-- First establish some base parameters for our users
WITH config AS (
    SELECT
        14 AS short_term,
        90 AS medium_term,
        360 AS long_term,
        CAST('2023-01-01' AS timestamp) AS date_cutoff
),
-- Then establish a standard core set of user data
users_with_churn_stats AS (
    SELECT id, active, billing_state,
           DATE_TRUNC('month', created_at) AS month_created,
           created_at, free_trial_ends_at, updated_at,
           updated_at::date - created_at::date AS lifespan
    FROM users, config
    -- We'll only look at newish users.
    WHERE created_at >= config.date_cutoff
),
-- Next use that core data to extract the records we want to analyze
-- and categorize them by date and status
users_to_examine AS (
    -- First the users who exited just after the trial
    SELECT 'quick-exit' AS category, uwcs.*
    FROM users_with_churn_stats uwcs, config
    WHERE billing_state = 'CHURNED'
      AND lifespan <= config.short_term

    UNION

    -- Next, users who gave the tools some time but still left
    SELECT 'fair-trial' AS category, uwcs.*
    FROM users_with_churn_stats uwcs, config
    WHERE billing_state = 'CHURNED'
      AND lifespan < config.medium_term
      AND lifespan > config.short_term

    UNION

    -- Then some longer-time users who still churned.
    -- We'll cut this off after 6 months since afterwards
    -- company closures, etc. could factor in.

    SELECT 'short-termer' AS category, uwcs.*
    FROM users_with_churn_stats uwcs, config
    WHERE billing_state = 'CHURNED'
      AND lifespan >= config.medium_term
      AND lifespan < config.long_term

    UNION

    -- Finally, people who are still kicking.
    -- This cohort is going to be a little wrong for older
    -- dates since it only includes those who are STILL around.
    SELECT 'active-user' AS category, uwcs.*
    FROM users_with_churn_stats uwcs, config
    WHERE BILLING_STATE != 'CHURNED'
		AND lifespan >= config.long_term
),
-- Well add booking forms created by era
booking_form_counts AS (
    SELECT bf.user_id,
           SUM(CASE WHEN created_age < config.short_term THEN 1 ELSE 0 END) AS short_term,
           SUM(CASE WHEN created_age >= config.short_term AND created_age < config.medium_term THEN 1 ELSE 0 END) AS medium_term,
           SUM(CASE WHEN created_age >= config.medium_term AND created_age < config.long_term THEN 1 ELSE 0 END) AS long_term,
           COUNT(*) AS total
    FROM config, (
        SELECT booking_forms.user_id, booking_forms.created_at::date - users.created_at::date AS created_age
        FROM config, booking_forms JOIN users ON booking_forms.user_id = users.id
        WHERE booking_forms.created_at >= config.date_cutoff
            AND users.created_at >= config.date_cutoff
    ) bf
    GROUP BY bf.user_id
),
-- Bookings made by era
booking_counts AS (
   SELECT bk.user_id,
       SUM(CASE WHEN created_age < config.short_term THEN 1 ELSE 0 END) AS short_term,
       SUM(CASE WHEN created_age >= config.short_term AND created_age < config.medium_term THEN 1 ELSE 0 END) AS medium_term,
       SUM(CASE WHEN created_age >= config.medium_term AND created_age < config.long_term THEN 1 ELSE 0 END) AS long_term,
       COUNT(*) AS total
    FROM config, (
        SELECT booking_forms.user_id,  bookings.created_at::date - users.created_at::date AS created_age
        FROM config, booking_forms
            JOIN users ON booking_forms.user_id = users.id
            JOIN bookings ON bookings.booking_form_id = booking_forms.id
        WHERE booking_forms.created_at >= config.date_cutoff
            AND bookings.created_at >= config.date_cutoff
            AND users.created_at >= config.date_cutoff
    ) bk
    GROUP BY bk.user_id
),
-- Employees added by era
employee_counts AS (
    SELECT empl.user_id,
           SUM(CASE WHEN created_age < config.short_term THEN 1 ELSE 0 END) AS short_term,
           SUM(CASE WHEN created_age >= config.short_term AND created_age < config.medium_term THEN 1 ELSE 0 END) AS medium_term,
           SUM(CASE WHEN created_age >= config.medium_term AND created_age < config.long_term THEN 1 ELSE 0 END) AS long_term,
           COUNT(*) AS total
    FROM config, (
        SELECT employees.user_id,  employees.created_at::date - users.created_at::date AS created_age
        FROM config, employees JOIN users ON employees.user_id = users.id
        WHERE employees.created_at >= config.date_cutoff
            AND users.created_at >= config.date_cutoff
    ) empl
    GROUP BY empl.user_id
),
-- Contacts created by era
contact_counts AS (
    SELECT cust.user_id,
           SUM(CASE WHEN created_age < config.short_term THEN 1 ELSE 0 END) AS short_term,
           SUM(CASE WHEN created_age >= config.short_term AND created_age < config.medium_term THEN 1 ELSE 0 END) AS medium_term,
           SUM(CASE WHEN created_age >= config.medium_term AND created_age < config.long_term THEN 1 ELSE 0 END) AS long_term,
           COUNT(*) AS total
    FROM config, (
        SELECT customers.user_id,  customers.created_at::date - users.created_at::date AS created_age
        FROM config, customers JOIN users ON customers.user_id = users.id
        WHERE customers.created_at >= config.date_cutoff
            AND users.created_at >= config.date_cutoff
    ) cust
    GROUP BY cust.user_id
),
-- Finally, we'll flatten it all out into a repurposable flat table
SELECT users_to_examine.id,
       users_to_examine.category,
       COALESCE(booking_form_counts.short_term, 0) AS booking_forms_short_term,
       COALESCE(booking_form_counts.medium_term, 0) AS booking_forms_medium_term,
       COALESCE(booking_form_counts.long_term, 0) AS booking_forms_long_term,
       COALESCE(booking_form_counts.total, 0) AS booking_forms,
       COALESCE(booking_counts.short_term, 0) AS bookings_short_term,
       COALESCE(booking_counts.medium_term, 0) AS bookings_medium_term,
       COALESCE(booking_counts.long_term, 0) AS bookings_long_term,
       COALESCE(booking_counts.total, 0) AS bookings,
       COALESCE(employee_counts.short_term, 0) AS employees_short_term,
       COALESCE(employee_counts.medium_term, 0) AS employees_medium_term,
       COALESCE(employee_counts.long_term, 0) AS employees_long_term,
       COALESCE(employee_counts.total, 0) AS employees,
       COALESCE(contact_counts.short_term, 0) AS contacts_short_term,
       COALESCE(contact_counts.medium_term, 0) AS contacts_medium_term,
       COALESCE(contact_counts.long_term, 0) AS contacts_long_term,
       COALESCE(contact_counts.total, 0) AS contacts
FROM users_to_examine
    LEFT OUTER JOIN booking_form_counts ON booking_form_counts.user_id = users_to_examine.id
    LEFT OUTER JOIN booking_counts ON booking_counts.user_id = users_to_examine.id
    LEFT OUTER JOIN employee_counts ON employee_counts.user_id = users_to_examine.id
    LEFT OUTER JOIN contact_counts ON contact_counts.user_id = users_to_examine.id
;
