# The software in this package is distributed under the GNU General
# Public License version 2 (with a special exception described below).
#
# A copy of GNU General Public License (GPL) is included in this distribution,
# in the file COPYING.GPL.
#
# As a special exception, if other files instantiate templates or use macros
# or inline functions from this file, or you compile this file and link it
# with other works to produce a work based on this file, this file
# does not by itself cause the resulting work to be covered
# by the GNU General Public License.
#
# However the source code for this file must still be made available
# in accordance with section (3) of the GNU General Public License.
#
# This exception does not invalidate any other reasons why a work based
# on this file might be covered by the GNU General Public License.
#
# Copyright (c) 2016-2018 Intra2net AG <info@intra2net.com>

"""
Utility for HTTP based interaction with the arnied web page.

Copyright: Intra2net AG
"""

import re
import ssl
import http.client as client
import urllib.parse as parse
import socket
import logging

log = logging.getLogger('pyi2ncommon.web_interface')


#: FQDN of local machine
LOCALHOST = socket.gethostname()


def find_in_form(regex, form="status", escape=False, check_certs=True):
    """
    Find a regex in given I2N web page form.

    :param str regex: regular expression to find
    :param str form: form name to open
    :param bool escape: whether to escape the regex
    :param check_certs: forwarded to :py:func:`web_page_request`, see doc there
    :returns: whether the regex was found
    :rtype: bool
    """
    data = web_page_request(method="GET", url="/arnie?form=" + form,
                            check_certs=check_certs)
    if escape:
        regex = re.escape(regex)
    if re.search(regex, data):
        return True
    else:
        log.debug("'%s' could not be found in:\n%s", regex, data)
        return False


def web_page_request(method="GET", url="/", body=None, check_certs=True):
    """
    Send an HTTPS request and return any response data.

    SSL certificates are checked against a default set of certificates
    installed on you system. This can be disabled (not recommended, security
    implications!) by setting `check_certs` to `False`. To allow a secure
    connection to host with e.g. a self-signed certificate, the caller can
    load this certificate by specifying `check_certs=/path/to/cert.pem`.
    (see also: :py:meth:`ssl.SSLContext.load_verify_locations`). Note that the
    certificate has to be issued for the same server name that we try to
    access, i.e. :py:data:`LOCALHOST`.

    :param str method: GET or POST method for the request
    :param str url: url location within the remote host
    :param body: dictionary to be parsed and added to the url
    :type body: {str, str} or None
    :param check_certs: Whether or not to check ssl certificates for connection
                        or file name to a certificate file
    :type check_certs: bool or str
    :returns: data from the response if any
    :rtype: str
    """
    body = parse.urlencode(body) if body is not None else ""
    headers = {"Content-Type": "application/x-www-form-urlencoded",
               "Accept": "text/plain"}

    if isinstance(check_certs, str):
        context = ssl.create_default_context(cafile=check_certs)
    elif check_certs:
        context = ssl.create_default_context()
    else:
        # disable certificate checks
        context = ssl._create_unverified_context()
    conn = client.HTTPSConnection(LOCALHOST, context=context)
    conn.request(method, url, body, headers)
    resp = conn.getresponse()
    logging.info("Request status %s and response %s",
                 resp.status, resp.reason)
    if resp.status != 200:
        raise client.HTTPException("POST request failed.")
    data = resp.read().decode()
    conn.close()

    return data