# coding=utf-8
#
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# 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
#
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# pytype: skip-file
# pylint:disable=line-too-long

# beam-playground:
#   name: LatestPerKey
#   description: Demonstration of Latest transform usage per key.
#   multifile: false
#   default_example: false
#   context_line: 45
#   categories:
#     - Core Transforms
#   complexity: BASIC
#   tags:
#     - transforms
#     - timestamps
#     - latest


def latest_per_key(test=None):
  # [START latest_per_key]
  import apache_beam as beam
  import time

  def to_unix_time(time_str, format='%Y-%m-%d %H:%M:%S'):
    return time.mktime(time.strptime(time_str, format))

  with beam.Pipeline() as pipeline:
    latest_elements_per_key = (
        pipeline
        | 'Create crops' >> beam.Create([
            ('spring', {
                'item': '🥕', 'harvest': '2020-06-28 00:00:00'
            }),
            ('spring', {
                'item': '🍓', 'harvest': '2020-06-16 00:00:00'
            }),
            ('summer', {
                'item': '🥕', 'harvest': '2020-07-17 00:00:00'
            }),
            ('summer', {
                'item': '🍓', 'harvest': '2020-08-26 00:00:00'
            }),
            ('summer', {
                'item': '🍆', 'harvest': '2020-09-04 00:00:00'
            }),
            ('summer', {
                'item': '🥬', 'harvest': '2020-09-18 00:00:00'
            }),
            ('summer', {
                'item': '🍅', 'harvest': '2020-09-22 00:00:00'
            }),
            ('autumn', {
                'item': '🍅', 'harvest': '2020-10-01 00:00:00'
            }),
            ('autumn', {
                'item': '🥬', 'harvest': '2020-10-20 00:00:00'
            }),
            ('autumn', {
                'item': '🍆', 'harvest': '2020-10-26 00:00:00'
            }),
            ('winter', {
                'item': '🥬', 'harvest': '2020-02-24 00:00:00'
            }),
        ])
        | 'With timestamps' >> beam.Map(
            lambda pair: beam.window.TimestampedValue(
                (pair[0], pair[1]['item']), to_unix_time(pair[1]['harvest'])))
        | 'Get latest elements per key' >> beam.combiners.Latest.PerKey()
        | beam.Map(print))
    # [END latest_per_key]
    if test:
      test(latest_elements_per_key)


if __name__ == '__main__':
  latest_per_key()
