#!/usr/bin/env python
# pylint: disable=no-name-in-module,unused-import
#
# A library that provides a Python interface to the Telegram Bot API
# Copyright (C) 2015-2016
# Leandro Toledo de Souza <devs@python-telegram-bot.org>
#
# This program is free software: you can redistribute it and/or modify
# it under the terms of the GNU Lesser 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 Lesser Public License for more details.
#
# You should have received a copy of the GNU Lesser Public License
# along with this program.  If not, see [http://www.gnu.org/licenses/].

"""This module contains methods to make POST and GET requests"""

import functools
import json
import socket
from ssl import SSLError

try:
    # python2
    from httplib import HTTPException
except ImportError:
    # python3
    from http.client import HTTPException

try:
    # python3
    from urllib.request import urlopen, urlretrieve, Request
    from urllib.error import HTTPError, URLError
except ImportError:
    # python2
    from urllib import urlretrieve
    from urllib2 import urlopen, Request, URLError
    from urllib2 import HTTPError

from telegram import (InputFile, TelegramError)
from telegram.error import Unauthorized, NetworkError, TimedOut


def _parse(json_data):
    """Try and parse the JSON returned from Telegram and return an empty
    dictionary if there is any error.

    Args:
      url:
        urllib.urlopen object

    Returns:
      A JSON parsed as Python dict with results.
    """
    decoded_s = json_data.decode('utf-8')
    try:
        data = json.loads(decoded_s)
    except ValueError:
        raise TelegramError('Invalid server response')

    if not data.get('ok') and data.get('description'):
        return data['description']

    return data['result']


def _try_except_req(func):
    """Decorator for requests to handle known exceptions"""
    @functools.wraps(func)
    def decorator(*args, **kwargs):
        try:
            return func(*args, **kwargs)

        except HTTPError as error:
            # `HTTPError` inherits from `URLError` so `HTTPError` handling must
            # come first.
            errcode = error.getcode()

            if errcode in (401, 403):
                raise Unauthorized()
            elif errcode == 502:
                raise NetworkError('Bad Gateway')

            try:
                message = _parse(error.read())
            except ValueError:
                message = 'Unknown HTTPError {0}'.format(error.getcode())

            raise NetworkError('{0} ({1})'.format(message, errcode))

        except URLError as error:
            raise NetworkError('URLError: {0}'.format(error.reason))

        except (SSLError, socket.timeout) as error:
            err_s = str(error)
            if 'operation timed out' in err_s:
                raise TimedOut()

            raise NetworkError(err_s)

        except HTTPException as error:
            raise NetworkError('HTTPException: {0!r}'.format(error))

    return decorator


@_try_except_req
def get(url):
    """Request an URL.
    Args:
      url:
        The web location we want to retrieve.

    Returns:
      A JSON object.
    """
    result = urlopen(url).read()

    return _parse(result)


@_try_except_req
def post(url,
         data,
         timeout=None,
         network_delay=2.):
    """Request an URL.
    Args:
      url:
        The web location we want to retrieve.
      data:
        A dict of (str, unicode) key/value pairs.
      timeout:
        float. If this value is specified, use it as the definitive timeout (in
        seconds) for urlopen() operations. [Optional]
      network_delay:
        float. If using the timeout specified in `data` (which is a timeout for
        the Telegram servers operation), then `network_delay` as an extra delay
        (in seconds) to compensate for network latency.
        default: 2 [Optional]

    Notes:
      If neither `timeout` nor `data['timeout']` is specified. The underlying
      defaults are used.

    Returns:
      A JSON object.

    """
    urlopen_kwargs = {}

    if timeout is not None:
        urlopen_kwargs['timeout'] = timeout
    elif 'timeout' in data:
        urlopen_kwargs['timeout'] = data['timeout'] + network_delay

    if InputFile.is_inputfile(data):
        data = InputFile(data)
        request = Request(url,
                          data=data.to_form(),
                          headers=data.headers)
    else:
        data = json.dumps(data)
        request = Request(url,
                          data=data.encode(),
                          headers={'Content-Type': 'application/json'})

    result = urlopen(request, **urlopen_kwargs).read()
    return _parse(result)


@_try_except_req
def download(url,
             filename):
    """Download a file by its URL.
    Args:
      url:
        The web location we want to retrieve.

      filename:
        The filename within the path to download the file.
    """

    urlretrieve(url, filename)