Post processor script for flnews

#!/usr/bin/env ruby
#encoding: UTF-8

=begin
/***************************************************************************
 *   ©2023-2023, Michael Uplawski <michael.uplawski@uplawski.eu>           *
 *                                                                         *
 *   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, write to the                         *
 *   Free Software Foundation, Inc.,                                       *
 *   59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.             *
 ***************************************************************************/
=end

# 17/3/2023 Linux only
#
# 7/3/2023 Rewrite. Defined functions for routine work, condensed the
# main routine. Read configuration from file.
#
# 5/3/2023 cosmetics, suprefluous module removed, 
# orthograpy in comments, superfluous line-break removed.

#TODO: verify URLs for syntax conformance.

# This script is Linux only
if ! /linux/ =~ RUBY_PLATFORM
  msg = "ERROR ! This script #{$0} cannot be used with #{RUBY_PLATFORM}"
  msg << "\n\tABORTING! Bye."
  STDERR.puts msg
  exit false
end

require 'yaml'
require "ostruct"

# a frugal logging function
def debout(msg)
  if $log && !$log.empty?
    begin
      log = File.open($log, 'a') 
      log.puts "\n" << Time.now.to_s << "\t" << msg
      log.close
    rescue Exception => ex
      STDERR.puts "Cannot use the log-file (#{log}): " << ex.message
      exit false
    end
  end
end
# called by the newsgroup_hook()
# choose a signature, if there is not already one.
def group_sig(groups)
  # .., either by comparing the entire group-name
  if $config.GROUP_SIGS.keys.include?(groups)
    $signature = "" << $config.GROUP_SIGS[groups] 
    # .., or by applying a regexp.
  else
    $config.GROUP_SIGS.each do |g, s|
      $signature = "" << s if groups.match(g)
    end
  end
end

# called by the newsgroup_hook()
def group_intro(groups, article)
  $intro = nil 
  debout "setting intro for group " << groups
  if $config.GROUP_INTROS.keys.include?(groups)
    $intro = $config.GROUP_INTROS[groups] 
  else
    $config.GROUP_INTROS.each do |gr, intro|
      $intro ||= intro if groups.match(gr)
      if $intro
        debout "matched group against " << gr
      end
    end
  end
  debout('group_intro is ' << $intro.to_s)
end

# called by the newsgroup_hook()
# Only 1 group!
def group_xnay(group)
  $XNAY = nil
  xgs = $config.XNAY_GROUPS
  if xgs && !xgs.empty? && xgs.detect {|g| group.match(g) }
    debout("setting XNAY")
    $XNAY = "X-No-Archive: YES" 
  end
end
# -----------> Hooks <-------------
def newsgroup_hook(groups, article)
  # .., if there is only one group 
  if groups.split(',').length == 1 
    groups.strip!
    # find some signature if need be
    group_sig(groups)
    # adapt the intro, too
    group_intro(groups, article)
    # set XNAY if needed
    group_xnay(groups)
  end  
end

# <---------- End Hooks ---------->

# set intro, if intro
def set_intro(body)
  # first line should be empty.
  new_body = Array.new
  fup_name = nil
=begin UNUSED
  fup_date = nil
  fup_time = nil
=end
  debout('FUP_NAME is ' << $config.FUP_NAME)
  body.each_with_index do |line, i|
    # find the name in the intro-line
    if !line.strip.empty? && !fup_name
      fup_name = line.match(Regexp.new($config.FUP_NAME) ) do |md|
        md.length == 2 ? md[1] : md[0]
      end
      # All that follows depends on the presence of a name
      # in the intro-string.
      if fup_name && !fup_name.strip.empty?
        if(body[i+1].start_with?('>'))
          debout("\tfound intro " << line)
          debout "testing group " << $config.FUP_GROUP
          fup_group = line.match(Regexp.new($config.FUP_GROUP) ) { |md| md.length == 2 ? md[1] : nil} 
          debout "group is " << fup_group.to_s
=begin
UNUSED
  fup_date = line.match(Regexp.new($config.FUP_DATE) ) { |md| md.length == 2 ? md[1] : nil} 
  fup_time = line.match(Regexp.new($config.FUP_TIME) ) { |md| md.length == 2 ? md[1] : nil} 
  debout('FUP_DATE is not set!') if !fup_date
  debout('FUP_TIME is not set!') if !fup_time
=end
          debout("name is " << fup_name.to_s)
          # variables are part of the $intro.
          $intro.sub!('%fup_name%', fup_name) if fup_name && $intro && !$intro.empty?
          $intro.sub!('%fup_group%', fup_group)  if fup_group && $intro && !$intro.empty?
          if($intro && !$intro.strip.empty?)
            debout("\tsetting intro " << $intro.to_s)
            new_body << $intro 
          else
            debout("\tkeeping intro " << line)
            new_body << line
          end

        end
      else
        # usual lines are just kept as they are.
        debout('no name in line ' << line)
        new_body << line
      end
    else
      # empty lines too
      new_body << line
    end

  end
  debout "new body is " << new_body.to_s
  new_body
end

# returns the header-lines of the article
def headers(article)
  debout "setting headers"
  hend = false
  headers = article.split(LN).collect do |line|
    # Take note of the empty line between
    # headers and body, skip remainder.
    hend ||= line.strip.empty? 
    if !hend
      header = line.split(':')
      if header && header.length == 2 && "Newsgroups" == header[0].strip
        # Newsgroups header found, react as you must.
        newsgroup_hook header[1], article
      end
      line
      # end of headers reached
    end
  end
  # X-No-Archive
  headers << $XNAY if $XNAY 
  # Custom-headers
  headers += $config.CUSTOM_HEADERS
  headers.compact
end

# returns the body-lines off the article
def body(article)
  bstart = false 
  abody = article.split(LN).collect do |l|
    # Start collecting only at the
    # empty line between header and body.
    bstart ||= l.strip.empty?
    # ... but include that empty line.
    l if bstart
  end
  abody.compact!
  # returns a new version of the body, with a
  # possibly altered intro-line
  set_intro(abody)
end

# The value in $signature is set by the newsgroup_hook.
# This will add the line to the current article body
def set_signature(article)
  nsig = article.split(LN).count{|s| s == "-- "}
  # several signatures should be avoided!
  if nsig > 1 
    debout "Found #{nsig} signatures"
    debout "PSE remove a few and leave ... like only 1 intact."
    exit false
  else
    article << LN.dup << "-- " << LN << $signature << LN if $signature
  end
end

############### main routine ##################
# remove previous log, if existing
# read configuration from file in the same directory as this script (Bugfix)!

CONFIG = File.dirname( __FILE__) << File::SEPARATOR << "flnews_post_proc.conf"
debout('reading config')
if File.exist?(CONFIG) && File.readable?(CONFIG)
  begin
    $config = OpenStruct.new (Psych.load_file(CONFIG))
  rescue Exception => ex
    STDERR.puts("Cannot read from configuration-file: " << ex.message)
    STDERR.puts("Post-processing aborted!")
    exit false
  end
end

$log = $config.DEBUG_LOG
if $log && !$log.empty?
  begin
    File.unlink $log if File.exist?($log)
  rescue Exception => ex
    STDERR.puts 'Cannot delete the log-file (#{$log})'
    exit false
  end
end

debout("config is " << $config.to_s)
# line-break in the final article
LN = "\r\n"

# Default, no signature.
$signature = nil 


if (!STDIN.tty?)
  # read from STDIN
  artext = ARGF.read
  # There is content, get headers and body
  if !artext.strip.empty?
    # extract header- and body-lines
    # ... add custom headers
    # ... change intro, if need be
    ahead = headers(artext)
    abody = body(artext)
    # Join all together again.
    # TODO default signature (currently empty)
    newart = ahead.join(LN) + LN + abody.join(LN) 
    debout('new article: ' << newart)
    # add and/or alter signature
    set_signature(newart)

    # --------------> for debugging
    begin
      outfile = "/tmp/new_Article"
      File.open(outfile, 'w') do |f|
        f.write(newart)
      end
    rescue Exception => ex
      debout "Cannot write #{outfile}: " << ex.message
      exit false
    end
    # <------------------ 

    # The real thing. Write to STDOOUT.
    # ------------ HEUREKA ! ---------
    puts newart
    # ------------ END HEUREKA -------
    # Bin ich'n Tier, ey ...
    exit true
  else
    debout "Cannot read the article"
    exit false
  end
else
  usage = "\nWhat do you want me to do? Where is the article to post-process?"
  usage << "\nUsage: "
  usage << "\n\t#{$0} < article.text"
  debout usage
  STDERR.puts usage
  exit false 
end
# EOF

#/***************************************************************************
# *   ©2023-2023, Michael Uplawski <michael.uplawski@uplawski.eu>           *
# *                                                                         *
# *   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, write to the                         *
# *   Free Software Foundation, Inc.,                                       *
# *   59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.             *
# ***************************************************************************/

# This is a YAML file. Keep intact these three dashes.
  ---

# FUP_NAME 
# A Regular Expression, describing the string which contains the name of
# previous poster who is the author of a quoted post.  This string is
# recognized in the original article and may be used with the fitting element
# from GROUP_INTRO, below. The Regexp-format is that of the Regexp class in
# Ruby, noted as a String. Beware to mask a backslash '\' by another one, 
# like in the example. A capture-group '()' serves to extract the name from the
# match result. 
# Leave this field empty to keep the default from the FLNews configuration
# intact.
# CONTENT: A String equivalent of a regular expression.
# DEFAULT: EMPTY
# EXAMPLE1: "Am \\d+.\\d+.\\d{2,4} um \\d+:\\d+ schrieb (.*):"
# EXAMPLE2: "(.*) wrote:"
  FUP_NAME: '(.*) wrote in'

# FUP_DATE (unused)
# A Regular Expression, describing the string which contains the date of the
# previous post, that you are referring to in the followup.  Leave this field
# empty to ignore the date depending on your chosen GROUP_INTROS (see below).
# CONTENT: A String equivalent of a regular expression.
# DEFAULT: EMPTY
# EXAMPLE: "Am (\\d+.\\d+.\\d{2,4}) um"
  FUP_DATE: ''

# FUP_TIME (unused)
# A Regular Expression, describing the string which contains the time of day,
# when the previous post, that you are referring to in the followup, had been
# published.  
# Leave this field empty to ignore the time, depending on your chosen
# GROUP_INTROS (see below).  
# CONTENT: A String equivalent of a regular expression.
# DEFAULT: EMPTY
# EXAMPLE: "um \\d+:\\d+ schrie[b]  FUP_TIME: ''

#FUP_GROUP
# A Regular Expression, describing the string which contains the newsgroup
# where the previous post, that you are referring to in the followup, had been
# published.  
# Leave this field empty to ignore the precise group.
# CONTENT: A String equivalent of a regular expression.
# DEFAULT: EMPTY
# EXAMPLE: "wrote in (.*)"
  FUP_GROUP: 'wrote in (.*):'

# GROUP_INTROS:
# Introductory strings, referring to the previous poster who is the author of a
# quoted post. If you match the newsgroup of the post (see FUP_GROUP), you can 
# use these variables in the result. 
# Currently only %fup_name% and %fup_group% are reproduced in the resulting 
# introductory string.
# CONTENT: A newsgroup or regexp, followed by a colon, a space and a String
# ending in \r\n.  
# DEFAULT: As configured in FLNews
# EXAMPLE: alt.test: "Thus spoke #{fup_name} on that baleful #{fup_date}:\r\n"
    GROUP_INTROS:
    de.*: "%fup_name% hat geschrieben:\r\n"
    uk.*: "%fup_name% wrote:\r\n"
    fr.*: "%fup_name% a écrit:\r\n"

# GROUP_SIGS
# A signature line per Newsgroup. 
# CONTENT: A newsgroup or regexp, followed by a colon, a space and a String, ending in \r\n
# DEFAULT: As configured in flnews
# EXAMPLE: alt.test: "Signature for alt.test"
    GROUP_SIGS:
    fr.test: "newsgroup_hook fr.test\r\n2ème ligne, guillemets"
    de.*: Es ist an der Zeit
    fr.*: "Le progrès, ce n'est pas l'acquisition de biens. C'est l'élévation de\r\n\nl'individu,
    son émancipation, sa compréhension du monde. Et pour ça il\r\n\nfaut du temps
    pour lire, s'instruire, se consacrer aux autres.\r\n\n(Christiane Taubira)\r\n"

# CUSTOM_HEADERS
# Additional headers for the outgoing article
# CONTENT: A dash and space, then a String, comprising the name of the header, ending in a 
#          colon and the value of the header
# DEFAULT: undefined
# EXAMPLE: - 'X-My-Header: nothing fancy'
    CUSTOM_HEADERS:

# XNAY_GROUPS:
# The newsgroups, where a header X-No-Archive: YES shall be set.
# CONTENT: a dash and space, then a String, containing the name of the group
#          or a regexp.
# DEFAULT: empty
# EXAMPLE: - "alt.test"
XNAY_GROUPS:
- ".*.test"

# DEBUG_LOG:
# The name of a file, where debug messages are written. Setting this
# variable will enable the log. Leave empty to disable logging.
# CONTENT: The name of a writable file, which will be overwritten.
# DEFAULT: empty
# EXAMPLE: '/tmp/a_log-file.txt'
DEBUG_LOG: '/tmp/flnews_post_proc.log'