price_getter.py

import asyncio
import aiohttp
import aiofiles
import json
from datetime import datetime, timedelta


async def fetch(url):
    async with aiohttp.ClientSession() as session:
        async with session.get(url) as response:
            return await response.json()


async def open_file(filename):
    async with aiofiles.open(filename, mode='r') as f:
        return await f.read()


def date_generator(from_date, to_date):
    curr = from_date
    while curr <= to_date:
        yield curr
        curr += timedelta(days=1)


async def price_writer(currency, fiat):
    pair = fiat + '_' + currency
    response = await fetch(
        'https://min-api.cryptocompare.com/'
        'data/histoday?fsym={}&tsym={}&allData=true'.format(currency, fiat)
    )
    price_data = response['Data']
    sorted_data = [
        {
            datetime.utcfromtimestamp(data['time']).strftime('%Y-%m-%d'):
            data for data in price_data
        }
    ]
    async with aiofiles.open('{}.json'.format(pair), mode='w') as f:
        await f.write(json.dumps(sorted_data, sort_keys=True, indent=4))
    print("Wrote data for pair {}_{}".format(currency, fiat))


async def price_getter(currency, fiat, from_date, to_date):
    pair = fiat + '_' + currency
    price_list = await (open_file('{}.json'.format(pair)))
    price_data = json.loads(price_list)
    try:
        prices = [price_data[0][d.strftime('%Y-%m-%d')]
                  for d in date_generator(datetime.utcfromtimestamp(from_date),
                                          datetime.utcfromtimestamp(to_date))]
    except ValueError:
        return []
    except KeyError:
        return []
    return prices


async def run():
    currencies = ['ETH', 'BTC']
    fiats = ['USD', 'AUD', 'JPY']
    for currency in currencies:
        for fiat in fiats:
            await price_writer(currency, fiat)
    prices = await price_getter('ETH', 'USD', 1535328000, 1535328000)
    print(prices)

if __name__ == '__main__':
    loop = asyncio.get_event_loop()
    loop.run_until_complete(run())