module PgCtrl
  module Utils
    def set_opts(opts, *attrs) 
      attrs.map { |a| self.instance_variable_set("@#{a}", opts[a]) }
    end
  end

  class RDBMSObjectSet
    def initialize
      @by_name = {}
      @by_oid = {}
    end

    def size() @by_name.size end
    def empty?() @by_name.empty? end

    def [](key) Fixnum === key ? @by_oid[key] : @by_name[key] end
    def add(value) @by_oid[value.oid] = @by_name[value.name] = value end

    def keys() @by_name.keys end
    def values() @by_name.values end

    def each(&block) @by_name.each(&block) end
    def map(&block) @by_name.map(&block) end
  end

  class RDBMS
    LOAD_USERS_QUERY = %(
      select  oid as OID,
              rolname as NAME,
              rolsuper as IS_SUPERUSER,
              rolcreaterole as CAN_CREATE_ROLE,
              rolcreatedb as CAN_CREATE_DB,
              rolcanlogin as CAN_LOGIN,
              case when rolname = current_user then true else false end as
                  IS_CURRENT_USER
      from    pg_roles
    )

    def load_users
      @connection.each_hash(LOAD_USERS_QUERY) { |r|
        @users.add User.new(self, r[:oid], r[:name], r)
        @user = @users[r[:name]] if r[:is_current_user]
      }
    end

    LOAD_DATABASES_QUERY = %(
      select  pg_database.oid as OID,
              datname as NAME,
              rolname as OWNER,
              pg_encoding_to_char(encoding) as ENCODING,
              datcollate as LC_COLLATE,
              datctype as LC_CTYPE,
              datistemplate as IS_TEMPLATE,
              datallowconn as CAN_CONNECT,
              datacl as ACL,
              case when datname = current_database() then true else false end as
                  IS_CURRENT_DATABASE
      from    pg_database
      join    pg_roles on datdba = pg_roles.oid
    )

    def load_databases
      @connection.each_hash(LOAD_DATABASES_QUERY) { |r|
        @databases.add \
            Database.new(self, r[:oid], r[:name], @users[r[:owner]], r)
        @database = @databases[r[:name]] if r[:is_current_database]
      }
    end

    def load_data
      @users = RDBMSObjectSet.new
      @databases = RDBMSObjectSet.new
      load_users
      load_databases
    end
  end
end