import ccxt

def static_var(varname, value):
    def decorate(func):
        setattr(func, varname, value)
        return func
    return decorate

max_digits = 18
current_assets = {
        "ETH":  int(2.00000000 * 10**max_digits),
        "BTC":  int(1.23000000 * 10**max_digits),
        "ZEC":  int(2.00000000 * 10**max_digits),
        "SC" :  int(2.000000000 * 10**max_digits),
        }

repartition_pertenthousand = {
        "BTC":  2857,
        "ZEC":  3701,
        "DOGE": 1805,
        "DGB":  1015,
        "SC":    623,
        }

market = ccxt.poloniex()

def formatted_price(value):
    return round(value / 10**max_digits, 8)

@static_var("cache", {})
def get_ticker(c1, c2, market):
    def invert(ticker):
        return {
                "bid": float(1/ticker["ask"]),
                "ask": float(1/ticker["bid"]),
                }

    if (c1, c2, market.__class__) in get_ticker.cache:
        return get_ticker.cache[(c1, c2, market.__class__)]
    if (c2, c1, market.__class__) in get_ticker.cache:
        return invert(get_ticker.cache[(c2, c1, market.__class__)])

    try:
        get_ticker.cache[(c1, c2, market.__class__)] = market.fetch_ticker("{}/{}".format(c1, c2))
    except ccxt.ExchangeError:
        try:
            get_ticker.cache[(c2, c1, market.__class__)] = market.fetch_ticker("{}/{}".format(c2, c1))
        except ccxt.ExchangeError:
            get_ticker.cache[(c1, c2, market.__class__)] = None
    return get_ticker(c1, c2, market)

def assets_value(assets, market, base_currency="BTC"):
    repartition_in_base_currency = {}
    for currency, asset_value in assets.items():
        if currency == base_currency:
            repartition_in_base_currency[currency] = asset_value
        else:
            asset_ticker = get_ticker(currency, base_currency, market)
            if asset_ticker is None:
                raise Exception("This asset is not available in the chosen market")
            repartition_in_base_currency[currency] = int(asset_ticker["bid"] * asset_value)
    return repartition_in_base_currency

def dispatch_assets(base_currency_value, repartition_pertenthousand, market, base_currency="BTC"):
    sum_pertenthousand = sum([v for k, v in repartition_pertenthousand.items()])
    repartition_in_base_currency = {}
    for currency, ptt in repartition_pertenthousand.items():
        repartition_in_base_currency[currency] = int(ptt * base_currency_value / sum_pertenthousand)
    return repartition_in_base_currency

def give_orders(current_assets, repartition_pertenthousand, market, base_currency="BTC"):
    value_in_base = assets_value(current_assets, market, base_currency=base_currency)
    total_base_value = sum([ v for k, v in value_in_base.items()])

    new_repartition = dispatch_assets(total_base_value, repartition_pertenthousand, market, base_currency=base_currency)
    mouvements = {}

    for key in set(value_in_base.keys()).union(set(new_repartition.keys())):
        mouvements[key] = value_in_base.get(key, 0) - new_repartition.get(key, 0)

    print("assets before repartition:")
    for currency, value in current_assets.items():
        print("holding {} {}".format(
            formatted_price(value),
            currency))
    print("------------")
    for currency, value in mouvements.items():
        if currency == base_currency:
            continue
        asset_ticker = get_ticker(currency, base_currency, market)
        if value > 0:
            action = "sell"
            currency_price = int(value / asset_ticker["bid"])
        else:
            action = "buy"
            currency_price = int(value / asset_ticker["ask"])
        if value != 0:
            print("need to {} {} {}'s worth of {}, i.e. {} {}".format(
                action,
                formatted_price(abs(value)),
                base_currency,
                currency,
                formatted_price(abs(currency_price)),
                currency))
    print("------------\nassets after repartition:")
    for currency, value in new_repartition.items():
        print("holding {} {}".format(formatted_price(value), currency))

give_orders(current_assets, repartition_pertenthousand, market)