-- Add event_log_changes function
--
-- New schema version: 0.4.4
--
-- ATTENTION:
--
-- ENSURE YOU HAVE BACKED UP THE DATABASE BEFORE RUNNING THIS SCRIPT.
--
--
-- NOTE: This upgrade affects all schemas in the database.
-- NOTE: Each application starts a transaction, which must be committed
-- or rolled back.
--
-- This adds a function event_log_changes which returns the subset of
-- events from event_log_full which have been modified on or after a
-- given timestamp.
--
-- To apply, run as the dougal user:
--
-- psql <<EOF
-- \i $THIS_FILE
-- COMMIT;
-- EOF
--
-- NOTE: It can be applied multiple times without ill effect.
--

BEGIN;

CREATE OR REPLACE PROCEDURE pg_temp.show_notice (notice text) AS $$
BEGIN
	RAISE NOTICE '%', notice;
END;
$$ LANGUAGE plpgsql;

CREATE OR REPLACE PROCEDURE pg_temp.upgrade_survey_schema (schema_name text) AS $outer$
BEGIN

	RAISE NOTICE 'Updating schema %', schema_name;
	-- We need to set the search path because some of the trigger
	-- functions reference other tables in survey schemas assuming
	-- they are in the search path.
	EXECUTE format('SET search_path TO %I,public', schema_name);

	CREATE OR REPLACE FUNCTION event_log_changes(ts0 timestamptz)
		RETURNS SETOF event_log_full
		LANGUAGE sql
		AS $$
		SELECT *
		FROM event_log_full
		WHERE lower(validity) > ts0 OR upper(validity) IS NOT NULL AND upper(validity) > ts0
		ORDER BY lower(validity);
	$$;

END;
$outer$ LANGUAGE plpgsql;

CREATE OR REPLACE PROCEDURE pg_temp.upgrade () AS $outer$
DECLARE
	row RECORD;
	current_db_version TEXT;
BEGIN

	SELECT value->>'db_schema' INTO current_db_version FROM public.info WHERE key = 'version';

	IF current_db_version >= '0.4.4' THEN
		RAISE EXCEPTION
			USING MESSAGE='Patch already applied';
	END IF;

	IF current_db_version != '0.4.3' THEN
		RAISE EXCEPTION
			USING MESSAGE='Invalid database version: ' || current_db_version,
				HINT='Ensure all previous patches have been applied.';
	END IF;

	FOR row IN
		SELECT schema_name FROM information_schema.schemata
		WHERE schema_name LIKE 'survey_%'
		ORDER BY schema_name
	LOOP
		CALL pg_temp.upgrade_survey_schema(row.schema_name);
	END LOOP;
END;
$outer$ LANGUAGE plpgsql;

CALL pg_temp.upgrade();

CALL pg_temp.show_notice('Cleaning up');
DROP PROCEDURE pg_temp.upgrade_survey_schema (schema_name text);
DROP PROCEDURE pg_temp.upgrade ();

CALL pg_temp.show_notice('Updating db_schema version');
INSERT INTO public.info VALUES ('version', '{"db_schema": "0.4.4"}')
ON CONFLICT (key) DO UPDATE
	SET value = public.info.value || '{"db_schema": "0.4.4"}' WHERE public.info.key = 'version';


CALL pg_temp.show_notice('All done. You may now run "COMMIT;" to persist the changes');
DROP PROCEDURE pg_temp.show_notice (notice text);

--
--NOTE Run `COMMIT;` now if all went well
--