# -*- coding: UTF-8 -*
##############################################################################
# ScoDoc
# Copyright (c) 1999 - 2023 Emmanuel Viennet.  All rights reserved.
# See LICENSE
##############################################################################

"""ScoDoc models: Groups & partitions
"""
from operator import attrgetter
from sqlalchemy.exc import IntegrityError

from app import db, log
from app.models import SHORT_STR_LEN
from app.models import GROUPNAME_STR_LEN
from app.scodoc import sco_utils as scu
from app.scodoc.sco_exceptions import AccessDenied, ScoValueError


class Partition(db.Model):
    """Partition: découpage d'une promotion en groupes"""

    __table_args__ = (db.UniqueConstraint("formsemestre_id", "partition_name"),)

    id = db.Column(db.Integer, primary_key=True)
    partition_id = db.synonym("id")
    formsemestre_id = db.Column(
        db.Integer,
        db.ForeignKey("notes_formsemestre.id"),
        index=True,
    )
    # "TD", "TP", ... (NULL for 'all')
    partition_name = db.Column(db.String(SHORT_STR_LEN))
    # Numero = ordre de presentation)
    numero = db.Column(db.Integer, nullable=False, default=0)
    # Calculer le rang ?
    bul_show_rank = db.Column(
        db.Boolean(), nullable=False, default=False, server_default="false"
    )
    # Montrer quand on indique les groupes de l'étudiant ?
    show_in_lists = db.Column(
        db.Boolean(), nullable=False, default=True, server_default="true"
    )
    # Editable (créer/renommer groupes) ? (faux pour les groupes de parcours)
    groups_editable = db.Column(
        db.Boolean(), nullable=False, default=True, server_default="true"
    )
    groups = db.relationship(
        "GroupDescr",
        backref=db.backref("partition", lazy=True),
        lazy="dynamic",
        cascade="all, delete-orphan",
        order_by="GroupDescr.numero",
    )

    def __init__(self, **kwargs):
        super(Partition, self).__init__(**kwargs)
        if self.numero is None:
            # génère numero à la création
            last_partition = Partition.query.order_by(Partition.numero.desc()).first()
            if last_partition:
                self.numero = last_partition.numero + 1
            else:
                self.numero = 1

    def __repr__(self):
        return f"""<{self.__class__.__name__} {self.id} "{self.partition_name or '(default)'}">"""

    @classmethod
    def check_name(
        cls, formsemestre: "FormSemestre", partition_name: str, existing=False
    ) -> bool:
        """check if a partition named 'partition_name' can be created in the given formsemestre.
        If existing is True, allow a partition_name already existing in the formsemestre.
        """
        if not isinstance(partition_name, str):
            return False
        if not (0 < len(partition_name.strip()) < SHORT_STR_LEN):
            return False
        if (not existing) and (
            partition_name in [p.partition_name for p in formsemestre.partitions]
        ):
            return False
        return True

    def is_parcours(self) -> bool:
        "Vrai s'il s'agit de la partition de parcours"
        return self.partition_name == scu.PARTITION_PARCOURS

    def to_dict(self, with_groups=False, str_keys: bool = False) -> dict:
        """as a dict, with or without groups.
        If str_keys, convert integer dict keys to strings (useful for JSON)
        """
        d = dict(self.__dict__)
        d["partition_id"] = self.id
        d.pop("_sa_instance_state", None)
        d.pop("formsemestre", None)

        if with_groups:
            groups = sorted(self.groups, key=attrgetter("numero", "group_name"))
            # un dict et non plus une liste, pour JSON
            if str_keys:
                d["groups"] = {
                    str(group.id): group.to_dict(with_partition=False)
                    for group in groups
                }
            else:
                d["groups"] = {
                    group.id: group.to_dict(with_partition=False) for group in groups
                }
        return d

    def get_etud_group(self, etudid: int) -> "GroupDescr":
        "Le groupe de l'étudiant dans cette partition, ou None si pas présent"
        return (
            GroupDescr.query.filter_by(partition_id=self.id)
            .join(group_membership)
            .filter_by(etudid=etudid)
            .first()
        )

    def set_etud_group(self, etud: "Identite", group: "GroupDescr") -> bool:
        """Affect etudid to group_id in given partition.
        Raises IntegrityError si conflit,
        or ValueError si ce group_id n'est pas dans cette partition
        ou que l'étudiant n'est pas inscrit au semestre.
        Return True si changement, False s'il était déjà dans ce groupe.
        """
        if not group.id in (g.id for g in self.groups):
            raise ScoValueError(
                f"""Le groupe {group.id} n'est pas dans la partition {
                    self.partition_name or "tous"}"""
            )
        if etud.id not in (e.id for e in self.formsemestre.etuds):
            raise ScoValueError(
                f"""étudiant {etud.nomprenom} non inscrit au formsemestre du groupe {
                    group.group_name}"""
            )
        try:
            existing_row = (
                db.session.query(group_membership)
                .filter_by(etudid=etud.id)
                .join(GroupDescr)
                .filter_by(partition_id=self.id)
                .first()
            )
            if existing_row:
                existing_group_id = existing_row[1]
                if group.id == existing_group_id:
                    return False
                # Fait le changement avec l'ORM sinon risque élevé de blocage
                existing_group = GroupDescr.query.get(existing_group_id)
                db.session.commit()
                group.etuds.append(etud)
                existing_group.etuds.remove(etud)
                db.session.add(etud)
                db.session.add(existing_group)
                db.session.add(group)
            else:
                new_row = group_membership.insert().values(
                    etudid=etud.id, group_id=group.id
                )
                db.session.execute(new_row)
            db.session.commit()
        except IntegrityError:
            db.session.rollback()
            raise
        return True

    def create_group(self, group_name="", default=False) -> "GroupDescr":
        "Crée un groupe dans cette partition"
        if not self.formsemestre.can_change_groups():
            raise AccessDenied(
                """Vous n'avez pas le droit d'effectuer cette opération, 
                ou bien le semestre est verrouillé !"""
            )
        if group_name:
            group_name = group_name.strip()
        if not group_name and not default:
            raise ValueError("invalid group name: ()")
        if not GroupDescr.check_name(self, group_name, default=default):
            raise ScoValueError(
                f"Le groupe {group_name} existe déjà dans cette partition"
            )
        numeros = [g.numero if g.numero is not None else 0 for g in self.groups]
        if len(numeros) > 0:
            new_numero = max(numeros) + 1
        else:
            new_numero = 0
        group = GroupDescr(partition=self, group_name=group_name, numero=new_numero)
        db.session.add(group)
        db.session.commit()
        log(f"create_group: created group_id={group.id}")
        #
        return group


class GroupDescr(db.Model):
    """Description d'un groupe d'une partition"""

    __tablename__ = "group_descr"
    __table_args__ = (db.UniqueConstraint("partition_id", "group_name"),)

    id = db.Column(db.Integer, primary_key=True)
    group_id = db.synonym("id")
    partition_id = db.Column(db.Integer, db.ForeignKey("partition.id"))
    #  "A", "C2", ...  (NULL for 'all'):
    group_name = db.Column(db.String(GROUPNAME_STR_LEN))
    # Numero = ordre de presentation
    numero = db.Column(db.Integer, nullable=False, default=0)

    etuds = db.relationship(
        "Identite",
        secondary="group_membership",
        lazy="dynamic",
    )

    def __repr__(self):
        return (
            f"""<{self.__class__.__name__} {self.id} "{self.group_name or '(tous)'}">"""
        )

    def get_nom_with_part(self) -> str:
        "Nom avec partition: 'TD A'"
        return f"{self.partition.partition_name or ''} {self.group_name or '-'}"

    def to_dict(self, with_partition=True) -> dict:
        """as a dict, with or without partition"""
        d = dict(self.__dict__)
        d.pop("_sa_instance_state", None)
        if with_partition:
            d["partition"] = self.partition.to_dict(with_groups=False)
        return d

    @classmethod
    def check_name(
        cls, partition: "Partition", group_name: str, existing=False, default=False
    ) -> bool:
        """check if a group named 'group_name' can be created in the given partition.
        If existing is True, allow a group_name already existing in the partition.
        If default, name must be empty and default group must not yet exists.
        """
        if not isinstance(group_name, str):
            return False
        if not default and not (0 < len(group_name.strip()) < GROUPNAME_STR_LEN):
            return False
        if (not existing) and (group_name in [g.group_name for g in partition.groups]):
            return False
        return True


group_membership = db.Table(
    "group_membership",
    db.Column("etudid", db.Integer, db.ForeignKey("identite.id", ondelete="CASCADE")),
    db.Column("group_id", db.Integer, db.ForeignKey("group_descr.id")),
    db.UniqueConstraint("etudid", "group_id"),
)
# class GroupMembership(db.Model):
#     """Association groupe / étudiant"""

#     __tablename__ = "group_membership"
#     __table_args__ = (db.UniqueConstraint("etudid", "group_id"),)
#     id = db.Column(db.Integer, primary_key=True)
#     etudid = db.Column(db.Integer, db.ForeignKey("identite.id", ondelete="CASCADE"))
#     group_id = db.Column(db.Integer, db.ForeignKey("group_descr.id"))