The signature verification process for webhooks has been abstracted. Instead of performing the check directly in the handleWebhook method, it has been moved to a separate service class: PostgresDatabaseWebhookVerifierService. This refactor improves modularity and enables extending or replacing the verification logic more comfortably. The WEBHOOK_SENDER_PROVIDER environment variable is used to determine which verifier service to use.
This commit updates various components in the billing flow due to a new schema that supports multiple line items per plan. The added flexibility rendered 'line-items-mapper.ts' redundant, which has been removed. Additionally, webhooks have been created for handling account membership insertions and deletions, as well as handling subscription deletions when an account is deleted. This message also introduces a new service to handle sending out invitation emails. Lastly, the validation of the billing provider has been improved for increased security and stability.
