forked from brmlab/brmbar-github
83 lines
2.6 KiB
Python
83 lines
2.6 KiB
Python
# vim: set fileencoding=utf8
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class Currency:
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"""Currency
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Each account has a currency (1 Kč, 1 Club Maté, ...), pairs of
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currencies have (asymmetric) exchange rates."""
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def __init__(self, db, id, name):
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self.db = db
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self.id = id
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self.name = name
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@classmethod
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def default(cls, db):
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"""Default wallet currency"""
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return cls.load(db, name="Kč")
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@classmethod
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def load(cls, db, id=None):
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"""Constructor for existing currency"""
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if id is None:
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raise NameError("Currency.load(): Specify id")
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name = db.execute_and_fetch("SELECT name FROM currencies WHERE id = %s", [id])
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name = name[0]
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return cls(db, id=id, name=name)
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@classmethod
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def create(cls, db, name):
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"""Constructor for new currency"""
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id = db.execute_and_fetch("SELECT public.create_currency(%s)", [name])
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return cls(db, id=id, name=name)
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def rates(self, other):
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"""Return tuple ($buy, $sell) of rates of $self in relation to $other (brmbar.Currency):
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$buy is the price of $self in means of $other when buying it (into brmbar)
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$sell is the price of $self in means of $other when selling it (from brmbar)"""
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# buy rate
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res = self.db.execute_and_fetch(
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"SELECT public.find_buy_rate(%s, %s)", [self.id, other.id]
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)
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if res is None:
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raise NameError("Something fishy in find_buy_rate.")
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buy = res[0]
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if buy < 0:
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raise NameError(
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"Currency.rate(): Unknown conversion "
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+ other.name()
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+ " to "
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+ self.name()
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)
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# sell rate
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res = self.db.execute_and_fetch(
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"SELECT public.find_sell_rate(%s, %s)", [self.id, other.id]
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)
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if res is None:
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raise NameError("Something fishy in find_sell_rate.")
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sell = res[0]
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if sell < 0:
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raise NameError(
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"Currency.rate(): Unknown conversion "
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+ self.name()
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+ " to "
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+ other.name()
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)
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return (buy, sell)
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def str(self, amount):
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return "{:.2f} {}".format(amount, self.name)
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def update_sell_rate(self, target, rate):
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self.db.execute(
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"SELECT public.update_currency_sell_rate(%s, %s, %s)",
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[self.id, target.id, rate],
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)
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def update_buy_rate(self, source, rate):
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self.db.execute(
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"SELECT public.update_currency_buy_rate(%s, %s, %s)",
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[self.id, source.id, rate],
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)
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