#   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.

# beam-playground:
#   name: co-group-by-key
#   description: CoGroupByKey example.
#   multifile: false
#   context_line: 74
#   categories:
#     - Quickstart
#   complexity: BASIC
#   tags:
#     - hellobeam

import apache_beam as beam

# Output PCollection
class Output(beam.PTransform):
    class _OutputFn(beam.DoFn):
        def __init__(self, prefix=''):
            super().__init__()
            self.prefix = prefix

        def process(self, element):
            print(self.prefix+str(element))

    def __init__(self, label=None,prefix=''):
        super().__init__(label)
        self.prefix = prefix

    def expand(self, input):
        input | beam.ParDo(self._OutputFn(self.prefix))


class WordsAlphabet:
    def __init__(self, alphabet, fruit, country):
        self.alphabet = alphabet
        self.fruit = fruit
        self.country = country

    def __str__(self):
        return "WordsAlphabet(alphabet:'%s', fruit='%s', country='%s')" % (self.alphabet, self.fruit, self.country)


def apply_transforms(fruits, countries):
    def map_to_alphabet_kv(word):
        return (word[0], word)

    def cogbk_result_to_wordsalphabet(cgbk_result):
        (alphabet, words) = cgbk_result
        return WordsAlphabet(alphabet, words['fruits'][0], words['countries'][0])

    fruits_kv = (fruits | 'Fruit to KV' >> beam.Map(map_to_alphabet_kv))
    countries_kv = (countries | 'Country to KV' >> beam.Map(map_to_alphabet_kv))

    return ({'fruits': fruits_kv, 'countries': countries_kv}
            | beam.CoGroupByKey()
            | beam.Map(cogbk_result_to_wordsalphabet))


with beam.Pipeline() as p:
  fruits = p | 'Fruits' >> beam.Create(['apple', 'banana', 'cherry'])
  countries = p | 'Countries' >> beam.Create(['australia', 'brazil', 'canada'])

  (apply_transforms(fruits, countries) | Output())

