.Column(
        db.Integer,
        db.CheckConstraint(f"final_part_mark BETWEEN {MIN_MARK} AND {MAX_MARK}"),
        nullable=True,
    )

    student_id = db.Column(db.Integer, db.ForeignKey("student.id"), nullable=False)
    part_id = db.Column(db.Integer, db.ForeignKey("part.id"), nullable=False)
    group_id = db.Column(db.Integer, db.ForeignKey("group.id"), nullable=True)

    experiment_marks = db.relationship("ExperimentMark", backref="part_student", lazy=True)

    __table_args__ = (
        db.UniqueConstraint(student_id, part_id),
        db.UniqueConstraint(student_id, group_id),
    )

    def check(part, group):
        if group is not None and group.program != part.program:
            raise DataBaseException(
                f"Group's program {group.program} and student part's program {part.program} do not match!"
            )

    def __init__(self, student, part, group=None):
        PartStudent.check(part, group)

        super().__init__(student=student, part=part, group=group)

    def customUpdate(self, group, final_part_mark):
        Part.check(group, self.part)

        self.group = group
        self.final_part_mark = final_part_mark

    def checkThenSetFinalPartMark(self):
        finalWeightingSum = 0
        finalMark = 0
        groupExperiments = []

        for experimentMark in self.experiment_marks:
            if None in (experimentMark.oral_mark, experimentMark.protocol_mark):
                # Not all marks are set!
                return

            groupExperiment = experimentMark.group_experiment
            groupExperiments.append(groupExperiment)

            semesterExperiment = groupExperiment.semester_experiment

            finalWeighting = semesterExperiment.final_weighting
            finalWeightingSum += finalWeighting

            finalMark += finalWeighting * experimentMark.final_experiment_mark

        if set(groupExperiments) != set(self.group.group_experiments):
            flash(f"{self} does not have an experiment mark for every group experiment in his group!", "warning")
            return

        oldFinalPartMark = self.final_part_mark

        try:
            self.final_part_mark = roundHalfUpToInt(finalMark / finalWeightingSum)

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

            db.session.rollback()
        else:
            if current_user.has_role("admin"):
                if oldFinalPartMark != self.final_part_mark:
                    category = "danger" if oldFinalPartMark and oldFinalPartMark > self.final_part_mark else "info"

                    flash(
                        f"Final part mark changed for {self} from {oldFinalPartMark} to {self.final_part_mark}.",
                        category,
                    )
                else:
                    flash(f"Final part mark did not change for {self} from {oldFinalPartMark}.", "warning")

    def repr(self):
        return f"{self.student.repr()} {self.part.repr()}"

    def __repr__(self):
        return f"<PARTSTD {self.repr()}>"


class Group(db.Model):
    id = db.Column(db.Integer, primary_key=True)
    number = db.Column(db.Integer, db.CheckConstraint(f"number >= {MIN_GROUP_NUMBER}"), nullable=False)

    semester_id = db.Column(db.Integer, db.ForeignKey("semester.id"), nullable=False)
    program_id = db.Column(db.Integer, db.ForeignKey("program.id"), nullable=False)

    part_students = db.relationship("PartStudent", backref="group", lazy=True)
    group_experiments = db.relationship("GroupExperiment", backref="group", lazy=True)

    __table_args__ = (db.UniqueConstraint(number, semester_id, program_id),)

    def check(part_students, program=None):
        commonProgram = part_students[0].part.program

        if program and program != commonProgram:
            raise DataBaseException("Group's program and students' program mismatch!")

        for partStudent in part_students[1:]:
            if partStudent.part.program != commonProgram:
                raise DataBaseException(f"Part Students {part_students} are not in the same program!")

    def customInit(part_students):
        Group.check(part_students)

        semester = part_students[0].part.semester
        program = part_students[0].part.program

        groupWithHighestNumber = (
            Group.query.filter(Group.semester == semester, Group.program == program)
            .order_by(Group.number.desc())
            .first()
        )

        if groupWithHighestNumber is not None:
            number = groupWithHighestNumber.number + 1
        else:
            number = 1

        return Group(
            program=program,
            number=number,
            part_students=part_students,
            semester=semester,
        )

    def customUpdate(self, part_students):
        Group.check(part_students, self.program)

        self.part_students = part_students

    def repr(self):
        return f"{self.number} {self.program.repr()} {self.semester.repr()}"

    def __repr__(self):
        return f"<GR {self.repr()}>"


class GroupExperiment(db.Model):
    # An experiment specified to a group
    id = db.Column(db.Integer, primary_key=True)

    semester_experiment_id = db.Column(db.Integer, db.ForeignKey("semester_experiment.id"), nullable=False)
    group_id = db.Column(db.Integer, db.ForeignKey("group.id"), nullable=False)

    appointments = db.relationship("Appointment", backref="group_experiment", lazy=True)
    experiment_marks = db.relationship("ExperimentMark", backref="group_experiment", lazy=True)

    __table_args__ = (db.UniqueConstraint(semester_experiment_id, group_id),)

    def __init__(self, semester_experiment, group):
        for partStudent in group.part_students:
            student = partStudent.student
            for partStudent in student.part_students:
                for experimentMark in partStudent.experiment_marks:
                    if experimentMark.group_experiment.semester_experiment.experiment == semester_experiment.experiment:
                        raise DataBaseException(
                            f"{student} has already done {semester_experiment.experiment} in {partStudent.part} and had {experimentMark}!"
                        )

        super().__init__(semester_experiment=semester_experiment, group=group)

        for partStudent in group.part_students:
            db.session.add(ExperimentMark(part_student=partStudent, group_experiment=self))

    def repr(self):
        return f"SemExp {self.semester_experiment.repr()}; Gr {self.group.repr()}"

    def __repr__(self):
        return f"<GREXP {self.repr()}>"


class Experiment(db.Model):
    id = db.Column(db.Integer, primary_key=True)
    number = db.Column(db.Integer, db.CheckConstraint(f"number >= {MIN_EXPERIMENT_NUMBER}"), nullable=False)
    title = db.Column(db.String(200), nullable=False)
    description = db.Column(db.Text, nullable=True)
    wiki_link = db.Column(db.String(300), nullable=True)
    building = db.Column(db.String(100), nullable=False)
    room = db.Column(db.String(100), nullable=False)
    responsibility = db.Column(db.String(200), nullable=True)
    duration_in_days = db.Column(
        db.Integer, db.CheckConstraint(f"duration_in_days >= {MIN_DURATION_IN_DAYS}"), nullable=False
    )
    active = db.Column(db.Boolean, default=True, nullable=False)

    program_id = db.Column(db.Integer, db.ForeignKey("program.id"), nullable=False)

    semester_experiments = db.relationship("SemesterExperiment", backref="experiment", lazy=True)

    __table_args__ = (db.UniqueConstraint(number, program_id),)

    def repr(self):
        return f"{self.number} {self.program.repr()}"

    def __repr__(self):
        return f"<EXP {self.repr()}>"


# Helper table for the many to many relationship between Assistant and SemesterExperiment
experiment_assistant = db.Table(
    "experiment_assistant",
    db.Column("semester_experiment_id", db.Integer, db.ForeignKey("semester_experiment.id"), primary_key=True),
    db.Column("assistant_id", db.Integer, db.ForeignKey("assistant.id"), primary_key=True),
)


class SemesterExperiment(db.Model):
    # An experiment in a specific semester
    id = db.Column(db.Integer, primary_key=True)
    oral_weighting = db.Column(
        db.Float,
        db.CheckConstraint("oral_weighting BETWEEN 0 AND 1"),
        default=0.5,
        nullable=False,
    )
    protocol_weighting = db.Column(
        db.Float,
        db.CheckConstraint("protocol_weighting BETWEEN 0 AND 1"),
        default=0.5,
        nullable=False,
    )
    final_weighting = db.Column(
        db.Float,
        db.CheckConstraint("final_weighting BETWEEN 0 AND 1"),
        default=1.0,
        nullable=False,
    )

    experiment_id = db.Column(db.Integer, db.ForeignKey("experiment.id"), nullable=False)
    semester_id = db.Column(db.Integer, db.ForeignKey("semester.id"), nullable=False)

    assistants = db.relationship(
        "Assistant", secondary=experiment_assistant, lazy=True, backref=db.backref("semester_experiments", lazy=True)
    )
    group_experiments = db.relationship("GroupExperiment", backref="semester_experiment", lazy=True)

    __table_args__ = (db.UniqueConstraint(experiment_id, semester_id),)

    def checkAndRoundWeightings(self):
        roundedOralWeighting = round(self.oral_weighting, 2)
        roundedProtocolWeighting = round(self.protocol_weighting, 2)

        weightingSum = round(roundedOralWeighting + roundedProtocolWeighting, 2)

        if weightingSum != 1:
            raise DataBaseException(
                f"Oral and protocol weightings (rounded to 2 decimal digits) sum to {weightingSum} and not 1.00!"
            )

        self.oral_weighting = roundedOralWeighting
        self.protocol_weighting = roundedProtocolWeighting

    def updateFinalExperimentAndPartMarks(self):
        for groupExperiment in self.group_experiments:
            for experimentMark in groupExperiment.experiment_marks:
                experimentMark.updateFinalExperimentMark()

        for groupExperiment in self.group_experiments:
            for partStudent in groupExperiment.group.part_students:
                partStudent.checkThenSetFinalPartMark()

    def repr(self):
        return f"{self.experiment.repr()} {self.semester.repr()}"

    def __repr__(self):
        return f"<SEMEXP {self.repr()}>"


class Assistant(db.Model):
    id = db.Column(db.Integer, primary_key=True)

    user_id = db.Column(db.Integer, db.ForeignKey("user.id"), nullable=False, unique=True)

    appointments = db.relationship("Appointment", backref="assistant", lazy=True)
    experiment_marks = db.relationship("ExperimentMark", backref="assistant", lazy=True)

    def repr(self):
        return f"{self.user.first_name} {self.user.last_name}"

    def __repr__(self):
        return f"<ASST: {self.repr()}>"


class Admin(db.Model):
    id = db.Column(db.Integer, primary_key=True)

    user_id = db.Column(db.Integer, db.ForeignKey("user.id"), nullable=False, unique=True)

    experiment_marks = db.relationship("ExperimentMark", backref="admin", lazy=True)

    def repr(self):
        return f"{self.user.first_name} {self.user.last_name}"

    def __repr__(self):
        return f"<ADMIN: {self.repr()}>"


class Appointment(db.Model):
    id = db.Column(db.Integer, primary_key=True)
    date = db.Column(db.Date, nullable=False)  # To be specified with the python package "datetime"
    special = db.Column(db.Boolean, default=False, nullable=False)  # In the break or not

    group_experiment_id = db.Column(db.Integer, db.ForeignKey("group_experiment.id"), nullable=False)
    assistant_id = db.Column(db.Integer, db.ForeignKey("assistant.id"), nullable=False)

    def checkAndGetAssistant(assistant, groupExperiment):
        semesterExperiment = groupExperiment.semester_experiment
        semesterExperimentAssistants = semesterExperiment.assistants

        if not semesterExperimentAssistants:
            raise DataBaseException(f"{semesterExperiment} does not have assistants yet!")

        if assistant:
            if assistant not in semesterExperimentAssistants:
                raise DataBaseException(f"{assistant} not responsible for {semesterExperiment}!")
        else:
            if len(semesterExperimentAssistants) == 1:
                assistant = semesterExperimentAssistants[0]
            else:
                raise DataBaseException(
                    f"Experiment {semesterExperiment} has more than one assistant. You have to assign one of these assistants: {semesterExperimentAssistants}"
                )

        return assistant

    def customInit(date, special, group_experiment, assistant):
        assistant = Appointment.checkAndGetAssistant(assistant, group_experiment)

        return Appointment(
            date=date,
            special=special,
            group_experiment=group_experiment,
            assistant=assistant,
        )

    def customUpdate(self, date, special, assistant, group_experiment):
        assistant = Appointment.checkAndGetAssistant(assistant, group_experiment)

        self.date = date
        self.special = special
        self.assistant = assistant
        self.group_experiment = group_experiment

    def repr(self):
        return f"{self.date} {self.group_experiment.repr()}"

    def __repr__(self):
        return f"<APPT {self.repr()}>"


class Part(db.Model):
    id = db.Column(db.Integer, primary_key=True)
    number = db.Column(db.Integer, db.CheckConstraint(f"number >= {MIN_PART_NUMBER}"), nullable=False)

    program_id = db.Column(db.Integer, db.ForeignKey("program.id"), nullable=False)
    semester_id = db.Column(db.Integer, db.ForeignKey("semester.id"), nullable=False)

    part_students = db.relationship("PartStudent", backref="part", lazy=True)

    __table_args__ = (db.UniqueConstraint(program_id, number, semester_id),)

    def repr(self):
        return f"{self.program.repr()}{self.number} {self.semester.repr()}"

    def __repr__(self):
        return f"<PART {self.repr()}>"


class Semester(db.Model):
    id = db.Column(db.Integer, primary_key=True)
    label = db.Column(db.String(10), db.CheckConstraint("label IN ('WS', 'SS')"), nullable=False)
    year = db.Column(db.Integer, db.CheckConstraint(f"year BETWEEN {MIN_YEAR} AND {MAX_YEAR}"), nullable=False)

    parts = db.relationship("Part", backref="semester", lazy=True)
    semester_experiments = db.relationship("SemesterExperiment", backref="semester", lazy=True)
    active_users = db.relationship("User", backref="active_semester", lazy=True)
    groups = db.relationship("Group", backref="semester", lazy=True)

    __table_args__ = (db.UniqueConstraint(label, year),)

    def initFromOldSemester(label, year, oldSemester, transferParts, transferAssistants):
        semester = Semester(label=label, year=year)

        if transferParts:
            semester.transferPartsFrom(oldSemester)

        for experiment in Experiment.query.filter(Experiment.active == True):
            newSemesterExperiment = SemesterExperiment(experiment=experiment, semester=semester)

            if transferAssistants:
                for oldSemesterExperiment in oldSemester.semester_experiments:
                    if oldSemesterExperiment.experiment == experiment:
                        newSemesterExperiment.assistants = oldSemesterExperiment.assistants

            db.session.add(newSemesterExperiment)

        return semester

    def transferPartsFrom(self, oldSemester):
        for part in oldSemester.parts:
            db.session.add(Part(program=part.program, number=part.number, semester=self))

    def repr(self):
        return f"{self.label}{self.year}"

    def __repr__(self):
        return f"<SEM {self.repr()}>"


class ExperimentMark(db.Model):
    # A mark for a student after a specific experiment

    def final_experiment_mark_update(context):
        params = context.get_current_parameters()

        experimentMark = ExperimentMark.query.get(params["experiment_mark_id"])

        oral_mark = params.get("oral_mark")
        if oral_mark is None:
            oral_mark = experimentMark.oral_mark
            if oral_mark is None:
                return

        protocol_mark = params.get("protocol_mark")
        if protocol_mark is None:
            protocol_mark = experimentMark.protocol_mark
            if protocol_mark is None:
                return

        semesterExperiment = experimentMark.group_experiment.semester_experiment

        return roundHalfUpToInt(
            semesterExperiment.oral_weighting * oral_mark + semesterExperiment.protocol_weighting * protocol_mark
        )

    id = db.Column(db.Integer, primary_key=True)

    oral_mark = db.Column(
        db.Integer,
        db.CheckConstraint(f"oral_mark BETWEEN {MIN_MARK} AND {MAX_MARK}"),
        nullable=True,
    )
    protocol_mark = db.Column(
        db.Integer,
        db.CheckConstraint(f"oral_mark BETWEEN {MIN_MARK} AND {MAX_MARK}"),
        nullable=True,
    )

    final_experiment_mark = db.Column(
        db.Integer,
        db.CheckConstraint(f"oral_mark BETWEEN {MIN_MARK} AND {MAX_MARK}"),
        onupdate=final_experiment_mark_update,
        nullable=True,
    )

    part_student_id = db.Column(db.Integer, db.ForeignKey("part_student.id"), nullable=False)
    group_experiment_id = db.Column(db.Integer, db.ForeignKey("group_experiment.id"), nullable=False)
    assistant_id = db.Column(
        db.Integer, db.ForeignKey("assistant.id"), nullable=True
    )  # The last assistant who edited the mark
    admin_id = db.Column(db.Integer, db.ForeignKey("admin.id"), nullable=True)  # The last admin who edited the mark

    __table_args__ = (db.UniqueConstraint(part_student_id, group_experiment_id),)

    def __init__(self, part_student, group_experiment):
        if not part_student.group:
            raise DataBaseException("The part student does not have a group yet!")
        else:
            if group_experiment not in part_student.group.group_experiments:
                raise DataBaseException("The group of the part student does not have the given group experiment!")

        super().__init__(part_student=part_student, group_experiment=group_experiment)

    def updateFinalExperimentMark(self):
        if None not in (self.oral_mark, self.protocol_mark):
            semesterExperiment = self.group_experiment.semester_experiment
            self.final_experiment_mark = roundHalfUpToInt(
                semesterExperiment.oral_weighting * self.oral_mark
                + semesterExperiment.protocol_weighting * self.protocol_mark
            )

    def repr(self):
        return f"Mark {self.final_experiment_mark}; Exp {self.group_experiment.semester_experiment.repr()}"

    def __repr__(self):
        return f"<EXPMARK {self.repr()}>"


class User(db.Model, FsUserMixin):
    first_name = db.Column(db.String(100), nullable=False)
    last_name = db.Column(db.String(100), nullable=False)
    phone_number = db.Column(db.String(50), nullable=True)
    mobile_phone_number = db.Column(db.String(50), nullable=True)
    building = db.Column(db.String(100), nullable=True)
    room = db.Column(db.String(100), nullable=True)

    active_semester_id = db.Column(db.Integer, db.ForeignKey("semester.id"), nullable=True)

    admin = db.relationship("Admin", backref="user", lazy=False, uselist=False)
    assistant = db.relationship("Assistant", backref="user", lazy=True, uselist=False)

    def repr(self):
        return f"{self.first_name} {self.last_name}"

    def __repr__(self):
        return f"<USR {self.repr()}>"


class Role(db.Model, FsRoleMixin):
    def repr(self):
        return f"{self.name}"

    def __repr__(self):
        return f"<ROLE {self.repr()}>"


class Program(db.Model):
    id = db.Column(db.Integer, primary_key=True)
    label = db.Column(db.String(25), nullable=False, unique=True)

    parts = db.relationship("Part", backref="program", lazy=True)
    experiments = db.relationship("Experiment", backref="program", lazy=True)
    groups = db.relationship("Group", backref="program", lazy=True)

    def repr(self):
        return f"{self.label}"

    def __repr__(self):
        return f"<PROG {self.repr()}>"