defmodule Realtime.Tenants.Migrations.UpdateSubscriptionCheckFiltersForInFilterNonTextTypes do
  @moduledoc false

  use Ecto.Migration

  def change do
    execute("
    create or replace function realtime.subscription_check_filters()
        returns trigger
        language plpgsql
    as $$
    /*
    Validates that the user defined filters for a subscription:
    - refer to valid columns that the claimed role may access
    - values are coercable to the correct column type
    */
    declare
        col_names text[] = coalesce(
                array_agg(c.column_name order by c.ordinal_position),
                '{}'::text[]
            )
            from
                information_schema.columns c
            where
                format('%I.%I', c.table_schema, c.table_name)::regclass = new.entity
                and pg_catalog.has_column_privilege(
                    (new.claims ->> 'role'),
                    format('%I.%I', c.table_schema, c.table_name)::regclass,
                    c.column_name,
                    'SELECT'
                );
        filter realtime.user_defined_filter;
        col_type regtype;

        in_val jsonb;
    begin
        for filter in select * from unnest(new.filters) loop
            -- Filtered column is valid
            if not filter.column_name = any(col_names) then
                raise exception 'invalid column for filter %', filter.column_name;
            end if;

            -- Type is sanitized and safe for string interpolation
            col_type = (
                select atttypid::regtype
                from pg_catalog.pg_attribute
                where attrelid = new.entity
                      and attname = filter.column_name
            );
            if col_type is null then
                raise exception 'failed to lookup type for column %', filter.column_name;
            end if;

            -- Set maximum number of entries for in filter
            if filter.op = 'in'::realtime.equality_op then
                in_val = realtime.cast(filter.value, (col_type::text || '[]')::regtype);
                if coalesce(jsonb_array_length(in_val), 0) > 100 then
                    raise exception 'too many values for `in` filter. Maximum 100';
                end if;
            else
                -- raises an exception if value is not coercable to type
                perform realtime.cast(filter.value, col_type);
            end if;

        end loop;

        -- Apply consistent order to filters so the unique constraint on
        -- (subscription_id, entity, filters) can't be tricked by a different filter order
        new.filters = coalesce(
            array_agg(f order by f.column_name, f.op, f.value),
            '{}'
        ) from unnest(new.filters) f;

        return new;
    end;
    $$;
    ")
  end
end
