feat(nestjs): migrate to NestJS

packages/server/src/modules/VendorCreditsApplyBills/VendorCreditApplyBills.controller.ts

@@ -0,0 +1,50 @@
+import { Body, Controller, Delete, Get, Param, Post } from '@nestjs/common';
+import { VendorCreditApplyBillsApplicationService } from './VendorCreditApplyBillsApplication.service';
+import { IVendorCreditApplyToInvoicesDTO } from './types/VendorCreditApplyBills.types';
+import { ApiTags } from '@nestjs/swagger';
+
+@Controller('vendor-credits')
+@ApiTags('vendor-credits-apply-bills')
+export class VendorCreditApplyBillsController {
+  constructor(
+    private readonly vendorCreditApplyBillsApplication: VendorCreditApplyBillsApplicationService,
+  ) {}
+
+  @Get(':vendorCreditId/bills-to-apply')
+  async getVendorCreditToApplyBills(
+    @Param('vendorCreditId') vendorCreditId: number,
+  ) {
+    return this.vendorCreditApplyBillsApplication.getVendorCreditToApplyBills(
+      vendorCreditId,
+    );
+  }
+
+  @Post(':vendorCreditId/apply-to-bills')
+  async applyVendorCreditToBills(
+    @Param('vendorCreditId') vendorCreditId: number,
+    @Body() applyCreditToBillsDTO: IVendorCreditApplyToInvoicesDTO,
+  ) {
+    return this.vendorCreditApplyBillsApplication.applyVendorCreditToBills(
+      vendorCreditId,
+      applyCreditToBillsDTO,
+    );
+  }
+
+  @Delete('applied-bills/:vendorCreditAppliedBillId')
+  async deleteAppliedBillToVendorCredit(
+    @Param('vendorCreditAppliedBillId') vendorCreditAppliedBillId: number,
+  ) {
+    return this.vendorCreditApplyBillsApplication.deleteAppliedBillToVendorCredit(
+      vendorCreditAppliedBillId,
+    );
+  }
+
+  @Get(':vendorCreditId/applied-bills')
+  async getAppliedBillsToVendorCredit(
+    @Param('vendorCreditId') vendorCreditId: number,
+  ) {
+    return this.vendorCreditApplyBillsApplication.getAppliedBillsToVendorCredit(
+      vendorCreditId,
+    );
+  }
+}

packages/server/src/modules/VendorCreditsApplyBills/VendorCreditApplyBills.module.ts

@@ -0,0 +1,38 @@
+import { Module } from '@nestjs/common';
+import { ApplyVendorCreditSyncBillsService } from './command/ApplyVendorCreditSyncBills.service';
+import { ApplyVendorCreditSyncInvoicedService } from './command/ApplyVendorCreditSyncInvoiced.service';
+import { DeleteApplyVendorCreditToBillService } from './command/DeleteApplyVendorCreditToBill.service';
+import { ApplyVendorCreditToBillsService } from './command/ApplyVendorCreditToBills.service';
+import { GetAppliedBillsToVendorCreditService } from './queries/GetAppliedBillsToVendorCredit.service';
+import { GetVendorCreditToApplyBills } from './queries/GetVendorCreditToApplyBills.service';
+import { VendorCreditApplyBillsApplicationService } from './VendorCreditApplyBillsApplication.service';
+import { VendorCreditApplyBillsController } from './VendorCreditApplyBills.controller';
+import { BillsModule } from '../Bills/Bills.module';
+import { BillPaymentsModule } from '../BillPayments/BillPayments.module';
+import { VendorCreditDTOTransformService } from '../VendorCredit/commands/VendorCreditDTOTransform.service';
+import { ItemsModule } from '../Items/items.module';
+import { BranchesModule } from '../Branches/Branches.module';
+import { WarehousesModule } from '../Warehouses/Warehouses.module';
+import { VendorCreditsModule } from '../VendorCredit/VendorCredits.module';
+
+@Module({
+  imports: [
+    BillsModule,
+    BillPaymentsModule,
+    ItemsModule,
+    BranchesModule,
+    WarehousesModule,
+    VendorCreditsModule
+  ],
+  providers: [
+    ApplyVendorCreditSyncBillsService,
+    ApplyVendorCreditSyncInvoicedService,
+    ApplyVendorCreditToBillsService,
+    DeleteApplyVendorCreditToBillService,
+    GetAppliedBillsToVendorCreditService,
+    GetVendorCreditToApplyBills,
+    VendorCreditApplyBillsApplicationService,
+  ],
+  controllers: [VendorCreditApplyBillsController],
+})
+export class VendorCreditApplyBillsModule {}

packages/server/src/modules/VendorCreditsApplyBills/VendorCreditApplyBillsApplication.service.ts

@@ -0,0 +1,67 @@
+import { ApplyVendorCreditToBillsService } from './command/ApplyVendorCreditToBills.service';
+import { DeleteApplyVendorCreditToBillService } from './command/DeleteApplyVendorCreditToBill.service';
+import { GetAppliedBillsToVendorCreditService } from './queries/GetAppliedBillsToVendorCredit.service';
+import { GetVendorCreditToApplyBills } from './queries/GetVendorCreditToApplyBills.service';
+import { IVendorCreditApplyToInvoicesDTO } from './types/VendorCreditApplyBills.types';
+
+export class VendorCreditApplyBillsApplicationService {
+  /**
+   * @param {ApplyVendorCreditToBillsService} applyVendorCreditToBillsService
+   * @param {DeleteApplyVendorCreditToBillService} deleteApplyVendorCreditToBillService
+   * @param {GetVendorCreditToApplyBills} getVendorCreditToApplyBillsService
+   * @param {GetAppliedBillsToVendorCreditService} getAppliedBillsToVendorCreditService
+   */
+  constructor(
+    private readonly applyVendorCreditToBillsService: ApplyVendorCreditToBillsService,
+    private readonly deleteApplyVendorCreditToBillService: DeleteApplyVendorCreditToBillService,
+    private readonly getVendorCreditToApplyBillsService: GetVendorCreditToApplyBills,
+    private readonly getAppliedBillsToVendorCreditService: GetAppliedBillsToVendorCreditService,
+  ) {}
+
+  /**
+   * Retrieve bills that valid apply to the given vendor credit.
+   * @param {number} vendorCreditId
+   * @returns {Promise<any[]>}
+   */
+  async getVendorCreditToApplyBills(vendorCreditId: number) {
+    return this.getVendorCreditToApplyBillsService.getCreditToApplyBills(
+      vendorCreditId,
+    );
+  }
+
+  /**
+   * Apply credit note to the given bills.
+   * @param {number} vendorCreditId
+   * @param {IVendorCreditApplyToInvoicesDTO} applyCreditToBillsDTO
+   */
+  async applyVendorCreditToBills(
+    vendorCreditId: number,
+    applyCreditToBillsDTO: IVendorCreditApplyToInvoicesDTO,
+  ) {
+    return this.applyVendorCreditToBillsService.applyVendorCreditToBills(
+      vendorCreditId,
+      applyCreditToBillsDTO,
+    );
+  }
+
+  /**
+   * Delete applied bill to the given vendor credit.
+   * @param {number} vendorCreditAppliedBillId
+   */
+  async deleteAppliedBillToVendorCredit(vendorCreditAppliedBillId: number) {
+    return this.deleteApplyVendorCreditToBillService.deleteApplyVendorCreditToBills(
+      vendorCreditAppliedBillId,
+    );
+  }
+
+  /**
+   * Retrieve applied bills to the given vendor credit.
+   * @param {number} vendorCreditId
+   * @returns {Promise<any[]>}
+   */
+  async getAppliedBillsToVendorCredit(vendorCreditId: number) {
+    return this.getAppliedBillsToVendorCreditService.getAppliedBills(
+      vendorCreditId,
+    );
+  }
+}

packages/server/src/modules/VendorCreditsApplyBills/VendorCreditsApplyBills.constants.ts

@@ -0,0 +1,12 @@
+export const ERRORS = {
+  VENDOR_CREDIT_NOT_FOUND: 'VENDOR_CREDIT_NOT_FOUND',
+  VENDOR_CREDIT_ALREADY_OPENED: 'VENDOR_CREDIT_ALREADY_OPENED',
+  VENDOR_CREDIT_HAS_NO_REMAINING_AMOUNT:
+    'VENDOR_CREDIT_HAS_NO_REMAINING_AMOUNT',
+  VENDOR_CREDIT_APPLY_TO_BILLS_NOT_FOUND:
+    'VENDOR_CREDIT_APPLY_TO_BILLS_NOT_FOUND',
+  BILLS_HAS_NO_REMAINING_AMOUNT: 'BILLS_HAS_NO_REMAINING_AMOUNT',
+  VENDOR_CREDIT_HAS_REFUND_TRANSACTIONS:
+    'VENDOR_CREDIT_HAS_REFUND_TRANSACTIONS',
+  VENDOR_CREDIT_HAS_APPLIED_BILLS: 'VENDOR_CREDIT_HAS_APPLIED_BILLS',
+};

packages/server/src/modules/VendorCreditsApplyBills/command/ApplyVendorCreditSyncBills.service.ts

@@ -0,0 +1,49 @@
+import Bluebird from 'bluebird';
+import { Inject, Injectable } from '@nestjs/common';
+import { Knex } from 'knex';
+import { IVendorCreditAppliedBill } from '../types/VendorCreditApplyBills.types';
+import { Bill } from '@/modules/Bills/models/Bill';
+import { TenantModelProxy } from '@/modules/System/models/TenantBaseModel';
+
+@Injectable()
+export class ApplyVendorCreditSyncBillsService {
+  constructor(
+    @Inject(Bill.name)
+    private readonly billModel: TenantModelProxy<typeof Bill>,
+  ) {}
+
+  /**
+   * Increment bills credited amount.
+   * @param {IVendorCreditAppliedBill[]} vendorCreditAppliedBills
+   * @param {Knex.Transaction} trx
+   */
+  public incrementBillsCreditedAmount = async (
+    vendorCreditAppliedBills: IVendorCreditAppliedBill[],
+    trx?: Knex.Transaction,
+  ) => {
+    await Bluebird.each(
+      vendorCreditAppliedBills,
+      (vendorCreditAppliedBill: IVendorCreditAppliedBill) => {
+        return this.billModel()
+          .query(trx)
+          .where('id', vendorCreditAppliedBill.billId)
+          .increment('creditedAmount', vendorCreditAppliedBill.amount);
+      },
+    );
+  };
+
+  /**
+   * Decrement bill credited amount.
+   * @param {IVendorCreditAppliedBill} vendorCreditAppliedBill
+   * @param {Knex.Transaction} trx
+   */
+  public decrementBillCreditedAmount = async (
+    vendorCreditAppliedBill: IVendorCreditAppliedBill,
+    trx?: Knex.Transaction,
+  ) => {
+    await this.billModel()
+      .query(trx)
+      .findById(vendorCreditAppliedBill.billId)
+      .decrement('creditedAmount', vendorCreditAppliedBill.amount);
+  };
+}

packages/server/src/modules/VendorCreditsApplyBills/command/ApplyVendorCreditSyncInvoiced.service.ts

@@ -0,0 +1,49 @@
+import { Inject, Injectable } from '@nestjs/common';
+import { Knex } from 'knex';
+import { VendorCredit } from '@/modules/VendorCredit/models/VendorCredit';
+import { TenantModelProxy } from '@/modules/System/models/TenantBaseModel';
+
+@Injectable()
+export class ApplyVendorCreditSyncInvoicedService {
+  /**
+   * @param {TenantModelProxy<typeof VendorCredit>} vendorCreditModel - The vendor credit model.
+   */
+  constructor(
+    @Inject(VendorCredit.name)
+    private readonly vendorCreditModel: TenantModelProxy<typeof VendorCredit>,
+  ) {}
+
+  /**
+   * Increment vendor credit invoiced amount.
+   * @param {number} vendorCreditId - Vendor credit id.
+   * @param {number} amount - Amount to increment.
+   * @param {Knex.Transaction} trx - Knex transaction.
+   */
+  public incrementVendorCreditInvoicedAmount = async (
+    vendorCreditId: number,
+    amount: number,
+    trx?: Knex.Transaction,
+  ) => {
+    await this.vendorCreditModel()
+      .query(trx)
+      .findById(vendorCreditId)
+      .increment('invoicedAmount', amount);
+  };
+
+  /**
+   * Decrement credit note invoiced amount.
+   * @param {number} vendorCreditId - Vendor credit id.
+   * @param {number} amount - Amount to decrement.
+   * @param {Knex.Transaction} trx - Knex transaction.
+   */
+  public decrementVendorCreditInvoicedAmount = async (
+    vendorCreditId: number,
+    amount: number,
+    trx?: Knex.Transaction,
+  ) => {
+    await this.vendorCreditModel()
+      .query(trx)
+      .findById(vendorCreditId)
+      .decrement('invoicedAmount', amount);
+  };
+}

packages/server/src/modules/VendorCreditsApplyBills/command/ApplyVendorCreditToBills.service.ts

@@ -0,0 +1,136 @@
+import { Inject, Injectable } from '@nestjs/common';
+import { Knex } from 'knex';
+import { sumBy } from 'lodash';
+import {
+  IVendorCreditApplyToBillsCreatedPayload,
+  IVendorCreditApplyToInvoicesDTO,
+  IVendorCreditApplyToInvoicesModel,
+} from '../types/VendorCreditApplyBills.types';
+import { ERRORS } from '../VendorCreditsApplyBills.constants';
+import { VendorCreditAppliedBill } from '../models/VendorCreditAppliedBill';
+import { VendorCredit } from '@/modules/VendorCredit/models/VendorCredit';
+import { BillPaymentValidators } from '@/modules/BillPayments/commands/BillPaymentValidators.service';
+import { EventEmitter2 } from '@nestjs/event-emitter';
+import { UnitOfWork } from '@/modules/Tenancy/TenancyDB/UnitOfWork.service';
+import { Bill } from '@/modules/Bills/models/Bill';
+import { ServiceError } from '@/modules/Items/ServiceError';
+import { events } from '@/common/events/events';
+import { VendorCreditDTOTransformService } from '@/modules/VendorCredit/commands/VendorCreditDTOTransform.service';
+import { TenantModelProxy } from '@/modules/System/models/TenantBaseModel';
+
+@Injectable()
+export class ApplyVendorCreditToBillsService {
+  /**
+   * @param {UnitOfWork} uow - The unit of work service.
+   * @param {EventEmitter2} eventPublisher - The event emitter service.
+   * @param {BillPaymentValidators} billPaymentValidators - The bill payment validators service.
+   * @param {TenantModelProxy<typeof VendorCreditAppliedBill>} vendorCreditAppliedBillModel - The vendor credit applied bill model.
+   * @param {TenantModelProxy<typeof VendorCredit>} vendorCreditModel - The vendor credit model.
+   */
+  constructor(
+    private readonly uow: UnitOfWork,
+    private readonly eventPublisher: EventEmitter2,
+    private readonly billPaymentValidators: BillPaymentValidators,
+    private readonly vendorCreditDTOTransform: VendorCreditDTOTransformService,
+
+    @Inject(VendorCreditAppliedBill.name)
+    private readonly vendorCreditAppliedBillModel: TenantModelProxy<
+      typeof VendorCreditAppliedBill
+    >,
+
+    @Inject(VendorCredit.name)
+    private readonly vendorCreditModel: TenantModelProxy<typeof VendorCredit>,
+  ) {}
+
+  /**
+   * Apply credit note to the given invoices.
+   * @param {number} creditNoteId
+   * @param {IApplyCreditToInvoicesDTO} applyCreditToInvoicesDTO
+   */
+  public applyVendorCreditToBills = async (
+    vendorCreditId: number,
+    applyCreditToBillsDTO: IVendorCreditApplyToInvoicesDTO,
+  ): Promise<void> => {
+    // Retrieves the vendor credit or throw not found service error.
+    const vendorCredit = await this.vendorCreditModel()
+      .query()
+      .findById(vendorCreditId)
+      .throwIfNotFound();
+
+    // Transfomes credit apply to bills DTO to model object.
+    const vendorCreditAppliedModel = this.transformApplyDTOToModel(
+      applyCreditToBillsDTO,
+      vendorCredit,
+    );
+
+    // Validate bills entries existance.
+    const appliedBills =
+      await this.billPaymentValidators.validateBillsExistance(
+        vendorCreditAppliedModel.entries,
+        vendorCredit.vendorId,
+      );
+
+    // Validate bills has remaining amount to apply.
+    this.validateBillsRemainingAmount(
+      appliedBills,
+      vendorCreditAppliedModel.amount,
+    );
+    // Validate vendor credit remaining credit amount.
+    this.vendorCreditDTOTransform.validateCreditRemainingAmount(
+      vendorCredit,
+      vendorCreditAppliedModel.amount,
+    );
+    // Saves vendor credit applied to bills under unit-of-work envirement.
+    return this.uow.withTransaction(async (trx: Knex.Transaction) => {
+      // Inserts vendor credit applied to bills graph to the storage layer.
+      const vendorCreditAppliedBills = await this.vendorCreditAppliedBillModel()
+        .query(trx)
+        .insertGraph(vendorCreditAppliedModel.entries);
+
+      // Triggers `IVendorCreditApplyToBillsCreatedPayload` event.
+      await this.eventPublisher.emitAsync(
+        events.vendorCredit.onApplyToInvoicesCreated,
+        {
+          trx,
+          vendorCredit,
+          vendorCreditAppliedBills,
+        } as IVendorCreditApplyToBillsCreatedPayload,
+      );
+    });
+  };
+
+  /**
+   * Transformes apply DTO to model.
+   * @param {IApplyCreditToInvoicesDTO} applyDTO
+   * @param {ICreditNote} creditNote
+   * @returns {IVendorCreditApplyToInvoicesModel}
+   */
+  private transformApplyDTOToModel = (
+    applyDTO: IVendorCreditApplyToInvoicesDTO,
+    vendorCredit: VendorCredit,
+  ): IVendorCreditApplyToInvoicesModel => {
+    const entries = applyDTO.entries.map((entry) => ({
+      billId: entry.billId,
+      amount: entry.amount,
+      vendorCreditId: vendorCredit.id,
+    }));
+    const amount = sumBy(applyDTO.entries, 'amount');
+
+    return {
+      amount,
+      entries,
+    };
+  };
+
+  /**
+   * Validate bills remaining amount.
+   * @param {IBill[]} bills
+   * @param {number} amount
+   */
+  private validateBillsRemainingAmount = (bills: Bill[], amount: number) => {
+    const invalidBills = bills.filter((bill) => bill.dueAmount < amount);
+    if (invalidBills.length > 0) {
+      throw new ServiceError(ERRORS.BILLS_HAS_NO_REMAINING_AMOUNT);
+    }
+  };
+}

packages/server/src/modules/VendorCreditsApplyBills/command/DeleteApplyVendorCreditToBill.service.ts

@@ -0,0 +1,71 @@
+import { Inject, Injectable } from '@nestjs/common';
+import { UnitOfWork } from '@/modules/Tenancy/TenancyDB/UnitOfWork.service';
+import { EventEmitter2 } from '@nestjs/event-emitter';
+import { ServiceError } from '@/modules/Items/ServiceError';
+import { events } from '@/common/events/events';
+import { IVendorCreditApplyToBillDeletedPayload } from '../types/VendorCreditApplyBills.types';
+import { VendorCredit } from '@/modules/VendorCredit/models/VendorCredit';
+import { ERRORS } from '../VendorCreditsApplyBills.constants';
+import { VendorCreditAppliedBill } from '../models/VendorCreditAppliedBill';
+import { TenantModelProxy } from '@/modules/System/models/TenantBaseModel';
+
+@Injectable()
+export class DeleteApplyVendorCreditToBillService {
+  /**
+   * @param {UnitOfWork} uow - The unit of work service.
+   * @param {EventEmitter2} eventPublisher - The event emitter service.
+   * @param {typeof VendorCreditAppliedBill} vendorCreditAppliedBillModel - The vendor credit applied bill model.
+   * @param {typeof VendorCredit} vendorCreditModel - The vendor credit model.
+   */
+  constructor(
+    private readonly uow: UnitOfWork,
+    private readonly eventPublisher: EventEmitter2,
+
+    @Inject(VendorCreditAppliedBill.name)
+    private readonly vendorCreditAppliedBillModel: TenantModelProxy<
+      typeof VendorCreditAppliedBill
+    >,
+
+    @Inject(VendorCredit.name)
+    private readonly vendorCreditModel: TenantModelProxy<typeof VendorCredit>,
+  ) {}
+
+  /**
+   * Delete apply vendor credit to bill transaction.
+   * @param {number} appliedCreditToBillId
+   * @returns {Promise<void>}
+   */
+  public async deleteApplyVendorCreditToBills(appliedCreditToBillId: number) {
+    const oldCreditAppliedToBill = await this.vendorCreditAppliedBillModel()
+      .query()
+      .findById(appliedCreditToBillId);
+
+    if (!oldCreditAppliedToBill) {
+      throw new ServiceError(ERRORS.VENDOR_CREDIT_APPLY_TO_BILLS_NOT_FOUND);
+    }
+    // Retrieve the vendor credit or throw not found service error.
+    const vendorCredit = await this.vendorCreditModel()
+      .query()
+      .findById(oldCreditAppliedToBill.vendorCreditId)
+      .throwIfNotFound();
+
+    // Deletes vendor credit apply under unit-of-work environment.
+    return this.uow.withTransaction(async (trx) => {
+      // Delete vendor credit applied to bill transaction.
+      await this.vendorCreditAppliedBillModel()
+        .query(trx)
+        .findById(appliedCreditToBillId)
+        .delete();
+
+      // Triggers `onVendorCreditApplyToInvoiceDeleted` event.
+      await this.eventPublisher.emitAsync(
+        events.vendorCredit.onApplyToInvoicesDeleted,
+        {
+          vendorCredit,
+          oldCreditAppliedToBill,
+          trx,
+        } as IVendorCreditApplyToBillDeletedPayload,
+      );
+    });
+  }
+}

packages/server/src/modules/VendorCreditsApplyBills/models/VendorCreditAppliedBill.ts

@@ -0,0 +1,59 @@
+import { Model } from 'objection';
+// import TenantModel from 'models/TenantModel';
+// import ModelSetting from './ModelSetting';
+// import CustomViewBaseModel from './CustomViewBaseModel';
+// import ModelSearchable from './ModelSearchable';
+import { BaseModel } from '@/models/Model';
+import { VendorCredit } from '../../VendorCredit/models/VendorCredit';
+import { Bill } from '@/modules/Bills/models/Bill';
+
+export class VendorCreditAppliedBill extends BaseModel {
+  public amount!: number;
+  public billId!: number;
+  public vendorCreditId!: number;
+
+  public vendorCredit!: VendorCredit;
+  public bill!: Bill;
+
+  /**
+   * Table name
+   */
+  static get tableName() {
+    return 'vendor_credit_applied_bill';
+  }
+
+  /**
+   * Timestamps columns.
+   */
+  public get timestamps() {
+    return ['created_at', 'updated_at'];
+  }
+
+  /**
+   * Relationship mapping.
+   */
+  static get relationMappings() {
+    const { Bill } = require('../../Bills/models/Bill');
+    const { VendorCredit } = require('../../VendorCredit/models/VendorCredit');
+
+    return {
+      bill: {
+        relation: Model.BelongsToOneRelation,
+        modelClass: Bill,
+        join: {
+          from: 'vendor_credit_applied_bill.billId',
+          to: 'bills.id',
+        },
+      },
+
+      vendorCredit: {
+        relation: Model.BelongsToOneRelation,
+        modelClass: VendorCredit,
+        join: {
+          from: 'vendor_credit_applied_bill.vendorCreditId',
+          to: 'vendor_credits.id',
+        },
+      },
+    };
+  }
+}

packages/server/src/modules/VendorCreditsApplyBills/queries/GetAppliedBillsToVendorCredit.service.ts

@@ -0,0 +1,45 @@
+import { Inject, Injectable } from '@nestjs/common';
+import { VendorCreditAppliedBillTransformer } from './VendorCreditAppliedBillTransformer';
+import { TransformerInjectable } from '@/modules/Transformer/TransformerInjectable.service';
+import { VendorCreditAppliedBill } from '@/modules/VendorCreditsApplyBills/models/VendorCreditAppliedBill';
+import { VendorCredit } from '@/modules/VendorCredit/models/VendorCredit';
+import { TenantModelProxy } from '@/modules/System/models/TenantBaseModel';
+
+@Injectable()
+export class GetAppliedBillsToVendorCreditService {
+  constructor(
+    private readonly transformer: TransformerInjectable,
+
+    @Inject(VendorCreditAppliedBill.name)
+    private readonly vendorCreditAppliedBillModel: TenantModelProxy<
+      typeof VendorCreditAppliedBill
+    >,
+
+    @Inject(VendorCredit.name)
+    private readonly vendorCreditModel: TenantModelProxy<typeof VendorCredit>,
+  ) {}
+
+  /**
+   * Get applied bills to vendor credit.
+   * @param {number} vendorCreditId
+   * @returns
+   */
+  public getAppliedBills = async (vendorCreditId: number) => {
+    const vendorCredit = await this.vendorCreditModel()
+      .query()
+      .findById(vendorCreditId)
+      .throwIfNotFound();
+
+    const appliedToBills = await this.vendorCreditAppliedBillModel()
+      .query()
+      .where('vendorCreditId', vendorCreditId)
+      .withGraphFetched('bill')
+      .withGraphFetched('vendorCredit');
+
+    // Transforms the models to POJO.
+    return this.transformer.transform(
+      appliedToBills,
+      new VendorCreditAppliedBillTransformer(),
+    );
+  };
+}

packages/server/src/modules/VendorCreditsApplyBills/queries/GetVendorCreditToApplyBills.service.ts

@@ -0,0 +1,49 @@
+import { Inject, Injectable } from '@nestjs/common';
+import { VendorCreditToApplyBillTransformer } from './VendorCreditToApplyBillTransformer';
+import { VendorCredit } from '@/modules/VendorCredit/models/VendorCredit';
+import { Bill } from '@/modules/Bills/models/Bill';
+import { TransformerInjectable } from '@/modules/Transformer/TransformerInjectable.service';
+import { TenantModelProxy } from '@/modules/System/models/TenantBaseModel';
+
+@Injectable()
+export class GetVendorCreditToApplyBills {
+  /**
+   * @param {TransformerService} transformerService - The transformer service.
+   * @param {typeof Bill} billModel - The bill model.
+   * @param {typeof VendorCredit} vendorCreditModel - The vendor credit model.
+   */
+  constructor(
+    private readonly transformerService: TransformerInjectable,
+    @Inject(Bill.name)
+    private readonly billModel: TenantModelProxy<typeof Bill>,
+
+    @Inject(VendorCredit.name)
+    private readonly vendorCreditModel: TenantModelProxy<typeof VendorCredit>,
+  ) {}
+
+  /**
+   * Retrieve bills that valid apply to the given vendor credit.
+   * @param {number} vendorCreditId
+   * @returns {Promise<any[]>}
+   */
+  public async getCreditToApplyBills(vendorCreditId: number) {
+    // Retrieve vendor credit or throw not found service error.
+    const vendorCredit = await this.vendorCreditModel()
+      .query()
+      .findById(vendorCreditId)
+      .throwIfNotFound();
+
+    // Retrieve open bills associated to the given vendor.
+    const openBills = await this.billModel()
+      .query()
+      .where('vendor_id', vendorCredit.vendorId)
+      .modify('dueBills')
+      .modify('published');
+
+    // Transform the bills to POJO.
+    return this.transformerService.transform(
+      openBills,
+      new VendorCreditToApplyBillTransformer(),
+    );
+  }
+}

packages/server/src/modules/VendorCreditsApplyBills/queries/VendorCreditAppliedBillTransformer.ts

@@ -0,0 +1,67 @@
+import { Transformer } from "@/modules/Transformer/Transformer";
+import { VendorCreditAppliedBill } from "@/modules/VendorCreditsApplyBills/models/VendorCreditAppliedBill";
+
+export class VendorCreditAppliedBillTransformer extends Transformer {
+  /**
+   * Includeded attributes.
+   * @returns {string[]}
+   */
+  public includeAttributes = (): string[] => {
+    return [
+      'formattedAmount',
+      'vendorCreditNumber',
+      'vendorCreditDate',
+      'billNumber',
+      'billReferenceNo',
+      'formattedVendorCreditDate',
+      'formattedBillDate',
+    ];
+  };
+
+  /**
+   * Exclude attributes.
+   * @returns {string[]}
+   */
+  public excludeAttributes = (): string[] => {
+    return ['bill', 'vendorCredit'];
+  };
+
+  /**
+   * 
+   * @param item 
+   * @returns 
+   */
+  protected formattedAmount = (item: VendorCreditAppliedBill) => {
+    return this.formatNumber(item.amount, {
+      currencyCode: item.vendorCredit.currencyCode,
+    });
+  };
+
+  protected vendorCreditNumber = (item) => {
+    return item.vendorCredit.vendorCreditNumber;
+  };
+
+  protected vendorCreditDate = (item) => {
+    return item.vendorCredit.vendorCreditDate;
+  };
+
+  protected formattedVendorCreditDate = (item) => {
+    return this.formatDate(item.vendorCredit.vendorCreditDate);
+  };
+
+  protected billNumber = (item) => {
+    return item.bill.billNo;
+  };
+
+  protected billReferenceNo = (item) => {
+    return item.bill.referenceNo;
+  };
+
+  protected BillDate = (item) => {
+    return item.bill.billDate;
+  };
+
+  protected formattedBillDate = (item) => {
+    return this.formatDate(item.bill.billDate);
+  };
+}

packages/server/src/modules/VendorCreditsApplyBills/queries/VendorCreditToApplyBillTransformer.ts

@@ -0,0 +1,69 @@
+import { Bill } from '@/modules/Bills/models/Bill';
+import { Transformer } from '@/modules/Transformer/Transformer';
+
+export class VendorCreditToApplyBillTransformer extends Transformer {
+  /**
+   * Include these attributes to sale invoice object.
+   * @returns {Array}
+   */
+  public includeAttributes = (): string[] => {
+    return [
+      'formattedBillDate',
+      'formattedDueDate',
+      'formattedAmount',
+      'formattedDueAmount',
+      'formattedPaymentAmount',
+    ];
+  };
+
+  /**
+   * Retrieve formatted bill date.
+   * @param {Bill} bill
+   * @returns {String}
+   */
+  protected formattedBillDate = (bill: Bill): string => {
+    return this.formatDate(bill.billDate);
+  };
+
+  /**
+   * Retrieve formatted due date.
+   * @param {Bill} bill
+   * @returns {string}
+   */
+  protected formattedDueDate = (bill: Bill): string => {
+    return this.formatDate(bill.dueDate);
+  };
+
+  /**
+   * Retrieve formatted bill amount.
+   * @param {Bill} bill
+   * @returns {string}
+   */
+  protected formattedAmount = (bill: Bill): string => {
+    return this.formatNumber(bill.amount, {
+      currencyCode: bill.currencyCode,
+    });
+  };
+
+  /**
+   * Retrieve formatted bill due amount.
+   * @param {Bill} bill
+   * @returns {string}
+   */
+  protected formattedDueAmount = (bill: Bill): string => {
+    return this.formatNumber(bill.dueAmount, {
+      currencyCode: bill.currencyCode,
+    });
+  };
+
+  /**
+   * Retrieve formatted payment amount.
+   * @param {Bill} bill
+   * @returns {string}
+   */
+  protected formattedPaymentAmount = (bill: Bill): string => {
+    return this.formatNumber(bill.paymentAmount, {
+      currencyCode: bill.currencyCode,
+    });
+  };
+}

packages/server/src/modules/VendorCreditsApplyBills/subscribers/ApplyVendorCreditSyncBillsSubscriber.ts

@@ -0,0 +1,61 @@
+// import { Injectable } from '@nestjs/common';
+// import { InjectModel } from '@nestjs/objection';
+// import events from '@/subscribers/events';
+// import {
+//   IVendorCreditApplyToBillDeletedPayload,
+//   IVendorCreditApplyToBillsCreatedPayload,
+// } from '@/interfaces';
+// import { ApplyVendorCreditSyncBillsService } from '../command/ApplyVendorCreditSyncBills.service';
+// import { VendorCreditApplyToBill } from '../models/VendorCreditApplyToBill';
+
+// @Injectable()
+// export default class ApplyVendorCreditSyncBillsSubscriber {
+//   constructor(
+//     private readonly syncBillsWithVendorCredit: ApplyVendorCreditSyncBillsService,
+//     @InjectModel(VendorCreditApplyToBill)
+//     private readonly vendorCreditApplyToBillModel: typeof VendorCreditApplyToBill,
+//   ) {}
+
+//   /**
+//    * Attaches events with handlers.
+//    */
+//   attach(bus) {
+//     bus.subscribe(
+//       events.vendorCredit.onApplyToInvoicesCreated,
+//       this.incrementAppliedBillsOnceCreditCreated
+//     );
+//     bus.subscribe(
+//       events.vendorCredit.onApplyToInvoicesDeleted,
+//       this.decrementAppliedBillsOnceCreditDeleted
+//     );
+//   }
+
+//   /**
+//    * Increment credited amount of applied bills once the vendor credit transaction created.
+//    * @param {IVendorCreditApplyToBillsCreatedPayload}  paylaod -
+//    */
+//   private incrementAppliedBillsOnceCreditCreated = async ({
+//     vendorCreditAppliedBills,
+//     trx,
+//   }: IVendorCreditApplyToBillsCreatedPayload) => {
+//     await this.syncBillsWithVendorCredit.incrementBillsCreditedAmount(
+//       vendorCreditAppliedBills,
+//       trx
+//     );
+//   };
+
+//   /**
+//    * Decrement credited amount of applied bills once the vendor credit
+//    * transaction delted.
+//    * @param {IVendorCreditApplyToBillDeletedPayload} payload
+//    */
+//   private decrementAppliedBillsOnceCreditDeleted = async ({
+//     oldCreditAppliedToBill,
+//     trx,
+//   }: IVendorCreditApplyToBillDeletedPayload) => {
+//     await this.syncBillsWithVendorCredit.decrementBillCreditedAmount(
+//       oldCreditAppliedToBill,
+//       trx
+//     );
+//   };
+// }

packages/server/src/modules/VendorCreditsApplyBills/subscribers/ApplyVendorCreditSyncInvoicedSubscriber.ts

@@ -0,0 +1,70 @@
+// import { Service, Inject } from 'typedi';
+// import { sumBy } from 'lodash';
+// import HasTenancyService from '@/services/Tenancy/TenancyService';
+// import ApplyVendorCreditSyncInvoiced from '../command/ApplyVendorCreditSyncInvoiced.service';
+// import events from '@/subscribers/events';
+// import {
+//   IVendorCreditApplyToBillDeletedPayload,
+//   IVendorCreditApplyToBillsCreatedPayload,
+// } from '../types/VendorCreditApplyBills.types';
+
+// @Service()
+// export default class ApplyVendorCreditSyncInvoicedSubscriber {
+//   @Inject()
+//   tenancy: HasTenancyService;
+
+//   @Inject()
+//   syncCreditWithInvoiced: ApplyVendorCreditSyncInvoiced;
+
+//   /**
+//    * Attaches events with handlers.
+//    */
+//   attach(bus) {
+//     bus.subscribe(
+//       events.vendorCredit.onApplyToInvoicesCreated,
+//       this.incrementBillInvoicedOnceCreditApplied
+//     );
+//     bus.subscribe(
+//       events.vendorCredit.onApplyToInvoicesDeleted,
+//       this.decrementBillInvoicedOnceCreditApplyDeleted
+//     );
+//   }
+
+//   /**
+//    * Increment vendor credit invoiced amount once the apply transaction created.
+//    * @param {IVendorCreditApplyToBillsCreatedPayload} payload -
+//    */
+//   private incrementBillInvoicedOnceCreditApplied = async ({
+//     vendorCredit,
+//     tenantId,
+//     vendorCreditAppliedBills,
+//     trx,
+//   }: IVendorCreditApplyToBillsCreatedPayload) => {
+//     const amount = sumBy(vendorCreditAppliedBills, 'amount');
+
+//     await this.syncCreditWithInvoiced.incrementVendorCreditInvoicedAmount(
+//       tenantId,
+//       vendorCredit.id,
+//       amount,
+//       trx
+//     );
+//   };
+
+//   /**
+//    * Decrement vendor credit invoiced amount once the apply transaction deleted.
+//    * @param {IVendorCreditApplyToBillDeletedPayload} payload -
+//    */
+//   private decrementBillInvoicedOnceCreditApplyDeleted = async ({
+//     tenantId,
+//     vendorCredit,
+//     oldCreditAppliedToBill,
+//     trx,
+//   }: IVendorCreditApplyToBillDeletedPayload) => {
+//     await this.syncCreditWithInvoiced.decrementVendorCreditInvoicedAmount(
+//       tenantId,
+//       oldCreditAppliedToBill.vendorCreditId,
+//       oldCreditAppliedToBill.amount,
+//       trx
+//     );
+//   };
+// }

packages/server/src/modules/VendorCreditsApplyBills/types/VendorCreditApplyBills.types.ts

@@ -0,0 +1,48 @@
+import { Knex } from 'knex';
+import { VendorCredit } from '@/modules/VendorCredit/models/VendorCredit';
+
+export interface IVendorCreditApplyToBillsCreatedPayload {
+  vendorCredit: VendorCredit;
+  vendorCreditAppliedBills: IVendorCreditAppliedBill[];
+  trx: Knex.Transaction;
+}
+
+export interface IVendorCreditApplyToBillsCreatingPayload {
+  trx: Knex.Transaction;
+}
+
+export interface IVendorCreditApplyToBillsCreatePayload {
+  trx: Knex.Transaction;
+}
+
+export interface IVendorCreditApplyToBillDeletedPayload {
+  vendorCredit: VendorCredit;
+  oldCreditAppliedToBill: IVendorCreditAppliedBill;
+  trx: Knex.Transaction;
+}
+
+export interface IVendorCreditApplyToInvoiceDTO {
+  amount: number;
+  billId: number;
+}
+
+export interface IVendorCreditApplyToInvoicesDTO {
+  entries: IVendorCreditApplyToInvoiceDTO[];
+}
+
+export interface IVendorCreditApplyToInvoiceModel {
+  billId: number;
+  amount: number;
+  vendorCreditId: number;
+}
+
+export interface IVendorCreditApplyToInvoicesModel {
+  entries: IVendorCreditApplyToInvoiceModel[];
+  amount: number;
+}
+
+export interface IVendorCreditAppliedBill {
+  billId: number;
+  amount: number;
+  vendorCreditId: number;
+}