import types
import pytest
from unittest.mock import MagicMock
from octopus.flows.dim_refresh import generator
from sqlalchemy.engine import Engine


def test_get_min_max_list(monkeypatch):
    """Generator method should output generator
    """

    context = {
        'destination_s3_key': 'dim_label/data/dim_label.txt.gz',
        'chunk_size': 100000,
        'table': 'vendor',
        'bucket': 'prod-staging-dim-imports',
        'primary_key': 'id',
        'query': '''some query'''
    }

    engine = MagicMock()
    connection = MagicMock()
    engine.connect.return_value = connection
    connection.execute.return_value = [
        {'min_id': 10, 'max_id': 20},
        {'min_id': 20, 'max_id': 30}]
    monkeypatch.setattr(
        generator, 'get_engine', MagicMock(return_value=engine))

    data = generator.get_min_max_list(
        context.get('primary_key'),
        context.get('chunk_size'),
        context.get('table'))

    assert generator.get_engine.called
    assert engine.connect.called

    assert len(data.get('min_max_pair')) == len(
        connection.execute.return_value)

    for i, return_value in enumerate(connection.execute.return_value):
        assert connection.execute.return_value[i].get(
            'min_id') == return_value.get('min_id')
        assert connection.execute.return_value[i].get(
            'max_id') == return_value.get('max_id')


def test_missing_primary_key():
    with pytest.raises(Exception):
        generator.get_min_max_list(None, None, None)


def test_generator():
    """Generator method should output generator
    """

    context = {
        'destination_s3_key': 'dim_label/data/dim_label.txt.gz',
        'chunk_size': 100000,
        'table': 'vendor',
        'bucket': 'prod-staging-dim-imports',
        'primary_key': 'id',
        'query': '''some query''',
        'bootstrap.min_max_pair': [
            {'min_id': 10, 'max_id': 20},
            {'min_id': 20, 'max_id': 30}]
    }

    gen = generator.get_generator(context)
    assert isinstance(gen, types.GeneratorType)

    # Go through the generator
    data = list(gen)

    for i, return_value in enumerate(context.get('bootstrap.min_max_pair')):
        assert data[i].get('generator.min_id') == return_value.get('min_id')
        assert data[i].get('generator.max_id') == return_value.get('max_id')


def test_primary_key_required_exception():
    """ Testing exception thrown when no primary key is provided
    """

    context = {}
    assert not list(generator.get_generator(context))


def test_get_range_sql_output():
    """ Testing the output type of get_range_sql
    """

    primary_key = 'id'
    chunk_size = 1000
    table = 'sometable'
    assert isinstance(generator.get_range_sql(primary_key, chunk_size, table),
                      str)


def test_get_engine():
    """ Testing if get_engine method return Engine object
    """

    assert isinstance(generator.get_engine(), Engine)