#!/usr/bin/env python3
# -*- coding: utf-8 -*-

# Copyright (c) 2022 Karl Fogel
# 
# This program is free software: you can redistribute it and/or modify
# it under the terms of the GNU General 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
# General Public License for more details.
# 
# If you did not receive a copy of the GNU General Public License
# along with this program, see <http://www.gnu.org/licenses/>.

"""Print any Gnome 3 dbus notifications to stdout.

The purpose of this program is to enable you to see notifications
after they've vanished from your screen. , As you know, Gnome always
shows a notification at the moment your phone rings (or whatever), and
the notification disappears right when you finally get a chance to
glance at it.

A typical way to run this is is from a shell init file, with output
going to some place that you can then grab notifications from.  E.g.:

  gnotifications > ~/.cache/gnotifications.out &
"""

import re
import sys
import datetime
import subprocess

def main():
    with subprocess.Popen(["dbus-monitor",
                           "interface='org.freedesktop.Notifications'"], 
                          stdout=subprocess.PIPE, bufsize=1, 
                          universal_newlines=True) as proc:
        # We're watching for multi-line beasts like this:
        #
        #   method call time=1652471532.319641 sender=:1.463 -> destination=:1.43 serial=7 path=/org/freedesktop/Notifications; interface=org.freedesktop.Notifications; member=Notify
        #   
        #      string "notify-send"
        #   
        #      uint32 0
        #   
        #      string ""
        #   
        #      string "fish"
        #   
        #      string ""
        #   
        #      array [
        #   
        #      ]
        #   
        #      array [
        #   
        #         dict entry(
        #   
        #            string "urgency"
        #   
        #            variant             byte 1
        #   
        #         )
        #   
        #         dict entry(
        #   
        #            string "sender-pid"
        #   
        #            variant             int64 204391
        #   
        #         )
        #   
        #      ]
        #   
        #      int32 -1 
        #
        # The trouble is, for some reason that message comes across
        # the dbus twice, with the same message and same timestamp,
        # so we have to check for that and ignore the second message.
        
        # Buncha flags for old-fashioned grunt parsing.
        seen_method    = False
        last_timestamp = None
        this_timestamp = None
        last_message   = None
        seen_array     = False
        in_match_zone  = False
        for line in proc.stdout:
            if in_match_zone:
                m = re.match("^ *string +\"(.+)\"$", line)
                if m is not None:
                    this_message = m.group(1)
                    if not ((last_timestamp is not None)
                            and (this_timestamp == last_timestamp)
                            and (this_message == last_message)):
                        sys.stdout.write(f"{this_timestamp} UTC: {this_message}\n")
                        sys.stdout.flush()
                        last_message = this_message
                        last_timestamp = this_timestamp
                    else:  # a repeat message with the same timestamp
                        last_timestamp = None
                        last_message = None
            if m := re.match("^method call time=(\\d+)\\.\\d+ .*; *member=Notify$", line):
                seen_method = True
                # See https://blog.ganssle.io/articles/2019/11/utcnow.html and 
                # https://discuss.python.org/t/deprecating-utcnow-and-utcfromtimestamp/26221
                utc_ts_tmp = datetime.datetime.fromtimestamp(
                    int(m.group(1)), 
                    tz=datetime.timezone.utc).strftime('%Y-%m-%d %H:%M:%S')
                if last_timestamp is not None and utc_ts_tmp == last_timestamp:
                    this_timestamp = last_timestamp
                else:
                    last_timestamp = None
                    this_timestamp = utc_ts_tmp
            elif seen_method and re.match("^ *uint32 +0$", line):
                in_match_zone = True
            elif in_match_zone and re.match("^ +array \\[$", line):
                seen_method = False
                in_match_zone = False


if __name__ == '__main__':
  main()