#! /usr/bin/env python2
# -*- coding: utf8 -*-

import os


def application(environ, start_response):
    parameters_list = environ['QUERY_STRING'].split("&")
    param_value = {}
    for item in parameters_list:
        param, value = item.split("=")
        param_value[param] = value
    ipv4_file_path = os.path.join(environ['DOCUMENT_ROOT'], "tmp/ipv4_address")
    ipv6_file_path = os.path.join(environ['DOCUMENT_ROOT'], "tmp/ipv6_address")
    try:
        file_v4 = open(ipv4_file_path, "r")
        file_v6 = open(ipv6_file_path, "r")
    except IOError:
        old_ipv4 = ""
        old_ipv6 = ""
    else:
        old_ipv4 = file_v4.readline()
        old_ipv6 = file_v6.readline()
        file_v4.close()
        file_v6.close()
    try:
        new_ipv4 = param_value["ipv4"]
    except KeyError:
        new_ipv4 = ""
    try:
        new_ipv6 = param_value["ipv6"]
    except KeyError:
        new_ipv6 = ""
    response_status = "200 IP didn't change"
    response_body = ""
    error = False
    if new_ipv4 == "" and new_ipv6 == "":
        # TODO: maybe implement some checking if it is a correct IPv4
        # address here
        response_status = "400 Bad Request"
        response_body = "The IP address you defined was empty or " \
                        "invalid."
    else:
        if new_ipv4 != old_ipv4 and new_ipv4 != "":
            try:
                file = open(ipv4_file_path, "w")
            except IOError:
                error = True
            else:
                file.write(param_value['ipv4'])
                file.close()
                response_status = "200 OK"
                response_body = "The new IP address has been saved, thanks " \
                                "and have a nice day!"
        if new_ipv6 != old_ipv6 and new_ipv6 != "":
            try:
                file = open(ipv6_file_path, "w")
            except IOError:
                error = True
            else:
                file.write(param_value["ipv6"])
                file.close()
                response_status = "200 OK"
                response_body = "The new IP address has been saved, thanks " \
                                "and have a nice day!"
    if error is True:
        response_status = "503 Internal server error"
        response_body = "There has been an error serving your request."

    response_headers = [('Content-Type', 'text/plain'),
                        ('Content-Length',
                         str(len(response_body.encode('utf8'))))]
    start_response(response_status, response_headers)
    return [response_body.encode('utf8')]