"""
Declare and configure the models for the People core application
"""

import json
import os
import smtplib
import uuid
from datetime import timedelta
from logging import getLogger

from django.conf import settings
from django.contrib.auth import models as auth_models
from django.contrib.auth.base_user import AbstractBaseUser
from django.contrib.sites.models import Site
from django.core import exceptions, mail, validators
from django.db import models, transaction
from django.template.loader import render_to_string
from django.utils import timezone
from django.utils.functional import lazy
from django.utils.text import slugify
from django.utils.translation import gettext_lazy as _
from django.utils.translation import override

import jsonschema
from timezone_field import TimeZoneField

from core.enums import WebhookStatusChoices
from core.utils.webhooks import scim_synchronizer

logger = getLogger(__name__)

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()
        return 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(
                condition=~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(
                condition=~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 occurred
            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 User(AbstractBaseUser, BaseModel, auth_models.PermissionsMixin):
    """User model to work with OIDC only authentication."""

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

    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)
    name = models.CharField(_("name"), max_length=100, 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 = auth_models.UserManager()

    USERNAME_FIELD = "sub"
    REQUIRED_FIELDS = []

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

    def __str__(self):
        return self.name if self.name else self.email or f"User {self.sub}"

    def save(self, *args, **kwargs):
        """
        If it's a new user, give her access to the relevant teams.
        """

        if self._state.adding:
            self._convert_valid_invitations()

        super().save(*args, **kwargs)

    def clean(self):
        """Validate fields."""
        super().clean()
        if self.email:
            self.email = User.objects.normalize_email(self.email)

        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 _convert_valid_invitations(self):
        """
        Convert valid invitations to team accesses.
        Expired invitations are ignored.
        """

        valid_invitations = Invitation.objects.filter(
            email=self.email,
            created_at__gte=(
                timezone.now()
                - timedelta(seconds=settings.INVITATION_VALIDITY_DURATION)
            ),
        ).select_related("team")

        if not valid_invitations.exists():
            return

        TeamAccess.objects.bulk_create(
            [
                TeamAccess(user=self, team=invitation.team, role=invitation.role)
                for invitation in valid_invitations
            ]
        )
        valid_invitations.delete()

    def email_user(self, subject, message, from_email=None, **kwargs):
        """Email this user."""
        if not self.email:
            raise ValueError("You must first set an email for the user.")
        mail.send_mail(subject, message, from_email, [self.email], **kwargs)


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)
    slug = models.SlugField(max_length=100, unique=True, null=False, editable=False)

    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 save(self, *args, **kwargs):
        """Override save function to compute the slug."""
        self.slug = self.get_slug()
        return super().save(*args, **kwargs)

    def get_slug(self):
        """Compute slug value from name."""
        return slugify(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": bool(role),
            "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 save(self, *args, **kwargs):
        """
        Override save function to fire webhooks on any addition or update
        to a team access.
        """

        if self._state.adding:
            self.team.webhooks.update(status=WebhookStatusChoices.PENDING)
            with transaction.atomic():
                instance = super().save(*args, **kwargs)
                scim_synchronizer.add_user_to_group(self.team, self.user)
        else:
            instance = super().save(*args, **kwargs)

        return instance

    def delete(self, *args, **kwargs):
        """
        Override delete method to fire webhooks on  to team accesses.
        Don't allow deleting a team access until it is successfully synchronized with all
        its webhooks.
        """
        self.team.webhooks.update(status=WebhookStatusChoices.PENDING)
        with transaction.atomic():
            arguments = self.team, self.user
            super().delete(*args, **kwargs)
            scim_synchronizer.remove_user_from_group(*arguments)

    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,
        }


class TeamWebhook(BaseModel):
    """Webhooks fired on changes in teams."""

    team = models.ForeignKey(Team, related_name="webhooks", on_delete=models.CASCADE)
    url = models.URLField(_("url"))
    secret = models.CharField(_("secret"), max_length=255, null=True, blank=True)
    status = models.CharField(
        max_length=10,
        default=WebhookStatusChoices.PENDING,
        choices=WebhookStatusChoices.choices,
    )

    class Meta:
        db_table = "people_team_webhook"
        verbose_name = _("Team webhook")
        verbose_name_plural = _("Team webhooks")

    def __str__(self):
        return f"Webhook to {self.url} for {self.team}"

    def get_headers(self):
        """Build header dict from webhook object."""
        headers = {"Content-Type": "application/json"}
        if self.secret:
            headers["Authorization"] = f"Bearer {self.secret:s}"
        return headers


class Invitation(BaseModel):
    """User invitation to teams."""

    email = models.EmailField(_("email address"), null=False, blank=False)
    team = models.ForeignKey(
        Team,
        on_delete=models.CASCADE,
        related_name="invitations",
    )
    role = models.CharField(
        max_length=20, choices=RoleChoices.choices, default=RoleChoices.MEMBER
    )
    issuer = models.ForeignKey(
        User,
        on_delete=models.CASCADE,
        related_name="invitations",
    )

    class Meta:
        db_table = "people_invitation"
        verbose_name = _("Team invitation")
        verbose_name_plural = _("Team invitations")
        constraints = [
            models.UniqueConstraint(
                fields=["email", "team"], name="email_and_team_unique_together"
            )
        ]

    def __str__(self):
        return f"{self.email} invited to {self.team}"

    def save(self, *args, **kwargs):
        """Make invitations read-only."""
        if self.created_at:
            raise exceptions.PermissionDenied()
        super().save(*args, **kwargs)

        self.email_invitation()

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

        # Check if a user already exists for the provided email
        if User.objects.filter(email=self.email).exists():
            raise exceptions.ValidationError(
                {"email": _("This email is already associated to a registered user.")}
            )

    @property
    def is_expired(self):
        """Calculate if invitation is still valid or has expired."""
        if not self.created_at:
            return None

        validity_duration = timedelta(seconds=settings.INVITATION_VALIDITY_DURATION)
        return timezone.now() > (self.created_at + validity_duration)

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

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

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

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

    def email_invitation(self):
        """Email invitation to the user."""
        try:
            with override(self.issuer.language):
                template_vars = {
                    "title": _("Invitation to join Desk!"),
                    "site": Site.objects.get_current(),
                }
                msg_html = render_to_string("mail/html/invitation.html", template_vars)
                msg_plain = render_to_string("mail/text/invitation.txt", template_vars)
                mail.send_mail(
                    _("Invitation to join Desk!"),
                    msg_plain,
                    settings.EMAIL_FROM,
                    [self.email],
                    html_message=msg_html,
                    fail_silently=False,
                )

        except smtplib.SMTPException as exception:
            logger.error("invitation to %s was not sent: %s", self.email, exception)