CREATE MATERIALIZED VIEW user_cohort_analysis AS

	SELECT 
		TO_CHAR(pu.cohort_month, 'YYYY-MM') AS MONTH,
		COUNT(DISTINCT pu.id) AS users_in_cohort,
		COUNT(DISTINCT pe.user_id) AS enrolled_users,
		COUNT(DISTINCT plv.user_id) AS active_users,
		ROUND(COUNT(DISTINCT plv.user_id) * 100.0 / COUNT(DISTINCT pu.id), 2) || '%' AS retention_rate,
		ROUND(AVG((SELECT COUNT(*) FROM pet_courses pc)) / COUNT(DISTINCT pu.id), 2) AS avg_courses_per_user,	
		(SELECT 
			ROUND(AVG(table_first_viewed_at.first_viewed_at::date - pu2.registration_date::date), 2)
		FROM pet_users pu2
		LEFT JOIN (
			SELECT 
				plv2.user_id,
				MIN(plv2.viewed_at) AS first_viewed_at
			FROM pet_lesson_views plv2
			GROUP BY plv2.user_id
		) AS table_first_viewed_at
		
			ON pu2.id = table_first_viewed_at.user_id
			
		WHERE DATE_TRUNC('month', pu2.registration_date) = pu.cohort_month
		) AS avg_time_to_first_view
		
	FROM (
		SELECT
			*,
			DATE_TRUNC('month', registration_date) AS cohort_month
		FROM pet_users
	) AS pu
	LEFT JOIN pet_enrollments pe ON pu.id = pe.user_id
	LEFT JOIN pet_lesson_views plv ON pu.id = plv.user_id
	
	GROUP BY pu.cohort_month
	ORDER BY pu.cohort_month;