#! /usr/bin/ruby
# NAME
#   mauvesend - send alert(s) to a given alert station
#
# SYNOPSIS
#   mauvesend [<destination>]
#               [ --help | -h ] [ --manual | -m ] [ --version | -V ]
#               [--source | -o <source>] [--replace | -p] [--verbose | -v]
#               [--id <alertid> ... ]
#
# OPTIONS
# <destination>   Where the alert should go. This can be either a hostname or
#                 an IP address, and optionally a port, separated by a colon.
#                 The default port is 32741.
#
#                 If no destination is supplied, the value from the file
#                 /etc/mauvealert/mauvesend.destination is used. If no
#                 destination can be determined, an error is raised.
#
#                 If a hostname is given and no port is specified, SRV records
#                 are used to determine where the alerts should go to. The SRV
#                 prefix is _mauvealert._udp. If no SRV records are found, A
#                 records are used instead.
#
#                 IPv6 addresses can be used, but must be enclosed in square
#                 brackets, e.g. [2001:41c8::12].
#
# --source, -o <source>  identify the source of the alert (defaults to
#                        hostname, but you might want to name your monitoring
#                        systems more explicitly).
#
# --replace, -p          Send an update replacing all other alerts for this
#                        source -- any previous alerts not specified in this
#                        update are assumed to be cleared. If you specify this
#                        option, you don't have to supply *any* alerts to raise
#                        or clear (in which case all alerts from that source
#                        will be cleared).
#
# --verbose, -v          If you specify this option once, it will print the
#                        transmission ID of the packet for debugging. If you
#                        specify it twice, it will print the entire data
#                        structure.
#
# --help, -h             Display a short help message, and exit.
#
# --manual, -m           Display this manual, and exit.
#
# --version, -V          Display the version number for Mauve and exit.
#
# You can specify any number of alerts in an update - every time you specify
# --id starts a new alert.
#
# --id, -i <alertid>       Unique specified for each alert raised. This should
#                          be unique on a per-source basis, i.e. for an
#                          individual application or host.
#
# --summary, -s <summary>  Text for humans describing the nature of the alert,
#                          first 100 characters are only ones guaranteed to make
#                          it to pagers, twitter, SMS etc.
#
# --detail, -d <detail>    HTML fragment describing the alert in more detail,
#                          no limit on length.
#
# --subject, -u <subject>  Set the subject of the alert (i.e. the server/entity
#                          that this alert concerns). If no subject is
#                          specified, it is assumed to be the same as <source>,
#                          detailed above.
#
# --raise, -r <time>       Mark the alert to be (re)raised at the given time.
#                          If no time is supplied, "now" is assumed. See
#                          SPECIFYING TIMES below for the format of <time>.
#
# --clear, -c <time>       Mark the alert to be cleared at the given time. If
#                          no time is specified, "now" is assumed. See
#                          SPECIFYING TIMES below for the format of <time>.
#
# --suppress, -e <time>    Notifications about this alert should not be sent
#                          until the given time.  This allows notifications
#                          about flapping alerts to be suppressed for a period
#                          of time, or alerts about planned maintenance to be
#                          suppressed. See SPECIFYING TIMES below for the
#                          format of <time>.
#
# SPECIFYING TIMES
#
# Times can be specified for an alert to be raised or cleared. This can be
# specified as any time in the past or future. The format is + or -, followed
# by a number, followed by a letter determining the units, one of s, m, h, d,
# representing seconds, minutes, hours, and days, respectively. If no units are
# specified, seconds is assumed. If no sign or unit is specified, an absolute
# number of seconds since midnight UTC, 1st Jan 1970 is expected.
#
# Some example times are:
#
# now   Immediately
# +10m  In 10 minutes time
# -10h  10 Hours ago
#
# SENISBLE USAGE
#
# Mauve uses UDP to transmit data, which means that there is no guarrantee a
# single packet will reach the server. Therefore:
#
#  * The host/application should send "raise" notification regularly until the
#    alert clears, whereupon it should regularly send "cleared" notifications.
#
#  * When setting a heartbeat-type alert, make sure that the raise time is more
#    than double the period of the "clear" notifications. For example, if the
#    host is sending a clear every 120 seconds, the raise time should be
#    greater than 240 seconds, preferably greater than 360 seconds to allow for
#    packets going missing, reducing the likelihood of false alerts.
#
# Try to convey salient details about the alerts in the relevant fields. A
# typical short alert from Mauve might read
#
#   RAISED: <subject>: <summary> -- <source>
#
# Make sure that the alert will be understood with just those three fields
# displayed.
#
#  * Keep the summary brief and salient.
#
#  * Keep the summary constant, unless there has been a material change to the
#    nature of the alert. Mauve may re-send any messages when the subject
#    changes. If something is changing quickly, like load averages, best not
#    to put them in the summary.
#
#  * Make sure that the subject is set correctly. Remember if no subject is
#    set, then the source of the alert is used instead.
#
#  * Make sure that the source is correct too -- nothing worse than an alert
#    that comes in with an ambiguous origin.
#
#  * The alert ID is used internally by Mauve to keep alerts consistent. This
#    must be unique on a per-source basis. It is OK to have many alerts with the
#    ID "heartbeat" as long as the source of the alert is different in each case.
#
# The raise and clear times can be specified, if needed, but generally leaving
# them empty, i.e. setting them to "now" is sufficient. Mauve remembers when
# an alert is first raised.
#
# EXAMPLES
#
# To raise an alert:
#
#   mauvesend -i mailqueue -s smtp-out-1.example.com \\
#     -d "Mail queue has <b>54232</b> messages in it. That's <em>LOADS</em>" \\
#     -u "Mail queue too big on outgoing SMTP server" -r
#
# To clear an alert:
#
#   mauvesend -i mailqueue -s smtp-out-1.example.com -c
#
# To create a "heartbeat" alert, i.e. one that says "Currently OK, but raise in the future if nothing more is heard":
#
#   mauvesend -i heartbeat -d "No heartbeat received for 1.2.3.4. Could be down!" -s "heartbeat failed"  -c -r +10m
#
# SEE ALSO
#
#  mauveconsole(1), mauveserver(1)
#
# AUTHOR
#
# Patrick J Cherry <patrick@bytemark.co.uk>
#

require 'getoptlong'

%w(sender mauve_time version proto).each do |r|
  begin
    require "mauve/#{r}"
  rescue LoadError => ex
    STDERR.puts "*** "+ex.to_s
  end
end

NOW = Time.now

def error(msg)
  STDERR.print "*** Error: #{msg}\n"
  STDERR.print "*** For help, type: #{$0} -h\n"
  exit 1
end

def parse_time_spec(spec = "now")
  #
  # Default to now
  #
  spec = "now" if spec.empty?

  case spec
    when "now"
      NOW

    when /^\d+$/
      spec.to_i

    when /^(\+|-)?(\d+)([smhd])?$/
      if $1 == "-"
        multiplier = -1
      else
        multiplier = 1
      end

      multiplier *= case $3
        when "m" then 60
        when "h" then 3600
        when "d" then 86400
        else
          1
      end

      NOW + $2.to_i * multiplier

    else
      raise ArgumentError, "Unrecognised time format #{spec.inspect}"

  end
end

begin
  begin
    update = Mauve::Proto::AlertUpdate.new
    update.replace = false
    update.alert = []
  rescue NameError
    #
    # Do nothing .. When generating manpages in the build process we don't need
    # to have Protobuf available.
    #
    update = nil
  end
  message = nil
  verbose = 0
  help    = false
  manual  = false
  version = false

  opts = GetoptLong.new(
    ['-h', '--help',    GetoptLong::NO_ARGUMENT],
    ['-m', '--manual', GetoptLong::NO_ARGUMENT],
    ['-V', '--version', GetoptLong::NO_ARGUMENT],
    ['-o', '--source',  GetoptLong::OPTIONAL_ARGUMENT],
    ['-p', '--replace', GetoptLong::NO_ARGUMENT],
    ['-i', '--id',      GetoptLong::OPTIONAL_ARGUMENT],
    ['-s', '--summary', GetoptLong::OPTIONAL_ARGUMENT],
    ['-u', '--subject', GetoptLong::OPTIONAL_ARGUMENT],
    ['-c', '--clear',   GetoptLong::OPTIONAL_ARGUMENT],
    ['-r', '--raise',   GetoptLong::OPTIONAL_ARGUMENT],
    ['-e', '--suppress', GetoptLong::OPTIONAL_ARGUMENT],
    ['-d', '--detail',  GetoptLong::OPTIONAL_ARGUMENT],
    ['-v', '--verbose', GetoptLong::NO_ARGUMENT]
  ).each do |opt,arg|

    #
    # Can catch empty arguments better if we set the GetoptLong things to
    # "optional" rather than "required" and catch the empty arg here.
    error "#{opt} cannot be empty" if arg.empty? and not %w(-h -m -V -p -v -c -r).include?(opt)

    case opt
      when '-h'
        help = true
      when '-m'
        manual = true
      when '-V'
        version = true
      when '-p'
        error "Cannot send update -- not all libraries are available" if update.nil?
        update.replace = true
      when '-i'
        error "Cannot send update -- not all libraries are available" if update.nil?
        error "Cannot specify the same ID twice in one update -- ID #{arg}" if update.alert.any?{|a| a.id == arg}
        message = Mauve::Proto::Alert.new
        message.id = arg
        update.alert << message
      when '-o'
        error "Cannot send update -- not all libraries are available" if update.nil?
        error "Can only specify one source" if update.source
        update.source = arg
      when '-v'
        verbose += 1
      else
        error "Cannot send update -- not all libraries are available" if update.nil?
        error "Must specify --id before message" unless message
        case opt
          when '-s' then message.summary = arg
          when '-u' then message.subject = arg
          when '-d' then message.detail = arg
          when '-c' then message.clear_time = parse_time_spec(arg).to_i
          when '-r' then message.raise_time = parse_time_spec(arg).to_i
          when '-e' then message.suppress_until = parse_time_spec(arg).to_i
          else
            error "Unknown option #{opt}"
        end
    end
  end

  # CAUTION! Kwality kode.
  #
  if manual or help
    # Open the file, stripping the shebang line
    lines = File.open(__FILE__){|fh| fh.readlines}[1..-1]

    found_synopsis = false

    lines.each do |line|

      line.chomp!
      break if line.empty?

      if help and !found_synopsis
        found_synopsis = (line =~ /^#\s+SYNOPSIS\s*$/)
        next
      end

      puts line[2..-1].to_s

      break if help and found_synopsis and line =~ /^#\s*$/

    end
  end

  puts "#{$0}: version "+Mauve::VERSION if version

  exit 0 if help or version or manual

  error "Cannot send update -- not all libraries are available" if update.nil?
  error "No alerts specified" unless !update.alert.empty? || update.replace

  Mauve::Sender.new(ARGV).send(update, verbose)

rescue ArgumentError => ae
  error ae.message

rescue StandardError => ae
  error ae.message

end