Add LndHub db/models, and quick stats for admin views

app/models/lndhub_account.rb

@@ -0,0 +1,21 @@
+class LndhubAccount < LndhubBase
+  self.table_name = "accounts"
+  self.inheritance_column = :_type_disabled
+
+  has_many :ledgers, class_name: "LndhubAccountLedger",
+                     foreign_key: "account_id"
+
+  belongs_to :user, class_name: "LndhubUser",
+                    foreign_key: "user_id"
+
+  scope :current,  -> { where(type: "current") }
+  scope :outgoing, -> { where(type: "outgoing") }
+  scope :incoming, -> { where(type: "incoming") }
+  scope :fees,     -> { where(type: "fees") }
+
+  scope :with_balances, -> {
+    current.joins(:user).joins(:ledgers)
+      .group("accounts.id", "users.login")
+      .select("accounts.id, users.login, SUM(account_ledgers.amount) AS balance")
+  }
+end