## Author: Alois Mahdal at zxcvb cz
# Front-end for very primitive remote logging service. Use htlog.cgi
# as back-end: put it on a HTTP server and provide URL as "path" option
# when instantiating this class
#
# htlogr.py
#
# Copyright (c) 2013, Alois Mahdal. All rights reserved.
#
# This library is free software; you can redistribute it and/or
# modify it under the terms of the GNU Lesser General Public
# License as published by the Free Software Foundation; either
# version 2.1 of the License, or (at your option) any later version.
#
# This library 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 General Public License for more details.
#
# You should have received a copy of the GNU Lesser General Public
# License along with this library; if not, write to the Free Software
# Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston,
# MA 02110-1301  USA
#


import httplib
import urlparse
import urllib


class htlogr:

    def __init__(self, url):
        self.DIV_VALUE = "="
        self.DIV_FIELD = ";"
        self.url = url
        self.parsed_url = urlparse.urlparse(url)
        self.conn = httplib.HTTPConnection(self.parsed_url.hostname)
        self.last_error = None

    def _zipup_params(self, params):
        args = []
        for name, value in params.iteritems():
            if params[name]:
                value = str(value)
                args.append("%s=%s" % (name, urllib.quote(value)))
        return "&".join(args)

    def _serialize(self, data):
        fields = []
        for key in sorted(data.keys()):
            value = data[key]
            fields.append("%s%s%s" % (key, self.DIV_VALUE, value))
        return self.DIV_FIELD.join(fields)

    def log(self, msg, tag=None, i=None):
        params = {"msg": msg, "tag": tag, "i": i}
        pq = "%s?%s" % (self.parsed_url.path, self._zipup_params(params))
        self.conn.request("GET", pq)
        self.last_error = None
        return_msg = None
        try:
            r = self.conn.getresponse()
            assert r.status == 200, ("logging server returned error %s,"
                                     "message not logged" % r.status)
            return_msg = r.read()
        except httplib.BadStatusLine as e:
            return_msg = ("httplib does not like this line:\n\n    %s"
                          % e.line)
            self.last_error = return_msg
        return return_msg

    def data(self, data, tag=None, i=None):
        assert isinstance(data, dict), "data must be dict"
        msg = self._serialize(data)
        return self.log(msg, tag=tag, i=i)