from django.conf import settings
from django.db import connection, models
from django.test import SimpleTestCase, skipUnlessDBFeature

from .models import Book, ChildModel1, ChildModel2


class IndexesTests(SimpleTestCase):

    def test_suffix(self):
        self.assertEqual(models.Index.suffix, 'idx')

    def test_repr(self):
        index = models.Index(fields=['title'])
        multi_col_index = models.Index(fields=['title', 'author'])
        self.assertEqual(repr(index), "<Index: fields='title'>")
        self.assertEqual(repr(multi_col_index), "<Index: fields='title, author'>")

    def test_eq(self):
        index = models.Index(fields=['title'])
        same_index = models.Index(fields=['title'])
        another_index = models.Index(fields=['title', 'author'])
        index.model = Book
        same_index.model = Book
        another_index.model = Book
        self.assertEqual(index, same_index)
        self.assertNotEqual(index, another_index)

    def test_index_fields_type(self):
        with self.assertRaisesMessage(ValueError, 'Index.fields must be a list.'):
            models.Index(fields='title')

    def test_raises_error_without_field(self):
        msg = 'At least one field is required to define an index.'
        with self.assertRaisesMessage(ValueError, msg):
            models.Index()

    def test_max_name_length(self):
        msg = 'Index names cannot be longer than 30 characters.'
        with self.assertRaisesMessage(ValueError, msg):
            models.Index(fields=['title'], name='looooooooooooong_index_name_idx')

    def test_name_constraints(self):
        msg = 'Index names cannot start with an underscore (_).'
        with self.assertRaisesMessage(ValueError, msg):
            models.Index(fields=['title'], name='_name_starting_with_underscore')

        msg = 'Index names cannot start with a number (0-9).'
        with self.assertRaisesMessage(ValueError, msg):
            models.Index(fields=['title'], name='5name_starting_with_number')

    def test_name_auto_generation(self):
        index = models.Index(fields=['author'])
        index.set_name_with_model(Book)
        self.assertEqual(index.name, 'model_index_author_0f5565_idx')

        # '-' for DESC columns should be accounted for in the index name.
        index = models.Index(fields=['-author'])
        index.set_name_with_model(Book)
        self.assertEqual(index.name, 'model_index_author_708765_idx')

        # fields may be truncated in the name. db_column is used for naming.
        long_field_index = models.Index(fields=['pages'])
        long_field_index.set_name_with_model(Book)
        self.assertEqual(long_field_index.name, 'model_index_page_co_69235a_idx')

        # suffix can't be longer than 3 characters.
        long_field_index.suffix = 'suff'
        msg = 'Index too long for multiple database support. Is self.suffix longer than 3 characters?'
        with self.assertRaisesMessage(AssertionError, msg):
            long_field_index.set_name_with_model(Book)

    def test_deconstruction(self):
        index = models.Index(fields=['title'], db_tablespace='idx_tbls')
        index.set_name_with_model(Book)
        path, args, kwargs = index.deconstruct()
        self.assertEqual(path, 'django.db.models.Index')
        self.assertEqual(args, ())
        self.assertEqual(
            kwargs,
            {'fields': ['title'], 'name': 'model_index_title_196f42_idx', 'db_tablespace': 'idx_tbls'}
        )

    def test_clone(self):
        index = models.Index(fields=['title'])
        new_index = index.clone()
        self.assertIsNot(index, new_index)
        self.assertEqual(index.fields, new_index.fields)

    def test_name_set(self):
        index_names = [index.name for index in Book._meta.indexes]
        self.assertEqual(index_names, ['model_index_title_196f42_idx'])

    def test_abstract_children(self):
        index_names = [index.name for index in ChildModel1._meta.indexes]
        self.assertEqual(index_names, ['model_index_name_440998_idx'])
        index_names = [index.name for index in ChildModel2._meta.indexes]
        self.assertEqual(index_names, ['model_index_name_b6c374_idx'])

    @skipUnlessDBFeature('supports_tablespaces')
    def test_db_tablespace(self):
        with connection.schema_editor() as editor:
            # Index with db_tablespace attribute.
            for fields in [
                # Field with db_tablespace specified on model.
                ['shortcut'],
                # Field without db_tablespace specified on model.
                ['author'],
                # Multi-column with db_tablespaces specified on model.
                ['shortcut', 'isbn'],
                # Multi-column without db_tablespace specified on model.
                ['title', 'author'],
            ]:
                with self.subTest(fields=fields):
                    index = models.Index(fields=fields, db_tablespace='idx_tbls2')
                    self.assertIn('"idx_tbls2"', index.create_sql(Book, editor).lower())
            # Indexes without db_tablespace attribute.
            for fields in [['author'], ['shortcut', 'isbn'], ['title', 'author']]:
                with self.subTest(fields=fields):
                    index = models.Index(fields=fields)
                    # The DEFAULT_INDEX_TABLESPACE setting can't be tested
                    # because it's evaluated when the model class is defined.
                    # As a consequence, @override_settings doesn't work.
                    if settings.DEFAULT_INDEX_TABLESPACE:
                        self.assertIn(
                            '"%s"' % settings.DEFAULT_INDEX_TABLESPACE,
                            index.create_sql(Book, editor).lower()
                        )
                    else:
                        self.assertNotIn('TABLESPACE', index.create_sql(Book, editor))
            # Field with db_tablespace specified on the model and an index
            # without db_tablespace.
            index = models.Index(fields=['shortcut'])
            self.assertIn('"idx_tbls"', index.create_sql(Book, editor).lower())
