require 'pg'

require 'common/agendav_plugin'
require 'rm/rm_plugin'


# Handle the removal of Agendav users from its database. Agendav has
# no concept of domains.
#
class AgendavRm

  include AgendavPlugin
  include RmPlugin


  # Remove *user* from the Agendav database. This should remove him
  # from _every_ table in which he is referenced.
  #
  # We do not raise an error if the user doesn't exist. This is due to
  # an unfortunate problem with the "user exists" check in AgenDAV.
  # The AgenDAV "shares" table is not tied directly to a username, so
  # we are forced to use a regexp match to decide what rows to delete
  # from that table. We do so regardless of whether or not the username
  # exists in the "prefs" table, because that table stores only non-
  # default preferences -- not all users' preferences.
  #
  # @param user [User] the user to remove.
  #
  def remove_user(user)
    sql_queries = ['DELETE FROM prefs WHERE username = $1;']

    # The "shares" table contains principal URLs, and the "@" symbol
    # is usually encoded to "%40". These queries do a regex match on
    # the username after replacing the "%40" with a "@".
    #
    # As a precaution, I haven chosen not to delete based on the
    # "calendar" field here. Nobody should have a calendar named
    # "user%40example.com", but it's not impossible -- and we don't
    # want to delete that calendar when the not-necessarily-related
    # "user@example.com" account is removed. And the usual appearance
    # of the user's email address in the "calendar" field happens when
    # he is also the owner, so the calendar does get deleted in the
    # normal situation.
    sql_queries << "DELETE FROM shares WHERE REPLACE(owner,'%40','@')    ~ $1;"
    sql_queries << "DELETE FROM shares WHERE REPLACE(\"with\",'%40','@') ~ $1;"

    connection = PG::Connection.new(@db_hash)
    begin
      sql_queries.each do |sql_query|
        connection.sync_exec_params(sql_query, [user.to_s()])
      end
    ensure
      # Make sure the connection gets closed even if a query explodes.
      connection.close()
    end
  end

end