refactor: split the services to multiple service classes (#202)

packages/server/src/services/Purchases/BillPayments/GetBillPayment.ts

@@ -0,0 +1,51 @@
+import { IBillPayment } from '@/interfaces';
+import HasTenancyService from '@/services/Tenancy/TenancyService';
+import { Inject, Service } from 'typedi';
+import { ERRORS } from './constants';
+import { ServiceError } from '@/exceptions';
+import { BillPaymentTransformer } from './BillPaymentTransformer';
+import { TransformerInjectable } from '@/lib/Transformer/TransformerInjectable';
+import { BillsValidators } from '../Bills/BillsValidators';
+import { BillPaymentValidators } from './BillPaymentValidators';
+
+@Service()
+export class GetBillPayment {
+  @Inject()
+  private tenancy: HasTenancyService;
+
+  @Inject()
+  private transformer: TransformerInjectable;
+
+  @Inject()
+  private validators: BillPaymentValidators;
+
+  /**
+   * Retrieve bill payment.
+   * @param {number} tenantId
+   * @param {number} billPyamentId
+   * @return {Promise<IBillPayment>}
+   */
+  public async getBillPayment(
+    tenantId: number,
+    billPyamentId: number
+  ): Promise<IBillPayment> {
+    const { BillPayment } = this.tenancy.models(tenantId);
+
+    const billPayment = await BillPayment.query()
+      .withGraphFetched('entries.bill')
+      .withGraphFetched('vendor')
+      .withGraphFetched('paymentAccount')
+      .withGraphFetched('transactions')
+      .withGraphFetched('branch')
+      .findById(billPyamentId);
+
+    // Validates the bill payment existance.
+    this.validators.validateBillPaymentExistance(billPayment);
+
+    return this.transformer.transform(
+      tenantId,
+      billPayment,
+      new BillPaymentTransformer()
+    );
+  }
+}