"""Models used by django-watson."""

from __future__ import unicode_literals

import uuid

from django.db import models
from django.contrib.contenttypes.models import ContentType
from django.utils.encoding import python_2_unicode_compatible, force_text
from django.utils.functional import cached_property

try:
    from django.contrib.contenttypes.fields import GenericForeignKey
except ImportError:
    from django.contrib.contenttypes.generic import GenericForeignKey


INTEGER_FIELDS = (models.IntegerField, models.AutoField,)
BIG_INTEGER_FIELDS = (models.BigIntegerField,)

try:
    BIG_INTEGER_FIELDS += (models.BigAutoField,)
except AttributeError:  # Django < 2.0.
    pass


def has_int_pk(model):
    """Tests whether the given model has an integer primary key."""
    pk = model._meta.pk
    return (
        isinstance(pk, INTEGER_FIELDS) and
        not isinstance(pk, BIG_INTEGER_FIELDS)
    ) or (
        isinstance(pk, models.ForeignKey) and has_int_pk(pk.remote_field.model)
    )


def get_str_pk(obj, connection):
    return obj.pk.hex if isinstance(obj.pk, uuid.UUID) and connection.vendor != "postgresql" else force_text(obj.pk)


META_CACHE_KEY = "_meta_cache"


@python_2_unicode_compatible
class SearchEntry(models.Model):

    """An entry in the search index."""

    engine_slug = models.CharField(
        max_length=200,
        db_index=True,
        default="default",
    )

    content_type = models.ForeignKey(
        ContentType,
        on_delete=models.CASCADE,
    )

    object_id = models.TextField()

    object_id_int = models.IntegerField(
        blank=True,
        null=True,
        db_index=True,
    )

    object = GenericForeignKey()

    title = models.CharField(
        max_length=1000,
    )

    description = models.TextField(
        blank=True,
    )

    content = models.TextField(
        blank=True,
    )

    url = models.CharField(
        max_length=1000,
        blank=True,
    )

    meta_encoded = models.TextField()

    def _deserialize_meta(self):
        from watson.search import SearchEngine
        engine = SearchEngine._created_engines[self.engine_slug]
        model = ContentType.objects.get_for_id(self.content_type_id).model_class()
        adapter = engine.get_adapter(model)
        return adapter.deserialize_meta(self.meta_encoded)

    @cached_property
    def meta(self):
        """Returns the meta information stored with the search entry."""
        # Attempt to use the cached value.
        if hasattr(self, META_CACHE_KEY):
            return getattr(self, META_CACHE_KEY)
        # Decode the meta.
        meta_value = self._deserialize_meta()
        setattr(self, META_CACHE_KEY, meta_value)
        return meta_value

    def get_absolute_url(self):
        """Returns the URL of the referenced object."""
        return self.url

    def __str__(self):
        """Returns a string representation."""
        return self.title

    class Meta:
        verbose_name_plural = "search entries"
        app_label = 'watson'