#!/opt/homebrew/bin/python3
#
# units_cur for units, a program for updated currency exchange rates
#
# Copyright (C) 2017-2018, 2022
# Free Software Foundation, Inc
#
# This program is free software; you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation; either version 3 of the License, or
# (at your option) any later version.
#
# 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 General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program; if not, write to the Free Software
# Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
#    
#
# This program was written by Adrian Mariano (adrianm@gnu.org)
#

# For Python 2 & 3 compatibility
from __future__ import absolute_import, division, print_function
#
#

version = '5.0'

# Version 5.0:
#
# Rewrite to support multiple different data sources due to disappearance
# of the Yahoo feed.  Includes support for base currency selection. 
#
# Version 4.3: 20 July 2018
#
# Validate rate data from server
#
# Version 4.2: 18 April 2018
#
# Handle case of empty/malformed entry returned from the server
#
# Version 4.1: 30 October 2017
#
# Fixed to include USD in the list of currency codes.  
#
# Version 4: 2 October 2017 
#
# Complete rewrite to use Yahoo YQL API due to removal of TimeGenie RSS feed.
# Switched to requests library using JSON.  One program now runs under
# Python 2 or Python 3.  Thanks to Ray Hamel for some help with this update.  

# Normal imports
import requests
import codecs
import json
from argparse import ArgumentParser
from collections import OrderedDict
from datetime import date
from os import linesep
from os.path import getmtime
from sys import exit, stderr, stdout

datestr = date.today().isoformat()

output_dir='/usr/local/com/units/'

currency_file = output_dir + 'currency.units'
cpi_file = output_dir + 'cpi.units'

# valid metals 

validmetals = ['silver','gold','platinum']

PRIMITIVE = '!        # Base unit, the primitive unit of currency'

# This exchange rate table lists the currency ISO 4217 codes, their
# long text names, and any fixed definitions.  If the definition is
# empty then units_cur will query the server for a value.

rate_index = 1
currency = OrderedDict([
    ('ATS', ['austriaschilling',  '1|13.7603 euro']),
    ('BEF', ['belgiumfranc',      '1|40.3399 euro']),
    ('CYP', ['cypruspound',       '1|0.585274 euro']),
    ('EEK', ['estoniakroon',      '1|15.6466 euro # Equal to 1|8 germanymark']),
    ('FIM', ['finlandmarkka',     '1|5.94573 euro']),
    ('FRF', ['francefranc',       '1|6.55957 euro']),
    ('DEM', ['germanymark',       '1|1.95583 euro']),
    ('GRD', ['greecedrachma',     '1|340.75 euro']),
    ('IEP', ['irelandpunt',       '1|0.787564 euro']),
    ('ITL', ['italylira',         '1|1936.27 euro']),
    ('LVL', ['latvialats',        '1|0.702804 euro']),
    ('LTL', ['lithuanialitas',    '1|3.4528 euro']),
    ('LUF', ['luxembourgfranc',   '1|40.3399 euro']),
    ('MTL', ['maltalira',         '1|0.4293 euro']),
    ('SKK', ['slovakiakoruna',    '1|30.1260 euro']),
    ('SIT', ['sloveniatolar',     '1|239.640 euro']),
    ('ESP', ['spainpeseta',       '1|166.386 euro']),
    ('NLG', ['netherlandsguilder','1|2.20371 euro']),
    ('PTE', ['portugalescudo',    '1|200.482 euro']),
    ('CVE', ['capeverdeescudo',   '1|110.265 euro']),
    ('BGN', ['bulgarialev',       '1|1.9558 euro']),
    ('BAM', ['bosniaconvertiblemark','germanymark']),
    ('KMF', ['comorosfranc',      '1|491.96775 euro']),
    ('XOF', ['westafricafranc',   '1|655.957 euro']),
    ('XPF', ['cfpfranc',          '1|119.33 euro']),
    ('XAF', ['centralafricacfafranc','1|655.957 euro']),
    ('AED', ['uaedirham','']),
    ('AFN', ['afghanistanafghani','']),
    ('ALL', ['albanialek','']),
    ('AMD', ['armeniadram','']),
    ('ANG', ['antillesguilder','']),
    ('AOA', ['angolakwanza','']),
    ('ARS', ['argentinapeso','']),
    ('AUD', ['australiadollar','']),
    ('AWG', ['arubaflorin','']),
    ('AZN', ['azerbaijanmanat','']),
    ('BAM', ['bosniaconvertiblemark','']),
    ('BBD', ['barbadosdollar','']),
    ('BDT', ['bangladeshtaka','']),
    ('BGN', ['bulgarialev','']),
    ('BHD', ['bahraindinar','']),
    ('BIF', ['burundifranc','']),
    ('BMD', ['bermudadollar','']),
    ('BND', ['bruneidollar','']),
    ('BOB', ['boliviaboliviano','']),
    ('BRL', ['brazilreal','']),
    ('BSD', ['bahamasdollar','']),
    ('BTN', ['bhutanngultrum','']),
    ('BWP', ['botswanapula','']),
    ('BYN', ['belarusruble','']),
    ('BYR', ['oldbelarusruble','1|10000 BYN']),  
    ('BZD', ['belizedollar','']),
    ('CAD', ['canadadollar','']),
    ('CDF', ['drcfranccongolais','']),
    ('CHF', ['swissfranc','']),
    ('CLP', ['chilepeso','']),
    ('CNY', ['chinayuan','']),
    ('COP', ['colombiapeso','']),
    ('CRC', ['costaricacolon','']),
    ('CUP', ['cubapeso','']),
    ('CVE', ['capeverdeescudo','']),
    ('CZK', ['czechiakoruna','']),
    ('DJF', ['djiboutifranc','']),
    ('DKK', ['denmarkkrone','']),
    ('DOP', ['dominicanrepublicpeso','']),
    ('DZD', ['algeriadinar','']),
    ('EGP', ['egyptpound','']),
    ('ERN', ['eritreanakfa','']),
    ('ETB', ['ethiopiabirr','']),
    ('EUR', ['euro','']),
    ('FJD', ['fijidollar','']),
    ('FKP', ['falklandislandspound','']),
    ('GBP', ['ukpound','']),
    ('GEL', ['georgialari','']),
    ('GHS', ['ghanacedi','']),
    ('GIP', ['gibraltarpound','']),
    ('GMD', ['gambiadalasi','']),
    ('GNF', ['guineafranc','']),
    ('GTQ', ['guatemalaquetzal','']),
    ('GYD', ['guyanadollar','']),
    ('HKD', ['hongkongdollar','']),
    ('HNL', ['honduraslempira','']),
    ('HRK', ['croatiakuna','']),
    ('HTG', ['haitigourde','']),
    ('HUF', ['hungaryforint','']),
    ('IDR', ['indonesiarupiah','']),
    ('ILS', ['israelnewshekel','']),
    ('INR', ['indiarupee','']),
    ('IQD', ['iraqdinar','']),
    ('IRR', ['iranrial','']),
    ('ISK', ['icelandkrona','']),
    ('JMD', ['jamaicadollar','']),
    ('JOD', ['jordandinar','']),
    ('JPY', ['japanyen','']),
    ('KES', ['kenyaschilling','']),
    ('KGS', ['kyrgyzstansom','']),
    ('KHR', ['cambodiariel','']),
    ('KMF', ['comorosfranc','']),
    ('KPW', ['northkoreawon','']),
    ('KRW', ['southkoreawon','']),
    ('KWD', ['kuwaitdinar','']),
    ('KYD', ['caymanislandsdollar','']),
    ('KZT', ['kazakhstantenge','']),
    ('LAK', ['laokip','']),
    ('LBP', ['lebanonpound','']),
    ('LKR', ['srilankarupee','']),
    ('LRD', ['liberiadollar','']),
    ('LSL', ['lesotholoti','']),
    ('LYD', ['libyadinar','']),
    ('MAD', ['moroccodirham','']),
    ('MDL', ['moldovaleu','']),
    ('MGA', ['madagascarariary','']),
    ('MKD', ['macedoniadenar','']),
    ('MMK', ['myanmarkyat','']),
    ('MNT', ['mongoliatugrik','']),  
    ('MOP', ['macaupataca','']),
    ('MRO', ['mauritaniaoldouguiya','1|10 MRU']),
    ('MRU', ['mauritaniaouguiya', '']), 
    ('MUR', ['mauritiusrupee','']),
    ('MVR', ['maldiverufiyaa','']),
    ('MWK', ['malawikwacha','']),
    ('MXN', ['mexicopeso','']),
    ('MYR', ['malaysiaringgit','']),
    ('MZN', ['mozambiquemetical','']),
    ('NAD', ['namibiadollar','']),
    ('NGN', ['nigerianaira','']),
    ('NIO', ['nicaraguacordobaoro','']),
    ('NOK', ['norwaykrone','']),
    ('NPR', ['nepalrupee','']),
    ('NZD', ['newzealanddollar','']),
    ('OMR', ['omanrial','']),
    ('PAB', ['panamabalboa','']),
    ('PEN', ['perunuevosol','']),
    ('PGK', ['papuanewguineakina','']),
    ('PHP', ['philippinepeso','']),
    ('PKR', ['pakistanrupee','']),
    ('PLN', ['polandzloty','']),
    ('PYG', ['paraguayguarani','']),
    ('QAR', ['qatarrial','']),
    ('RON', ['romanianewlei','']),
    ('RSD', ['serbiadinar','']),
    ('RUB', ['russiaruble','']),
    ('RWF', ['rwandafranc','']),
    ('SAR', ['saudiarabiariyal','']),
    ('SBD', ['solomonislandsdollar','']),
    ('SCR', ['seychellesrupee','']),
    ('SDG', ['sudanpound','']),
    ('SEK', ['swedenkrona','']),
    ('SGD', ['singaporedollar','']),
    ('SHP', ['sainthelenapound','']),
#    ('SLL', ['sierraleoneoldleone','1|1000 SLE']),
#    ('SLE', ['sierraleoneleone','']),
    ('SOS', ['somaliaschilling','']),
    ('SRD', ['surinamedollar','']),
    ('SSP', ['southsudanpound','']),
    ('STD', ['saotome&principeolddobra','']),
    ('STN', ['saotome&principedobra','']),
#    ('SVC', ['elsalvadorcolon','']),  # eliminated in 2001
    ('SYP', ['syriapound','']),
    ('SZL', ['swazilandlilangeni','']),
    ('THB', ['thailandbaht','']),
    ('TJS', ['tajikistansomoni','']),
    ('TMT', ['turkmenistanmanat','']),
    ('TND', ['tunisiadinar','']),
    ('TOP', ["tongapa'anga",'']),
    ('TRY', ['turkeylira','']),
    ('TTD', ['trinidadandtobagodollar','']),
    ('TWD', ['taiwandollar','']),
    ('TZS', ['tanzaniashilling','']),
    ('UAH', ['ukrainehryvnia','']),
    ('UGX', ['ugandaschilling','']),
    ('USD', ['US$', '']),
    ('UYU', ['uruguaypeso','']),
    ('UZS', ['uzbekistansum','']),
    ('VEF', ['venezuelabolivarfuerte','']),
    ('VES', ['venezuelabolivarsoberano','']),
    ('VND', ['vietnamdong','']),
    ('VUV', ['vanuatuvatu','']),
    ('WST', ['samoatala','']),
    ('XAF', ['centralafricacfafranc','']),
    ('XCD', ['eastcaribbeandollar','']),
    ('XDR', ['specialdrawingrights','']),
    ('YER', ['yemenrial','']),
    ('ZAR', ['southafricarand','']),
    ('ZMW', ['zambiakwacha','']),
    ('ZWL', ['zimbabwedollar','']),
    ('FOK', ['faroeislandskróna','DKK']),
    ('GGP', ['guernseypound', 'GBP']),
    ('IMP', ['isleofmanpound','GBP']),
    ('JEP', ['jerseypound','GBP']),
    ('KID', ['kiribatidollar','AUD']),
    ('TVD', ['tuvaludollar','AUD']),
])


def validfloat(x):
  try:
    float(x)
    return True
  except ValueError:
    return False

def addrate(verbose,form,code,rate):
  if code not in currency.keys():
    if (verbose):
      stderr.write('Got unknown currency with code {}\n'.format(code))
  else:
    if not currency[code][rate_index]:
      if validfloat(rate):
        currency[code][rate_index] = form.format(rate)
      else:
        stderr.write('Got invalid rate "{}" for currency "{}"\n'.format(
                                  rate, code))
    elif verbose:
      if currency[code][rate_index] != form.format(rate):
        stderr.write('Got value "{}" for currency "{}" but '
                   'it is already defined as {}\n'.format(rate, code,
                                                  currency[code][rate_index]))

def getjson(address,args=None):
  try:
    res = requests.get(address,args)
    res.raise_for_status()
    return(res.json())
  except requests.exceptions.RequestException as e:
    stderr.write('Error connecting to currency server:\n{}.\n'.format(e))
    exit(1)
        
########################################################
#
#  Connect to floatrates for currency update
#

def floatrates(verbose,base,dummy):
  webdata = getjson('https://www.floatrates.com/daily/'+base+'.json')
  for index in webdata:
    entry = webdata[index]
    if 'rate' not in entry or 'code' not in entry:    # Skip empty/bad entries
      if verbose:
        stderr.write('Got bad entry from server: '+str(entry)+'\n')
    else:      
      addrate(verbose,'{} '+base,entry['code'],entry['inverseRate'])
  currency[base][rate_index] = PRIMITIVE
  return('FloatRates ('+base+' base)')

########################################################
#
# Connect to European central bank site
#

def eubankrates(verbose,base,dummy):
  if verbose and base!='EUR':
    stderr.write('European bank uses euro for base currency.  Specified base {} ignored.\n'.format(base))
  import xml.etree.ElementTree as ET
  try:
    res=requests.get('https://www.ecb.europa.eu/stats/eurofxref/eurofxref-daily.xml')
    res.raise_for_status()
    data = ET.fromstring(res.content)[2][0]
  except requests.exceptions.RequestException as e:
    stderr.write('Error connecting to currency server:\n{}.\n'.
                 format(e))
    exit(1)
  for entry in data.iter():
    if entry.get('time'):
      continue
    rate = entry.get('rate')
    code = entry.get('currency')
    if not rate or not code:                # Skip empty/bad entries
      if verbose:
        stderr.write('Got bad entry from server, code {} and rate {}\n'.format(code,rate))
    else:      
      addrate(verbose,'1|{} euro', code, rate)
  currency['EUR'][rate_index]=PRIMITIVE
  return('the European Central Bank (euro base)')
      
########################################################
#
# Connect to fixer.io (requires API key)
#
# Free API key does not allow changing base currency
# With free key only euro base is supported, and https is not allowed
#
      
def fixer(verbose,base,key):
  if not key:
    stderr.write('API key required for this source\n')
    exit(1)
  if verbose and base!='EUR':
    stderr.write('Fixer uses euro for base currency.  Specified base {} ignored.\n'.format(base))
  webdata = getjson('http://data.fixer.io/api/latest', {'access_key':key})
  if not webdata['success']:
    stderr.write('Currency server error: '+webdata['error']['info'])
    exit(1)
  for code in webdata['rates']:
    addrate(verbose,'1|{} euro', code, webdata['rates'][code])
  currency['EUR'][rate_index] = PRIMITIVE
  return('Fixer (euro base)')

########################################################
#
# Connect to openexchangerates (requires API key)
#
# Free API key does not allow changing the base currency
#
         
def openexchangerates(verbose,base,key):
  if not key:
    stderr.write('API key required for this source\n')
    exit(1)
  if verbose and base!='USD':
    stderr.write('Open Exchange Rates uses US dollar for base currency.  Specified base {} ignored.\n'.format(base))
  webdata = getjson('https://openexchangerates.org/api/latest.json',
                    {'app_id':key}
                    )
  for code in webdata['rates']:
    addrate(verbose,'1|{} US$', code, webdata['rates'][code])
  currency['USD'][rate_index] = PRIMITIVE
  return('open exchange rates (USD base)')

########################################################
#
# Connect to exchangerate-api.com
#
# The open access endpoint gives updates once per day.
# User can optionally supply a paid account's API key to get newer data and more precision.
# Base currency can be changed with both open and paid versions of the API.
#

def exchangerate_api(verbose,base,key):
  if not key:
    webdata = getjson('https://open.er-api.com/v6/latest/'+base)
    if not webdata['result'] or webdata['result'] != 'success':
      stderr.write('Currency server error: '+webdata['error-type']+'\n')
      exit(1)
    for code, rate in webdata['rates'].items() :
      addrate(verbose,'1|{} '+base,code,rate)
  else:
    webdata = getjson('https://v6.exchangerate-api.com/v6/'+key+'/latest/'+base)
    if not webdata['result'] or webdata['result'] != 'success':
      stderr.write('Currency server error: '+webdata['error-type']+'\n')
      exit(1)
    for code, rate in webdata['conversion_rates'].items() :
      addrate(verbose,'1|{} '+base,code,rate)
  currency[base][rate_index] = PRIMITIVE
  return('exchangerate-api.com ('+base+' base)')


#######################################################
#
# list of valid source names and corresponding functions
#

sources = {       
  'exchangerate_api': exchangerate_api,  
  'floatrates': floatrates,
  'eubank' : eubankrates,
  'fixer' : fixer,
  'openexchangerates': openexchangerates,
}

default_currency = 'exchangerate_api'

#######################################################
#
# Argument Processing
#

ap = ArgumentParser(
    description="Update currency information for 'units' "
    "into the specified filenames or the default currency "
    "file name {} and CPI file name {}.  The special "
    "filename '-' will send either or both files to "
    "stdout.".format(currency_file,cpi_file),
)

ap.add_argument(
    'currency_file',
    default=currency_file,
    help='the file to update',
    metavar='currency_file',
    nargs='?',
    type=str,
)

ap.add_argument(
    'cpi_file',
    default=cpi_file,
    help='the file to update',
    metavar='cpi_file',
    nargs='?',
    type=str,
)

ap.add_argument('-V','--version',
                action='version',
                version='%(prog)s version ' + version,
                help='display units_cur version',
)

ap.add_argument('-v','--verbose',
                action='store_true',
                help='display details when fetching currency data',
)

ap.add_argument('-s','--source',choices=list(sources.keys()),
                default=default_currency, 
                help='set currency data source (default: {})'.format(default_currency),
)

ap.add_argument('-b','--base',default='USD',
                help='set the base currency (when allowed by source).  BASE should be a 3 letter ISO currency code, e.g. USD.  The specified currency will be the primitive currency unit used by units.  Only the floatrates source supports this option.',
)                

ap.add_argument('-k','--key',default='',
                help='set API key for sources that require it'
)

ap.add_argument('--blskey',default='',
                help='set BLS key for fetching CPI data'
)


args = ap.parse_args()  
currency_file = args.currency_file
cpi_file = args.cpi_file
verbose = args.verbose
source = args.source
base = args.base
apikey = args.key
cpikey = args.blskey

if base not in currency.keys():
  stderr.write('Base currency {} is not a known currency code.\n'.format(base))
  exit(1)

########################################################
#
# Fetch currency data from specified curerncy source
#

sourcename = sources[source](verbose,base,apikey)
            
# Delete currencies where we have no rate data
for code in list(currency.keys()):
  if not currency[code][rate_index]:
    if verbose:
      stderr.write('No data for {}\n'.format(code))
    del currency[code]

cnames = [currency[code][0] for code in currency.keys()]
crates = [currency[code][1] for code in currency.keys()]

codestr = '\n'.join('{:23}{}'.
   format(code, name) for (code,name) in zip(currency.keys(), cnames))

maxlen = max(len(name) for name in cnames) + 2

ratestr = '\n'.join(
    '{:{}}{}'.format(name, maxlen, rate) for (name, rate) in zip(cnames, crates)
    )

#######################################################
#
# Get precious metals data and bitcoin
#

metals = getjson('https://services.packetizer.com/spotprices',{'f':'json'})
bitcoin = getjson('https://services.packetizer.com/btc',{'f':'json'})

metallist = ['']*len(validmetals)
for metal, price in metals.items():
  if metal in validmetals:
    metalindex = validmetals.index(metal)
    if validfloat(price):
      if not metallist[metalindex]:
        metallist[validmetals.index(metal)] = '{:19}{} US$/troyounce'.format(
                                                         metal + 'price', price)
      elif verbose:
        stderr.write('Got value "{}" for metal "{}" but '
                     'it is already defined\n'.format(price,metal))
    else:
      stderr.write('Got invalid rate "{}" for metal "{}"\n'.format(price,metal))
  elif metal != 'date' and verbose:  # Don't print a message for the "date" entry
    stderr.write('Got unknown metal "{}" with value "{}"\n'.format(metal,price))
metalstr = '\n'.join(metallist)

if validfloat(bitcoin['usd']):
  bitcoinstr = '{:{}}{} US$ # From services.packetizer.com/btc\n'.format(
                'bitcoin',maxlen,bitcoin['usd'])
else:
  stderr.write('Got invalid bitcoin rate "{}"\n', bitcoint['usd'])
  bitcointstr=''

#######################################################
#
# Get CPI data
#

docpi=False
if cpi_file=='-':
  docpi=True
else:
  try:
    filedate = getmtime(cpi_file)
    filedate = date.fromtimestamp(filedate)
    today = date.today()
    dmonth = (today.month-filedate.month) + 12*(today.year-filedate.year)
    if dmonth>1 or (dmonth==1 and today.day>18):
      docpi=True
  except FileNotFoundError:
    docpi=True
  
if docpi:
  headers = {'Content-type': 'application/json'}
  yearlist = list(range(date.today().year,1912,-10))
  if yearlist[-1]>1912:
    yearlist.append(1912)
  cpi=[]
  lastcpi = 0
  query = {"seriesid": ['CUUR0000SA0']}
  if cpikey:
    query["registrationkey"]=cpikey
  ########################################################################
  # The api.bls.gov site currently (2024-02-15) resolves to an
  # IPv4 address which works, and an IPv6 address which does
  # not.  The urllib3 package does not currently implement the
  # Happy Eyeballs algorithm, nor any other mechanism to re-try
  # hung connections with alternative addresses returned by DNS.
  # In the interest of expediency, we temporarily force the
  # connection to api.bls.gov to only use IPv4; hopefully at
  # some future date either urllib3 will gain the necessary
  # features and/or the BLS will fix their configuration so
  # that all A and AAAA records for api.bls.gov resolve to an
  # operational server.  At that time we can remove the three
  # references to "requests.packages.urllib3.util.connection.HAS_IPV6"
  # in this function.
  ########################################################################
  save_rpuucH = requests.packages.urllib3.util.connection.HAS_IPV6
  requests.packages.urllib3.util.connection.HAS_IPV6 = False
  for endyear in range(len(yearlist)-1):
    query["startyear"]=str(yearlist[endyear+1]+1)
    query["endyear"]=str(yearlist[endyear])
    data = json.dumps(query)
    p = requests.post('https://api.bls.gov/publicAPI/v2/timeseries/data/', data=data, headers=headers)
    json_data = json.loads(p.text)
    if json_data['status']=="REQUEST_NOT_PROCESSED":
      docpi=False
      stderr.write("Unable to update CPI data: Exceeded daily threshold for BLS requests\n")
      break
    for series in json_data['Results']['series']:
        for item in series['data']:
            if not ('M01' <= item['period'] <= 'M12'):
                continue
            year = int(item['year']) + int(item['period'][1:])/12
            value = item['value']
            cpi.append(' '*10 + "{} {} \\".format(year,value))
            if lastcpi==0:
              lastcpi=value
              lastyear=year
            firstcpi=value
            firstyear=year
  requests.packages.urllib3.util.connection.HAS_IPV6 = save_rpuucH              
if docpi:   # Check again because request may have failed
  cpi.reverse()
  cpistr = '\n'.join(cpi)

  cpi_text = ("""!message Consumer price index data from US BLS, {datestr}

UScpi[1] noerror \\
{cpistr}

UScpi_now          {lastcpi}
UScpi_lastdate     {lastyear}

USdollars_in(date) units=[1;$] domain=[{firstyear},{lastyear}] \\
                               range=[1,{maxinfl}] \\
                               US$ UScpi_now / UScpi(date) ;\\
                               ~UScpi(US$ UScpi_now / USdollars_in)
USinflation_since(date) units=[1;1] domain=[{firstyear},{lastyear}] \\
                               range=[1,{maxinfl}] \\
                                UScpi_now / UScpi(date) ;\\
                               ~UScpi(UScpi_now / USinflation_since)

""".format(datestr=datestr,cpistr=cpistr,maxinfl=float(lastcpi)/float(firstcpi),lastcpi=lastcpi,
           firstyear=firstyear,lastyear=lastyear)
  ).replace('\n', linesep)  
  
#######################################################
#
# Format output and write the currency file
#

currency_text = (
"""# ISO Currency Codes

{codestr}

# Currency exchange rates source 

!message Currency exchange rates from {sourcename} on {datestr}

{ratestr}
{bitcoinstr}

# Precious metals prices from Packetizer (services.packetizer.com/spotprices)

{metalstr}

""".format(codestr=codestr, datestr=datestr, ratestr=ratestr, metalstr=metalstr,
           bitcoinstr=bitcoinstr, sourcename=sourcename)
).replace('\n', linesep)


######################################

try:
    if currency_file == '-':
        codecs.StreamReader(stdout, codecs.getreader('utf8')).write(currency_text)
    else:    
        with codecs.open(currency_file, 'w', 'utf8') as of:
            of.write(currency_text)
except IOError as e:
    stderr.write('Unable to write to output file:\n{}\n'.format(e))
    exit(1)

if docpi:    
  try:
      if cpi_file == '-':
          codecs.StreamReader(stdout, codecs.getreader('utf8')).write(cpi_text)
      else:    
          with codecs.open(cpi_file, 'w', 'utf8') as of:
              of.write(cpi_text)
  except IOError as e:
      stderr.write('Unable to write to output file:\n{}\n'.format(e))
      exit(1)