dougal-software/etc/db/upgrades/upgrade22-v0.3.9-add-replace-placeholders-function.sql

-- Fix not being able to edit a time-based event.
--
-- New schema version: 0.3.9
--
-- 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 defines a replace_placeholders() function, taking as arguments
-- a text string and either a timestamp or a sequence / point pair. It
-- uses the latter arguments to find metadata from which it can extract
-- relevant information and replace it into the text string wherever the
-- appropriate placeholders appear. For instance, given a call such as
-- replace_placeholders('The position is @POS@', NULL, 11, 2600) it will
-- replace '@POS@' with the position of point 2600 in sequence 11, if it
-- exists (or leave the placeholder untouched otherwise).
--
-- A scan_placeholders() procedure is also defined, which calls the above
-- function on the entire event log.
--
-- 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 $outer$
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 replace_placeholders (
		text_in text, tstamp timestamptz, sequence integer, point integer
	)
	RETURNS text
	AS $$
	DECLARE
		position geometry;
		metadata jsonb;
		text_out text;

		json_query text;
		json_result jsonb;
		expect_recursion boolean := false;
	BEGIN

		text_out := text_in;

		-- We only get a position if we are going to need it…
		IF regexp_match(text_out, '@DMS@|@POS@|@DEG@') IS NOT NULL THEN
			position := ST_Transform(event_position(tstamp, sequence, point), 4326);
		END IF;

		-- …and likewise with the metadata.
		IF regexp_match(text_out, '@BSP@|@WD@|@CMG@|@EN@|@GRID@|@(\$\..*?)@@') IS NOT NULL THEN
			metadata := event_meta(tstamp, sequence, point);
		END IF;

		-- We shortcut the evaluation if neither of the above regexps matched
		IF position IS NULL AND metadata IS NULL THEN
			RETURN text_out;
		END IF;

		IF position('@DMS@' IN text_out) != 0 THEN
			text_out := replace(text_out, '@DMS@', ST_AsLatLonText(position));
		END IF;

		IF position('@POS@' IN text_out) != 0 THEN
			text_out := replace(text_out, '@POS@', replace(ST_AsLatLonText(position, 'D.DDDDDD'), ' ', ', '));
		END IF;

		IF position('@DEG@' IN text_out) != 0 THEN
			text_out := replace(text_out, '@DEG@', replace(ST_AsLatLonText(position, 'D.DDDDDD'), ' ', ', '));
		END IF;

		IF position('@EN@' IN text_out) != 0 THEN
			IF metadata ? 'easting' AND metadata ? 'northing' THEN
				text_out := replace(text_out, '@EN@', (metadata->>'easting') || ', ' || (metadata->>'northing'));
			END IF;
		END IF;

		IF position('@GRID@' IN text_out) != 0 THEN
			IF metadata ? 'easting' AND metadata ? 'northing' THEN
				text_out := replace(text_out, '@GRID@', (metadata->>'easting') || ', ' || (metadata->>'northing'));
			END IF;
		END IF;

		IF position('@CMG@' IN text_out) != 0 THEN
			IF metadata ? 'bearing' THEN
				text_out := replace(text_out, '@CMG@', metadata->>'bearing');
			END IF;
		END IF;

		IF position('@BSP@' IN text_out) != 0 THEN
			IF metadata ? 'speed' THEN
				text_out := replace(text_out, '@BSP@', round((metadata->>'speed')::numeric * 3600 / 1852, 1)::text);
			END IF;
		END IF;

		IF position('@WD@' IN text_out) != 0 THEN
			IF metadata ? 'waterDepth' THEN
				text_out := replace(text_out, '@WD@', metadata->>'waterDepth');
			END IF;
		END IF;

		json_query := (regexp_match(text_out, '@(\$\..*?)@@'))[1];
		IF json_query IS NOT NULL THEN
			json_result := jsonb_path_query_array(metadata, json_query::jsonpath);
			IF jsonb_array_length(json_result) = 1 THEN
				text_out := replace(text_out, '@'||json_query||'@@', json_result->>0);
			ELSE
				text_out := replace(text_out, '@'||json_query||'@@', json_result::text);
			END IF;
			-- There might be multiple JSONPath queries, so we may have to recurse
			expect_recursion := true;
		END IF;

		IF expect_recursion IS TRUE AND text_in != text_out THEN
			--RAISE NOTICE 'Recursing %', text_out;
			-- We don't know if we have found all the JSONPath expression
			-- so we do another pass.
			RETURN replace_placeholders(text_out, tstamp, sequence, point);
		ELSE
			RETURN text_out;
		END IF;

	END;
	$$ LANGUAGE plpgsql;

	COMMENT ON FUNCTION replace_placeholders (text, timestamptz, integer, integer) IS
	'Replace certain placeholder strings in the input text with data obtained from shot or real-time data.';


	CREATE OR REPLACE PROCEDURE scan_placeholders ()
	LANGUAGE sql
	AS $$
		-- We update non read-only events via the event_log view to leave a trace
		-- of the fact that placeholders were replaced (and when).
		-- Note that this will not replace placeholders of old edits.
		UPDATE event_log
		SET remarks = replace_placeholders(remarks, tstamp, sequence, point)
		FROM (
			SELECT id
			FROM event_log e
			WHERE
				(meta->'readonly')::boolean IS NOT TRUE AND (
					regexp_match(remarks, '@DMS@|@POS@|@DEG@') IS NOT NULL OR
					regexp_match(remarks, '@BSP@|@WD@|@CMG@|@EN@|@GRID@|@(\$\..*?)@@') IS NOT NULL
				)
		) t
		WHERE event_log.id = t.id;

		-- And then we update read-only events directly on the event_log_full table
		-- (as of this version of the schema we're prevented from updating read-only
		-- events via event_log anyway).
		UPDATE event_log_full
		SET remarks = replace_placeholders(remarks, tstamp, sequence, point)
		FROM (
			SELECT uid
			FROM event_log_full e
			WHERE
				(meta->'readonly')::boolean IS TRUE AND (
					regexp_match(remarks, '@DMS@|@POS@|@DEG@') IS NOT NULL OR
					regexp_match(remarks, '@BSP@|@WD@|@CMG@|@EN@|@GRID@|@(\$\..*?)@@') IS NOT NULL
				)
		) t
		WHERE event_log_full.uid = t.uid;
	$$;

	COMMENT ON PROCEDURE scan_placeholders () IS
	'Run replace_placeholders() on the entire event log.';

END;
$outer$ LANGUAGE plpgsql;

CREATE OR REPLACE PROCEDURE pg_temp.upgrade () AS $outer$
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;
$outer$ LANGUAGE plpgsql;

CALL pg_temp.upgrade();

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

CALL show_notice('Updating db_schema version');
INSERT INTO public.info VALUES ('version', '{"db_schema": "0.3.9"}')
ON CONFLICT (key) DO UPDATE
	SET value = public.info.value || '{"db_schema": "0.3.9"}' 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
--