collab: Add separate billing_customers table (#15457)

This PR adds a new `billing_customers` table to hold the billing
customers.

Previously we were storing both the `stripe_customer_id` and
`stripe_subscription_id` in the `billable_subscriptions` table. However,
this creates problems when we need to correlate subscription events back
to the subscription record, as we don't know the user that the Stripe
event corresponds to.

By moving the `stripe_customer_id` to a separate table we can create the
Stripe customer earlier in the flow—before we create the Stripe Checkout
session—and associate that customer with a user. This way when we
receive events down the line we can use the Stripe customer ID to
correlate it back to the user.

We're doing some destructive actions to the `billing_subscriptions`
table, but this is fine, as we haven't started using them yet.

Release Notes:

- N/A

crates/collab/src/db/queries/billing_customers.rs

@@ -0,0 +1,42 @@
+use super::*;
+
+#[derive(Debug)]
+pub struct CreateBillingCustomerParams {
+    pub user_id: UserId,
+    pub stripe_customer_id: String,
+}
+
+impl Database {
+    /// Creates a new billing customer.
+    pub async fn create_billing_customer(
+        &self,
+        params: &CreateBillingCustomerParams,
+    ) -> Result<billing_customer::Model> {
+        self.transaction(|tx| async move {
+            let customer = billing_customer::Entity::insert(billing_customer::ActiveModel {
+                user_id: ActiveValue::set(params.user_id),
+                stripe_customer_id: ActiveValue::set(params.stripe_customer_id.clone()),
+                ..Default::default()
+            })
+            .exec_with_returning(&*tx)
+            .await?;
+
+            Ok(customer)
+        })
+        .await
+    }
+
+    /// Returns the billing customer for the user with the specified ID.
+    pub async fn get_billing_customer_by_user_id(
+        &self,
+        user_id: UserId,
+    ) -> Result<Option<billing_customer::Model>> {
+        self.transaction(|tx| async move {
+            Ok(billing_customer::Entity::find()
+                .filter(billing_customer::Column::UserId.eq(user_id))
+                .one(&*tx)
+                .await?)
+        })
+        .await
+    }
+}

crates/collab/src/db/queries/billing_subscriptions.rs

@@ -4,8 +4,7 @@ use super::*;
 
 #[derive(Debug)]
 pub struct CreateBillingSubscriptionParams {
-    pub user_id: UserId,
-    pub stripe_customer_id: String,
+    pub billing_customer_id: BillingCustomerId,
     pub stripe_subscription_id: String,
     pub stripe_subscription_status: StripeSubscriptionStatus,
 }
@@ -18,8 +17,7 @@ impl Database {
     ) -> Result<()> {
         self.transaction(|tx| async move {
             billing_subscription::Entity::insert(billing_subscription::ActiveModel {
-                user_id: ActiveValue::set(params.user_id),
-                stripe_customer_id: ActiveValue::set(params.stripe_customer_id.clone()),
+                billing_customer_id: ActiveValue::set(params.billing_customer_id),
                 stripe_subscription_id: ActiveValue::set(params.stripe_subscription_id.clone()),
                 stripe_subscription_status: ActiveValue::set(params.stripe_subscription_status),
                 ..Default::default()
@@ -56,7 +54,8 @@ impl Database {
     ) -> Result<Vec<billing_subscription::Model>> {
         self.transaction(|tx| async move {
             let subscriptions = billing_subscription::Entity::find()
-                .filter(billing_subscription::Column::UserId.eq(user_id))
+                .inner_join(billing_customer::Entity)
+                .filter(billing_customer::Column::UserId.eq(user_id))
                 .order_by_asc(billing_subscription::Column::Id)
                 .all(&*tx)
                 .await?;
@@ -73,8 +72,9 @@ impl Database {
     ) -> Result<Vec<billing_subscription::Model>> {
         self.transaction(|tx| async move {
             let subscriptions = billing_subscription::Entity::find()
+                .inner_join(billing_customer::Entity)
                 .filter(
-                    billing_subscription::Column::UserId.eq(user_id).and(
+                    billing_customer::Column::UserId.eq(user_id).and(
                         billing_subscription::Column::StripeSubscriptionStatus
                             .eq(StripeSubscriptionStatus::Active),
                     ),