from django.db import connection
from django.db.migrations.executor import MigrationExecutor
from django.db.migrations.graph import MigrationGraph
from django.test import modify_settings, override_settings, TestCase
from django.apps.registry import apps as global_apps

from .test_base import MigrationTestBase


@modify_settings(INSTALLED_APPS={'append': 'migrations2'})
class ExecutorTests(MigrationTestBase):
    """
    Tests the migration executor (full end-to-end running).

    Bear in mind that if these are failing you should fix the other
    test failures first, as they may be propagating into here.
    """

    available_apps = ["migrations", "migrations2", "django.contrib.auth", "django.contrib.contenttypes"]

    @override_settings(MIGRATION_MODULES={"migrations": "migrations.test_migrations"})
    def test_run(self):
        """
        Tests running a simple set of migrations.
        """
        executor = MigrationExecutor(connection)
        # Let's look at the plan first and make sure it's up to scratch
        plan = executor.migration_plan([("migrations", "0002_second")])
        self.assertEqual(
            plan,
            [
                (executor.loader.graph.nodes["migrations", "0001_initial"], False),
                (executor.loader.graph.nodes["migrations", "0002_second"], False),
            ],
        )
        # Were the tables there before?
        self.assertTableNotExists("migrations_author")
        self.assertTableNotExists("migrations_book")
        # Alright, let's try running it
        executor.migrate([("migrations", "0002_second")])
        # Are the tables there now?
        self.assertTableExists("migrations_author")
        self.assertTableExists("migrations_book")
        # Rebuild the graph to reflect the new DB state
        executor.loader.build_graph()
        # Alright, let's undo what we did
        plan = executor.migration_plan([("migrations", None)])
        self.assertEqual(
            plan,
            [
                (executor.loader.graph.nodes["migrations", "0002_second"], True),
                (executor.loader.graph.nodes["migrations", "0001_initial"], True),
            ],
        )
        executor.migrate([("migrations", None)])
        # Are the tables gone?
        self.assertTableNotExists("migrations_author")
        self.assertTableNotExists("migrations_book")

    @override_settings(MIGRATION_MODULES={"migrations": "migrations.test_migrations_squashed"})
    def test_run_with_squashed(self):
        """
        Tests running a squashed migration from zero (should ignore what it replaces)
        """
        executor = MigrationExecutor(connection)
        # Check our leaf node is the squashed one
        leaves = [key for key in executor.loader.graph.leaf_nodes() if key[0] == "migrations"]
        self.assertEqual(leaves, [("migrations", "0001_squashed_0002")])
        # Check the plan
        plan = executor.migration_plan([("migrations", "0001_squashed_0002")])
        self.assertEqual(
            plan,
            [
                (executor.loader.graph.nodes["migrations", "0001_squashed_0002"], False),
            ],
        )
        # Were the tables there before?
        self.assertTableNotExists("migrations_author")
        self.assertTableNotExists("migrations_book")
        # Alright, let's try running it
        executor.migrate([("migrations", "0001_squashed_0002")])
        # Are the tables there now?
        self.assertTableExists("migrations_author")
        self.assertTableExists("migrations_book")
        # Rebuild the graph to reflect the new DB state
        executor.loader.build_graph()
        # Alright, let's undo what we did. Should also just use squashed.
        plan = executor.migration_plan([("migrations", None)])
        self.assertEqual(
            plan,
            [
                (executor.loader.graph.nodes["migrations", "0001_squashed_0002"], True),
            ],
        )
        executor.migrate([("migrations", None)])
        # Are the tables gone?
        self.assertTableNotExists("migrations_author")
        self.assertTableNotExists("migrations_book")

    @override_settings(MIGRATION_MODULES={
        "migrations": "migrations.test_migrations",
        "migrations2": "migrations2.test_migrations_2",
    })
    def test_empty_plan(self):
        """
        Tests that re-planning a full migration of a fully-migrated set doesn't
        perform spurious unmigrations and remigrations.

        There was previously a bug where the executor just always performed the
        backwards plan for applied migrations - which even for the most recent
        migration in an app, might include other, dependent apps, and these
        were being unmigrated.
        """
        # Make the initial plan, check it
        executor = MigrationExecutor(connection)
        plan = executor.migration_plan([
            ("migrations", "0002_second"),
            ("migrations2", "0001_initial"),
        ])
        self.assertEqual(
            plan,
            [
                (executor.loader.graph.nodes["migrations", "0001_initial"], False),
                (executor.loader.graph.nodes["migrations", "0002_second"], False),
                (executor.loader.graph.nodes["migrations2", "0001_initial"], False),
            ],
        )
        # Fake-apply all migrations
        executor.migrate([
            ("migrations", "0002_second"),
            ("migrations2", "0001_initial")
        ], fake=True)
        # Rebuild the graph to reflect the new DB state
        executor.loader.build_graph()
        # Now plan a second time and make sure it's empty
        plan = executor.migration_plan([
            ("migrations", "0002_second"),
            ("migrations2", "0001_initial"),
        ])
        self.assertEqual(plan, [])
        # Erase all the fake records
        executor.recorder.record_unapplied("migrations2", "0001_initial")
        executor.recorder.record_unapplied("migrations", "0002_second")
        executor.recorder.record_unapplied("migrations", "0001_initial")

    @override_settings(MIGRATION_MODULES={"migrations": "migrations.test_migrations"})
    def test_soft_apply(self):
        """
        Tests detection of initial migrations already having been applied.
        """
        state = {"faked": None}

        def fake_storer(phase, migration, fake):
            state["faked"] = fake
        executor = MigrationExecutor(connection, progress_callback=fake_storer)
        # Were the tables there before?
        self.assertTableNotExists("migrations_author")
        self.assertTableNotExists("migrations_tribble")
        # Run it normally
        self.assertEqual(
            executor.migration_plan([("migrations", "0001_initial")]),
            [
                (executor.loader.graph.nodes["migrations", "0001_initial"], False),
            ],
        )
        executor.migrate([("migrations", "0001_initial")])
        # Are the tables there now?
        self.assertTableExists("migrations_author")
        self.assertTableExists("migrations_tribble")
        # We shouldn't have faked that one
        self.assertEqual(state["faked"], False)
        # Rebuild the graph to reflect the new DB state
        executor.loader.build_graph()
        # Fake-reverse that
        executor.migrate([("migrations", None)], fake=True)
        # Are the tables still there?
        self.assertTableExists("migrations_author")
        self.assertTableExists("migrations_tribble")
        # Make sure that was faked
        self.assertEqual(state["faked"], True)
        # Finally, migrate forwards; this should fake-apply our initial migration
        executor.loader.build_graph()
        self.assertEqual(
            executor.migration_plan([("migrations", "0001_initial")]),
            [
                (executor.loader.graph.nodes["migrations", "0001_initial"], False),
            ],
        )
        executor.migrate([("migrations", "0001_initial")])
        self.assertEqual(state["faked"], True)
        # And migrate back to clean up the database
        executor.loader.build_graph()
        executor.migrate([("migrations", None)])
        self.assertTableNotExists("migrations_author")
        self.assertTableNotExists("migrations_tribble")

    @override_settings(
        MIGRATION_MODULES={
            "migrations": "migrations.test_migrations_custom_user",
            "django.contrib.auth": "django.contrib.auth.migrations",
        },
        AUTH_USER_MODEL="migrations.Author",
    )
    def test_custom_user(self):
        """
        Regression test for #22325 - references to a custom user model defined in the
        same app are not resolved correctly.
        """
        executor = MigrationExecutor(connection)
        self.assertTableNotExists("migrations_author")
        self.assertTableNotExists("migrations_tribble")
        # Migrate forwards
        executor.migrate([("migrations", "0001_initial")])
        self.assertTableExists("migrations_author")
        self.assertTableExists("migrations_tribble")
        # Make sure the soft-application detection works (#23093)
        # Change get_table_list to not return auth_user during this as
        # it wouldn't be there in a normal run, and ensure migrations.Author
        # exists in the global app registry temporarily.
        old_get_table_list = connection.introspection.get_table_list
        connection.introspection.get_table_list = lambda c: [x for x in old_get_table_list(c) if x != "auth_user"]
        migrations_apps = executor.loader.project_state(("migrations", "0001_initial")).render()
        global_apps.get_app_config("migrations").models["author"] = migrations_apps.get_model("migrations", "author")
        try:
            migration = executor.loader.get_migration("auth", "0001_initial")
            self.assertEqual(executor.detect_soft_applied(migration), True)
        finally:
            connection.introspection.get_table_list = old_get_table_list
            del global_apps.get_app_config("migrations").models["author"]
        # And migrate back to clean up the database
        executor.loader.build_graph()
        executor.migrate([("migrations", None)])
        self.assertTableNotExists("migrations_author")
        self.assertTableNotExists("migrations_tribble")


class FakeLoader(object):
    def __init__(self, graph, applied):
        self.graph = graph
        self.applied_migrations = applied


class FakeMigration(object):
    """Really all we need is any object with a debug-useful repr."""
    def __init__(self, name):
        self.name = name

    def __repr__(self):
        return 'M<%s>' % self.name


class ExecutorUnitTests(TestCase):
    """(More) isolated unit tests for executor methods."""
    def test_minimize_rollbacks(self):
        """
        Minimize unnecessary rollbacks in connected apps.

        When you say "./manage.py migrate appA 0001", rather than migrating to
        just after appA-0001 in the linearized migration plan (which could roll
        back migrations in other apps that depend on appA 0001, but don't need
        to be rolled back since we're not rolling back appA 0001), we migrate
        to just before appA-0002.
        """
        a1_impl = FakeMigration('a1')
        a1 = ('a', '1')
        a2_impl = FakeMigration('a2')
        a2 = ('a', '2')
        b1_impl = FakeMigration('b1')
        b1 = ('b', '1')
        graph = MigrationGraph()
        graph.add_node(a1, a1_impl)
        graph.add_node(a2, a2_impl)
        graph.add_node(b1, b1_impl)
        graph.add_dependency(None, b1, a1)
        graph.add_dependency(None, a2, a1)

        executor = MigrationExecutor(None)
        executor.loader = FakeLoader(graph, {a1, b1, a2})

        plan = executor.migration_plan({a1})

        self.assertEqual(plan, [(a2_impl, True)])

    def test_minimize_rollbacks_branchy(self):
        """
        Minimize rollbacks when target has multiple in-app children.

        a: 1 <---- 3 <--\
              \ \- 2 <--- 4
               \       \
        b:      \- 1 <--- 2
        """
        a1_impl = FakeMigration('a1')
        a1 = ('a', '1')
        a2_impl = FakeMigration('a2')
        a2 = ('a', '2')
        a3_impl = FakeMigration('a3')
        a3 = ('a', '3')
        a4_impl = FakeMigration('a4')
        a4 = ('a', '4')
        b1_impl = FakeMigration('b1')
        b1 = ('b', '1')
        b2_impl = FakeMigration('b2')
        b2 = ('b', '2')
        graph = MigrationGraph()
        graph.add_node(a1, a1_impl)
        graph.add_node(a2, a2_impl)
        graph.add_node(a3, a3_impl)
        graph.add_node(a4, a4_impl)
        graph.add_node(b1, b1_impl)
        graph.add_node(b2, b2_impl)
        graph.add_dependency(None, a2, a1)
        graph.add_dependency(None, a3, a1)
        graph.add_dependency(None, a4, a2)
        graph.add_dependency(None, a4, a3)
        graph.add_dependency(None, b2, b1)
        graph.add_dependency(None, b1, a1)
        graph.add_dependency(None, b2, a2)

        executor = MigrationExecutor(None)
        executor.loader = FakeLoader(graph, {a1, b1, a2, b2, a3, a4})

        plan = executor.migration_plan({a1})

        should_be_rolled_back = [b2_impl, a4_impl, a2_impl, a3_impl]
        exp = [(m, True) for m in should_be_rolled_back]
        self.assertEqual(plan, exp)