feat: Payment system with voucher cards.

feat: Design with inversion dependency injection architecture.
feat: Prettier http middleware.
feat: Re-write items categories with preferred accounts.

server/src/services/Subscription/Subscription.ts

@@ -0,0 +1,48 @@
+import { Tenant, Plan } from '@/system/models';
+import { IPaymentContext } from '@/interfaces';
+import { NotAllowedChangeSubscriptionPlan } from '@/exceptions';
+
+export default class Subscription<PaymentModel> {
+  paymentContext: IPaymentContext|null;
+
+  /**
+   * Constructor method.
+   * @param {IPaymentContext}
+   */
+  constructor(payment?: IPaymentContext) {
+    this.paymentContext = payment;
+  }
+
+  /**
+   * Subscripe to the given plan.
+   * @param {Plan} plan 
+   * @throws {NotAllowedChangeSubscriptionPlan}
+   */
+  async subscribe(
+    tenant: Tenant,
+    plan: Plan,
+    paymentModel?: PaymentModel,
+    subscriptionSlug: string = 'main',
+  ) {
+    if (plan.price < 0) {
+      await this.paymentContext.makePayment(paymentModel);
+    }
+    const subscription = await tenant.$relatedQuery('subscriptions')
+      .modify('subscriptionBySlug', subscriptionSlug)
+      .first();
+
+    // No allowed to re-new the the subscription while the subscription is active.
+    if (subscription && subscription.active()) {
+      throw new NotAllowedChangeSubscriptionPlan;
+
+    // In case there is already subscription associated to the given tenant.
+    // renew it.
+    } else if(subscription && subscription.inactive()) {
+      await subscription.renew(plan);
+
+    // No stored past tenant subscriptions create new one.
+    } else {
+      await tenant.newSubscription(subscriptionSlug, plan);
+    }        
+  }
+}