- 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/Vendor.js

@@ -15,4 +15,41 @@ export default class Vendor extends TenantModel {
   static get timestamps() {
     return ['createdAt', 'updatedAt'];
   }
+
+  /**
+   * Changes the vendor balance.
+   * @param {Integer} customerId 
+   * @param {Number} amount 
+   * @return {Promise}
+   */
+  static async changeBalance(vendorId, amount) {
+    const changeMethod = amount > 0 ? 'increment' : 'decrement';
+
+    return this.tenant()
+      .query()
+      .where('id', vendorId)
+      [changeMethod]('balance', Math.abs(amount));
+  }  
+
+  static changeDiffBalance(vendorId, oldVendorId, amount, oldAmount) {
+    const diffAmount = (amount - oldAmount) * -1;
+    const asyncOpers = [];
+
+    if (vendorId != oldVendorId) {
+      const oldVendorOper = Vendor.changeBalance(
+        oldVendorId,
+        oldAmount
+      );
+      const vendorOper = Vendor.changeBalance(
+        vendorId,
+        (amount + diffAmount) * -1
+      );
+      asyncOpers.push(vendorOper);
+      asyncOpers.push(oldVendorOper);
+    } else {
+      const balanceChangeOper = Vendor.changeBalance(vendorId, diffAmount);
+      asyncOpers.push(balanceChangeOper);
+    }
+    return Promise.all(asyncOpers);
+  }
 }