import json
from datetime import datetime, timedelta
from functools import reduce
from pprint import pprint

import boto3
from boto3.dynamodb.conditions import Key, Attr, And, Or

dynamodb = boto3.resource('dynamodb', region_name='us-east-1')
table = dynamodb.Table('prod-carveout_change_log')


def day_list(s1, s2):
    start = datetime.strptime(s1, "%Y-%m-%d")
    end = datetime.strptime(s2, "%Y-%m-%d")
    return [(start + timedelta(days=n)).strftime('%Y-%m-%d') for n in range((end - start).days + 1)]


dates = day_list('2020-11-24', '2020-12-11')
date_exp = reduce(lambda a, x: Or(a, Key('date_added').begins_with(x)), dates[1:],
                  Key('date_added').begins_with(dates[0]))

scan_kwargs = {
    'FilterExpression': And(Attr('change_details').begins_with('Territories'), date_exp),
    'ProjectionExpression': "date_added, upc, user_name, change_details"
}

done = False
start_key = None
data = []
while not done:
    if start_key:
        scan_kwargs['ExclusiveStartKey'] = start_key
    response = table.scan(**scan_kwargs)
    items = response.get('Items', [])
    if len(items) > 0:
        data.extend(items)
        print(f"{len(data)} found")

    start_key = response.get('LastEvaluatedKey', None)
    done = (start_key is None)

with open("data_file.json", "w") as write_file:
    json.dump(data, write_file, indent=2, sort_keys=True)

# while 'LastEvaluatedKey' in response:
#     response = table.scan(ExclusiveStartKey=response['LastEvaluatedKey'])
#     data.extend(response['Items'])