note
	description: "Objects that provide an interface to access information in the database."
	author: "Patrick Ruckstuhl <patrick@tario.org>"
	date: "$Date$"
	revision: "$Revision$"

deferred class
	DATABASE_ACCESS

inherit
	A_SHARED_LOGGERS

	EXCEPTIONS

	O_ERRORS

feature {NONE} -- Initialization

	make (a_db_handler: like db_handler; a_db_interface: like db_interface)
			-- Initialize Access Layer Object.
			-- If `a_db_interface' is provided, it can be used to call other access-layer functions
		require
			a_db_handler_ok: a_db_handler /= Void
		do
			db_handler := a_db_handler
			db_interface := a_db_interface
			create select_query.make (Current)
		ensure
			db_handler_set: db_handler = a_db_handler
			interface_set: db_interface = a_db_interface
		end

feature {DATABASE_ACCESS, WI_FULL_WORKITEM} -- Interface access

	db_interface: BASE_INTERFACE
			-- Common Interface to all DB-Access classes

feature {DATABASE_QUERY} -- Database access

	db_handler: DATABASE_HANDLER
			-- Database handler.

	handle_errors_and_warnings
			-- Check for database errors and warnings and log them.
		local
			l_control: DB_CONTROL
			l_warning: STRING
		do
			l_control := db_handler.db_control
				-- any errors?
			if not l_control.is_ok then
				node_logger.fatal ("Database error: "+l_control.error_message)
				l_control.reset

					-- reconnect to the db as this may have been a connection lost error
				l_control.disconnect
				l_control.connect

				raise (except_database_error)
			end
			l_warning := l_control.warning_message
			if l_warning /= Void and then not l_warning.is_empty then
				node_logger.warn ("Database warning: "+l_control.warning_message)
			end
			l_control.reset
		end

feature {NONE} -- Implementation helper

	select_query: DATABASE_SELECT_QUERY
			-- Query object for select queries.

feature -- Select queries

	last_insert_id: INTEGER
			-- Get id of last autoincrement
		local
			l_res: SELECTION_RESULT
		do
			l_res := select_query.execute_query ("SELECT LAST_INSERT_ID() AS id")
			handle_errors_and_warnings
			l_res.start
			Result := l_res.read_integer ("id")
		end


invariant
	db_handler_not_void: db_handler /= Void
	select_query_not_void: select_query /= Void

end