from datetime import datetime, timedelta
from decimal import Decimal
from unittest import skipIf, skipUnless

from django.db import connection
from django.db.models import CharField, TextField, Value as V
from django.db.models.expressions import RawSQL
from django.db.models.functions import (
    Coalesce, Greatest, Least, Length, Lower, Now, Upper,
)
from django.test import TestCase, skipIfDBFeature, skipUnlessDBFeature
from django.utils import timezone

from .models import Article, Author, DecimalModel, Fan

lorem_ipsum = """
    Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod
    tempor incididunt ut labore et dolore magna aliqua."""


class FunctionTests(TestCase):

    def test_coalesce(self):
        Author.objects.create(name='John Smith', alias='smithj')
        Author.objects.create(name='Rhonda')
        authors = Author.objects.annotate(display_name=Coalesce('alias', 'name'))

        self.assertQuerysetEqual(
            authors.order_by('name'), [
                'smithj',
                'Rhonda',
            ],
            lambda a: a.display_name
        )

        with self.assertRaisesMessage(ValueError, 'Coalesce must take at least two expressions'):
            Author.objects.annotate(display_name=Coalesce('alias'))

    def test_coalesce_mixed_values(self):
        a1 = Author.objects.create(name='John Smith', alias='smithj')
        a2 = Author.objects.create(name='Rhonda')
        ar1 = Article.objects.create(
            title="How to Django",
            text=lorem_ipsum,
            written=timezone.now(),
        )
        ar1.authors.add(a1)
        ar1.authors.add(a2)

        # mixed Text and Char
        article = Article.objects.annotate(
            headline=Coalesce('summary', 'text', output_field=TextField()),
        )

        self.assertQuerysetEqual(
            article.order_by('title'), [
                lorem_ipsum,
            ],
            lambda a: a.headline
        )

        # mixed Text and Char wrapped
        article = Article.objects.annotate(
            headline=Coalesce(Lower('summary'), Lower('text'), output_field=TextField()),
        )

        self.assertQuerysetEqual(
            article.order_by('title'), [
                lorem_ipsum.lower(),
            ],
            lambda a: a.headline
        )

    def test_coalesce_ordering(self):
        Author.objects.create(name='John Smith', alias='smithj')
        Author.objects.create(name='Rhonda')

        authors = Author.objects.order_by(Coalesce('alias', 'name'))
        self.assertQuerysetEqual(
            authors, [
                'Rhonda',
                'John Smith',
            ],
            lambda a: a.name
        )

        authors = Author.objects.order_by(Coalesce('alias', 'name').asc())
        self.assertQuerysetEqual(
            authors, [
                'Rhonda',
                'John Smith',
            ],
            lambda a: a.name
        )

        authors = Author.objects.order_by(Coalesce('alias', 'name').desc())
        self.assertQuerysetEqual(
            authors, [
                'John Smith',
                'Rhonda',
            ],
            lambda a: a.name
        )

    def test_greatest(self):
        now = timezone.now()
        before = now - timedelta(hours=1)

        Article.objects.create(
            title="Testing with Django",
            written=before,
            published=now,
        )

        articles = Article.objects.annotate(
            last_updated=Greatest('written', 'published'),
        )
        self.assertEqual(articles.first().last_updated, now)

    @skipUnlessDBFeature('greatest_least_ignores_nulls')
    def test_greatest_ignores_null(self):
        now = timezone.now()

        Article.objects.create(title="Testing with Django", written=now)

        articles = Article.objects.annotate(
            last_updated=Greatest('written', 'published'),
        )
        self.assertEqual(articles.first().last_updated, now)

    @skipIfDBFeature('greatest_least_ignores_nulls')
    def test_greatest_propagates_null(self):
        now = timezone.now()

        Article.objects.create(title="Testing with Django", written=now)

        articles = Article.objects.annotate(
            last_updated=Greatest('written', 'published'),
        )
        self.assertIsNone(articles.first().last_updated)

    @skipIf(connection.vendor == 'mysql', "This doesn't work on MySQL")
    def test_greatest_coalesce_workaround(self):
        past = datetime(1900, 1, 1)
        now = timezone.now()

        Article.objects.create(title="Testing with Django", written=now)

        articles = Article.objects.annotate(
            last_updated=Greatest(
                Coalesce('written', past),
                Coalesce('published', past),
            ),
        )
        self.assertEqual(articles.first().last_updated, now)

    @skipUnless(connection.vendor == 'mysql', "MySQL-specific workaround")
    def test_greatest_coalesce_workaround_mysql(self):
        past = datetime(1900, 1, 1)
        now = timezone.now()

        Article.objects.create(title="Testing with Django", written=now)

        past_sql = RawSQL("cast(%s as datetime)", (past,))
        articles = Article.objects.annotate(
            last_updated=Greatest(
                Coalesce('written', past_sql),
                Coalesce('published', past_sql),
            ),
        )
        self.assertEqual(articles.first().last_updated, now)

    def test_greatest_all_null(self):
        Article.objects.create(title="Testing with Django", written=timezone.now())

        articles = Article.objects.annotate(last_updated=Greatest('published', 'updated'))
        self.assertIsNone(articles.first().last_updated)

    def test_greatest_one_expressions(self):
        with self.assertRaisesMessage(ValueError, 'Greatest must take at least two expressions'):
            Greatest('written')

    def test_greatest_related_field(self):
        author = Author.objects.create(name='John Smith', age=45)
        Fan.objects.create(name='Margaret', age=50, author=author)

        authors = Author.objects.annotate(
            highest_age=Greatest('age', 'fans__age'),
        )
        self.assertEqual(authors.first().highest_age, 50)

    def test_greatest_update(self):
        author = Author.objects.create(name='James Smith', goes_by='Jim')

        Author.objects.update(alias=Greatest('name', 'goes_by'))

        author.refresh_from_db()
        self.assertEqual(author.alias, 'Jim')

    def test_greatest_decimal_filter(self):
        obj = DecimalModel.objects.create(n1=Decimal('1.1'), n2=Decimal('1.2'))
        self.assertCountEqual(
            DecimalModel.objects.annotate(
                greatest=Greatest('n1', 'n2'),
            ).filter(greatest=Decimal('1.2')),
            [obj],
        )

    def test_least(self):
        now = timezone.now()
        before = now - timedelta(hours=1)

        Article.objects.create(
            title="Testing with Django",
            written=before,
            published=now,
        )

        articles = Article.objects.annotate(
            first_updated=Least('written', 'published'),
        )
        self.assertEqual(articles.first().first_updated, before)

    @skipUnlessDBFeature('greatest_least_ignores_nulls')
    def test_least_ignores_null(self):
        now = timezone.now()

        Article.objects.create(title="Testing with Django", written=now)

        articles = Article.objects.annotate(
            first_updated=Least('written', 'published'),
        )
        self.assertEqual(articles.first().first_updated, now)

    @skipIfDBFeature('greatest_least_ignores_nulls')
    def test_least_propagates_null(self):
        now = timezone.now()

        Article.objects.create(title="Testing with Django", written=now)

        articles = Article.objects.annotate(
            first_updated=Least('written', 'published'),
        )
        self.assertIsNone(articles.first().first_updated)

    @skipIf(connection.vendor == 'mysql', "This doesn't work on MySQL")
    def test_least_coalesce_workaround(self):
        future = datetime(2100, 1, 1)
        now = timezone.now()

        Article.objects.create(title="Testing with Django", written=now)

        articles = Article.objects.annotate(
            last_updated=Least(
                Coalesce('written', future),
                Coalesce('published', future),
            ),
        )
        self.assertEqual(articles.first().last_updated, now)

    @skipUnless(connection.vendor == 'mysql', "MySQL-specific workaround")
    def test_least_coalesce_workaround_mysql(self):
        future = datetime(2100, 1, 1)
        now = timezone.now()

        Article.objects.create(title="Testing with Django", written=now)

        future_sql = RawSQL("cast(%s as datetime)", (future,))
        articles = Article.objects.annotate(
            last_updated=Least(
                Coalesce('written', future_sql),
                Coalesce('published', future_sql),
            ),
        )
        self.assertEqual(articles.first().last_updated, now)

    def test_least_all_null(self):
        Article.objects.create(title="Testing with Django", written=timezone.now())

        articles = Article.objects.annotate(first_updated=Least('published', 'updated'))
        self.assertIsNone(articles.first().first_updated)

    def test_least_one_expressions(self):
        with self.assertRaisesMessage(ValueError, 'Least must take at least two expressions'):
            Least('written')

    def test_least_related_field(self):
        author = Author.objects.create(name='John Smith', age=45)
        Fan.objects.create(name='Margaret', age=50, author=author)

        authors = Author.objects.annotate(
            lowest_age=Least('age', 'fans__age'),
        )
        self.assertEqual(authors.first().lowest_age, 45)

    def test_least_update(self):
        author = Author.objects.create(name='James Smith', goes_by='Jim')

        Author.objects.update(alias=Least('name', 'goes_by'))

        author.refresh_from_db()
        self.assertEqual(author.alias, 'James Smith')

    def test_least_decimal_filter(self):
        obj = DecimalModel.objects.create(n1=Decimal('1.1'), n2=Decimal('1.2'))
        self.assertCountEqual(
            DecimalModel.objects.annotate(
                least=Least('n1', 'n2'),
            ).filter(least=Decimal('1.1')),
            [obj],
        )

    def test_nested_function_ordering(self):
        Author.objects.create(name='John Smith')
        Author.objects.create(name='Rhonda Simpson', alias='ronny')

        authors = Author.objects.order_by(Length(Coalesce('alias', 'name')))
        self.assertQuerysetEqual(
            authors, [
                'Rhonda Simpson',
                'John Smith',
            ],
            lambda a: a.name
        )

        authors = Author.objects.order_by(Length(Coalesce('alias', 'name')).desc())
        self.assertQuerysetEqual(
            authors, [
                'John Smith',
                'Rhonda Simpson',
            ],
            lambda a: a.name
        )

    def test_now(self):
        ar1 = Article.objects.create(
            title='How to Django',
            text=lorem_ipsum,
            written=timezone.now(),
        )
        ar2 = Article.objects.create(
            title='How to Time Travel',
            text=lorem_ipsum,
            written=timezone.now(),
        )

        num_updated = Article.objects.filter(id=ar1.id, published=None).update(published=Now())
        self.assertEqual(num_updated, 1)

        num_updated = Article.objects.filter(id=ar1.id, published=None).update(published=Now())
        self.assertEqual(num_updated, 0)

        ar1.refresh_from_db()
        self.assertIsInstance(ar1.published, datetime)

        ar2.published = Now() + timedelta(days=2)
        ar2.save()
        ar2.refresh_from_db()
        self.assertIsInstance(ar2.published, datetime)

        self.assertQuerysetEqual(
            Article.objects.filter(published__lte=Now()),
            ['How to Django'],
            lambda a: a.title
        )
        self.assertQuerysetEqual(
            Article.objects.filter(published__gt=Now()),
            ['How to Time Travel'],
            lambda a: a.title
        )

    def test_func_transform_bilateral(self):
        class UpperBilateral(Upper):
            bilateral = True

        try:
            CharField.register_lookup(UpperBilateral)
            Author.objects.create(name='John Smith', alias='smithj')
            Author.objects.create(name='Rhonda')
            authors = Author.objects.filter(name__upper__exact='john smith')
            self.assertQuerysetEqual(
                authors.order_by('name'), [
                    'John Smith',
                ],
                lambda a: a.name
            )
        finally:
            CharField._unregister_lookup(UpperBilateral)

    def test_func_transform_bilateral_multivalue(self):
        class UpperBilateral(Upper):
            bilateral = True

        try:
            CharField.register_lookup(UpperBilateral)
            Author.objects.create(name='John Smith', alias='smithj')
            Author.objects.create(name='Rhonda')
            authors = Author.objects.filter(name__upper__in=['john smith', 'rhonda'])
            self.assertQuerysetEqual(
                authors.order_by('name'), [
                    'John Smith',
                    'Rhonda',
                ],
                lambda a: a.name
            )
        finally:
            CharField._unregister_lookup(UpperBilateral)

    def test_function_as_filter(self):
        Author.objects.create(name='John Smith', alias='SMITHJ')
        Author.objects.create(name='Rhonda')
        self.assertQuerysetEqual(
            Author.objects.filter(alias=Upper(V('smithj'))),
            ['John Smith'], lambda x: x.name
        )
        self.assertQuerysetEqual(
            Author.objects.exclude(alias=Upper(V('smithj'))),
            ['Rhonda'], lambda x: x.name
        )