/*
This macro displays a metric value common in two sources, current and previous,
and computes the relative increment of current vs. previous.

It's designed to be placed within a SELECT statement.

It ensure safe divide by zero division by applying a nullif function.

*/
{% macro calculate_safe_relative_increment(
    metric, current="current", previous="previous_year"
) %}
    {{ current }}.{{ metric }},
    {{ previous }}.{{ metric }} as {{ previous }}_{{ metric }},
    cast({{ current }}.{{ metric }} as decimal) / nullif({{ previous }}.{{ metric }}, 0)
    - 1 as relative_increment_{{ metric }}
{% endmacro %}