currency_converter.py

#Below is not my code. I wanted to try and reverse engineer someone elses.
#
#http://www.codecoms.com/2014/09/Currency-Converter-in-Python/

#!/usr/bin/python
import sys, os, os.path, urllib2, re, cookielib, time, datetime, locale

file = 'conv_rates.txt' #file containing the exchange rates

locale.setlocale( locale.LC_ALL, '' )

def check_file(file):
    #check that the file exists and it's not empty
    if os.path.exists(file) == False or os.stat(file).st_size == 0:
        grab_web_rates()

    #check that the file is no more than 24 hours old
    if  time.time() - os.path.getmtime(file) > 86400: #file older than 24 hours
        #grab the currency exchange data form the internet
        grab_web_rates()
    else: #file is up to date
        return create_exchange_dict()

def create_exchange_dict():
    exchange_rates_dict = {}
    conversion_rates = open (file, 'r') #open file read only

    for line in conversion_rates:
        exchange_rates_dict[line.split(",")[0]] = line.split(",")[1]

    conversion_rates.close()
    return exchange_rates_dict

def grab_web_rates():
    conversion_rates = open (file, 'w')
    web = urllib2.urlopen('http://www.x-rates.com/table/?from=USD')
    html = web.read()
    line = 1
    titles = re.findall(r'<td class=\'rtRates\'>
    <a href=\'/graph/\?from=(.*?)</td>', html)
    for title in titles:
        title = title.replace("amp;to=", "")
        title = title.replace("&", "-")
        title = title.replace("'>", ",")
        title = title.replace("</a>", " ")
        title = title.replace("  ", "")
        title = title.rstrip()
        conversion_rates.write(title + ' \n')
        line += 1
        if line >= 23:
            break
    conversion_rates.close()

def get_result(choice, amount):
    dict = create_exchange_dict()
    for exchange,rate in dict.items():
        if exchange == choice:
            result = amount * float(rate)
            return rate, result
            break
        else:
            error = "Exchange not found! -get_result()- "

def format_currency(value):
    return "{:,.2f}".format(value)

def checkChoice(choice):
    if str.isdigit(choice): #check that the selection is a digit or exit
        return True
    else:
        os.system('clear')
        print "Thanks for using Currency Calculator! \n"
        exit()

def main():
    os.system('clear')
    print '''
    Chose the Conversion:
    1. US Dollar -> Euro
    2. Euro -> US Dollar
    3. US Dollar -> British Pound
    4. British Pound -> US Dollar
    5. US Dollar -> Canadian Dollar
    6. Canadian Dollar -> US Dollar
    7. US Dollar -> Chines Yuan
    8. Chines Yuan -> US Dollar
    9. US Dollar -> Peso Argentino
    10. Peso Argentino -> US Dollar
    0. Exit
    '''
    choice = raw_input("\t")

    checkChoice(choice)
    choice = int(choice)

    #Exit script if the selection is not whithin the allowed range
    if choice == 0 or choice > 10:
        os.system('clear')
        print "Thanks for using Currency Calculator! \n"
        exit()

    while choice != 0:
        check_file(file)
        amount = raw_input("Amount: ")

        #Strips commas if found
        if ',' in amount:
            amount = ''.join(e for e in amount if e.isdigit() or e == '.')
            amount = float(amount)
        else:
            amount = float(amount)

        if choice == 1: #USD->Euro
            os.system('clear')
            choice = "USD-EUR"
            r = get_result(choice, amount)
            result = r[1]
            rate = r[0]
            e=u'\u20ac' #euro symbol
            amount = locale.currency( amount, grouping=True )
            print "Your amount (USD): ", amount
            print "Converts to (EUR): ", e, format_currency(result)
            print "The Euro (EUR) -> US Dollar exchange rate is: ", rate
            break

        elif choice  == 2: #EURO->USD
            os.system('clear')
            choice = "EUR-USD"
            r = get_result(choice, amount)
            result = r[1]
            rate = r[0]
            e=u'\u20ac' #euro symbol
            amount = format_currency(amount)
            print "Your amount (EUR): ", e, amount
            print "Converts to (USD): ", locale.currency(result, grouping=True)
            print "The US Dollar -> Euro (EUR) exchange rate is: ", rate
            break

        elif choice == 3: #GBP->USD
            choice = "USD-GBP"
            os.system('clear')
            r = get_result(choice, amount)
            result = r[1]
            rate = r[0]
            e = u'\xA3' #British Pound symbol
            amount = locale.currency( amount, grouping=True )
            print "Your amount (USD): ", amount
            print "Converts to (GBP): ", e, format_currency(result)
            print "The US Dollar -> British Pound (GBP) exchange rate is: ", rate
            break

        elif choice == 4: #USD->GBP
            choice = "GBP-USD"
            os.system('clear')
            r = get_result(choice, amount)
            result = r[1]
            rate = r[0]
            e = u'\xA3' #British Pound symbol
            amount = format_currency(amount)
            print "Your amount (GBP): ", e, amount
            print "Converts to (USD): ", locale.currency(result, grouping=True )
            print "The British Pound (GBP) -> US Dollar exchange rate is: ", rate
            break

        elif choice == 5: #CAD->USD
            choice = "USD-CAD"
            os.system('clear')
            r = get_result(choice, amount)
            result = r[1]
            rate = r[0]
            amount = locale.currency( amount, grouping=True )
            result = locale.currency( result, grouping=True )
            print "Your amount (USD): ", amount
            print "Converts to (CAD): ", result
            print "The US Dollar -> Canadian Dollar (CAD) exchange rate is: ", rate
            break

        elif choice == 6: #USD->CAD
            choice = "CAD-USD"
            os.system('clear')
            r = get_result(choice, amount)
            result = r[1]
            rate = r[0]
            amount = locale.currency( amount, grouping=True )
            result = locale.currency( result, grouping=True )
            print "Your amount (CAD): ", amount
            print "Converts to (USD): ", result
            print "The Canadian Dollar (CAD) -> US Dollar exchange rate is: ", rate
            break

        elif choice == 7: #USD->CNY
            choice = "USD-CNY"
            os.system('clear')
            r = get_result(choice, amount)
            result = r[1]
            rate = r[0]
            amount = locale.currency( amount, grouping=True )
            print "Your amount (CNY): ", amount
            print "Converts to Yuan (USD): " , format_currency(result)
            print "The US Dollar -> Chinese Yuan (CNY) exchange rate is: ", rate
            break

        elif choice == 8: #CNY->USD
            choice = "CNY-USD"
            os.system('clear')
            r = get_result(choice, amount)
            result = r[1]
            rate = r[0]
            print "Your amount (CNY): ", format_currency(amount)
            print "Converts to Yuan (USD): " , locale.currency( result, grouping=True )
            print "The Chinese Yuan (CNY) -> US Dollar exchange rate is: ", rate
            break

        elif choice == 9: #USD->ARS
            choice = "USD-ARS"
            os.system('clear')
            r = get_result(choice, amount)
            result = r[1]
            rate = r[0]
            amount = locale.currency( amount, grouping=True )
            print "Your amount (USD): ", amount
            print "Converts in Peso Argentino (ARS): " , format_currency(result)
            print "The US Dollar -> Peso Argentino (ARS) exchange rate is: ", rate
            break

        elif choice == 10: #ARS->USD
            choice = "ARS-USD"
            os.system('clear')
            r = get_result(choice, amount)
            result = r[1]
            rate = r[0]
            print "Your amount (ARS): ", format_currency(amount)
            print "Converts to US Dollar (USD): " , locale.currency(result, grouping=True)
            print "The Peso Argentino (ARS) -> US Dollar exchange rate is: ", rate
            break

        elif choice > 10:
            exit()
        break

#execution
main()