-- subquery to prepare the data
with prep_traffic as (
select
    user_pseudo_id,
    (select value.int_value from unnest(event_params) where key = 'ga_session_id') as session_id,
    max((select value.string_value from unnest(event_params) where key = 'medium')) as medium,
    max((select value.string_value from unnest(event_params) where key = 'source')) as source,
    max((select value.string_value from unnest(event_params) where key = 'campaign')) as campaign,
    max((select value.string_value from unnest(event_params) where key = 'session_engaged')) as session_engaged,
    max((select value.int_value from unnest(event_params) where key = 'engagement_time_msec')) as engagement_time_msec,
    -- change event_name to the event(s) you want to count
    countif(event_name = 'page_view') as event_count,
    -- change event_name to the conversion event(s) you want to count
    countif(event_name = 'add_payment_info') as conversions,
    sum(ecommerce.purchase_revenue) as total_revenue   
from
    -- change this to your google analytics 4 bigquery export location
    `bigquery-341716.analytics_278788286.events_*`
where
    -- change the date range by using static and/or dynamic dates
    _table_suffix between '20220705' and format_date('%Y%m%d',date_sub(current_date(), interval 1 day))
group by 
    user_pseudo_id,
    session_id)

-- main query
select
    concat(ifnull(source,'(direct)'),' / ',ifnull(medium,'(none)')) as session_source_medium,
    -- ifnull(medium,'(none)') as session_medium,
    -- ifnull(source,'(direct)') as session_source,
    -- ifnull(campaign,'(direct)') as session_campaign,
    /* -- definitions of the channel grouping based on the source / medium of every session
    case
        when source is null and (medium = '(not set)' or medium is null) then 'Direct'
        when medium = 'organic' then 'Organic Search'
        when regexp_contains(medium, r'^(social|social-network|social-media|sm|social network|social media)$') then 'Social'
        when medium = 'email' then 'Email'
        when medium = 'affiliate' then 'Affiliates'
        when medium = 'referral' then 'Referral'
        when regexp_contains(medium, r'^(cpc|ppc|paidsearch)$') then 'Paid Search'
        when regexp_contains(medium, r' ^(cpv|cpa|cpp|content-text)$') then 'Other Advertising'
        when regexp_contains(medium, r'^(display|cpm|banner)$') then 'Display'
        else '(Other)' end as session_default_channel_grouping,
    */
    count(distinct user_pseudo_id) as users,
    count(distinct concat(user_pseudo_id,session_id)) as sessions,
    count(distinct case when session_engaged = '1' then concat(user_pseudo_id,session_id) end) as engaged_sessions,
    safe_divide(count(distinct case when session_engaged = '1' then concat(user_pseudo_id,session_id) end),count(distinct user_pseudo_id)) as engaged_sessions_per_user,
    safe_divide(count(distinct case when session_engaged = '1' then concat(user_pseudo_id,session_id) end),count(distinct concat(user_pseudo_id,session_id))) as engagement_rate,
    sum(event_count) as event_count,
    sum(conversions) as conversions,
    ifnull(sum(total_revenue),0) as total_revenue
from
    prep_traffic
group by
    session_source_medium
    -- ,session_medium
    -- ,session_source
    -- ,session_campaign
    -- ,session_default_channel_grouping
order by
    users desc