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/system/models/Tenant.js

@@ -1,4 +1,6 @@
 import BaseModel from '@/models/Model';
+import { Model } from 'objection';
+import SubscriptionPeriod from '@/services/Subscription/SubscriptionPeriod';
 
 export default class Tenant extends BaseModel {
   /**
@@ -7,4 +9,63 @@ export default class Tenant extends BaseModel {
   static get tableName() {
     return 'tenants';
   }
+
+  /**
+   * Query modifiers.
+   */
+  static modifiers() {
+    return {
+      subscriptions(builder) {
+        builder.withGraphFetched('subscriptions');
+      },
+    };
+  }
+
+  /**
+   * Relations mappings.
+   */
+  static get relationMappings() {
+    const PlanSubscription = require('./Subscriptions/PlanSubscription');
+
+    return {
+      subscriptions: {
+        relation: Model.HasManyRelation,
+        modelClass: this.relationBindKnex(PlanSubscription.default),
+        join: {
+          from: 'tenants.id',
+          to: 'subscription_plan_subscriptions.tenantId',
+        }
+      },
+    }
+  }
+
+  /**
+   * Retrieve the subscribed plans ids.
+   * @return {number[]}
+   */
+  async subscribedPlansIds() {
+    const { subscriptions } = this;
+    return chain(subscriptions).map('planId').unq();
+  }
+
+  /**
+   * Records a new subscription for the associated tenant.
+   * @param {string} subscriptionSlug 
+   * @param {IPlan} plan 
+   */
+  newSubscription(subscriptionSlug, plan) {
+    const trial = new SubscriptionPeriod(plan.trialInterval, plan.trialPeriod)
+    const period = new SubscriptionPeriod(plan.invoiceInterval, plan.invoicePeriod, trial.getEndDate());
+
+    return this.$relatedQuery('subscriptions').insert({
+      slug: subscriptionSlug,
+      planId: plan.id,
+
+      trialStartedAt: trial.getStartDate(),
+      trialEndsAt: trial.getEndDate(),
+
+      startsAt: period.getStartDate(),
+      endsAt: period.getEndDate(),
+    });
+  }
 }