#!/usr/bin/env ruby

require 'toml'
require 'net/ldap'
require 'English'
require 'open3'

@mailman3_exec = '/usr/bin/mailman'
@configuration_file = '/etc/mailman3-ldap-sync.toml'
@configuration = nil

def read_configuration(path)
  begin
    TOML.load_file(path)
  rescue Errno::ENOENT => e
    puts "Could not open configuration file: #{e}"
    exit(1)
  end
end

def connect_ldap
  conn = Net::LDAP.new(
    host: @configuration['ldap']['host'],
    port: @configuration['ldap']['port'],
    encryption: :simple_tls,
    auth: {
      method: :simple,
      username: @configuration['ldap']['auth']['username'],
      password: @configuration['ldap']['auth']['password']
    }
  )

  ldap_addr = "#{@configuration['ldap']['host']}:#{@configuration['ldap']['port']}"
  begin
    if conn.bind
      conn
    else
      puts "Failed to authenticate against LDAP server: #{ldap_addr}"
      exit(1)
    end
  rescue Net::LDAP::LdapError => e
    puts "Failed to contact LDAP server: #{ldap_addr}"
    puts e
    exit(1)
  end
end

def get_mailman3_subscribers(list)
  unless File.executable?(@mailman3_exec)
    puts "could not execute #{@mailman3_exec}"
    exit(1)
  end

  # Execute mailman and check whether it exited successfuly
  raw = `#{@mailman3_exec} members #{list}`
  unless $CHILD_STATUS.exitstatus.zero?
    puts 'FAIL'
    exit(1)
  end

  # Return a list of mail addresses.
  raw.split("\n")
end

def add_subscribers_to(list, addresses)
  # The address is not subscribed to the list yet.
  print "Adding #{addresses.size} addresses... "

  # Subscribe the address to the list.
  Open3.popen3(@mailman3_exec, 'members', '-a', '-', list) do |stdin, stdout, _stderr, wait_thr|
    stdin.write(addresses.join("\n"))
    stdin.close_write

    process = wait_thr.value
    if process.exitstatus.zero?
      puts 'OK'
    else
      puts 'FAILED'
    end

    puts '> Mailman output:'
    puts stdout.read
  end
end

def sync_list(list_name, ldap_group_entry, ldap_conn)
  user_basetree = @configuration['ldap']['users']['basetree']
  list = "#{list_name}@#{@configuration['domain']}"

  ldap_members = ldap_group_entry.memberuid.map do |uid|
    filter = Net::LDAP::Filter.eq('uid', uid)
    matched_ldap_users = ldap_conn.search(base: user_basetree, filter: filter)
    if matched_ldap_users.nil? || matched_ldap_users.empty?
      ''
    else
      user = matched_ldap_users.first
      address = user.mail.first # 'mail' is an array for some reason.

      address
    end
  end

  ldap_members.select! {|e| not e.empty? }
  puts "Found #{ldap_group_entry.dn} with #{ldap_members.size} members"

  # Extract mail addresses from Mailman
  print 'Searchin mailman... '
  mailman3_subscribers = get_mailman3_subscribers(list)
  puts 'OK'
  puts "Found #{list} with #{mailman3_subscribers.size} subscribers"

  # Add found addresses to the list.
  add_subscribers_to(list, ldap_members)
end

def main
  # Parse configuration, bind to LDAP server
  configuration_file = ARGV[0] ? ARGV[0] : @configuration_file
  @configuration = read_configuration(configuration_file)
  ldap_conn = connect_ldap

  domain = @configuration['domain']
  list_basetree = @configuration['ldap']['lists']['basetree']
  lists = @configuration['lists']

  # Sync mailman3 lists with LDAP groups
  lists.each do |list_name|
    puts ">> Processing list #{list_name}@#{domain}"
    print 'Searching LDAP... '

    filter = Net::LDAP::Filter.eq('cn', list_name)
    matched_ldap_groups = ldap_conn.search(base: list_basetree, filter: filter)
    if matched_ldap_groups.nil? || matched_ldap_groups.empty?
      # Could not find matching LDAP group
      puts 'NOT FOUND'
    else
      puts 'OK'
      ldap_group_entry = matched_ldap_groups.first
      sync_list(list_name, ldap_group_entry, ldap_conn)
    end
  end
end

###
# Execute script:
main