require 'common/domain'
require 'common/plugin'
require 'common/user'
require 'pg'

# Code that all Postfixadmin plugins ({PostfixadminPrune},
# {PostfixadminRm}, {PostfixadminMv}) share.
#
module PostfixadminPlugin

  # We implement the Plugin "interface."
  include Plugin

  # Initialize this Postfixadmin {Plugin} with values in *cfg*.
  #
  # @param cfg [Configuration] the configuration for this plugin.
  #
  def initialize(cfg)
    @db_hash = {
      :host     => cfg.postfixadmin_dbhost,
      :port     => cfg.postfixadmin_dbport,
      :options  => cfg.postfixadmin_dbopts,
      :tty      => cfg.postfixadmin_dbtty,
      :dbname   => cfg.postfixadmin_dbname,
      :user     => cfg.postfixadmin_dbuser,
      :password => cfg.postfixadmin_dbpass }
  end


  # Obtain a list of domains from Postfixadmin. This is more efficient
  # than the {Plugin} default implementation because domains have
  # their own table in the database and we can easily select them
  # rather than filtering the list of users.
  #
  # @return [Array<Domain>] a list of the domains in Postfixadmin.
  #
  def list_domains()
    domains = []

    connection = PG::Connection.new(@db_hash)

    # 'ALL' is a magic domain, and we don't want it.
    sql_query = "SELECT domain FROM domain WHERE domain <> 'ALL';"

    begin
      connection.query(sql_query) do |result|
        domains = result.field_values('domain')
      end
    ensure
      # Make sure the connection gets closed even if the query explodes.
      connection.close()
    end

    return domains.map{ |d| Domain.new(d) }
  end


  # Return a list of Postfixadmin users.
  #
  # @return [Array<User>] a list of users contained in the
  #   Postfixadmin database.
  #
  def list_users()
    users = []

    connection = PG::Connection.new(@db_hash)

    sql_query = 'SELECT username FROM mailbox;'

    begin
      connection.query(sql_query) do |result|
        users = result.field_values('username')
      end
    ensure
      # Make sure the connection gets closed even if the query explodes.
      connection.close()
    end

    return users.map{ |u| User.new(u) }
  end



  # Efficiently list all Postfixadmin users belonging to the given
  # Postfixadmin *domains*.
  #
  # @param domains [Array<Domain>] the domains whose users we want.
  #
  # @return [Array<User>] a list of {User} objects belonging to
  #   *domains* for this plugin.
  #
  def list_domains_users(domains)
    usernames = []
    return usernames if domains.length() == 0

    connection = PG::Connection.new(@db_hash)

    # The number of parameters that we'll pass into our prepared query
    # is the number of domains that we're given. It's important that
    # we have at least one domain here.
    params = 1.upto(domains.length()).map{ |i| '$' + i.to_s() }.join(',')
    sql_query  = "SELECT username FROM mailbox WHERE domain IN (#{params});"

    begin
      # Now replace each Domain with its string representation and pass
      # those in as our individual parameters.
      connection.query(sql_query, domains.map{ |d| d.to_s() }) do |result|
        usernames = result.field_values('username')
      end
    ensure
      # Make sure the connection gets closed even if the query explodes.
      connection.close()
    end

    return usernames.map{ |u| User.new(u) }
  end


  # Get a list of all Postfixadmin aliases as a <tt>from => to</tt>
  # hash. This is useful for testing, since aliases should be removed
  # when either the "from user" or "to user" are removed.
  #
  # @return [Hash] all aliases known to Postfixadmin in the form of a
  #   <tt>from => to</tt> hash.
  #
  def list_aliases()
    aliases = []

    connection = PG::Connection.new(@db_hash)

    sql_query = 'SELECT address,goto FROM alias;'

    begin
      results = connection.query(sql_query)
      results.each do |row|
        # row should be a hash
        aliases << row
      end
    ensure
      # Make sure the connection gets closed even if the query explodes.
      connection.close()
    end

    return aliases
  end


  # A fast implementation of the "does this domain exist?"
  # operation. It only queries the database for the existence of
  # *domain* rather than a list of all domains (which is the default
  # implementation).
  #
  # @param domain [Domain] the domain whose existence is in question.
  #
  # @return [Boolean] true if *domain* exists in the Postfixadmin
  #   database and false otherwise.
  #
  def domain_exists(domain)
    count = 0

    connection = PG::Connection.new(@db_hash)

    sql_query = 'SELECT COUNT(domain) as count FROM domain WHERE domain = $1;'

    begin
      connection.query(sql_query, [domain.to_s()]) do |result|
        return false if result.ntuples() < 1
        count = result.getvalue(0,0).to_i()

        return false if count.nil?
      end
    ensure
      # Make sure the connection gets closed even if the query explodes.
      connection.close()
    end

    return (count > 0)
  end

end