dougal-software/etc/db/upgrades/upgrade16-v0.3.3-fix-event-log-edit.sql

-- Fix not being able to edit a time-based event.
--
-- New schema version: 0.3.3
--
-- 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.
--
-- The event_log_update() function that gets called when trying to update
-- the event_log view will not work if the caller does provide a timestamp
-- or sequence + point in the list of fields to be updated. See:
-- https://gitlab.com/wgp/dougal/software/-/issues/198
--
-- This fixes the problem by liberally using COALESCE() to merge the OLD
-- and NEW records.
--
-- 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 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 $$
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_update() RETURNS trigger
	LANGUAGE plpgsql
	AS $inner$
	BEGIN
		IF (TG_OP = 'INSERT') THEN

			-- Complete the tstamp if possible
			IF NEW.sequence IS NOT NULL AND NEW.point IS NOT NULL AND NEW.tstamp IS NULL THEN
				SELECT COALESCE(
					tstamp_from_sequence_shot(NEW.sequence, NEW.point),
					tstamp_interpolate(NEW.sequence, NEW.point)
				)
				INTO NEW.tstamp;
			END IF;

			-- Any id that is provided will be ignored. The generated
			-- id will match uid.
			INSERT INTO event_log_full
				(tstamp, sequence, point, remarks, labels, meta)
			VALUES (NEW.tstamp, NEW.sequence, NEW.point, NEW.remarks, NEW.labels, NEW.meta);

			RETURN NEW;

		ELSIF (TG_OP = 'UPDATE') THEN
			-- Set end of validity and create a new entry with id
			-- matching that of the old entry.

			-- NOTE: Do not allow updating an event that has meta.readonly = true
			IF EXISTS
				(SELECT *
				FROM event_log_full
				WHERE id = OLD.id AND (meta->>'readonly')::boolean IS TRUE)
			THEN
				RAISE check_violation USING MESSAGE = 'Cannot modify read-only entry';
				RETURN NULL;
			END IF;

			-- If the sequence / point has changed, and no new tstamp is provided, get one
			IF NEW.sequence <> OLD.sequence OR NEW.point <> OLD.point
				AND NEW.sequence IS NOT NULL AND NEW.point IS NOT NULL
				AND NEW.tstamp IS NULL OR NEW.tstamp = OLD.tstamp THEN
				SELECT COALESCE(
					tstamp_from_sequence_shot(NEW.sequence, NEW.point),
					tstamp_interpolate(NEW.sequence, NEW.point)
				)
				INTO NEW.tstamp;
			END IF;

			UPDATE event_log_full
			SET validity = tstzrange(lower(validity), current_timestamp)
			WHERE validity @> current_timestamp AND id = OLD.id;

			-- Any attempt to modify id will be ignored.
			INSERT INTO event_log_full
				(id, tstamp, sequence, point, remarks, labels, meta)
			VALUES (
				OLD.id,
				COALESCE(NEW.tstamp, OLD.tstamp),
				COALESCE(NEW.sequence, OLD.sequence),
				COALESCE(NEW.point, OLD.point),
				COALESCE(NEW.remarks, OLD.remarks),
				COALESCE(NEW.labels, OLD.labels),
				COALESCE(NEW.meta, OLD.meta)
			);

			RETURN NEW;

		ELSIF (TG_OP = 'DELETE') THEN
			-- Set end of validity.

			-- NOTE: We *do* allow deleting an event that has meta.readonly = true
			-- This could be of interest if for instance we wanted to keep the history
			-- of QC results for a point, provided that the QC routines write to
			-- event_log and not event_log_full
			UPDATE event_log_full
			SET validity = tstzrange(lower(validity), current_timestamp)
			WHERE validity @> current_timestamp AND id = OLD.id;

			RETURN NULL;
		END IF;
	END;
	$inner$;

	CREATE OR REPLACE TRIGGER event_log_tg INSTEAD OF INSERT OR DELETE OR UPDATE ON event_log FOR EACH ROW EXECUTE FUNCTION event_log_update();


END;
$$ LANGUAGE plpgsql;

CREATE OR REPLACE PROCEDURE pg_temp.upgrade_16 () AS $$
DECLARE
	row RECORD;
BEGIN
	FOR row IN
		SELECT schema_name FROM information_schema.schemata
		WHERE schema_name LIKE 'survey_%'
		ORDER BY schema_name
	LOOP
		CALL pg_temp.upgrade_survey_schema(row.schema_name);
	END LOOP;
END;
$$ LANGUAGE plpgsql;

CALL pg_temp.upgrade_16();

CALL show_notice('Cleaning up');
DROP PROCEDURE pg_temp.upgrade_survey_schema (schema_name text);
DROP PROCEDURE pg_temp.upgrade_16 ();

CALL show_notice('Updating db_schema version');
INSERT INTO public.info VALUES ('version', '{"db_schema": "0.3.3"}')
ON CONFLICT (key) DO UPDATE
	SET value = public.info.value || '{"db_schema": "0.3.3"}' WHERE public.info.key = 'version';


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

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