-- Trigger for when chunk rows are changed.
-- On Insert: create chunk table, add indexes, add constraints.
-- On Update: change constraints.
-- On Delete: drop table
CREATE OR REPLACE FUNCTION _timescaledb_internal.on_change_chunk()
    RETURNS TRIGGER LANGUAGE PLPGSQL AS
$BODY$
DECLARE
    kind                  pg_class.relkind%type;
BEGIN
    IF TG_OP = 'INSERT' THEN

        PERFORM _timescaledb_internal.create_chunk_table(NEW.schema_name, NEW.table_name,
                                                     h.schema_name, h.table_name, p.tablespace, 
                                                     p.keyspace_start, p.keyspace_end, pe.id)
        FROM _timescaledb_catalog.partition p
        INNER JOIN _timescaledb_catalog.partition_epoch pe ON (pe.id = p.epoch_id)
        INNER JOIN _timescaledb_catalog.hypertable h ON (h.id = pe.hypertable_id)
        WHERE p.id = NEW.partition_id;

        PERFORM _timescaledb_internal.create_chunk_index_row(NEW.schema_name, NEW.table_name,
                                hi.main_schema_name, hi.main_index_name, hi.definition)
        FROM _timescaledb_catalog.partition p
        INNER JOIN _timescaledb_catalog.partition_epoch pe ON (pe.id = p.epoch_id)
        INNER JOIN _timescaledb_catalog.hypertable_index hi ON (hi.hypertable_id = pe.hypertable_id)
        WHERE p.id = NEW.partition_id;

        -- todo: can go into create_local_data_table?
        PERFORM _timescaledb_internal.set_time_constraint(NEW.schema_name, NEW.table_name, NEW.start_time, NEW.end_time);
        RETURN NEW;
    ELSIF TG_OP = 'DELETE' THEN
        -- when deleting the chunk row from the metadata table,
        -- also DROP the actual chunk table that holds data.
        -- Note that the table could already be deleted in case this
        -- trigger fires as a result of a DROP TABLE on the hypertable
        -- that this chunk belongs to.

        EXECUTE format(
                $$
                SELECT c.relkind FROM pg_class c WHERE relname = '%I' AND relnamespace = '%I'::regnamespace
                $$, OLD.table_name, OLD.schema_name
        ) INTO kind;

        IF kind IS NULL THEN
            RETURN OLD;
        END IF;

        EXECUTE format(
            $$
            DROP TABLE %I.%I
            $$, OLD.schema_name, OLD.table_name
        );
        RETURN OLD;
    END IF;

    PERFORM _timescaledb_internal.on_trigger_error(TG_OP, TG_TABLE_SCHEMA, TG_TABLE_NAME);
END
$BODY$;