''' database schema for user data '''
from django.contrib.auth.models import AbstractUser
from django.db import models
from django.dispatch import receiver

from fedireads import activitypub
from fedireads.models.shelf import Shelf
from fedireads.settings import DOMAIN
from fedireads.signatures import create_key_pair
from .base_model import FedireadsModel


class User(AbstractUser):
    ''' a user who wants to read books '''
    private_key = models.TextField(blank=True, null=True)
    public_key = models.TextField(blank=True, null=True)
    inbox = models.CharField(max_length=255, unique=True)
    shared_inbox = models.CharField(max_length=255, blank=True, null=True)
    federated_server = models.ForeignKey(
        'FederatedServer',
        on_delete=models.PROTECT,
        null=True,
    )
    outbox = models.CharField(max_length=255, unique=True)
    summary = models.TextField(blank=True, null=True)
    local = models.BooleanField(default=True)
    fedireads_user = models.BooleanField(default=True)
    localname = models.CharField(
        max_length=255,
        null=True,
        unique=True
    )
    # name is your display name, which you can change at will
    name = models.CharField(max_length=100, blank=True, null=True)
    avatar = models.ImageField(upload_to='avatars/', blank=True, null=True)
    following = models.ManyToManyField(
        'self',
        symmetrical=False,
        through='UserFollows',
        through_fields=('user_subject', 'user_object'),
        related_name='followers'
    )
    follow_requests = models.ManyToManyField(
        'self',
        symmetrical=False,
        through='UserFollowRequest',
        through_fields=('user_subject', 'user_object'),
        related_name='follower_requests'
    )
    blocks = models.ManyToManyField(
        'self',
        symmetrical=False,
        through='UserBlocks',
        through_fields=('user_subject', 'user_object'),
        related_name='blocked_by'
    )
    favorites = models.ManyToManyField(
        'Status',
        symmetrical=False,
        through='Favorite',
        through_fields=('user', 'status'),
        related_name='favorite_statuses'
    )
    remote_id = models.CharField(max_length=255, null=True, unique=True)
    created_date = models.DateTimeField(auto_now_add=True)
    updated_date = models.DateTimeField(auto_now=True)
    manually_approves_followers = models.BooleanField(default=False)

    @property
    def activitypub_serialize(self):
        return activitypub.get_actor(self)


class UserRelationship(FedireadsModel):
    ''' many-to-many through table for followers '''
    user_subject = models.ForeignKey(
        'User',
        on_delete=models.PROTECT,
        related_name='%(class)s_user_subject'
    )
    user_object = models.ForeignKey(
        'User',
        on_delete=models.PROTECT,
        related_name='%(class)s_user_object'
    )
    # follow or follow_request for pending TODO: blocking?
    relationship_id = models.CharField(max_length=100)

    class Meta:
        abstract = True
        constraints = [
            models.UniqueConstraint(
                fields=['user_subject', 'user_object'],
                name='%(class)s_unique'
            ),
            models.CheckConstraint(
                check=~models.Q(user_subject=models.F('user_object')),
                name='%(class)s_no_self'
            )
        ]

    def get_remote_id(self):
        ''' use shelf identifier in remote_id '''
        base_path = self.user_subject.remote_id
        return '%s#%s/%d' % (base_path, self.status, self.id)


class UserFollows(UserRelationship):
    @property
    def status(self):
        return 'follows'

    @classmethod
    def from_request(cls, follow_request):
        return cls(
            user_subject=follow_request.user_subject,
            user_object=follow_request.user_object,
            relationship_id=follow_request.relationship_id,
        )


class UserFollowRequest(UserRelationship):
    @property
    def status(self):
        return 'follow_request'


class UserBlocks(UserRelationship):
    @property
    def status(self):
        return 'blocks'


class FederatedServer(FedireadsModel):
    ''' store which server's we federate with '''
    server_name = models.CharField(max_length=255, unique=True)
    # federated, blocked, whatever else
    status = models.CharField(max_length=255, default='federated')
    # is it mastodon, fedireads, etc
    application_type = models.CharField(max_length=255, null=True)
    application_version = models.CharField(max_length=255, null=True)


@receiver(models.signals.pre_save, sender=User)
def execute_before_save(sender, instance, *args, **kwargs):
    ''' populate fields for new local users '''
    # this user already exists, no need to poplate fields
    if instance.id or not instance.local:
        return

    # populate fields for local users
    instance.remote_id = 'https://%s/user/%s' % (DOMAIN, instance.username)
    instance.localname = instance.username
    instance.username = '%s@%s' % (instance.username, DOMAIN)
    instance.actor = instance.remote_id
    instance.inbox = '%s/inbox' % instance.remote_id
    instance.shared_inbox = 'https://%s/inbox' % DOMAIN
    instance.outbox = '%s/outbox' % instance.remote_id
    if not instance.private_key:
        instance.private_key, instance.public_key = create_key_pair()


@receiver(models.signals.post_save, sender=User)
def execute_after_save(sender, instance, created, *args, **kwargs):
    ''' create shelves for new users '''
    if not instance.local or not created:
        return

    shelves = [{
        'name': 'To Read',
        'identifier': 'to-read',
    }, {
        'name': 'Currently Reading',
        'identifier': 'reading',
    }, {
        'name': 'Read',
        'identifier': 'read',
    }]

    for shelf in shelves:
        Shelf(
            name=shelf['name'],
            identifier=shelf['identifier'],
            user=instance,
            editable=False
        ).save()