from sqlalchemy import Column
from sqlalchemy import inspect
from sqlalchemy import Integer
from sqlalchemy import MetaData
from sqlalchemy import PrimaryKeyConstraint
from sqlalchemy import String
from sqlalchemy import Table
from sqlalchemy.dialects import registry
from sqlalchemy.engine import default

from alembic import migration
from alembic.ddl import impl
from alembic.testing import assert_raises
from alembic.testing import assert_raises_message
from alembic.testing import config
from alembic.testing import eq_
from alembic.testing import mock
from alembic.testing.fixtures import TestBase
from alembic.util import CommandError

version_table = Table(
    "version_table",
    MetaData(),
    Column("version_num", String(32), nullable=False),
)
alembic_version_table = Table("alembic_version", MetaData())


def _up(from_, to_, branch_presence_changed=False):
    return migration.StampStep(from_, to_, True, branch_presence_changed)


def _down(from_, to_, branch_presence_changed=False):
    return migration.StampStep(from_, to_, False, branch_presence_changed)


class TestMigrationContext(TestBase):
    @classmethod
    def setup_class(cls):
        cls.bind = config.db

    def setUp(self):
        self.connection = self.bind.connect()
        self.transaction = self.connection.begin()

    def tearDown(self):
        self.transaction.rollback()
        with self.connection.begin():
            version_table.drop(self.connection, checkfirst=True)
            alembic_version_table.drop(self.connection, checkfirst=True)
        self.connection.close()

    def make_one(self, **kwargs):
        return migration.MigrationContext.configure(**kwargs)

    def get_revision(self):
        result = self.connection.execute(version_table.select())
        rows = result.fetchall()
        if len(rows) == 0:
            return None
        eq_(len(rows), 1)
        return rows[0]["version_num"]

    def test_config_default_version_table_name(self):
        context = self.make_one(dialect_name="sqlite")
        eq_(context._version.name, "alembic_version")

    def test_config_explicit_version_table_name(self):
        context = self.make_one(
            dialect_name="sqlite", opts={"version_table": "explicit"}
        )
        eq_(context._version.name, "explicit")
        eq_(context._version.primary_key.name, "explicit_pkc")

    def test_config_explicit_version_table_schema(self):
        context = self.make_one(
            dialect_name="sqlite", opts={"version_table_schema": "explicit"}
        )
        eq_(context._version.schema, "explicit")

    def test_config_explicit_no_pk(self):
        context = self.make_one(
            dialect_name="sqlite", opts={"version_table_pk": False}
        )
        eq_(len(context._version.primary_key), 0)

    def test_config_explicit_w_pk(self):
        context = self.make_one(
            dialect_name="sqlite", opts={"version_table_pk": True}
        )
        eq_(len(context._version.primary_key), 1)
        eq_(context._version.primary_key.name, "alembic_version_pkc")

    def test_get_current_revision_doesnt_create_version_table(self):
        context = self.make_one(
            connection=self.connection, opts={"version_table": "version_table"}
        )
        eq_(context.get_current_revision(), None)
        insp = inspect(self.connection)
        assert "version_table" not in insp.get_table_names()

    def test_get_current_revision(self):
        context = self.make_one(
            connection=self.connection, opts={"version_table": "version_table"}
        )
        version_table.create(self.connection)
        eq_(context.get_current_revision(), None)
        self.connection.execute(
            version_table.insert().values(version_num="revid")
        )
        eq_(context.get_current_revision(), "revid")

    def test_get_current_revision_error_if_starting_rev_given_online(self):
        context = self.make_one(
            connection=self.connection, opts={"starting_rev": "boo"}
        )
        assert_raises(CommandError, context.get_current_revision)

    def test_get_current_revision_offline(self):
        context = self.make_one(
            dialect_name="sqlite",
            opts={"starting_rev": "startrev", "as_sql": True},
        )
        eq_(context.get_current_revision(), "startrev")

    def test_get_current_revision_multiple_heads(self):
        version_table.create(self.connection)
        context = self.make_one(
            connection=self.connection, opts={"version_table": "version_table"}
        )
        updater = migration.HeadMaintainer(context, ())
        updater.update_to_step(_up(None, "a", True))
        updater.update_to_step(_up(None, "b", True))
        assert_raises_message(
            CommandError,
            "Version table 'version_table' has more than one head present; "
            "please use get_current_heads()",
            context.get_current_revision,
        )

    def test_get_heads(self):
        version_table.create(self.connection)
        context = self.make_one(
            connection=self.connection, opts={"version_table": "version_table"}
        )
        updater = migration.HeadMaintainer(context, ())
        updater.update_to_step(_up(None, "a", True))
        updater.update_to_step(_up(None, "b", True))
        eq_(context.get_current_heads(), ("a", "b"))

    def test_get_heads_offline(self):
        version_table.create(self.connection)
        context = self.make_one(
            connection=self.connection,
            opts={
                "starting_rev": "q",
                "version_table": "version_table",
                "as_sql": True,
            },
        )
        eq_(context.get_current_heads(), ("q",))

    def test_stamp_api_creates_table(self):
        context = self.make_one(connection=self.connection)
        assert (
            "alembic_version" not in inspect(self.connection).get_table_names()
        )

        script = mock.Mock(
            _stamp_revs=lambda revision, heads: [
                _up(None, "a", True),
                _up(None, "b", True),
            ]
        )

        context.stamp(script, "b")
        eq_(context.get_current_heads(), ("a", "b"))
        assert "alembic_version" in inspect(self.connection).get_table_names()


class UpdateRevTest(TestBase):
    __backend__ = True

    @classmethod
    def setup_class(cls):
        cls.bind = config.db

    def setUp(self):
        self.connection = self.bind.connect()
        self.context = migration.MigrationContext.configure(
            connection=self.connection, opts={"version_table": "version_table"}
        )
        with self.connection.begin():
            version_table.create(self.connection)
        self.updater = migration.HeadMaintainer(self.context, ())

    def tearDown(self):
        in_t = getattr(self.connection, "in_transaction", lambda: False)
        if in_t():
            self.connection.rollback()
        with self.connection.begin():
            version_table.drop(self.connection, checkfirst=True)
        self.connection.close()

    def _assert_heads(self, heads):
        eq_(set(self.context.get_current_heads()), set(heads))
        eq_(self.updater.heads, set(heads))

    def test_update_none_to_single(self):
        with self.connection.begin():
            self.updater.update_to_step(_up(None, "a", True))
            self._assert_heads(("a",))

    def test_update_single_to_single(self):
        with self.connection.begin():
            self.updater.update_to_step(_up(None, "a", True))
            self.updater.update_to_step(_up("a", "b"))
            self._assert_heads(("b",))

    def test_update_single_to_none(self):
        with self.connection.begin():
            self.updater.update_to_step(_up(None, "a", True))
            self.updater.update_to_step(_down("a", None, True))
            self._assert_heads(())

    def test_add_branches(self):
        with self.connection.begin():
            self.updater.update_to_step(_up(None, "a", True))
            self.updater.update_to_step(_up("a", "b"))
            self.updater.update_to_step(_up(None, "c", True))
            self._assert_heads(("b", "c"))
            self.updater.update_to_step(_up("c", "d"))
            self.updater.update_to_step(_up("d", "e1"))
            self.updater.update_to_step(_up("d", "e2", True))
            self._assert_heads(("b", "e1", "e2"))

    def test_teardown_branches(self):
        with self.connection.begin():
            self.updater.update_to_step(_up(None, "d1", True))
            self.updater.update_to_step(_up(None, "d2", True))
            self._assert_heads(("d1", "d2"))

            self.updater.update_to_step(_down("d1", "c"))
            self._assert_heads(("c", "d2"))

            self.updater.update_to_step(_down("d2", "c", True))

            self._assert_heads(("c",))
            self.updater.update_to_step(_down("c", "b"))
            self._assert_heads(("b",))

    def test_resolve_merges(self):
        with self.connection.begin():
            self.updater.update_to_step(_up(None, "a", True))
            self.updater.update_to_step(_up("a", "b"))
            self.updater.update_to_step(_up("b", "c1"))
            self.updater.update_to_step(_up("b", "c2", True))
            self.updater.update_to_step(_up("c1", "d1"))
            self.updater.update_to_step(_up("c2", "d2"))
            self._assert_heads(("d1", "d2"))
            self.updater.update_to_step(_up(("d1", "d2"), "e"))
            self._assert_heads(("e",))

    def test_unresolve_merges(self):
        with self.connection.begin():
            self.updater.update_to_step(_up(None, "e", True))

            self.updater.update_to_step(_down("e", ("d1", "d2")))
            self._assert_heads(("d2", "d1"))

            self.updater.update_to_step(_down("d2", "c2"))
            self._assert_heads(("c2", "d1"))

    def test_update_no_match(self):
        with self.connection.begin():
            self.updater.update_to_step(_up(None, "a", True))
            self.updater.heads.add("x")
            assert_raises_message(
                CommandError,
                "Online migration expected to match one row when updating "
                "'x' to 'b' in 'version_table'; 0 found",
                self.updater.update_to_step,
                _up("x", "b"),
            )

    def test_update_no_match_no_sane_rowcount(self):
        with self.connection.begin():
            self.updater.update_to_step(_up(None, "a", True))
            self.updater.heads.add("x")
            with mock.patch.object(
                self.connection.dialect, "supports_sane_rowcount", False
            ):
                self.updater.update_to_step(_up("x", "b"))

    def test_update_multi_match(self):
        with self.connection.begin():
            self.connection.execute(
                version_table.insert(), dict(version_num="a")
            )
            self.connection.execute(
                version_table.insert(), dict(version_num="a")
            )

            self.updater.heads.add("a")
            assert_raises_message(
                CommandError,
                "Online migration expected to match one row when updating "
                "'a' to 'b' in 'version_table'; 2 found",
                self.updater.update_to_step,
                _up("a", "b"),
            )

    def test_update_multi_match_no_sane_rowcount(self):
        with self.connection.begin():
            self.connection.execute(
                version_table.insert(), dict(version_num="a")
            )
            self.connection.execute(
                version_table.insert(), dict(version_num="a")
            )

            self.updater.heads.add("a")
            with mock.patch.object(
                self.connection.dialect, "supports_sane_rowcount", False
            ):
                self.updater.update_to_step(_up("a", "b"))

    def test_delete_no_match(self):
        with self.connection.begin():
            self.updater.update_to_step(_up(None, "a", True))

            self.updater.heads.add("x")
            assert_raises_message(
                CommandError,
                "Online migration expected to match one row when "
                "deleting 'x' in 'version_table'; 0 found",
                self.updater.update_to_step,
                _down("x", None, True),
            )

    def test_delete_no_matchno_sane_rowcount(self):
        with self.connection.begin():
            self.updater.update_to_step(_up(None, "a", True))

            self.updater.heads.add("x")
            with mock.patch.object(
                self.connection.dialect, "supports_sane_rowcount", False
            ):
                self.updater.update_to_step(_down("x", None, True))

    def test_delete_multi_match(self):
        with self.connection.begin():
            self.connection.execute(
                version_table.insert(), dict(version_num="a")
            )
            self.connection.execute(
                version_table.insert(), dict(version_num="a")
            )

            self.updater.heads.add("a")
            assert_raises_message(
                CommandError,
                "Online migration expected to match one row when "
                "deleting 'a' in 'version_table'; 2 found",
                self.updater.update_to_step,
                _down("a", None, True),
            )

    def test_delete_multi_match_no_sane_rowcount(self):
        with self.connection.begin():
            self.connection.execute(
                version_table.insert(), dict(version_num="a")
            )
            self.connection.execute(
                version_table.insert(), dict(version_num="a")
            )

            self.updater.heads.add("a")
            with mock.patch.object(
                self.connection.dialect, "supports_sane_rowcount", False
            ):
                self.updater.update_to_step(_down("a", None, True))


registry.register("custom_version", __name__, "CustomVersionDialect")


class CustomVersionDialect(default.DefaultDialect):
    name = "custom_version"


class CustomVersionTableImpl(impl.DefaultImpl):
    __dialect__ = "custom_version"

    def version_table_impl(
        self,
        *,
        version_table,
        version_table_schema,
        version_table_pk,
        **kw,
    ):
        vt = Table(
            version_table,
            MetaData(),
            Column("id", Integer, autoincrement=True),
            Column("version_num", String(32), nullable=False),
            schema=version_table_schema,
        )
        if version_table_pk:
            vt.append_constraint(
                PrimaryKeyConstraint("id", name=f"{version_table}_pkc")
            )
        return vt


class CustomVersionTableTest(TestMigrationContext):

    def test_custom_version_table(self):
        context = migration.MigrationContext.configure(
            dialect_name="custom_version",
        )
        eq_(len(context._version.columns), 2)
