#
# Licensed to the Apache Software Foundation (ASF) under one or more
# contributor license agreements.  See the NOTICE file distributed with
# this work for additional information regarding copyright ownership.
# The ASF licenses this file to You under the Apache License, Version 2.0
# (the "License"); you may not use this file except in compliance with
# the License.  You may obtain a copy of the License at
#
#    http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
#
"""Unit tests for the write transform."""

import logging
import unittest

import apache_beam as beam
from apache_beam.io import iobase
from apache_beam.testing.test_pipeline import TestPipeline
from apache_beam.testing.util import assert_that
from apache_beam.testing.util import is_empty
from apache_beam.transforms.ptransform import PTransform


class _TestSink(iobase.Sink):
  TEST_INIT_RESULT = 'test_init_result'

  def __init__(self, return_init_result=True, return_write_results=True):
    self.return_init_result = return_init_result
    self.return_write_results = return_write_results

  def initialize_write(self):
    if self.return_init_result:
      return _TestSink.TEST_INIT_RESULT

  def pre_finalize(self, init_result, writer_results):
    pass

  def finalize_write(self, init_result, writer_results,
                     unused_pre_finalize_result):
    self.init_result_at_finalize = init_result
    self.write_results_at_finalize = writer_results

  def open_writer(self, init_result, uid):
    writer = _TestWriter(init_result, uid, self.return_write_results)
    return writer


class _TestWriter(iobase.Writer):
  STATE_UNSTARTED, STATE_WRITTEN, STATE_CLOSED = 0, 1, 2
  TEST_WRITE_RESULT = 'test_write_result'

  def __init__(self, init_result, uid, return_write_results=True):
    self.state = _TestWriter.STATE_UNSTARTED
    self.init_result = init_result
    self.uid = uid
    self.write_output = []
    self.return_write_results = return_write_results

  def close(self):
    assert self.state in (
        _TestWriter.STATE_WRITTEN, _TestWriter.STATE_UNSTARTED)
    self.state = _TestWriter.STATE_CLOSED
    if self.return_write_results:
      return _TestWriter.TEST_WRITE_RESULT

  def write(self, value):
    if self.write_output:
      assert self.state == _TestWriter.STATE_WRITTEN
    else:
      assert self.state == _TestWriter.STATE_UNSTARTED

    self.state = _TestWriter.STATE_WRITTEN
    self.write_output.append(value)


class WriteToTestSink(PTransform):

  def __init__(self, return_init_result=True, return_write_results=True):
    self.return_init_result = return_init_result
    self.return_write_results = return_write_results
    self.last_sink = None
    self.label = 'write_to_test_sink'

  def expand(self, pcoll):
    self.last_sink = _TestSink(return_init_result=self.return_init_result,
                               return_write_results=self.return_write_results)
    return pcoll | beam.io.Write(self.last_sink)


class WriteTest(unittest.TestCase):
  DATA = ['some data', 'more data', 'another data', 'yet another data']

  def _run_write_test(self,
                      data,
                      return_init_result=True,
                      return_write_results=True):
    write_to_test_sink = WriteToTestSink(return_init_result,
                                         return_write_results)
    with TestPipeline() as p:
      result = p | beam.Create(data) | write_to_test_sink | beam.Map(list)

      assert_that(result, is_empty())

    sink = write_to_test_sink.last_sink
    self.assertIsNotNone(sink)

  def test_write(self):
    self._run_write_test(WriteTest.DATA)

  def test_write_with_empty_pcollection(self):
    data = []
    self._run_write_test(data)

  def test_write_no_init_result(self):
    self._run_write_test(WriteTest.DATA, return_init_result=False)

  def test_write_no_write_results(self):
    self._run_write_test(WriteTest.DATA, return_write_results=False)


if __name__ == '__main__':
  logging.getLogger().setLevel(logging.INFO)
  unittest.main()
