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##
## coinfetch - plugin-based cryptocurrency price converter
## Copyright (C) 2015-2016 Delwink, LLC
##
## This program is free software: you can redistribute it and/or modify
## it under the terms of the GNU Affero General Public License as published by
## the Free Software Foundation, version 3 only.
##
## This program is distributed in the hope that it will be useful,
## but WITHOUT ANY WARRANTY; without even the implied warranty of
## MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
## GNU Affero General Public License for more details.
##
## You should have received a copy of the GNU Affero General Public License
## along with this program. If not, see <http://www.gnu.org/licenses/>.
##
from importlib.machinery import SourceFileLoader
from os import listdir
from os.path import basename, dirname, exists, expanduser, isdir, join
from os.path import realpath
from requests import get
__version__ = '5.2.0'
class NoSuchPairException(Exception):
pass
class NoSuchKindException(Exception):
pass
## A cryptocurrency exchange rate ticker.
class Ticker():
## Constructor for this class.
# @param path The URL prefix for this ticker.
def __init__(self, path, kind=None):
self.path = path
## Defines how a currency pair is defined in the request URL.
# @param a The first currency.
# @param b The second currency.
# @return A pair string to be used in the request URL.
def get_pair(self, a, b):
return '{}_{}'.format(a, b)
## Extracts the exchange rate data from the server response.
# @param response Original response from the ticker server.
# @param The coin pair as a list/tuple.
# @return The data for the selected pair.
def get_pair_data(self, response, pair=None):
if type(pair) in (list, tuple):
return response.json()[self.get_pair(pair[0], pair[1])]
else:
raise TypeError('pair cannot be {}'.format(type(pair)))
## Gets the exchange rate between two currencies raised to a power.
# @param a The first currency.
# @param b The second currency.
# @param amt The number quantity of 'a' currency.
# @param power The power to which the calculation will be raised.
# @param kind The type of rate to calculate.
# @return The exchange rate between 'a' and 'b' currencies raised to
# 'power'.
def get_rate_pow(self, a, b, amt, power, kind):
r = get(self.path + self.get_pair(a, b))
try:
res = self.get_pair_data(r, (a, b))
except KeyError as e:
raise NoSuchPairException(str(e))
if kind not in res:
raise NoSuchKindException(kind)
return (float(res[kind]) ** power) * amt
## Calculates the exchange rate between two currencies.
# @param a The first currency.
# @param b The second currency.
# @param amt The number quantity of 'a' currency.
# @param kind The type of rate to calculate.
# @return The exchange rate between 'a' and 'b' currencies.
def get_rate(self, a, b, amt=1, kind='avg'):
try:
return self.get_rate_pow(a, b, amt, 1, kind)
except NoSuchPairException:
return self.get_rate_pow(b, a, amt, -1, kind)
_INDEX = {
'description': 0,
'value': 1
}
_PATH = [
dirname(realpath(__file__)),
'/usr/share/coinfetch',
'/usr/local/share/coinfetch',
join(expanduser('~'), '.coinfetch')
]
_tickers = {}
## Adds a directory to the configuration path.
# @param path The directory to be added.
def add_to_path(path):
_PATH.append(path)
## Gets the registered tickers and their descriptions.
# @return A list of tuples containing the ticker name and description.
def get_registered_tickers():
lst = []
for key in _tickers:
lst.append((key, _tickers[key][_INDEX['description']]))
return lst
## Gets a particular ticker object.
# @param key Name of the desired ticker.
# @return The Ticker object specified by 'key'.
def get_ticker(key):
return _tickers[key][_INDEX['value']]
## Registers a new ticker API.
# @param name Name of this ticker.
# @param description A brief description of this ticker.
# @param obj An instance of the ticker's implementation class.
def register_ticker(name, description, obj):
_tickers[name] = (description, obj)
## Loads a plugin or directory of plugins.
# @param path Path to the plugin file or a directory containing plugins.
def load(path):
if isdir(path):
for f in listdir(path):
if f.endswith('.py'):
load(join(path, f))
else:
SourceFileLoader('plugin', path).load_module()
## Loads all default plugins.
def load_default_plugins():
for d in _PATH:
plugindir = join(d, 'plugins')
if exists(plugindir):
load(plugindir)
## Clears the list of loaded plugins.
def unload_plugins():
global _tickers
_tickers = {}
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