""" 
----------------------------------------
Currency Converter
----------------------------------------
This is a straightforward project with a simple GUI. 
The name quite evidently describes the role of the 
project is to convert currencies from one unit into another. 
For example, converting Indian rupee to USD or euro. Tkinter, 
the standard Python interface can be used to design and develop 
this application. 
----------------------------------------
"""

import urllib.request
import json

def currency_converter(currency_from, currency_to, currency_input):
    yql_base_url = "https://query.yahooapis.com/v1/public/yql"
    yql_query = 'select%20*%20from%20yahoo.finance.xchange%20where%20pair' \
                '%20in%20("'+currency_from+currency_to+'")'
    yql_query_url = yql_base_url + "?q=" + yql_query + "&format=json&env=store%3A%2F%2Fdatatables.org%2Falltableswithkeys"
    try:
        yql_response = urllib.request.urlopen(yql_query_url)
        try:
            json_string = str(yql_response.read())
            json_string = json_string[2:]
            json_string = json_string[:-1]
            print(json_string)
            yql_json = json.loads(json_string)
            last_rate = yql_json['query']['results']['rate']['Rate']
            currency_output = currency_input * float(last_rate)
            return currency_output
        except (ValueError, KeyError, TypeError):
            print(yql_query_url)
            return "JSON format error"
    except IOError as e:
        print(str(e))

currency_input = 1

# currency codes : http://en.wikipedia.org/wiki/ISO_4217

currency_from = "USD"
currency_to = "TRY"
rate = currency_converter(currency_from, currency_to, currency_input)
print(rate)