from sqlalchemy import Integer, func, Boolean
from alembic.testing.fixtures import TestBase
from alembic.testing import config
from sqlalchemy import TIMESTAMP, MetaData, Table, Column, text
from sqlalchemy.engine.reflection import Inspector
from alembic import op, util

from alembic.testing import eq_, assert_raises_message
from alembic.testing.fixtures import capture_context_buffer, op_fixture
from alembic.testing.env import staging_env, _no_sql_testing_config, \
    three_rev_fixture, clear_staging_env

from alembic.migration import MigrationContext


class MySQLOpTest(TestBase):

    def test_rename_column(self):
        context = op_fixture('mysql')
        op.alter_column(
            't1', 'c1', new_column_name="c2", existing_type=Integer)
        context.assert_(
            'ALTER TABLE t1 CHANGE c1 c2 INTEGER NULL'
        )

    def test_rename_column_quotes_needed_one(self):
        context = op_fixture('mysql')
        op.alter_column('MyTable', 'ColumnOne', new_column_name="ColumnTwo",
                        existing_type=Integer)
        context.assert_(
            'ALTER TABLE `MyTable` CHANGE `ColumnOne` `ColumnTwo` INTEGER NULL'
        )

    def test_rename_column_quotes_needed_two(self):
        context = op_fixture('mysql')
        op.alter_column('my table', 'column one', new_column_name="column two",
                        existing_type=Integer)
        context.assert_(
            'ALTER TABLE `my table` CHANGE `column one` '
            '`column two` INTEGER NULL'
        )

    def test_rename_column_serv_default(self):
        context = op_fixture('mysql')
        op.alter_column(
            't1', 'c1', new_column_name="c2", existing_type=Integer,
            existing_server_default="q")
        context.assert_(
            "ALTER TABLE t1 CHANGE c1 c2 INTEGER NULL DEFAULT 'q'"
        )

    def test_rename_column_serv_compiled_default(self):
        context = op_fixture('mysql')
        op.alter_column(
            't1', 'c1', existing_type=Integer,
            server_default=func.utc_thing(func.current_timestamp()))
        # this is not a valid MySQL default but the point is to just
        # test SQL expression rendering
        context.assert_(
            "ALTER TABLE t1 ALTER COLUMN c1 "
            "SET DEFAULT utc_thing(CURRENT_TIMESTAMP)"
        )

    def test_rename_column_autoincrement(self):
        context = op_fixture('mysql')
        op.alter_column(
            't1', 'c1', new_column_name="c2", existing_type=Integer,
            existing_autoincrement=True)
        context.assert_(
            'ALTER TABLE t1 CHANGE c1 c2 INTEGER NULL AUTO_INCREMENT'
        )

    def test_col_add_autoincrement(self):
        context = op_fixture('mysql')
        op.alter_column('t1', 'c1', existing_type=Integer,
                        autoincrement=True)
        context.assert_(
            'ALTER TABLE t1 MODIFY c1 INTEGER NULL AUTO_INCREMENT'
        )

    def test_col_remove_autoincrement(self):
        context = op_fixture('mysql')
        op.alter_column('t1', 'c1', existing_type=Integer,
                        existing_autoincrement=True,
                        autoincrement=False)
        context.assert_(
            'ALTER TABLE t1 MODIFY c1 INTEGER NULL'
        )

    def test_col_dont_remove_server_default(self):
        context = op_fixture('mysql')
        op.alter_column('t1', 'c1', existing_type=Integer,
                        existing_server_default='1',
                        server_default=False)

        context.assert_()

    def test_alter_column_drop_default(self):
        context = op_fixture('mysql')
        op.alter_column("t", "c", existing_type=Integer, server_default=None)
        context.assert_(
            'ALTER TABLE t ALTER COLUMN c DROP DEFAULT'
        )

    def test_alter_column_remove_schematype(self):
        context = op_fixture('mysql')
        op.alter_column(
            "t", "c",
            type_=Integer,
            existing_type=Boolean(create_constraint=True, name="ck1"),
            server_default=None)
        context.assert_(
            'ALTER TABLE t MODIFY c INTEGER NULL'
        )

    def test_alter_column_modify_default(self):
        context = op_fixture('mysql')
        # notice we dont need the existing type on this one...
        op.alter_column("t", "c", server_default='1')
        context.assert_(
            "ALTER TABLE t ALTER COLUMN c SET DEFAULT '1'"
        )

    def test_col_not_nullable(self):
        context = op_fixture('mysql')
        op.alter_column('t1', 'c1', nullable=False, existing_type=Integer)
        context.assert_(
            'ALTER TABLE t1 MODIFY c1 INTEGER NOT NULL'
        )

    def test_col_not_nullable_existing_serv_default(self):
        context = op_fixture('mysql')
        op.alter_column('t1', 'c1', nullable=False, existing_type=Integer,
                        existing_server_default='5')
        context.assert_(
            "ALTER TABLE t1 MODIFY c1 INTEGER NOT NULL DEFAULT '5'"
        )

    def test_col_nullable(self):
        context = op_fixture('mysql')
        op.alter_column('t1', 'c1', nullable=True, existing_type=Integer)
        context.assert_(
            'ALTER TABLE t1 MODIFY c1 INTEGER NULL'
        )

    def test_col_multi_alter(self):
        context = op_fixture('mysql')
        op.alter_column(
            't1', 'c1', nullable=False, server_default="q", type_=Integer)
        context.assert_(
            "ALTER TABLE t1 MODIFY c1 INTEGER NOT NULL DEFAULT 'q'"
        )

    def test_alter_column_multi_alter_w_drop_default(self):
        context = op_fixture('mysql')
        op.alter_column(
            't1', 'c1', nullable=False, server_default=None, type_=Integer)
        context.assert_(
            "ALTER TABLE t1 MODIFY c1 INTEGER NOT NULL"
        )

    def test_col_alter_type_required(self):
        op_fixture('mysql')
        assert_raises_message(
            util.CommandError,
            "MySQL CHANGE/MODIFY COLUMN operations require the existing type.",
            op.alter_column, 't1', 'c1', nullable=False, server_default="q"
        )

    def test_drop_fk(self):
        context = op_fixture('mysql')
        op.drop_constraint("f1", "t1", "foreignkey")
        context.assert_(
            "ALTER TABLE t1 DROP FOREIGN KEY f1"
        )

    def test_drop_constraint_primary(self):
        context = op_fixture('mysql')
        op.drop_constraint('primary', 't1', type_='primary')
        context.assert_(
            "ALTER TABLE t1 DROP PRIMARY KEY"
        )

    def test_drop_unique(self):
        context = op_fixture('mysql')
        op.drop_constraint("f1", "t1", "unique")
        context.assert_(
            "ALTER TABLE t1 DROP INDEX f1"
        )

    def test_drop_check(self):
        op_fixture('mysql')
        assert_raises_message(
            NotImplementedError,
            "MySQL does not support CHECK constraints.",
            op.drop_constraint, "f1", "t1", "check"
        )

    def test_drop_unknown(self):
        op_fixture('mysql')
        assert_raises_message(
            TypeError,
            "'type' can be one of 'check', 'foreignkey', "
            "'primary', 'unique', None",
            op.drop_constraint, "f1", "t1", "typo"
        )

    def test_drop_generic_constraint(self):
        op_fixture('mysql')
        assert_raises_message(
            NotImplementedError,
            "No generic 'DROP CONSTRAINT' in MySQL - please "
            "specify constraint type",
            op.drop_constraint, "f1", "t1"
        )


class MySQLDefaultCompareTest(TestBase):
    __only_on__ = 'mysql'

    @classmethod
    def setup_class(cls):
        cls.bind = config.db
        staging_env()
        context = MigrationContext.configure(
            connection=cls.bind.connect(),
            opts={
                'compare_type': True,
                'compare_server_default': True
            }
        )
        connection = context.bind
        cls.autogen_context = {
            'imports': set(),
            'connection': connection,
            'dialect': connection.dialect,
            'context': context
        }

    @classmethod
    def teardown_class(cls):
        clear_staging_env()

    def setUp(self):
        self.metadata = MetaData(self.bind)

    def tearDown(self):
        self.metadata.drop_all()

    def _compare_default_roundtrip(self, type_, txt, alternate=None):
        if alternate:
            expected = True
        else:
            alternate = txt
            expected = False
        t = Table(
            "test", self.metadata,
            Column(
                "somecol", type_,
                server_default=text(txt) if txt else None
            )
        )
        t2 = Table("test", MetaData(),
                   Column("somecol", type_, server_default=text(alternate))
                   )
        assert self._compare_default(
            t, t2, t2.c.somecol, alternate
        ) is expected

    def _compare_default(
        self,
        t1, t2, col,
        rendered
    ):
        t1.create(self.bind)
        insp = Inspector.from_engine(self.bind)
        cols = insp.get_columns(t1.name)
        ctx = self.autogen_context['context']
        return ctx.impl.compare_server_default(
            None,
            col,
            rendered,
            cols[0]['default'])

    def test_compare_timestamp_current_timestamp(self):
        self._compare_default_roundtrip(
            TIMESTAMP(),
            "CURRENT_TIMESTAMP",
        )

    def test_compare_timestamp_current_timestamp_diff(self):
        self._compare_default_roundtrip(
            TIMESTAMP(),
            None, "CURRENT_TIMESTAMP",
        )
