#!/usr/bin/ruby -w

module MyBIND

ZONEFMT =<<EOS
zone "%s" {
  type slave;
  masters { %s};
  file "%s";
};
EOS

TYPE_RE = /type\s+slave\s*;/
MASTERS_LIST_RE = /masters\s+\{([^}]+)\}\s*;/
FILENAME_RE = /file\s+"([^"]+)"\s*;/
ZONENAME_RE = /^zone\s+"([^"]+)"/
ZONE_RE = /^zone\s+"[^"]+"\s*\{\s*
                    .*?
                 ^\s*\}\s*;\s*$/mx

#ZONE_RE = /^zone\s+"([^"]+)"\s*\{\s*
#               (?:(?:#{TYPE_RE}|#{FILENAME_RE}|#{MASTERS_LIST_RE})\s*)+
#            \s*\}\s*;\s*$/mx


# reads a named.conf.slave file
# and builds an array with information about
# zone name, masters list and filename
def self.readconf(conffilename)
  result = []
  File.read(conffilename).scan(ZONE_RE) do |m|
    if TYPE_RE.match(m)
      zonename = ZONENAME_RE.match(m)[1]
      masters_list = MASTERS_LIST_RE.match(m)[1].split(";").collect{|e| e.strip}
      filename = FILENAME_RE.match(m)[1]
      result << [zonename, masters_list, filename]
    end
  end
  result
end

# builds a conf string from a named.conf.slave hash
# with information about zone name, masters list and filename
def self.writeconf(hash)
  hash.keys.sort.inject("") do |conf, zonename|
    conf << ZONEFMT % [ zonename,
                        hash[zonename][:masters].sort.reverse.join("; "),
                        hash[zonename][:file] ]
  end
end

# merges two named.conf.slave arrays into a hash.
def self.mergeconf(a, b)
  zones = Hash.new {|h, k| h[k] = {:masters => []} }

  (a | b).each do |r|
    zones[r[0]][:masters] |= r[1]
    zones[r[0]][:file] = r[2]
  end

  zones
end

end # module MyBIND

if __FILE__ == $0

def usage
  warn "Usage:
  #{File.basename $0} slave_file_1 slave_file_2"
  exit 1
end

usage if ARGV.size != 2
filenames = ARGV

confs = filenames.inject([]) {|m, filename| m << MyBIND.readconf(filename)}
mergedconf = MyBIND.mergeconf(*confs)
print MyBIND.writeconf(mergedconf)

end