Plaid webhook processor

app/models/plaid_item/webhook_processor.rb

@@ -0,0 +1,51 @@
+class PlaidItem::WebhookProcessor
+  MissingItemError = Class.new(StandardError)
+
+  def initialize(webhook_body)
+    parsed = JSON.parse(webhook_body)
+    @webhook_type = parsed["webhook_type"]
+    @webhook_code = parsed["webhook_code"]
+    @item_id = parsed["item_id"]
+  end
+
+  def process
+    unless plaid_item
+      handle_missing_item
+      return
+    end
+
+    case [ webhook_type, webhook_code ]
+    when [ "TRANSACTIONS", "SYNC_UPDATES_AVAILABLE" ]
+      plaid_item.sync_later
+    when [ "INVESTMENTS_TRANSACTIONS", "DEFAULT_UPDATE" ]
+      plaid_item.sync_later
+    when [ "HOLDINGS", "DEFAULT_UPDATE" ]
+      plaid_item.sync_later
+    else
+      Rails.logger.warn("Unhandled Plaid webhook type: #{webhook_type}:#{webhook_code}")
+    end
+  rescue => e
+    # To always ensure we return a 200 to Plaid (to keep endpoint healthy), silently capture and report all errors
+    Sentry.capture_exception(e)
+  end
+
+  private
+    attr_reader :webhook_type, :webhook_code, :item_id
+
+    def plaid_item
+      @plaid_item ||= PlaidItem.find_by(plaid_id: item_id)
+    end
+
+    def handle_missing_item
+      return if plaid_item.present?
+
+      # If we cannot find an item in our DB, that means we've reached an invalid data state where
+      # the Plaid Item (upstream) still exists (and is being billed), but doesn't exist internally.
+      #
+      # Since we don't have the item which has the access token, there is nothing we can do programmatically
+      # here, so we just need to report it to Sentry and manually handle it.
+      Sentry.capture_exception(MissingItemError.new("Received Plaid webhook for item no longer in our DB.  Manual action required to resolve.")) do |scope|
+        scope.set_tags(plaid_item_id: item_id)
+      end
+    end
+end