"""
Declare and configure the models for the People core application
"""
import json
import os
import uuid

from django.conf import settings
from django.contrib.auth import models as auth_models
from django.contrib.auth.base_user import AbstractBaseUser
from django.core import exceptions, mail, validators
from django.db import models
from django.utils.functional import lazy
from django.utils.translation import gettext_lazy as _

import jsonschema
from rest_framework_simplejwt.exceptions import InvalidToken
from rest_framework_simplejwt.settings import api_settings
from timezone_field import TimeZoneField

current_dir = os.path.dirname(os.path.abspath(__file__))
contact_schema_path = os.path.join(current_dir, "jsonschema", "contact_data.json")
with open(contact_schema_path, "r", encoding="utf-8") as contact_schema_file:
    contact_schema = json.load(contact_schema_file)


class RoleChoices(models.TextChoices):
    """Defines the possible roles a user can have in a team."""

    MEMBER = "member", _("Member")
    ADMIN = "administrator", _("Administrator")
    OWNER = "owner", _("Owner")


class BaseModel(models.Model):
    """
    Serves as an abstract base model for other models, ensuring that records are validated
    before saving as Django doesn't do it by default.

    Includes fields common to all models: a UUID primary key and creation/update timestamps.
    """

    id = models.UUIDField(
        verbose_name=_("id"),
        help_text=_("primary key for the record as UUID"),
        primary_key=True,
        default=uuid.uuid4,
        editable=False,
    )
    created_at = models.DateTimeField(
        verbose_name=_("created at"),
        help_text=_("date and time at which a record was created"),
        auto_now_add=True,
        editable=False,
    )
    updated_at = models.DateTimeField(
        verbose_name=_("updated at"),
        help_text=_("date and time at which a record was last updated"),
        auto_now=True,
        editable=False,
    )

    class Meta:
        abstract = True

    def save(self, *args, **kwargs):
        """Call `full_clean` before saving."""
        self.full_clean()
        super().save(*args, **kwargs)


class Contact(BaseModel):
    """User contacts"""

    base = models.ForeignKey(
        "self",
        on_delete=models.SET_NULL,
        related_name="overriding_contacts",
        null=True,
        blank=True,
    )
    owner = models.ForeignKey(
        settings.AUTH_USER_MODEL,
        on_delete=models.CASCADE,
        related_name="contacts",
        null=True,
        blank=True,
    )
    full_name = models.CharField(_("full name"), max_length=150, null=True, blank=True)
    short_name = models.CharField(_("short name"), max_length=30, null=True, blank=True)

    # avatar =
    # notes =
    data = models.JSONField(
        _("contact information"),
        help_text=_("A JSON object containing the contact information"),
        blank=True,
    )

    class Meta:
        db_table = "people_contact"
        # indexes = [
        #     GinIndex(
        #         fields=["full_name", "short_name"],
        #         name="names_gin_trgm_idx",
        #         opclasses=['gin_trgm_ops', 'gin_trgm_ops']
        #     ),
        # ]
        ordering = ("full_name", "short_name")
        verbose_name = _("contact")
        verbose_name_plural = _("contacts")
        unique_together = ("owner", "base")
        constraints = [
            models.CheckConstraint(
                check=~models.Q(base__isnull=False, owner__isnull=True),
                name="base_owner_constraint",
                violation_error_message="A contact overriding a base contact must be owned.",
            ),
            models.CheckConstraint(
                check=~models.Q(base=models.F("id")),
                name="base_not_self",
                violation_error_message="A contact cannot be based on itself.",
            ),
        ]

    def __str__(self):
        return self.full_name or self.short_name

    def clean(self):
        """Validate fields."""
        super().clean()

        # Check if the contact points to a base contact that itself points to another base contact
        if self.base_id and self.base.base_id:
            raise exceptions.ValidationError(
                "A contact cannot point to a base contact that itself points to a base contact."
            )

        # Validate the content of the "data" field against our jsonschema definition
        try:
            jsonschema.validate(self.data, contact_schema)
        except jsonschema.ValidationError as e:
            # Specify the property in the data in which the error occured
            field_path = ".".join(map(str, e.path))
            error_message = f"Validation error in '{field_path:s}': {e.message}"
            raise exceptions.ValidationError({"data": [error_message]}) from e


class UserManager(auth_models.UserManager):
    """
    Override user manager to get the related contact in the same query by default (Contact model)
    """

    def get_queryset(self):
        """Always select the related contact when doing a query on users."""
        return super().get_queryset().select_related("profile_contact")


class User(AbstractBaseUser, BaseModel, auth_models.PermissionsMixin):
    """User model to work with OIDC only authentication."""

    email = models.EmailField(_("email address"), unique=True, null=True, blank=True)
    profile_contact = models.OneToOneField(
        Contact,
        on_delete=models.SET_NULL,
        related_name="user",
        blank=True,
        null=True,
    )
    language = models.CharField(
        max_length=10,
        choices=lazy(lambda: settings.LANGUAGES, tuple)(),
        default=settings.LANGUAGE_CODE,
        verbose_name=_("language"),
        help_text=_("The language in which the user wants to see the interface."),
    )
    timezone = TimeZoneField(
        choices_display="WITH_GMT_OFFSET",
        use_pytz=False,
        default=settings.TIME_ZONE,
        help_text=_("The timezone in which the user wants to see times."),
    )
    is_device = models.BooleanField(
        _("device"),
        default=False,
        help_text=_("Whether the user is a device or a real user."),
    )
    is_staff = models.BooleanField(
        _("staff status"),
        default=False,
        help_text=_("Whether the user can log into this admin site."),
    )
    is_active = models.BooleanField(
        _("active"),
        default=True,
        help_text=_(
            "Whether this user should be treated as active. "
            "Unselect this instead of deleting accounts."
        ),
    )

    objects = UserManager()

    USERNAME_FIELD = "email"
    REQUIRED_FIELDS = []

    class Meta:
        db_table = "people_user"
        verbose_name = _("user")
        verbose_name_plural = _("users")

    def __str__(self):
        return (
            str(self.profile_contact)
            if self.profile_contact
            else self.email or str(self.id)
        )

    def clean(self):
        """Validate fields."""
        super().clean()

        if self.profile_contact_id and not self.profile_contact.owner == self:
            raise exceptions.ValidationError(
                "Users can only declare as profile a contact they own."
            )

    def email_user(self, subject, message, from_email=None, **kwargs):
        """Send an email to this user."""
        main_identity = self.identities.get(is_main=True)
        mail.send_mail(subject, message, from_email, [main_identity.email], **kwargs)

    @classmethod
    def get_email_field_name(cls):
        """
        Raise error when trying to get email field name from the user as we are using
        a separate Email model to allow several emails per user.
        """
        raise NotImplementedError(
            "This feature is deactivated to allow several emails per user."
        )


class Identity(BaseModel):
    """User identity"""

    sub_validator = validators.RegexValidator(
        regex=r"^[\w.@+-]+\Z",
        message=_(
            "Enter a valid sub. This value may contain only letters, "
            "numbers, and @/./+/-/_ characters."
        ),
    )

    user = models.ForeignKey(User, related_name="identities", on_delete=models.CASCADE)
    sub = models.CharField(
        _("sub"),
        help_text=_(
            "Required. 255 characters or fewer. Letters, numbers, and @/./+/-/_ characters only."
        ),
        max_length=255,
        unique=True,
        validators=[sub_validator],
    )
    email = models.EmailField(_("email address"), null=True, blank=True)
    is_main = models.BooleanField(
        _("main"),
        default=False,
        help_text=_("Designates whether the email is the main one."),
    )

    class Meta:
        db_table = "people_identity"
        ordering = ("-is_main", "email")
        verbose_name = _("identity")
        verbose_name_plural = _("identities")
        constraints = [
            # Uniqueness
            models.UniqueConstraint(
                fields=["user", "email"],
                name="unique_user_email",
                violation_error_message=_(
                    "This email address is already declared for this user."
                ),
            ),
        ]

    def __str__(self):
        main_str = "[main]" if self.is_main else ""
        return f"{self.email:s}{main_str:s}"

    def save(self, *args, **kwargs):
        """Ensure users always have one and only one main identity."""
        super().save(*args, **kwargs)
        if self.is_main is True:
            self.user.identities.exclude(id=self.id).update(is_main=False)

    def clean(self):
        """Normalize the email field and clean the 'is_main' field."""
        if self.email:
            self.email = User.objects.normalize_email(self.email)
        if not self.user.identities.exclude(pk=self.pk).filter(is_main=True).exists():
            if not self.created_at:
                self.is_main = True
            elif not self.is_main:
                raise exceptions.ValidationError(
                    {"is_main": "A user should have one and only one main identity."}
                )
        super().clean()


class Team(BaseModel):
    """
    Represents the link between teams and users, specifying the role a user has in a team.
    """

    name = models.CharField(max_length=100)

    users = models.ManyToManyField(
        User,
        through="TeamAccess",
        through_fields=("team", "user"),
        related_name="teams",
    )

    class Meta:
        db_table = "people_team"
        ordering = ("name",)
        verbose_name = _("Team")
        verbose_name_plural = _("Teams")

    def __str__(self):
        return self.name

    def get_abilities(self, user):
        """
        Compute and return abilities for a given user on the team.
        """
        is_owner_or_admin = False
        role = None

        if user.is_authenticated:
            try:
                role = self.user_role
            except AttributeError:
                try:
                    role = self.accesses.filter(user=user).values("role")[0]["role"]
                except (TeamAccess.DoesNotExist, IndexError):
                    role = None

            is_owner_or_admin = role in [RoleChoices.OWNER, RoleChoices.ADMIN]

        return {
            "get": True,
            "patch": is_owner_or_admin,
            "put": is_owner_or_admin,
            "delete": role == RoleChoices.OWNER,
            "manage_accesses": is_owner_or_admin,
        }


class TeamAccess(BaseModel):
    """Link table between teams and contacts."""

    team = models.ForeignKey(
        Team,
        on_delete=models.CASCADE,
        related_name="accesses",
    )
    user = models.ForeignKey(
        User,
        on_delete=models.CASCADE,
        related_name="accesses",
    )
    role = models.CharField(
        max_length=20, choices=RoleChoices.choices, default=RoleChoices.MEMBER
    )

    class Meta:
        db_table = "people_team_access"
        verbose_name = _("Team/user relation")
        verbose_name_plural = _("Team/user relations")
        constraints = [
            models.UniqueConstraint(
                fields=["user", "team"],
                name="unique_team_user",
                violation_error_message=_("This user is already in this team."),
            ),
        ]

    def __str__(self):
        return f"{self.user!s} is {self.role:s} in team {self.team!s}"

    def get_abilities(self, user):
        """
        Compute and return abilities for a given user taking into account
        the current state of the object.
        """
        is_team_owner_or_admin = False
        role = None

        if user.is_authenticated:
            try:
                role = self.user_role
            except AttributeError:
                try:
                    role = self._meta.model.objects.filter(
                        team=self.team_id, user=user
                    ).values("role")[0]["role"]
                except (self._meta.model.DoesNotExist, IndexError):
                    role = None

            is_team_owner_or_admin = role in [RoleChoices.OWNER, RoleChoices.ADMIN]

        if self.role == RoleChoices.OWNER:
            can_delete = (
                user.id == self.user_id
                and self.team.accesses.filter(role=RoleChoices.OWNER).count() > 1
            )
            set_role_to = [RoleChoices.ADMIN, RoleChoices.MEMBER] if can_delete else []
        else:
            can_delete = is_team_owner_or_admin
            set_role_to = []
            if role == RoleChoices.OWNER:
                set_role_to.append(RoleChoices.OWNER)
            if is_team_owner_or_admin:
                set_role_to.extend([RoleChoices.ADMIN, RoleChoices.MEMBER])

        # Remove the current role as we don't want to propose it as an option
        try:
            set_role_to.remove(self.role)
        except ValueError:
            pass

        return {
            "delete": can_delete,
            "get": bool(role),
            "patch": bool(set_role_to),
            "put": bool(set_role_to),
            "set_role_to": set_role_to,
        }


def oidc_user_getter(validated_token):
    """
    Given a valid OIDC token , retrieve, create or update corresponding user/contact/email from db.

    The token is expected to have the following fields in payload:
        - sub
        - email
        - ...
    """
    try:
        user_id = validated_token[api_settings.USER_ID_CLAIM]
    except KeyError as exc:
        raise InvalidToken(
            _("Token contained no recognizable user identification")
        ) from exc

    try:
        email_param = {"email": validated_token["email"]}
    except KeyError:
        email_param = {}

    user = (
        User.objects.filter(identities__sub=user_id)
        .annotate(identity_email=models.F("identities__email"))
        .distinct()
        .first()
    )

    if user is None:
        user = User.objects.create(password="!", **email_param)  # noqa: S106
        Identity.objects.create(user=user, sub=user_id, **email_param)
    elif email_param and validated_token["email"] != user.identity_email:
        Identity.objects.filter(sub=user_id).update(email=validated_token["email"])

    return user