class BtrieveSession
  SESSIONS = {}
  include Btrieve
  attr_reader :pathname, :client_id, :cache, :model_classes, :btrieve_schema
  attr_accessor :mappings, :mapping_functions, :relations

  def self.set_context(pathname)
    session = get_session
    if session
      raise Exception.new("The existing context in the current is set to a different pathname.")  if(session.pathname != pathname)
    else
      SESSIONS[Thread.current] = new(pathname)
    end
  end

  def self.get_session
    SESSIONS[Thread.current]
  end

  def transaction(&block)
    btr_op(self, BEGIN_TRANSACTION, NULL_BUFFER, NULL_BUFFER, NULL_BUFFER, NULL_KEY)
    begin
      yield
    rescue Exception => exception
      btr_op(self, ABORT_TRANSACTION, NULL_BUFFER, NULL_BUFFER, NULL_BUFFER, NULL_KEY)
      raise Exception.new("PSQL TX ABORTED!!! - #{exception.message}\n#{exception.backtrace.join("\n\t")}")
    end
    btr_op(self, END_TRANSACTION, NULL_BUFFER, NULL_BUFFER, NULL_BUFFER, NULL_KEY)
  end

  def get_table(url_tablename)
    tablename=BtrieveTable.url_to_tablename(url_tablename)
    table=@table_cache[tablename]||=BtrieveTable.new(tablename.to_sym, self)
    [table,table.version]
  end

  private

  def initialize(pathname)
    @cache = {}
    @model_classes = {}
    @table_cache = {}
    @pathname = pathname
    @client_id = "#{0.chr*12}#{[0x5257].pack('S')}#{rand(65535)}"
    btr_op(self, SET_DIRECTORY, NULL_BUFFER, NULL_BUFFER, @pathname, NULL_KEY)
    @btrieve_schema = BtrieveSchema.new(self)
  end
end