-- catalog

CREATE SCHEMA __pg_ivm__;

CREATE TABLE __pg_ivm__.pg_ivm_immv(
  immvrelid regclass NOT NULL,
  viewdef text NOT NULL,

  CONSTRAINT pg_ivm_immv_pkey PRIMARY KEY (immvrelid)
);

ALTER TABLE __pg_ivm__.pg_ivm_immv SET SCHEMA pg_catalog;

--CREATE UNIQUE INDEX ON pg_catalog.pg_ivm_immv USING btree (immvrelid);

SELECT pg_catalog.pg_extension_config_dump('pg_catalog.pg_ivm_immv', '');

-- functions

CREATE FUNCTION changes_partitions(pg_ddl_command)
RETURNS boolean
IMMUTABLE
STRICT
AS 'MODULE_PATHNAME', 'changes_partitions'
LANGUAGE C;

-- CREATE FUNCTION get_command_type(text, text, pg_ddl_command, text)
-- RETURNS void
-- IMMUTABLE
-- STRICT
-- AS 'MODULE_PATHNAME', 'get_command_type'
-- LANGUAGE C;

CREATE FUNCTION create_immv(text, text)
RETURNS bigint
STRICT
AS 'MODULE_PATHNAME', 'create_immv'
LANGUAGE C;

-- trigger functions

CREATE FUNCTION "IVM_immediate_before"()
RETURNS trigger
AS 'MODULE_PATHNAME', 'IVM_immediate_before'
LANGUAGE C;

CREATE FUNCTION "IVM_immediate_maintenance"()
RETURNS trigger
AS 'MODULE_PATHNAME', 'IVM_immediate_maintenance'
LANGUAGE C;

CREATE FUNCTION "IVM_prevent_immv_change"()
RETURNS trigger
AS 'MODULE_PATHNAME', 'IVM_prevent_immv_change'
LANGUAGE C;


/*
 * DDL trigger that removes entry from pg_ivm_immv
 */
CREATE FUNCTION pg_ivm_sql_drop_trigger_func()
RETURNS event_trigger AS $$
DECLARE
	pg_class_oid	OID;
	relids			REGCLASS[];

BEGIN
	pg_class_oid = 'pg_catalog.pg_class'::regclass;

	/* Find relids to remove */
	DELETE FROM pg_catalog.pg_ivm_immv
	USING pg_catalog.pg_event_trigger_dropped_objects() AS events
	WHERE immvrelid = events.objid AND
	      events.classid = pg_class_oid AND events.objsubid = 0;
END
$$ LANGUAGE plpgsql;

CREATE EVENT TRIGGER pg_ivm_sql_drop_trigger
ON sql_drop
EXECUTE PROCEDURE pg_catalog.pg_ivm_sql_drop_trigger_func();

-- Process ALTER TABLE, specifically ATTACH/DETACH PARTITION
-- TODO: Get incremental update working
CREATE OR REPLACE FUNCTION ivm_immediate_event()
 RETURNS event_trigger
 LANGUAGE plpgsql
AS $function$
DECLARE
  r record;
BEGIN
  FOR r IN SELECT * FROM pg_event_trigger_ddl_commands()
  LOOP
    IF changes_partitions(r.command) THEN
      PERFORM refresh_immv(
        convert_from(
          substring(tgargs FOR (position('\x00'::bytea in tgargs)-1)),
          'SQL_ASCII'
        )::oid::regclass::text,
        true)
      FROM pg_trigger
      WHERE tgfoid='"IVM_immediate_maintenance"'::regproc AND tgtype=4;
    END IF;
  END LOOP;
END;
$function$;

-- Run on any ALTER TABLE
CREATE EVENT TRIGGER IVM_trigger_event
ON ddl_command_end WHEN TAG IN ('ALTER TABLE')
EXECUTE PROCEDURE ivm_immediate_event();