# The core application of the Mia project.
#   by imacat <imacat@mail.imacat.idv.tw>, 2020/6/29

#  Copyright (c) 2020 imacat.
#
#  Licensed under the Apache License, Version 2.0 (the "License");
#  you may not use this file except in compliance with the License.
#  You may obtain a copy of the License at
#
#      http://www.apache.org/licenses/LICENSE-2.0
#
#  Unless required by applicable law or agreed to in writing, software
#  distributed under the License is distributed on an "AS IS" BASIS,
#  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
#  See the License for the specific language governing permissions and
#  limitations under the License.

"""The data models of the Mia core application.

"""
import datetime
import hashlib

from dirtyfields import DirtyFieldsMixin
from django.conf import settings
from django.db import models, connection, OperationalError, transaction
from django.db.models.functions import Now

from mia_core.utils import get_multi_lingual_attr, set_multi_lingual_attr, \
    new_pk


class Country(DirtyFieldsMixin, models.Model):
    """A country."""
    sn = models.PositiveIntegerField(primary_key=True)
    code = models.CharField(max_length=2, unique=True)
    name_en = models.CharField(max_length=64)
    name_zh_hant = models.CharField(
        max_length=32, null=True, db_column="name_zhtw")
    name_zh_hans = models.CharField(
        max_length=32, null=True, db_column="name_zhcn")
    is_special = models.BooleanField(
        default=False, db_column="special")
    created_at = models.DateTimeField(
        auto_now_add=True, db_column="created")
    created_by = models.ForeignKey(
        "User", on_delete=models.PROTECT,
        db_column="createdby", related_name="created_countries")
    updated_at = models.DateTimeField(
        auto_now=True, db_column="updated")
    updated_by = models.ForeignKey(
        "User", on_delete=models.PROTECT,
        db_column="updatedby", related_name="updated_countries")

    def __str__(self):
        """Returns the string representation of this country."""
        return self.code.__str__() + " " + self.name.__str__()

    @property
    def name(self):
        return get_multi_lingual_attr(self, "name", "en")

    @name.setter
    def name(self, value):
        set_multi_lingual_attr(self, "name", value)

    class Meta:
        db_table = "countries"


class User(DirtyFieldsMixin, models.Model):
    """A user."""
    sn = models.PositiveIntegerField(primary_key=True)
    login_id = models.CharField(max_length=32, unique=True, db_column="id")
    password = models.CharField(max_length=32, db_column="passwd")
    name = models.CharField(max_length=32)
    is_disabled = models.BooleanField(
        default=False, db_column="disabled")
    is_deleted = models.BooleanField(
        default=False, db_column="deleted")
    language = models.CharField(max_length=6, null=True, db_column="lang")
    visits = models.PositiveSmallIntegerField(default=0)
    visited_at = models.DateTimeField(null=True, db_column="visited")
    visited_ip = models.GenericIPAddressField(null=True, db_column="ip")
    visited_host = models.CharField(
        max_length=128, null=True, db_column="host")
    visited_country = models.ForeignKey(
        Country, on_delete=models.PROTECT, null=True,
        db_column="ct", to_field="code", related_name="users")
    created_at = models.DateTimeField(
        auto_now_add=True, db_column="created")
    created_by = models.ForeignKey(
        "self", on_delete=models.PROTECT,
        db_column="createdby", related_name="created_users")
    updated_at = models.DateTimeField(
        auto_now_add=True, db_column="updated")
    updated_by = models.ForeignKey(
        "self", on_delete=models.PROTECT,
        db_column="updatedby", related_name="updated_users")
    REQUIRED_FIELDS = ["sn", "name"]
    USERNAME_FIELD = "login_id"

    @property
    def is_anonymous(self):
        return False

    @property
    def is_authenticated(self):
        return True

    def set_password(self):
        pass

    def check_password(self):
        pass

    def __str__(self):
        """Returns the string representation of this user."""
        return "%s (%s)" % (
            self.name.__str__(), self.login_id.__str__())

    def save(self, current_user=None, force_insert=False, force_update=False,
             using=None, update_fields=None):
        if self.pk is None:
            self.pk = new_pk(User)
            if current_user is not None:
                self.created_by = current_user
        if current_user is not None:
            self.updated_by = current_user
        with transaction.atomic():
            super(User, self).save(
                force_insert=force_insert, force_update=force_update,
                using=using, update_fields=update_fields)
            User.objects.filter(pk=self.pk).update(updated_at=Now())

    class Meta:
        db_table = "users"
        app_label = "mia_core"

    def set_digest_password(self, login_id, password):
        self.password = self.md5(
            F"{login_id}:{settings.DIGEST_REALM}:{password}")

    @staticmethod
    def md5(value):
        m = hashlib.md5()
        m.update(value.encode("utf-8"))
        return m.hexdigest()

    def is_in_use(self):
        """Returns whether this user is in use.

        Returns:
            bool: True if this user is in use, or False otherwise.
        """
        for table in connection.introspection.table_names():
            if self._is_in_use_with(F"SELECT * FROM {table}"
                                    " WHERE createdby=%s OR updatedby=%s"):
                return True
            if self._is_in_use_with(
                    F"SELECT * FROM {table}"
                    " WHERE created_by_id=%s OR updated_by_id=%s"):
                return True
        return False

    def _is_in_use_with(self, sql):
        """Returns whether this user is in use with a specific SQL statement.

        Args:
            sql (str): The SQL query statement

        Returns:
            bool: True if this user is in use, or False otherwise.
        """
        with connection.cursor() as cursor:
            try:
                cursor.execute(sql, [self.pk, self.pk])
            except OperationalError:
                return False
            if cursor.fetchone() is None:
                return False
            return True