# Copyright (c) 2014 Ansible, Inc.
# All Rights Reserved.

from django.db import models
from django.db.models.signals import post_save
from django.dispatch import receiver

from awx.main.managers import InstanceManager
from awx.main.models import UnifiedJob


class Instance(models.Model):
    """A model representing an Ansible Tower instance, primary or secondary,
    running against this database.
    """
    objects = InstanceManager()

    uuid = models.CharField(max_length=40, unique=True)
    ip_address = models.GenericIPAddressField(protocol='both', unpack_ipv4=True)
    primary = models.BooleanField(default=False)
    created = models.DateTimeField(auto_now_add=True)
    modified = models.DateTimeField(auto_now=True)

    class Meta:
        app_label = 'main'

    @property
    def role(self):
        """Return the role of this instance, as a string."""
        if self.primary:
            return 'primary'
        return 'secondary'


class JobOrigin(models.Model):
    """A model representing the relationship between a unified job and
    the instance that was responsible for starting that job.

    It may be possible that a job has no origin (the common reason for this
    being that the job was started on Tower < 2.1 before origins were a thing).
    This is fine, and code should be able to handle it. A job with no origin
    is always assumed to *not* have the current instance as its origin.
    """
    unified_job = models.ForeignKey(UnifiedJob)
    instance = models.ForeignKey(Instance)
    created = models.DateTimeField(auto_now_add=True)
    modified = models.DateTimeField(auto_now=True)

    class Meta:
        app_label = 'main'



@receiver(post_save, sender=UnifiedJob)
def on_create(sender, instance, created=False, raw=False, **kwargs):
    """When a new job is created, save a record of its origin (the machine
    that started the job).
    """
    # Sanity check: We only want to create a JobOrigin record in cases where
    # we are making a new record, and in normal situations.
    #
    # In other situations, we simply do nothing.
    if raw or not created:
        return

    # Create the JobOrigin record, which attaches to the current instance
    # (which started the job).
    job_origin, new = JobOrigin.objects.get_or_create(
        instance=Instance.objects.me(),
        unified_job=instance,
    )