#!/usr/bin/ruby
#
# read-github-notification -- prevent your notifications inbox on
# github.com from filling up if you read github's email-based
# notifications from a text-based MUA such as mutt.

# Copyright (c) 2014 Adam Spiers <adam@spiers.net>
#
# 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.
#
# You should have received a copy of the GNU General Public License
# along with this program.  If not, see <http://www.gnu.org/licenses/>.
#
# Background
# ==========
#
# At the bottom of
#
#   https://help.github.com/articles/configuring-notification-emails/
#
# it says:
#
#   Shared read state
#   -----------------
#
#   If you read a notification email, it'll automatically be marked as
#   read in the Notifications section. An invisible image is embedded
#   in each mail message to enable this, which means that you must
#   allow viewing images from notifications@github.com in order for
#   this feature to work.
#
# However this doesn't automatically work if you use a text-based MUA
# such as mutt.
#
# Solution
# ========
#
# mutt has a nice message-hook feature where you can execute mutt
# functions for messages matching specific criteria.  So we can use
# that to pipe the whole email to this script whenever a message
# is being read for the first time:
#
#   message-hook "(~N|~O) ~f notifications@github.com" "push '<pipe-message>read-github-notification\n'"
#
# This script reads the email on STDIN (or from a filename argument),
# extracts the URL of the 1-pixel read notification beacon <img>, and
# sends an HTTP request for that image, so that github knows the
# notification has been read.

require 'net/http'

abort "Maximum of one filename argument" if ARGV.length > 1

BEACON_RE = %r!<img alt="" height="1" src="(https://github\.com/notifications/beacon/.+?\.gif)" width="1" />!
ARGF.each do |line|
  if line =~ BEACON_RE
    uri = URI($1)
    response = Net::HTTP.get_response(uri)
    case response
    when Net::HTTPSuccess
      exit 0  # github should now know we read the notification
    else
      abort response.body
    end
  end
end

abort "Couldn't find notification beacon <img> URL"