- feat: Sales estimates.

- feat: Sales invoices.
- feat: Sales payment receives.
- feat: Purchases bills.
- feat: Purchases bills payments that made to the vendors.

server/src/models/Customer.js

@@ -26,4 +26,42 @@ export default class Customer extends TenantModel {
       },
     };
   }
+
+  /**
+   * Change vendor balance.
+   * @param {Integer} customerId 
+   * @param {Numeric} amount 
+   */
+  static async changeBalance(customerId, amount) {
+    const changeMethod = amount > 0 ? 'increment' : 'decrement';
+
+    await this.tenant()
+      .query()
+      .where('id', customerId)
+      [changeMethod]('balance', Math.abs(amount));
+  }
+
+  /**
+   * Increment the given customer balance.
+   * @param {Integer} customerId
+   * @param {Integer} amount
+   */
+  static async incrementBalance(customerId, amount) {
+    await this.tenant()
+      .query()
+      .where('id', customerId)
+      .increment('balance', amount);
+  }
+
+  /**
+   * Decrement the given customer balance.
+   * @param {integer} customerId -
+   * @param {integer} amount -
+   */
+  static async decrementBalance(customerId, amount) {
+    await this.tenant()
+      .query()
+      .where('id', customerId)
+      .decrement('balance', amount);
+  }
 }