-- Upgrade the database from commit 83be83e4 to 53ed096e.
--
-- New schema version: 0.2.0
--
-- 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 migrates the file hashes to address issue #173.
-- The new hashes use size, modification time, creation time and the
-- first half of the MD5 hex digest of the file's absolute path.
--
-- It's a minor (rather than patch) version number increment because
-- changes to `bin/datastore.py` mean that the data is no longer
-- compatible with the hashing function.
--
-- To apply, run as the dougal user:
--
-- psql <<EOF
-- \i $THIS_FILE
-- COMMIT;
-- EOF
--
-- NOTE: It can take a while if run on a large database.
-- 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 migrate_hashes (schema_name text) AS $$
BEGIN
	RAISE NOTICE 'Migrating schema %', schema_name;
	-- We need to set the search path because some of the trigger
	-- functions reference other tables in survey schemas assuming
	-- they are in the search path.
	EXECUTE format('SET search_path TO %I,public', schema_name);
	EXECUTE format('UPDATE %I.files SET hash = array_to_string(array_append(trim_array(string_to_array(hash, '':''), 1), left(md5(path), 16)), '':'')', schema_name);
	EXECUTE 'SET search_path TO public'; -- Back to the default search path for good measure
END;
$$ LANGUAGE plpgsql;

CREATE OR REPLACE PROCEDURE upgrade_10 () AS $$
DECLARE
	row RECORD;
BEGIN
	FOR row IN
		SELECT schema_name FROM information_schema.schemata
		WHERE schema_name LIKE 'survey_%'
		ORDER BY schema_name
	LOOP
		CALL migrate_hashes(row.schema_name);
	END LOOP;
END;
$$ LANGUAGE plpgsql;

CALL upgrade_10();

CALL show_notice('Cleaning up');
DROP PROCEDURE migrate_hashes (schema_name text);
DROP PROCEDURE upgrade_10 ();

CALL show_notice('Updating db_schema version');
INSERT INTO public.info VALUES ('version', '{"db_schema": "0.2.0"}')
ON CONFLICT (key) DO UPDATE
	SET value = public.info.value || '{"db_schema": "0.2.0"}' 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
--