feat(nestjs): migrate to NestJS

packages/server/src/modules/Bills/Bills.application.ts

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+import { CreateBill } from './commands/CreateBill.service';
+import { EditBillService } from './commands/EditBill.service';
+import { GetBill } from './queries/GetBill';
+import { DeleteBill } from './commands/DeleteBill.service';
+import { IBillDTO, IBillEditDTO, IBillsFilter } from './Bills.types';
+import { GetDueBills } from './queries/GetDueBills.service';
+import { OpenBillService } from './commands/OpenBill.service';
+import { Injectable } from '@nestjs/common';
+import { GetBillsService } from './queries/GetBills.service';
+import { CreateBillDto, EditBillDto } from './dtos/Bill.dto';
+// import { GetBillPayments } from './queries/GetBillPayments';
+// import { GetBills } from './queries/GetBills';
+
+@Injectable()
+export class BillsApplication {
+  constructor(
+    private createBillService: CreateBill,
+    private editBillService: EditBillService,
+    private getBillService: GetBill,
+    private deleteBillService: DeleteBill,
+    private getDueBillsService: GetDueBills,
+    private openBillService: OpenBillService,
+    private getBillsService: GetBillsService,
+    // private getBillPaymentsService: GetBillPayments,
+  ) {}
+
+  /**
+   * Creates a new bill with associated GL entries.
+   * @param {IBillDTO} billDTO
+   * @returns
+   */
+  public createBill(billDTO: CreateBillDto) {
+    return this.createBillService.createBill(billDTO);
+  }
+
+  /**
+   * Edits the given bill with associated GL entries.
+   * @param {number} billId
+   * @param {IBillEditDTO} billDTO
+   * @returns
+   */
+  public editBill(billId: number, billDTO: EditBillDto) {
+    return this.editBillService.editBill(billId, billDTO);
+  }
+
+  /**
+   * Deletes the given bill with associated GL entries.
+   * @param {number} billId - Bill id.
+   * @returns {Promise<void>}
+   */
+  public deleteBill(billId: number) {
+    return this.deleteBillService.deleteBill(billId);
+  }
+
+  /**
+   * Retrieve bills data table list.
+   * @param {IBillsFilter} billsFilter -
+   */
+  public getBills(filterDTO: IBillsFilter) {
+    return this.getBillsService.getBills(filterDTO);
+  }
+
+  /**
+   * Retrieves the given bill details.
+   * @param {number} billId
+   * @returns
+   */
+  public getBill(billId: number) {
+    return this.getBillService.getBill(billId);
+  }
+
+  /**
+   * Open the given bill.
+   * @param {number} tenantId
+   * @param {number} billId
+   * @returns {Promise<void>}
+   */
+  public openBill(billId: number): Promise<void> {
+    return this.openBillService.openBill(billId);
+  }
+
+  /**
+   * Retrieves due bills of the given vendor.
+   * @param {number} tenantId
+   * @param {number} vendorId
+   * @returns
+   */
+  public getDueBills(vendorId?: number) {
+    return this.getDueBillsService.getDueBills(vendorId);
+  }
+
+  /**
+   * Retrieve the specific bill associated payment transactions.
+   * @param {number} tenantId
+   * @param {number} billId
+   */
+  // public getBillPayments(billId: number) {
+  //   return this.getBillPaymentsService.getBillPayments(billId);
+  // }
+}

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

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+export const ERRORS = {
+  BILL_NOT_FOUND: 'BILL_NOT_FOUND',
+  BILL_VENDOR_NOT_FOUND: 'BILL_VENDOR_NOT_FOUND',
+  BILL_ITEMS_NOT_PURCHASABLE: 'BILL_ITEMS_NOT_PURCHASABLE',
+  BILL_NUMBER_EXISTS: 'BILL_NUMBER_EXISTS',
+  BILL_ITEMS_NOT_FOUND: 'BILL_ITEMS_NOT_FOUND',
+  BILL_ENTRIES_IDS_NOT_FOUND: 'BILL_ENTRIES_IDS_NOT_FOUND',
+  NOT_PURCHASE_ABLE_ITEMS: 'NOT_PURCHASE_ABLE_ITEMS',
+  BILL_ALREADY_OPEN: 'BILL_ALREADY_OPEN',
+  BILL_NO_IS_REQUIRED: 'BILL_NO_IS_REQUIRED',
+  BILL_HAS_ASSOCIATED_PAYMENT_ENTRIES: 'BILL_HAS_ASSOCIATED_PAYMENT_ENTRIES',
+  VENDOR_HAS_BILLS: 'VENDOR_HAS_BILLS',
+  BILL_HAS_ASSOCIATED_LANDED_COSTS: 'BILL_HAS_ASSOCIATED_LANDED_COSTS',
+  BILL_ENTRIES_ALLOCATED_COST_COULD_DELETED:
+    'BILL_ENTRIES_ALLOCATED_COST_COULD_DELETED',
+  LOCATED_COST_ENTRIES_SHOULD_BIGGE_THAN_NEW_ENTRIES:
+    'LOCATED_COST_ENTRIES_SHOULD_BIGGE_THAN_NEW_ENTRIES',
+  LANDED_COST_ENTRIES_SHOULD_BE_INVENTORY_ITEMS:
+    'LANDED_COST_ENTRIES_SHOULD_BE_INVENTORY_ITEMS',
+  BILL_HAS_APPLIED_TO_VENDOR_CREDIT: 'BILL_HAS_APPLIED_TO_VENDOR_CREDIT',
+  BILL_AMOUNT_SMALLER_THAN_PAID_AMOUNT: 'BILL_AMOUNT_SMALLER_THAN_PAID_AMOUNT',
+};
+
+export const DEFAULT_VIEW_COLUMNS = [];
+
+export const DEFAULT_VIEWS = [
+  {
+    name: 'Draft',
+    slug: 'draft',
+    rolesLogicExpression: '1',
+    roles: [
+      { index: 1, fieldKey: 'status', comparator: 'equals', value: 'draft' },
+    ],
+    columns: DEFAULT_VIEW_COLUMNS,
+  },
+  {
+    name: 'Opened',
+    slug: 'opened',
+    rolesLogicExpression: '1',
+    roles: [
+      { index: 1, fieldKey: 'status', comparator: 'equals', value: 'opened' },
+    ],
+    columns: DEFAULT_VIEW_COLUMNS,
+  },
+  {
+    name: 'Unpaid',
+    slug: 'unpaid',
+    rolesLogicExpression: '1',
+    roles: [
+      { index: 1, fieldKey: 'status', comparator: 'equals', value: 'unpaid' },
+    ],
+    columns: DEFAULT_VIEW_COLUMNS,
+  },
+  {
+    name: 'Overdue',
+    slug: 'overdue',
+    rolesLogicExpression: '1',
+    roles: [
+      { index: 1, fieldKey: 'status', comparator: 'equals', value: 'overdue' },
+    ],
+    columns: DEFAULT_VIEW_COLUMNS,
+  },
+  {
+    name: 'Partially paid',
+    slug: 'partially-paid',
+    rolesLogicExpression: '1',
+    roles: [
+      {
+        index: 1,
+        fieldKey: 'status',
+        comparator: 'equals',
+        value: 'partially-paid',
+      },
+    ],
+    columns: DEFAULT_VIEW_COLUMNS,
+  },
+];
+
+export const BillsSampleData = [
+  {
+    'Bill No.': 'B-101',
+    'Reference No.': 'REF0',
+    Date: '2024-01-01',
+    'Due Date': '2024-03-01',
+    Vendor: 'Gabriel Kovacek',
+    'Exchange Rate': 1,
+    Note: 'Vel in sit sint.',
+    Open: 'T',
+    Item: 'VonRueden, Ruecker and Hettinger',
+    Quantity: 100,
+    Rate: 100,
+    'Line Description': 'Id a vel quis vel aut.',
+  },
+  {
+    'Bill No.': 'B-102',
+    'Reference No.': 'REF0',
+    Date: '2024-01-01',
+    'Due Date': '2024-03-01',
+    Vendor: 'Gabriel Kovacek',
+    'Exchange Rate': 1,
+    Note: 'Quia ut dolorem qui sint velit.',
+    Open: 'T',
+    Item: 'Thompson - Reichert',
+    Quantity: 200,
+    Rate: 50,
+    'Line Description':
+      'Nesciunt in adipisci quia ab reiciendis nam sed saepe consequatur.',
+  },
+  {
+    'Bill No.': 'B-103',
+    'Reference No.': 'REF0',
+    Date: '2024-01-01',
+    'Due Date': '2024-03-01',
+    Vendor: 'Gabriel Kovacek',
+    'Exchange Rate': 1,
+    Note: 'Dolore aut voluptatem minus pariatur alias pariatur.',
+    Open: 'T',
+    Item: 'VonRueden, Ruecker and Hettinger',
+    Quantity: 100,
+    Rate: 100,
+    'Line Description': 'Quam eligendi provident.',
+  },
+];

packages/server/src/modules/Bills/Bills.controller.ts

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+import { ApiOperation, ApiParam, ApiTags } from '@nestjs/swagger';
+import {
+  Controller,
+  Post,
+  Body,
+  Put,
+  Param,
+  Delete,
+  Get,
+  Query,
+} from '@nestjs/common';
+import { BillsApplication } from './Bills.application';
+import { IBillsFilter } from './Bills.types';
+import { CreateBillDto, EditBillDto } from './dtos/Bill.dto';
+
+@Controller('bills')
+@ApiTags('bills')
+export class BillsController {
+  constructor(private billsApplication: BillsApplication) {}
+
+  @Post()
+  @ApiOperation({ summary: 'Create a new bill.' })
+  createBill(@Body() billDTO: CreateBillDto) {
+    return this.billsApplication.createBill(billDTO);
+  }
+
+  @Put(':id')
+  @ApiOperation({ summary: 'Edit the given bill.' })
+  @ApiParam({
+    name: 'id',
+    required: true,
+    type: Number,
+    description: 'The bill id',
+  })
+  editBill(@Param('id') billId: number, @Body() billDTO: EditBillDto) {
+    return this.billsApplication.editBill(billId, billDTO);
+  }
+
+  @Delete(':id')
+  @ApiOperation({ summary: 'Delete the given bill.' })
+  @ApiParam({
+    name: 'id',
+    required: true,
+    type: Number,
+    description: 'The bill id',
+  })
+  deleteBill(@Param('id') billId: number) {
+    return this.billsApplication.deleteBill(billId);
+  }
+
+  @Get()
+  @ApiOperation({ summary: 'Retrieves the bills.' })
+  @ApiParam({
+    name: 'id',
+    required: true,
+    type: Number,
+    description: 'The bill id',
+  })
+  getBills(@Query() filterDTO: IBillsFilter) {
+    return this.billsApplication.getBills(filterDTO);
+  }
+
+  @Get(':id')
+  @ApiOperation({ summary: 'Retrieves the bill details.' })
+  @ApiParam({
+    name: 'id',
+    required: true,
+    type: Number,
+    description: 'The bill id',
+  })
+  getBill(@Param('id') billId: number) {
+    return this.billsApplication.getBill(billId);
+  }
+
+  @Post(':id/open')
+  @ApiOperation({ summary: 'Open the given bill.' })
+  @ApiParam({
+    name: 'id',
+    required: true,
+    type: Number,
+    description: 'The bill id',
+  })
+  openBill(@Param('id') billId: number) {
+    return this.billsApplication.openBill(billId);
+  }
+
+  @Get('due')
+  @ApiOperation({ summary: 'Retrieves the due bills.' })
+  getDueBills(@Body('vendorId') vendorId?: number) {
+    return this.billsApplication.getDueBills(vendorId);
+  }
+}

packages/server/src/modules/Bills/Bills.module.ts

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+import { Module } from '@nestjs/common';
+import { BillsApplication } from './Bills.application';
+import { CreateBill } from './commands/CreateBill.service';
+import { DeleteBill } from './commands/DeleteBill.service';
+import { GetBill } from './queries/GetBill';
+import { BillDTOTransformer } from './commands/BillDTOTransformer.service';
+import { EditBillService } from './commands/EditBill.service';
+import { GetDueBills } from './queries/GetDueBills.service';
+import { OpenBillService } from './commands/OpenBill.service';
+import { BillsValidators } from './commands/BillsValidators.service';
+import { ItemsEntriesService } from '../Items/ItemsEntries.service';
+import { BranchTransactionDTOTransformer } from '../Branches/integrations/BranchTransactionDTOTransform';
+import { BranchesSettingsService } from '../Branches/BranchesSettings';
+import { WarehouseTransactionDTOTransform } from '../Warehouses/Integrations/WarehouseTransactionDTOTransform';
+import { WarehousesSettings } from '../Warehouses/WarehousesSettings';
+import { ItemEntriesTaxTransactions } from '../TaxRates/ItemEntriesTaxTransactions.service';
+import { TenancyContext } from '../Tenancy/TenancyContext.service';
+import { BillsController } from './Bills.controller';
+import { BillLandedCostsModule } from '../BillLandedCosts/BillLandedCosts.module';
+import { BillGLEntriesSubscriber } from './subscribers/BillGLEntriesSubscriber';
+import { BillGLEntries } from './commands/BillsGLEntries';
+import { LedgerModule } from '../Ledger/Ledger.module';
+import { AccountsModule } from '../Accounts/Accounts.module';
+import { BillWriteInventoryTransactionsSubscriber } from './subscribers/BillWriteInventoryTransactionsSubscriber';
+import { BillInventoryTransactions } from './commands/BillInventoryTransactions';
+import { GetBillsService } from './queries/GetBills.service';
+import { DynamicListModule } from '../DynamicListing/DynamicList.module';
+import { InventoryCostModule } from '../InventoryCost/InventoryCost.module';
+
+@Module({
+  imports: [
+    BillLandedCostsModule,
+    LedgerModule,
+    AccountsModule,
+    DynamicListModule,
+    InventoryCostModule,
+  ],
+  providers: [
+    TenancyContext,
+    BillsApplication,
+    BranchTransactionDTOTransformer,
+    WarehouseTransactionDTOTransform,
+    WarehousesSettings,
+    ItemEntriesTaxTransactions,
+    BranchesSettingsService,
+    CreateBill,
+    EditBillService,
+    GetDueBills,
+    OpenBillService,
+    GetBill,
+    GetBillsService,
+    DeleteBill,
+    BillDTOTransformer,
+    BillsValidators,
+    BillGLEntries,
+    ItemsEntriesService,
+    BillGLEntriesSubscriber,
+    BillInventoryTransactions,
+    BillWriteInventoryTransactionsSubscriber,
+  ],
+  controllers: [BillsController],
+})
+export class BillsModule {}

packages/server/src/modules/Bills/Bills.types.ts

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+import { Knex } from 'knex';
+import { IItemEntryDTO } from '../TransactionItemEntry/ItemEntry.types';
+import { AttachmentLinkDTO } from '../Attachments/Attachments.types';
+import { Bill } from './models/Bill';
+import { IDynamicListFilter } from '../DynamicListing/DynamicFilter/DynamicFilter.types';
+import { CreateBillDto, EditBillDto } from './dtos/Bill.dto';
+
+export interface IBillDTO {
+  vendorId: number;
+  billNumber: string;
+  billDate: Date;
+  dueDate: Date;
+  referenceNo: string;
+  status: string;
+  note: string;
+  amount: number;
+  paymentAmount: number;
+  exchangeRate?: number;
+  open: boolean;
+  entries: IItemEntryDTO[];
+  branchId?: number;
+  warehouseId?: number;
+  projectId?: number;
+  isInclusiveTax?: boolean;
+  attachments?: AttachmentLinkDTO[];
+}
+
+export interface IBillEditDTO {
+  vendorId: number;
+  billNumber: string;
+  billDate: Date;
+  dueDate: Date;
+  referenceNo: string;
+  status: string;
+  note: string;
+  amount: number;
+  paymentAmount: number;
+  open: boolean;
+  entries: IItemEntryDTO[];
+
+  branchId?: number;
+  warehouseId?: number;
+  projectId?: number;
+  attachments?: AttachmentLinkDTO[];
+}
+
+export interface IBillsFilter extends IDynamicListFilter {
+  stringifiedFilterRoles?: string;
+  page: number;
+  pageSize: number;
+  filterQuery?: (q: any) => void;
+}
+
+export interface IBillCreatedPayload {
+  bill: Bill;
+  billDTO: CreateBillDto;
+  trx?: Knex.Transaction;
+}
+
+export interface IBillCreatingPayload {
+  billDTO: CreateBillDto;
+  trx: Knex.Transaction;
+}
+
+export interface IBillEditingPayload {
+  oldBill: Bill;
+  billDTO: EditBillDto;
+  trx: Knex.Transaction;
+}
+export interface IBillEditedPayload {
+  oldBill: Bill;
+  bill: Bill;
+  billDTO: EditBillDto;
+  trx?: Knex.Transaction;
+}
+
+export interface IBIllEventDeletedPayload {
+  // tenantId: number;
+  billId: number;
+  oldBill: Bill;
+  trx: Knex.Transaction;
+}
+
+export interface IBillEventDeletingPayload {
+  // tenantId: number;
+  oldBill: Bill;
+  trx: Knex.Transaction;
+}
+export enum BillAction {
+  Create = 'Create',
+  Edit = 'Edit',
+  Delete = 'Delete',
+  View = 'View',
+  NotifyBySms = 'NotifyBySms',
+}
+
+export interface IBillOpeningPayload {
+  trx: Knex.Transaction;
+  // tenantId: number;
+  oldBill: Bill;
+}
+
+export interface IBillOpenedPayload {
+  bill: Bill;
+  oldBill: Bill;
+  trx?: Knex.Transaction;
+  // tenantId: number;
+}

packages/server/src/modules/Bills/commands/BillDTOTransformer.service.ts

@@ -0,0 +1,152 @@
+import { Inject, Injectable } from '@nestjs/common';
+import { omit, sumBy } from 'lodash';
+import * as moment from 'moment';
+import * as R from 'ramda';
+import * as composeAsync from 'async/compose';
+import { formatDateFields } from '@/utils/format-date-fields';
+import { BranchTransactionDTOTransformer } from '@/modules/Branches/integrations/BranchTransactionDTOTransform';
+import { WarehouseTransactionDTOTransform } from '@/modules/Warehouses/Integrations/WarehouseTransactionDTOTransform';
+import { ItemEntry } from '@/modules/TransactionItemEntry/models/ItemEntry';
+import { Item } from '@/modules/Items/models/Item';
+import { Vendor } from '@/modules/Vendors/models/Vendor';
+import { ItemEntriesTaxTransactions } from '@/modules/TaxRates/ItemEntriesTaxTransactions.service';
+import { IBillDTO } from '../Bills.types';
+import { Bill } from '../models/Bill';
+import { assocItemEntriesDefaultIndex } from '@/utils/associate-item-entries-index';
+import { TenancyContext } from '@/modules/Tenancy/TenancyContext.service';
+import { TenantModelProxy } from '@/modules/System/models/TenantBaseModel';
+import { CreateBillDto } from '../dtos/Bill.dto';
+
+@Injectable()
+export class BillDTOTransformer {
+  constructor(
+    private branchDTOTransform: BranchTransactionDTOTransformer,
+    private warehouseDTOTransform: WarehouseTransactionDTOTransform,
+    private taxDTOTransformer: ItemEntriesTaxTransactions,
+    private tenancyContext: TenancyContext,
+
+    @Inject(ItemEntry.name)
+    private itemEntryModel: TenantModelProxy<typeof ItemEntry>,
+
+    @Inject(Item.name) private itemModel: TenantModelProxy<typeof Item>,
+  ) {}
+
+  /**
+   * Retrieve the bill entries total.
+   * @param {IItemEntry[]} entries
+   * @returns {number}
+   */
+  private getBillEntriesTotal(entries: ItemEntry[]): number {
+    return sumBy(entries, (e) => this.itemEntryModel().calcAmount(e));
+  }
+
+  /**
+   * Retrieve the bill landed cost amount.
+   * @param {CreateBillDto} billDTO
+   * @returns {number}
+   */
+  private getBillLandedCostAmount(billDTO: CreateBillDto): number {
+    const costEntries = billDTO.entries.filter((entry) => entry.landedCost);
+
+    // return this.getBillEntriesTotal(costEntries);
+
+    return 0;
+  }
+
+  /**
+   * Converts create bill DTO to model.
+   * @param {IBillDTO} billDTO
+   * @param {IBill} oldBill
+   * @returns {IBill}
+   */
+  public async billDTOToModel(
+    billDTO: CreateBillDto,
+    vendor: Vendor,
+    oldBill?: Bill,
+  ): Promise<Bill> {
+    const amount = sumBy(billDTO.entries, (e) =>
+      this.itemEntryModel().calcAmount(e),
+    );
+    // Retrieve the landed cost amount from landed cost entries.
+    const landedCostAmount = this.getBillLandedCostAmount(billDTO);
+
+    // Retrieve the authorized user.
+    const authorizedUser = await this.tenancyContext.getSystemUser();
+
+    // Bill number from DTO or frprom auto-increment.
+    const billNumber = billDTO.billNumber || oldBill?.billNumber;
+
+    const initialEntries = billDTO.entries.map((entry) => ({
+      referenceType: 'Bill',
+      isInclusiveTax: billDTO.isInclusiveTax,
+      ...omit(entry, ['amount']),
+    }));
+    const asyncEntries = await composeAsync(
+      // Associate tax rate from tax id to entries.
+      this.taxDTOTransformer.assocTaxRateFromTaxIdToEntries,
+      // Associate tax rate id from tax code to entries.
+      this.taxDTOTransformer.assocTaxRateIdFromCodeToEntries,
+      // Sets the default cost account to the bill entries.
+      this.setBillEntriesDefaultAccounts(),
+    )(initialEntries);
+
+    const entries = R.compose(
+      // Remove tax code from entries.
+      R.map(R.omit(['taxCode'])),
+      // Associate the default index to each item entry line.
+      assocItemEntriesDefaultIndex,
+    )(asyncEntries);
+
+    const initialDTO = {
+      ...formatDateFields(omit(billDTO, ['open', 'entries', 'attachments']), [
+        'billDate',
+        'dueDate',
+      ]),
+      amount,
+      landedCostAmount,
+      currencyCode: vendor.currencyCode,
+      exchangeRate: billDTO.exchangeRate || 1,
+      billNumber,
+      entries,
+      // Avoid rewrite the open date in edit mode when already opened.
+      ...(billDTO.open &&
+        !oldBill?.openedAt && {
+          openedAt: moment().toMySqlDateTime(),
+        }),
+      userId: authorizedUser.id,
+    };
+
+    const asyncDto = await composeAsync(
+      this.branchDTOTransform.transformDTO<Bill>,
+      this.warehouseDTOTransform.transformDTO<Bill>,
+    )(initialDTO);
+
+    return R.compose(
+      // Associates tax amount withheld to the model.
+      this.taxDTOTransformer.assocTaxAmountWithheldFromEntries,
+    )(asyncDto) as Bill;
+  }
+
+  /**
+   * Sets the default cost account to the bill entries.
+   */
+  private setBillEntriesDefaultAccounts() {
+    return async (entries: ItemEntry[]) => {
+      const entriesItemsIds = entries.map((e) => e.itemId);
+      const items = await this.itemModel()
+        .query()
+        .whereIn('id', entriesItemsIds);
+
+      return entries.map((entry) => {
+        const item = items.find((i) => i.id === entry.itemId);
+
+        return {
+          ...entry,
+          ...(item.type !== 'inventory' && {
+            costAccountId: entry.costAccountId || item.costAccountId,
+          }),
+        };
+      });
+    };
+  }
+}

packages/server/src/modules/Bills/commands/BillInventoryTransactions.ts

@@ -0,0 +1,75 @@
+// @ts-nocheck
+import { Knex } from 'knex';
+import { Bill } from '../models/Bill';
+import { Inject, Injectable } from '@nestjs/common';
+import { ItemsEntriesService } from '@/modules/Items/ItemsEntries.service';
+import { InventoryTransactionsService } from '@/modules/InventoryCost/commands/InventoryTransactions.service';
+import { TenantModelProxy } from '@/modules/System/models/TenantBaseModel';
+
+@Injectable()
+export class BillInventoryTransactions {
+  constructor(
+    private readonly itemsEntriesService: ItemsEntriesService,
+    private readonly inventoryTransactionsService: InventoryTransactionsService,
+
+    @Inject(Bill.name)
+    private readonly bill: TenantModelProxy<typeof Bill>,
+  ) {}
+
+  /**
+   * Records the inventory transactions from the given bill input.
+   * @param  {number} billId - Bill id.
+   * @return {Promise<void>}
+   */
+  public async recordInventoryTransactions(
+    billId: number,
+    override?: boolean,
+    trx?: Knex.Transaction,
+  ): Promise<void> {
+    // Retireve bill with assocaited entries and allocated cost entries.
+
+    const bill = await this.bill()
+      .query(trx)
+      .findById(billId)
+      .withGraphFetched('entries.allocatedCostEntries');
+
+    // Loads the inventory items entries of the given sale invoice.
+    const inventoryEntries =
+      await this.itemsEntriesService.filterInventoryEntries(bill.entries);
+    const transaction = {
+      transactionId: bill.id,
+      transactionType: 'Bill',
+      exchangeRate: bill.exchangeRate,
+
+      date: bill.billDate,
+      direction: 'IN',
+      entries: inventoryEntries,
+      createdAt: bill.createdAt,
+
+      warehouseId: bill.warehouseId,
+    };
+    await this.inventoryTransactionsService.recordInventoryTransactionsFromItemsEntries(
+      transaction,
+      override,
+      trx,
+    );
+  }
+
+  /**
+   * Reverts the inventory transactions of the given bill id.
+   * @param {number} tenantId - Tenant id.
+   * @param {number} billId - Bill id.
+   * @return {Promise<void>}
+   */
+  public async revertInventoryTransactions(
+    billId: number,
+    trx?: Knex.Transaction,
+  ) {
+    // Deletes the inventory transactions by the given reference id and type.
+    await this.inventoryTransactionsService.deleteInventoryTransactions(
+      billId,
+      'Bill',
+      trx,
+    );
+  }
+}

packages/server/src/modules/Bills/commands/BillPaymentsGLEntriesRewrite.ts

@@ -0,0 +1,76 @@
+// import { Knex } from 'knex';
+// import async from 'async';
+// import HasTenancyService from '@/services/Tenancy/TenancyService';
+// import { Inject, Service } from 'typedi';
+// import { BillPaymentGLEntries } from '../BillPayments/BillPaymentGLEntries';
+
+// @Service()
+// export class BillPaymentsGLEntriesRewrite {
+//   @Inject()
+//   public tenancy: HasTenancyService;
+
+//   @Inject()
+//   public paymentGLEntries: BillPaymentGLEntries;
+
+//   /**
+//    * Rewrites payments GL entries that associated to the given bill.
+//    * @param {number} tenantId
+//    * @param {number} billId
+//    * @param {Knex.Transaction} trx
+//    */
+//   public rewriteBillPaymentsGLEntries = async (
+//     tenantId: number,
+//     billId: number,
+//     trx?: Knex.Transaction
+//   ) => {
+//     const { BillPaymentEntry } = this.tenancy.models(tenantId);
+
+//     const billPaymentEntries = await BillPaymentEntry.query().where(
+//       'billId',
+//       billId
+//     );
+//     const paymentsIds = billPaymentEntries.map((e) => e.billPaymentId);
+
+//     await this.rewritePaymentsGLEntriesQueue(tenantId, paymentsIds, trx);
+//   };
+
+//   /**
+//    * Rewrites the payments GL entries under async queue.
+//    * @param {number} tenantId
+//    * @param {number[]} paymentsIds
+//    * @param {Knex.Transaction} trx
+//    */
+//   public rewritePaymentsGLEntriesQueue = async (
+//     tenantId: number,
+//     paymentsIds: number[],
+//     trx?: Knex.Transaction
+//   ) => {
+//     // Initiate a new queue for accounts balance mutation.
+//     const rewritePaymentGL = async.queue(this.rewritePaymentsGLEntriesTask, 10);
+
+//     paymentsIds.forEach((paymentId: number) => {
+//       rewritePaymentGL.push({ paymentId, trx, tenantId });
+//     });
+//     //
+//     if (paymentsIds.length > 0) await rewritePaymentGL.drain();
+//   };
+
+//   /**
+//    * Rewrites the payments GL entries task.
+//    * @param {number} tenantId -
+//    * @param {number} paymentId -
+//    * @param {Knex.Transaction} trx -
+//    * @returns {Promise<void>}
+//    */
+//   public rewritePaymentsGLEntriesTask = async ({
+//     tenantId,
+//     paymentId,
+//     trx,
+//   }) => {
+//     await this.paymentGLEntries.rewritePaymentGLEntries(
+//       tenantId,
+//       paymentId,
+//       trx
+//     );
+//   };
+// }

packages/server/src/modules/Bills/commands/BillPaymentsGLEntriesRewriteSubscriber.ts

@@ -0,0 +1,36 @@
+// import { Inject, Service } from 'typedi';
+// import events from '@/subscribers/events';
+// import { IBillEditedPayload } from '@/interfaces';
+// import { BillPaymentsGLEntriesRewrite } from './BillPaymentsGLEntriesRewrite';
+
+// @Service()
+// export class BillPaymentsGLEntriesRewriteSubscriber {
+//   @Inject()
+//   private billPaymentGLEntriesRewrite: BillPaymentsGLEntriesRewrite;
+
+//   /**
+//    * Attaches events with handles.
+//    */
+//   public attach(bus) {
+//     bus.subscribe(
+//       events.bill.onEdited,
+//       this.handlerRewritePaymentsGLOnBillEdited
+//     );
+//   }
+
+//   /**
+//    * Handles writing journal entries once bill created.
+//    * @param {IBillCreatedPayload} payload -
+//    */
+//   private handlerRewritePaymentsGLOnBillEdited = async ({
+//     tenantId,
+//     billId,
+//     trx,
+//   }: IBillEditedPayload) => {
+//     await this.billPaymentGLEntriesRewrite.rewriteBillPaymentsGLEntries(
+//       tenantId,
+//       billId,
+//       trx
+//     );
+//   };
+// }

packages/server/src/modules/Bills/commands/BillsExportable.ts

@@ -0,0 +1,37 @@
+// import { Inject, Service } from 'typedi';
+// import { Knex } from 'knex';
+// import { IBillsFilter } from '@/interfaces';
+// import { Exportable } from '@/services/Export/Exportable';
+// import { BillsApplication } from '../Bills.application';
+// import { EXPORT_SIZE_LIMIT } from '@/services/Export/constants';
+// import Objection from 'objection';
+
+// @Service()
+// export class BillsExportable extends Exportable {
+//   @Inject()
+//   private billsApplication: BillsApplication;
+
+//   /**
+//    * Retrieves the accounts data to exportable sheet.
+//    * @param {number} tenantId
+//    * @returns
+//    */
+//   public exportable(tenantId: number, query: IBillsFilter) {
+//     const filterQuery = (query) => {
+//       query.withGraphFetched('branch');
+//       query.withGraphFetched('warehouse');
+//     };
+//     const parsedQuery = {
+//       sortOrder: 'desc',
+//       columnSortBy: 'created_at',
+//       ...query,
+//       page: 1,
+//       pageSize: EXPORT_SIZE_LIMIT,
+//       filterQuery,
+//     } as IBillsFilter;
+
+//     return this.billsApplication
+//       .getBills(tenantId, parsedQuery)
+//       .then((output) => output.bills);
+//   }
+// }

packages/server/src/modules/Bills/commands/BillsGL.ts

@@ -0,0 +1,242 @@
+import { sumBy } from 'lodash';
+import { ILedgerEntry } from '@/modules/Ledger/types/Ledger.types';
+import { ItemEntry } from '@/modules/TransactionItemEntry/models/ItemEntry';
+import { Bill } from '../models/Bill';
+import { AccountNormal } from '@/modules/Accounts/Accounts.types';
+import { Ledger } from '@/modules/Ledger/Ledger';
+import { BillLandedCost } from '@/modules/BillLandedCosts/models/BillLandedCost';
+
+export class BillGL {
+  private bill: Bill;
+  private payableAccountId: number;
+  private taxPayableAccountId: number;
+  private purchaseDiscountAccountId: number;
+  private otherExpensesAccountId: number;
+
+  constructor(bill: Bill) {
+    this.bill = bill;
+  }
+
+  setPayableAccountId(payableAccountId: number) {
+    this.payableAccountId = payableAccountId;
+    return this;
+  }
+
+  setTaxPayableAccountId(taxPayableAccountId: number) {
+    this.taxPayableAccountId = taxPayableAccountId;
+    return this;
+  }
+
+  setPurchaseDiscountAccountId(purchaseDiscountAccountId: number) {
+    this.purchaseDiscountAccountId = purchaseDiscountAccountId;
+    return this;
+  }
+
+  setOtherExpensesAccountId(otherExpensesAccountId: number) {
+    this.otherExpensesAccountId = otherExpensesAccountId;
+    return this;
+  }
+
+  /**
+   * Retrieves the bill common entry.
+   * @returns {ILedgerEntry}
+   */
+  private get billCommonEntry() {
+    return {
+      debit: 0,
+      credit: 0,
+
+      currencyCode: this.bill.currencyCode,
+      exchangeRate: this.bill.exchangeRate || 1,
+
+      transactionId: this.bill.id,
+      transactionType: 'Bill',
+
+      date: moment(this.bill.billDate).format('YYYY-MM-DD'),
+      userId: this.bill.userId,
+
+      referenceNumber: this.bill.referenceNo,
+      transactionNumber: this.bill.billNumber,
+
+      branchId: this.bill.branchId,
+      projectId: this.bill.projectId,
+
+      createdAt: this.bill.createdAt,
+    };
+  }
+
+  /**
+   * Retrieves the bill item inventory/cost entry.
+   * @param {ItemEntry} entry -
+   * @param {number} index -
+   */
+  private getBillItemEntry(entry: ItemEntry, index: number): ILedgerEntry {
+    const commonJournalMeta = this.billCommonEntry;
+    const totalLocal = this.bill.exchangeRate * entry.totalExcludingTax;
+    const landedCostAmount = sumBy(entry.allocatedCostEntries, 'cost');
+
+    return {
+      ...commonJournalMeta,
+      debit: totalLocal + landedCostAmount,
+      accountId:
+        ['inventory'].indexOf(entry.item.type) !== -1
+          ? entry.item.inventoryAccountId
+          : entry.costAccountId,
+      index: index + 1,
+      indexGroup: 10,
+      itemId: entry.itemId,
+      accountNormal: AccountNormal.DEBIT,
+    };
+  }
+
+  /**
+   * Retrieves the bill landed cost entry.
+   * @param {BillLandedCost} landedCost - Landed cost
+   * @param {number} index - Index
+   */
+  private getBillLandedCostEntry(
+    landedCost: BillLandedCost,
+    index: number,
+  ): ILedgerEntry {
+    const commonJournalMeta = this.billCommonEntry;
+
+    return {
+      ...commonJournalMeta,
+      credit: landedCost.amount,
+      accountId: landedCost.costAccountId,
+      accountNormal: AccountNormal.DEBIT,
+      index: 1,
+      indexGroup: 20,
+    };
+  }
+
+  /**
+   * Retrieves the bill payable entry.
+   * @returns {ILedgerEntry}
+   */
+  private get billPayableEntry(): ILedgerEntry {
+    const commonJournalMeta = this.billCommonEntry;
+
+    return {
+      ...commonJournalMeta,
+      credit: this.bill.totalLocal,
+      accountId: this.payableAccountId,
+      contactId: this.bill.vendorId,
+      accountNormal: AccountNormal.CREDIT,
+      index: 1,
+      indexGroup: 5,
+    };
+  }
+
+  /**
+   * Retrieves the bill tax GL entry.
+   * @param {IBill} bill -
+   * @param {number} taxPayableAccountId -
+   * @param {IItemEntry} entry -
+   * @param {number} index -
+   * @returns {ILedgerEntry}
+   */
+  private getBillTaxEntry(entry: ItemEntry, index: number): ILedgerEntry {
+    const commonJournalMeta = this.billCommonEntry;
+
+    return {
+      ...commonJournalMeta,
+      debit: entry.taxAmount,
+      index,
+      indexGroup: 30,
+      accountId: this.taxPayableAccountId,
+      accountNormal: AccountNormal.CREDIT,
+      taxRateId: entry.taxRateId,
+      taxRate: entry.taxRate,
+    };
+  }
+
+  /**
+   * Retrieves the bill tax GL entries.
+   * @param {IBill} bill
+   * @param {number} taxPayableAccountId
+   * @returns {ILedgerEntry[]}
+   */
+  // private getBillTaxEntries = () => {
+  //   // Retrieves the non-zero tax entries.
+  //   const nonZeroTaxEntries = this.itemsEntriesService.getNonZeroEntries(
+  //     this.bill.entries,
+  //   );
+  //   const transformTaxEntry = this.getBillTaxEntry(
+  //     this.bill,
+  //     this.taxPayableAccountId,
+  //   );
+
+  //   return nonZeroTaxEntries.map(transformTaxEntry);
+  // };
+
+  /**
+   * Retrieves the purchase discount GL entry.
+   * @returns {ILedgerEntry}
+   */
+  private get purchaseDiscountEntry(): ILedgerEntry {
+    const commonEntry = this.billCommonEntry;
+
+    return {
+      ...commonEntry,
+      credit: this.bill.discountAmountLocal,
+      accountId: this.purchaseDiscountAccountId,
+      accountNormal: AccountNormal.DEBIT,
+      index: 1,
+      indexGroup: 40,
+    };
+  }
+
+  /**
+   * Retrieves the purchase other charges GL entry.
+   * @returns {ILedgerEntry}
+   */
+  private get adjustmentEntry(): ILedgerEntry {
+    const commonEntry = this.billCommonEntry;
+    const adjustmentAmount = Math.abs(this.bill.adjustmentLocal);
+
+    return {
+      ...commonEntry,
+      debit: this.bill.adjustmentLocal > 0 ? adjustmentAmount : 0,
+      credit: this.bill.adjustmentLocal < 0 ? adjustmentAmount : 0,
+      accountId: this.otherExpensesAccountId,
+      accountNormal: AccountNormal.DEBIT,
+      index: 1,
+      indexGroup: 40,
+    };
+  }
+
+  /**
+   * Retrieves the given bill GL entries.
+   * @returns {ILedgerEntry[]}
+   */
+  private getBillGLEntries = (): ILedgerEntry[] => {
+    const payableEntry = this.billPayableEntry;
+
+    const itemsEntries = this.bill.entries.map((entry, index) =>
+      this.getBillItemEntry(entry, index),
+    );
+    const landedCostEntries = this.bill.locatedLandedCosts.map(
+      (landedCost, index) => this.getBillLandedCostEntry(landedCost, index),
+    );
+
+    // Allocate cost entries journal entries.
+    return [
+      payableEntry,
+      ...itemsEntries,
+      ...landedCostEntries,
+      this.purchaseDiscountEntry,
+      this.adjustmentEntry,
+    ];
+  };
+
+  /**
+   * Retrieves the given bill ledger.
+   * @returns {Ledger}
+   */
+  public getBillLedger = () => {
+    const entries = this.getBillGLEntries();
+
+    return new Ledger(entries);
+  };
+}

packages/server/src/modules/Bills/commands/BillsGLEntries.ts

@@ -0,0 +1,100 @@
+import { Knex } from 'knex';
+import { LedgerStorageService } from '@/modules/Ledger/LedgerStorage.service';
+import { AccountRepository } from '@/modules/Accounts/repositories/Account.repository';
+import { Bill } from '../models/Bill';
+import { Inject, Injectable } from '@nestjs/common';
+import { BillGL } from './BillsGL';
+import { TenantModelProxy } from '@/modules/System/models/TenantBaseModel';
+
+@Injectable()
+export class BillGLEntries {
+  /**
+   * @param {LedgerStorageService} ledgerStorage - Ledger storage service.
+   * @param {AccountRepository} accountRepository - Account repository.
+   * @param {typeof Bill} billModel - Bill model.
+   */
+  constructor(
+    private readonly ledgerStorage: LedgerStorageService,
+    private readonly accountRepository: AccountRepository,
+
+    @Inject(Bill.name)
+    private readonly billModel: TenantModelProxy<typeof Bill>,
+  ) {}
+
+  /**
+   * Creates bill GL entries.
+   * @param {number} billId - Bill id.
+   * @param {Knex.Transaction} trx - Knex transaction.
+   */
+  public writeBillGLEntries = async (
+    billId: number,
+    trx?: Knex.Transaction,
+  ) => {
+    // Retrieves bill with associated entries and landed costs.
+    const bill = await this.billModel()
+      .query(trx)
+      .findById(billId)
+      .withGraphFetched('entries.item')
+      .withGraphFetched('entries.allocatedCostEntries')
+      .withGraphFetched('locatedLandedCosts.allocateEntries');
+
+    // Finds or create a A/P account based on the given currency.
+    const APAccount = await this.accountRepository.findOrCreateAccountsPayable(
+      bill.currencyCode,
+      {},
+      trx,
+    );
+    // Find or create tax payable account.
+    const taxPayableAccount =
+      await this.accountRepository.findOrCreateTaxPayable({}, trx);
+
+    // Find or create other expenses account.
+    const otherExpensesAccount =
+      await this.accountRepository.findOrCreateOtherExpensesAccount({}, trx);
+
+    // Find or create purchase discount account.
+    const purchaseDiscountAccount =
+      await this.accountRepository.findOrCreatePurchaseDiscountAccount({}, trx);
+
+    // Retrieves the bill ledger.
+    const billLedger = new BillGL(bill)
+      .setPayableAccountId(APAccount.id)
+      .setTaxPayableAccountId(taxPayableAccount.id)
+      .setPurchaseDiscountAccountId(purchaseDiscountAccount.id)
+      .setOtherExpensesAccountId(otherExpensesAccount.id)
+      .getBillLedger();
+
+    // Commit the GL enties on the storage.
+    await this.ledgerStorage.commit(billLedger, trx);
+  };
+
+  /**
+   * Reverts the given bill GL entries.
+   * @param {number} tenantId
+   * @param {number} billId
+   * @param {Knex.Transaction} trx
+   */
+  public revertBillGLEntries = async (
+    billId: number,
+    trx?: Knex.Transaction,
+  ) => {
+    await this.ledgerStorage.deleteByReference(billId, 'Bill', trx);
+  };
+
+  /**
+   * Rewrites the given bill GL entries.
+   * @param {number} tenantId
+   * @param {number} billId
+   * @param {Knex.Transaction} trx
+   */
+  public rewriteBillGLEntries = async (
+    billId: number,
+    trx?: Knex.Transaction,
+  ) => {
+    // Reverts the bill GL entries.
+    await this.revertBillGLEntries(billId, trx);
+
+    // Writes the bill GL entries.
+    await this.writeBillGLEntries(billId, trx);
+  };
+}

packages/server/src/modules/Bills/commands/BillsImportable.ts

@@ -0,0 +1,46 @@
+// import { Inject, Service } from 'typedi';
+// import { Knex } from 'knex';
+// import { Importable } from '@/services/Import/Importable';
+// import { CreateBill } from './CreateBill.service';
+// import { IBillDTO } from '@/interfaces';
+// import { BillsSampleData } from '../Bills.constants';
+
+// @Service()
+// export class BillsImportable extends Importable {
+//   @Inject()
+//   private createBillService: CreateBill;
+
+//   /**
+//    * Importing to account service.
+//    * @param {number} tenantId
+//    * @param {IAccountCreateDTO} createAccountDTO
+//    * @returns
+//    */
+//   public importable(
+//     tenantId: number,
+//     createAccountDTO: IBillDTO,
+//     trx?: Knex.Transaction
+//   ) {
+//     return this.createBillService.createBill(
+//       tenantId,
+//       createAccountDTO,
+//       {},
+//       trx
+//     );
+//   }
+
+//   /**
+//    * Concurrrency controlling of the importing process.
+//    * @returns {number}
+//    */
+//   public get concurrency() {
+//     return 1;
+//   }
+
+//   /**
+//    * Retrieves the sample data that used to download accounts sample sheet.
+//    */
+//   public sampleData(): any[] {
+//     return BillsSampleData;
+//   }
+// }

packages/server/src/modules/Bills/commands/BillsValidators.service.ts

@@ -0,0 +1,175 @@
+import { Inject, Injectable } from '@nestjs/common';
+import { ERRORS } from '../Bills.constants';
+import { Bill } from '../models/Bill';
+import { ServiceError } from '@/modules/Items/ServiceError';
+import { IItemEntryDTO } from '@/modules/TransactionItemEntry/ItemEntry.types';
+import { Item } from '@/modules/Items/models/Item';
+import { BillPaymentEntry } from '@/modules/BillPayments/models/BillPaymentEntry';
+import { BillLandedCost } from '@/modules/BillLandedCosts/models/BillLandedCost';
+import { VendorCreditAppliedBill } from '@/modules/VendorCreditsApplyBills/models/VendorCreditAppliedBill';
+import { transformToMap } from '@/utils/transform-to-key';
+import { TenantModelProxy } from '@/modules/System/models/TenantBaseModel';
+import { ItemEntryDto } from '@/modules/TransactionItemEntry/dto/ItemEntry.dto';
+import { BillEntryDto } from '../dtos/Bill.dto';
+
+@Injectable()
+export class BillsValidators {
+  constructor(
+    @Inject(Bill.name) private billModel: TenantModelProxy<typeof Bill>,
+
+    @Inject(BillPaymentEntry.name)
+    private billPaymentEntryModel: TenantModelProxy<typeof BillPaymentEntry>,
+
+    @Inject(BillLandedCost.name)
+    private billLandedCostModel: TenantModelProxy<typeof BillLandedCost>,
+
+    @Inject(VendorCreditAppliedBill.name)
+    private vendorCreditAppliedBillModel: TenantModelProxy<
+      typeof VendorCreditAppliedBill
+    >,
+
+    @Inject(Item.name) private itemModel: TenantModelProxy<typeof Item>,
+  ) {}
+
+  /**
+   * Validates the bill existance.
+   * @param {Bill | undefined | null} bill
+   */
+  public validateBillExistance(bill: Bill | undefined | null) {
+    if (!bill) {
+      throw new ServiceError(ERRORS.BILL_NOT_FOUND);
+    }
+  }
+
+  /**
+   * Validates the bill amount is bigger than paid amount.
+   * @param {number} billAmount
+   * @param {number} paidAmount
+   */
+  public validateBillAmountBiggerPaidAmount(
+    billAmount: number,
+    paidAmount: number,
+  ) {
+    if (billAmount < paidAmount) {
+      throw new ServiceError(ERRORS.BILL_AMOUNT_SMALLER_THAN_PAID_AMOUNT);
+    }
+  }
+
+  /**
+   * Validates the bill number existance.
+   */
+  public async validateBillNumberExists(
+    billNumber: string,
+    notBillId?: number,
+  ) {
+    const foundBills = await this.billModel()
+      .query()
+      .where('bill_number', billNumber)
+      .onBuild((builder) => {
+        if (notBillId) {
+          builder.whereNot('id', notBillId);
+        }
+      });
+
+    if (foundBills.length > 0) {
+      throw new ServiceError(
+        ERRORS.BILL_NUMBER_EXISTS,
+        'The bill number is not unique.',
+      );
+    }
+  }
+
+  /**
+   * Validate the bill has no payment entries.
+   * @param {number} billId - Bill id.
+   */
+  public async validateBillHasNoEntries(billId: number) {
+    // Retrieve the bill associate payment made entries.
+    const entries = await this.billPaymentEntryModel()
+      .query()
+      .where('bill_id', billId);
+
+    if (entries.length > 0) {
+      throw new ServiceError(ERRORS.BILL_HAS_ASSOCIATED_PAYMENT_ENTRIES);
+    }
+    return entries;
+  }
+
+  /**
+   * Validate the bill number require.
+   * @param {string} billNo -
+   */
+  public validateBillNoRequire(billNo: string) {
+    if (!billNo) {
+      throw new ServiceError(ERRORS.BILL_NO_IS_REQUIRED);
+    }
+  }
+
+  /**
+   * Validate bill transaction has no associated allocated landed cost transactions.
+   * @param {number} billId
+   */
+  public async validateBillHasNoLandedCost(billId: number) {
+    const billLandedCosts = await this.billLandedCostModel()
+      .query()
+      .where('billId', billId);
+
+    if (billLandedCosts.length > 0) {
+      throw new ServiceError(ERRORS.BILL_HAS_ASSOCIATED_LANDED_COSTS);
+    }
+  }
+
+  /**
+   * Validate transaction entries that have landed cost type should not be
+   * inventory items.
+   * @param {IItemEntryDTO[]} newEntriesDTO -
+   */
+  public async validateCostEntriesShouldBeInventoryItems(
+    newEntriesDTO: BillEntryDto[],
+  ) {
+    const entriesItemsIds = newEntriesDTO.map((e) => e.itemId);
+    const entriesItems = await this.itemModel()
+      .query()
+      .whereIn('id', entriesItemsIds);
+
+    const entriesItemsById = transformToMap(entriesItems, 'id');
+
+    // Filter the landed cost entries that not associated with inventory item.
+    const nonInventoryHasCost = newEntriesDTO.filter((entry) => {
+      const item = entriesItemsById.get(entry.itemId);
+
+      return entry.landedCost && item.type !== 'inventory';
+    });
+    if (nonInventoryHasCost.length > 0) {
+      throw new ServiceError(
+        ERRORS.LANDED_COST_ENTRIES_SHOULD_BE_INVENTORY_ITEMS,
+      );
+    }
+  }
+
+  /**
+   *
+   * @param {number} billId
+   */
+  public validateBillHasNoAppliedToCredit = async (billId: number) => {
+    const appliedTransactions = await this.vendorCreditAppliedBillModel()
+      .query()
+      .where('billId', billId);
+
+    if (appliedTransactions.length > 0) {
+      throw new ServiceError(ERRORS.BILL_HAS_APPLIED_TO_VENDOR_CREDIT);
+    }
+  };
+
+  /**
+   * Validate the given vendor has no associated bills transactions.
+   * @param {number} vendorId - Vendor id.
+   */
+  public async validateVendorHasNoBills(vendorId: number) {
+    const bills = await this.billModel().query().where('vendor_id', vendorId);
+
+    if (bills.length > 0) {
+      throw new ServiceError(ERRORS.VENDOR_HAS_BILLS);
+    }
+  }
+}

packages/server/src/modules/Bills/commands/CreateBill.service.ts

@@ -0,0 +1,99 @@
+import { Inject, Injectable } from '@nestjs/common';
+import { Knex } from 'knex';
+import {
+  IBillDTO,
+  IBillCreatedPayload,
+  IBillCreatingPayload,
+} from '../Bills.types';
+import { BillDTOTransformer } from './BillDTOTransformer.service';
+import { UnitOfWork } from '@/modules/Tenancy/TenancyDB/UnitOfWork.service';
+import { EventEmitter2 } from '@nestjs/event-emitter';
+import { BillsValidators } from './BillsValidators.service';
+import { ItemsEntriesService } from '@/modules/Items/ItemsEntries.service';
+import { Bill } from '../models/Bill';
+import { Vendor } from '@/modules/Vendors/models/Vendor';
+import { events } from '@/common/events/events';
+import { TenantModelProxy } from '@/modules/System/models/TenantBaseModel';
+import { CreateBillDto } from '../dtos/Bill.dto';
+
+@Injectable()
+export class CreateBill {
+  constructor(
+    private uow: UnitOfWork,
+    private eventPublisher: EventEmitter2,
+    private validators: BillsValidators,
+    private itemsEntriesService: ItemsEntriesService,
+    private transformerDTO: BillDTOTransformer,
+
+    @Inject(Bill.name)
+    private billModel: TenantModelProxy<typeof Bill>,
+
+    @Inject(Vendor.name)
+    private vendorModel: TenantModelProxy<typeof Vendor>,
+  ) {}
+
+  /**
+   * Creates a new bill and stored it to the storage.
+   * ----
+   * Precedures.
+   * ----
+   * - Insert bill transactions to the storage.
+   * - Insert bill entries to the storage.
+   * - Increment the given vendor id.
+   * - Record bill journal transactions on the given accounts.
+   * - Record bill items inventory transactions.
+   * ----
+   * @param  {IBillDTO} billDTO -
+   * @return {Promise<IBill>}
+   */
+  public async createBill(
+    billDTO: CreateBillDto,
+    trx?: Knex.Transaction,
+  ): Promise<Bill> {
+    // Retrieves the given bill vendor or throw not found error.
+    const vendor = await this.vendorModel()
+      .query()
+      .findById(billDTO.vendorId)
+      .throwIfNotFound();
+
+    // Validate the bill number uniqiness on the storage.
+    await this.validators.validateBillNumberExists(billDTO.billNumber);
+
+    // Validate items IDs existance.
+    await this.itemsEntriesService.validateItemsIdsExistance(billDTO.entries);
+
+    // Validate non-purchasable items.
+    await this.itemsEntriesService.validateNonPurchasableEntriesItems(
+      billDTO.entries,
+    );
+    // Validates the cost entries should be with inventory items.
+    await this.validators.validateCostEntriesShouldBeInventoryItems(
+      billDTO.entries,
+    );
+    // Transform the bill DTO to model object.
+    const billObj = await this.transformerDTO.billDTOToModel(billDTO, vendor);
+
+    // Write new bill transaction with associated transactions under UOW env.
+    return this.uow.withTransaction(async (trx: Knex.Transaction) => {
+      // Triggers `onBillCreating` event.
+      await this.eventPublisher.emitAsync(events.bill.onCreating, {
+        trx,
+        billDTO,
+      } as IBillCreatingPayload);
+
+      // Inserts the bill graph object to the storage.
+      const bill = await this.billModel()
+        .query(trx)
+        .upsertGraphAndFetch(billObj);
+
+      // Triggers `onBillCreated` event.
+      await this.eventPublisher.emitAsync(events.bill.onCreated, {
+        bill,
+        billDTO,
+        trx,
+      } as IBillCreatedPayload);
+
+      return bill;
+    }, trx);
+  }
+}

packages/server/src/modules/Bills/commands/DeleteBill.service.ts

@@ -0,0 +1,80 @@
+import { Inject, Injectable } from '@nestjs/common';
+import { Knex } from 'knex';
+import { events } from '@/common/events/events';
+import {
+  IBIllEventDeletedPayload,
+  IBillEventDeletingPayload,
+} from '../Bills.types';
+import { BillsValidators } from './BillsValidators.service';
+import { UnitOfWork } from '@/modules/Tenancy/TenancyDB/UnitOfWork.service';
+import { EventEmitter2 } from '@nestjs/event-emitter';
+import { ItemEntry } from '@/modules/TransactionItemEntry/models/ItemEntry';
+import { Bill } from '../models/Bill';
+import { TenantModelProxy } from '@/modules/System/models/TenantBaseModel';
+
+@Injectable()
+export class DeleteBill {
+  constructor(
+    private readonly validators: BillsValidators,
+    private readonly uow: UnitOfWork,
+    private readonly eventPublisher: EventEmitter2,
+
+    @Inject(Bill.name)
+    private readonly billModel: TenantModelProxy<typeof Bill>,
+
+    @Inject(ItemEntry.name)
+    private readonly itemEntryModel: TenantModelProxy<typeof ItemEntry>,
+  ) {}
+
+  /**
+   * Deletes the bill with associated entries.
+   * @param {number} billId
+   * @return {void}
+   */
+  public async deleteBill(billId: number) {
+    // Retrieve the given bill or throw not found error.
+    const oldBill = await this.billModel()
+      .query()
+      .findById(billId)
+      .withGraphFetched('entries');
+
+    // Validates the bill existence.
+    this.validators.validateBillExistance(oldBill);
+
+    // Validate the given bill has no associated landed cost transactions.
+    await this.validators.validateBillHasNoLandedCost(billId);
+
+    // Validate the purchase bill has no associated payments transactions.
+    await this.validators.validateBillHasNoEntries(billId);
+
+    // Validate the given bill has no associated reconciled with vendor credits.
+    await this.validators.validateBillHasNoAppliedToCredit(billId);
+
+    // Deletes bill transaction with associated transactions under
+    // unit-of-work environment.
+    return this.uow.withTransaction(async (trx: Knex.Transaction) => {
+      // Triggers `onBillDeleting` event.
+      await this.eventPublisher.emitAsync(events.bill.onDeleting, {
+        trx,
+        oldBill,
+      } as IBillEventDeletingPayload);
+
+      // Delete all associated bill entries.
+      await this.itemEntryModel()
+        .query(trx)
+        .where('reference_type', 'Bill')
+        .where('reference_id', billId)
+        .delete();
+
+      // Delete the bill transaction.
+      await Bill.query(trx).findById(billId).delete();
+
+      // Triggers `onBillDeleted` event.
+      await this.eventPublisher.emitAsync(events.bill.onDeleted, {
+        billId,
+        oldBill,
+        trx,
+      } as IBIllEventDeletedPayload);
+    });
+  }
+}

packages/server/src/modules/Bills/commands/EditBill.service.ts

@@ -0,0 +1,135 @@
+import {
+  IBillEditDTO,
+  IBillEditedPayload,
+  IBillEditingPayload,
+} from '../Bills.types';
+import { Inject, Injectable } from '@nestjs/common';
+import { BillsValidators } from './BillsValidators.service';
+import { ItemsEntriesService } from '@/modules/Items/ItemsEntries.service';
+import { UnitOfWork } from '@/modules/Tenancy/TenancyDB/UnitOfWork.service';
+import { EventEmitter2 } from '@nestjs/event-emitter';
+import { BillDTOTransformer } from './BillDTOTransformer.service';
+import { Bill } from '../models/Bill';
+import { events } from '@/common/events/events';
+import { Vendor } from '@/modules/Vendors/models/Vendor';
+import { Knex } from 'knex';
+import { TransactionLandedCostEntriesService } from '@/modules/BillLandedCosts/TransactionLandedCostEntries.service';
+import { TenantModelProxy } from '@/modules/System/models/TenantBaseModel';
+import { EditBillDto } from '../dtos/Bill.dto';
+
+@Injectable()
+export class EditBillService {
+  constructor(
+    private validators: BillsValidators,
+    private itemsEntriesService: ItemsEntriesService,
+    private uow: UnitOfWork,
+    private eventPublisher: EventEmitter2,
+    private transactionLandedCostEntries: TransactionLandedCostEntriesService,
+    private transformerDTO: BillDTOTransformer,
+
+    @Inject(Bill.name) private billModel: TenantModelProxy<typeof Bill>,
+    @Inject(Vendor.name) private contactModel: TenantModelProxy<typeof Vendor>,
+  ) {}
+
+  /**
+   * Edits details of the given bill id with associated entries.
+   *
+   * Precedures:
+   * -------
+   * - Update the bill transaction on the storage.
+   * - Update the bill entries on the storage and insert the not have id and delete
+   *   once that not presented.
+   * - Increment the diff amount on the given vendor id.
+   * - Re-write the inventory transactions.
+   * - Re-write the bill journal transactions.
+   * ------
+   * @param {Integer} billId - The given bill id.
+   * @param {IBillEditDTO} billDTO - The given new bill details.
+   * @return {Promise<IBill>}
+   */
+  public async editBill(billId: number, billDTO: EditBillDto): Promise<Bill> {
+    // Retrieve the given bill or throw not found error.
+    const oldBill = await this.billModel()
+      .query()
+      .findById(billId)
+      .withGraphFetched('entries');
+
+    // Validate bill existance.
+    this.validators.validateBillExistance(oldBill);
+
+    // Retrieve vendor details or throw not found service error.
+    const vendor = await this.contactModel()
+      .query()
+      .findById(billDTO.vendorId)
+      .modify('vendor')
+      .throwIfNotFound();
+
+    // Validate bill number uniqiness on the storage.
+    if (billDTO.billNumber) {
+      await this.validators.validateBillNumberExists(
+        billDTO.billNumber,
+        billId,
+      );
+    }
+    // Validate the entries ids existance.
+    await this.itemsEntriesService.validateEntriesIdsExistance(
+      billId,
+      'Bill',
+      billDTO.entries,
+    );
+    // Validate the items ids existance on the storage.
+    await this.itemsEntriesService.validateItemsIdsExistance(billDTO.entries);
+    // Accept the purchasable items only.
+    await this.itemsEntriesService.validateNonPurchasableEntriesItems(
+      billDTO.entries,
+    );
+
+    // Transforms the bill DTO to model object.
+    const billObj = await this.transformerDTO.billDTOToModel(
+      billDTO,
+      vendor,
+      oldBill,
+    );
+    // Validate bill total amount should be bigger than paid amount.
+    this.validators.validateBillAmountBiggerPaidAmount(
+      billObj.amount,
+      oldBill.paymentAmount,
+    );
+    // Validate landed cost entries that have allocated cost could not be deleted.
+    await this.transactionLandedCostEntries.validateLandedCostEntriesNotDeleted(
+      oldBill.entries,
+      billObj.entries,
+    );
+    // Validate new landed cost entries should be bigger than new entries.
+    await this.transactionLandedCostEntries.validateLocatedCostEntriesSmallerThanNewEntries(
+      oldBill.entries,
+      billObj.entries,
+    );
+    // Edits bill transactions and associated transactions under UOW envirement.
+    return this.uow.withTransaction(async (trx: Knex.Transaction) => {
+      // Triggers `onBillEditing` event.
+      await this.eventPublisher.emitAsync(events.bill.onEditing, {
+        oldBill,
+        billDTO,
+        trx,
+      } as IBillEditingPayload);
+
+      // Update the bill transaction.
+      const bill = await this.billModel()
+        .query(trx)
+        .upsertGraphAndFetch({
+          id: billId,
+          ...billObj,
+        });
+      // Triggers event `onBillEdited`.
+      await this.eventPublisher.emitAsync(events.bill.onEdited, {
+        oldBill,
+        bill,
+        billDTO,
+        trx,
+      } as IBillEditedPayload);
+
+      return bill;
+    });
+  }
+}

packages/server/src/modules/Bills/commands/OpenBill.service.ts

@@ -0,0 +1,66 @@
+import * as moment from 'moment';
+import { Inject, Injectable } from '@nestjs/common';
+import { ERRORS } from '../Bills.constants';
+import { BillsValidators } from './BillsValidators.service';
+import { IBillOpenedPayload, IBillOpeningPayload } from '../Bills.types';
+import { Bill } from '../models/Bill';
+import { EventEmitter2 } from '@nestjs/event-emitter';
+import { UnitOfWork } from '@/modules/Tenancy/TenancyDB/UnitOfWork.service';
+import { ServiceError } from '@/modules/Items/ServiceError';
+import { events } from '@/common/events/events';
+import { TenantModelProxy } from '@/modules/System/models/TenantBaseModel';
+
+@Injectable()
+export class OpenBillService {
+  constructor(
+    private readonly uow: UnitOfWork,
+    private readonly validators: BillsValidators,
+    private readonly eventPublisher: EventEmitter2,
+
+    @Inject(Bill.name)
+    private readonly billModel: TenantModelProxy<typeof Bill>,
+  ) {}
+
+  /**
+   * Mark the bill as open.
+   * @param {number} billId - Bill id.
+   * @return {Promise<void>}
+   */
+  public async openBill(billId: number): Promise<void> {
+    // Retrieve the given bill or throw not found error.
+    const oldBill = await this.billModel()
+      .query()
+      .findById(billId)
+      .withGraphFetched('entries');
+
+    // Validates the bill existence.
+    this.validators.validateBillExistance(oldBill);
+
+    if (oldBill.isOpen) {
+      throw new ServiceError(ERRORS.BILL_ALREADY_OPEN);
+    }
+
+    return this.uow.withTransaction(async (trx) => {
+      // Triggers `onBillCreating` event.
+      await this.eventPublisher.emitAsync(events.bill.onOpening, {
+        oldBill,
+        trx,
+      } as IBillOpeningPayload);
+
+      // Save the bill opened at on the storage.
+      const bill = await this.billModel()
+        .query(trx)
+        .patchAndFetchById(billId, {
+          openedAt: moment().toMySqlDateTime(),
+        })
+        .withGraphFetched('entries');
+
+      // Triggers `onBillCreating` event.
+      await this.eventPublisher.emitAsync(events.bill.onOpened, {
+        bill,
+        oldBill,
+        trx,
+      } as IBillOpenedPayload);
+    });
+  }
+}

packages/server/src/modules/Bills/dtos/Bill.dto.ts

@@ -0,0 +1,107 @@
+import { ItemEntryDto } from '@/modules/TransactionItemEntry/dto/ItemEntry.dto';
+import { Type } from 'class-transformer';
+import {
+  ArrayMinSize,
+  IsArray,
+  IsBoolean,
+  IsDate,
+  IsEnum,
+  IsInt,
+  IsNumber,
+  IsOptional,
+  IsPositive,
+  IsString,
+  Min,
+  MinLength,
+  ValidateNested,
+} from 'class-validator';
+
+enum DiscountType {
+  Percentage = 'percentage',
+  Amount = 'amount',
+}
+
+export class BillEntryDto extends ItemEntryDto {
+  @IsOptional()
+  @IsBoolean()
+  landedCost?: boolean;
+}
+
+class AttachmentDto {
+  @IsString()
+  key: string;
+}
+
+export class CommandBillDto {
+  @IsString()
+  billNumber: string;
+
+  @IsOptional()
+  @IsString()
+  referenceNo?: string;
+
+  @IsDate()
+  @Type(() => Date)
+  billDate: Date;
+
+  @IsOptional()
+  @IsDate()
+  @Type(() => Date)
+  dueDate?: Date;
+
+  @IsInt()
+  vendorId: number;
+
+  @IsOptional()
+  @IsNumber()
+  @IsPositive()
+  exchangeRate?: number;
+
+  @IsOptional()
+  @IsInt()
+  warehouseId?: number;
+
+  @IsOptional()
+  @IsInt()
+  branchId?: number;
+
+  @IsOptional()
+  @IsInt()
+  projectId?: number;
+
+  @IsOptional()
+  @IsString()
+  note?: string;
+
+  @IsBoolean()
+  open: boolean = false;
+
+  @IsBoolean()
+  isInclusiveTax: boolean = false;
+
+  @IsArray()
+  @ValidateNested({ each: true })
+  @Type(() => BillEntryDto)
+  @ArrayMinSize(1)
+  entries: BillEntryDto[];
+
+  @IsOptional()
+  @IsArray()
+  @ValidateNested({ each: true })
+  @Type(() => AttachmentDto)
+  attachments?: AttachmentDto[];
+
+  @IsEnum(DiscountType)
+  discountType: DiscountType = DiscountType.Amount;
+
+  @IsOptional()
+  @IsNumber()
+  discount?: number;
+
+  @IsOptional()
+  @IsNumber()
+  adjustment?: number;
+}
+
+export class CreateBillDto extends CommandBillDto {}
+export class EditBillDto extends CommandBillDto {}

packages/server/src/modules/Bills/models/Bill.ts

@@ -0,0 +1,659 @@
+import { Model, raw, mixin } from 'objection';
+import { castArray, difference, defaultTo } from 'lodash';
+import * as moment from 'moment';
+import * as R from 'ramda';
+// import TenantModel from 'models/TenantModel';
+// import BillSettings from './Bill.Settings';
+// import ModelSetting from './ModelSetting';
+// import CustomViewBaseModel from './CustomViewBaseModel';
+// import { DEFAULT_VIEWS } from '@/services/Purchases/Bills/constants';
+// import ModelSearchable from './ModelSearchable';
+import { BaseModel, PaginationQueryBuilderType } from '@/models/Model';
+import { ItemEntry } from '@/modules/TransactionItemEntry/models/ItemEntry';
+import { BillLandedCost } from '@/modules/BillLandedCosts/models/BillLandedCost';
+import { DiscountType } from '@/common/types/Discount';
+import type { Knex, QueryBuilder } from 'knex';
+import { TenantBaseModel } from '@/modules/System/models/TenantBaseModel';
+
+export class Bill extends TenantBaseModel {
+  public amount: number;
+  public paymentAmount: number;
+  public landedCostAmount: number;
+  public allocatedCostAmount: number;
+  public isInclusiveTax: boolean;
+  public taxAmountWithheld: number;
+  public exchangeRate: number;
+  public vendorId: number;
+  public billNumber: string;
+  public billDate: Date;
+  public dueDate: Date;
+  public referenceNo: string;
+  public status: string;
+  public note: string;
+  public currencyCode: string;
+  public creditedAmount: number;
+  public invLotNumber: string;
+  public invoicedAmount: number;
+  public openedAt: Date | string;
+  public userId: number;
+
+  public discountType: DiscountType;
+  public discount: number;
+  public adjustment: number;
+
+  public branchId: number;
+  public warehouseId: number;
+  public projectId: number;
+
+  public createdAt: Date;
+  public updatedAt: Date | null;
+
+  public entries?: ItemEntry[];
+  public locatedLandedCosts?: BillLandedCost[];
+  /**
+   * Timestamps columns.
+   */
+  get timestamps() {
+    return ['createdAt', 'updatedAt'];
+  }
+
+  /**
+   * Virtual attributes.
+   */
+  static get virtualAttributes() {
+    return [
+      'balance',
+      'dueAmount',
+      'isOpen',
+      'isPartiallyPaid',
+      'isFullyPaid',
+      'isPaid',
+      'remainingDays',
+      'overdueDays',
+      'isOverdue',
+      'unallocatedCostAmount',
+      'localAmount',
+      'localAllocatedCostAmount',
+      'billableAmount',
+      'amountLocal',
+
+      'discountAmount',
+      'discountAmountLocal',
+      'discountPercentage',
+
+      'adjustmentLocal',
+
+      'subtotal',
+      'subtotalLocal',
+      'subtotalExludingTax',
+      'taxAmountWithheldLocal',
+      'total',
+      'totalLocal',
+    ];
+  }
+
+  /**
+   * Invoice amount in base currency.
+   * @returns {number}
+   */
+  get amountLocal(): number {
+    return this.amount * this.exchangeRate;
+  }
+
+  /**
+   * Subtotal. (Tax inclusive) if the tax inclusive is enabled.
+   * @returns {number}
+   */
+  get subtotal(): number {
+    return this.amount;
+  }
+
+  /**
+   * Subtotal in base currency. (Tax inclusive) if the tax inclusive is enabled.
+   * @returns {number}
+   */
+  get subtotalLocal(): number {
+    return this.amountLocal;
+  }
+
+  /**
+   * Sale invoice amount excluding tax.
+   * @returns {number}
+   */
+  get subtotalExcludingTax(): number {
+    return this.isInclusiveTax
+      ? this.subtotal - this.taxAmountWithheld
+      : this.subtotal;
+  }
+
+  /**
+   * Tax amount withheld in base currency.
+   * @returns {number}
+   */
+  get taxAmountWithheldLocal(): number {
+    return this.taxAmountWithheld * this.exchangeRate;
+  }
+
+  /**
+   * Discount amount.
+   * @returns {number}
+   */
+  get discountAmount(): number {
+    return this.discountType === DiscountType.Amount
+      ? this.discount
+      : this.subtotal * (this.discount / 100);
+  }
+
+  /**
+   * Discount amount in local currency.
+   * @returns {number | null}
+   */
+  get discountAmountLocal(): number | null {
+    return this.discountAmount ? this.discountAmount * this.exchangeRate : null;
+  }
+
+  /**
+  /**
+   * Discount percentage.
+   * @returns {number | null}
+   */
+  get discountPercentage(): number | null {
+    return this.discountType === DiscountType.Percentage ? this.discount : null;
+  }
+
+  /**
+   * Adjustment amount in local currency.
+   * @returns {number | null}
+   */
+  get adjustmentLocal(): number | null {
+    return this.adjustment ? this.adjustment * this.exchangeRate : null;
+  }
+
+  /**
+   * Invoice total. (Tax included)
+   * @returns {number}
+   */
+  get total(): number {
+    const adjustmentAmount = defaultTo(this.adjustment, 0);
+
+    return R.compose(
+      R.add(adjustmentAmount),
+      R.subtract(R.__, this.discountAmount),
+      R.when(R.always(this.isInclusiveTax), R.add(this.taxAmountWithheld)),
+    )(this.subtotal);
+  }
+
+  /**
+   * Invoice total in local currency. (Tax included)
+   * @returns {number}
+   */
+  get totalLocal(): number {
+    return this.total * this.exchangeRate;
+  }
+
+  /**
+   * Invoice amount in organization base currency.
+   * @deprecated
+   * @returns {number}
+   */
+  get localAmount(): number {
+    return this.amountLocal;
+  }
+
+  /**
+   * Retrieves the local allocated cost amount.
+   * @returns {number}
+   */
+  get localAllocatedCostAmount(): number {
+    return this.allocatedCostAmount * this.exchangeRate;
+  }
+
+  /**
+   * Retrieves the local landed cost amount.
+   * @returns {number}
+   */
+  get localLandedCostAmount(): number {
+    return this.landedCostAmount * this.exchangeRate;
+  }
+
+  /**
+   * Retrieves the local unallocated cost amount.
+   * @returns {number}
+   */
+  get localUnallocatedCostAmount(): number {
+    return this.unallocatedCostAmount * this.exchangeRate;
+  }
+
+  /**
+   * Retrieve the balance of bill.
+   * @return {number}
+   */
+  get balance(): number {
+    return this.paymentAmount + this.creditedAmount;
+  }
+
+  /**
+   * Due amount of the given.
+   * @return {number}
+   */
+  get dueAmount(): number {
+    return Math.max(this.total - this.balance, 0);
+  }
+
+  /**
+   * Detarmine whether the bill is open.
+   * @return {boolean}
+   */
+  get isOpen(): boolean {
+    return !!this.openedAt;
+  }
+
+  /**
+   * Deetarmine whether the bill paid partially.
+   * @return {boolean}
+   */
+  get isPartiallyPaid(): boolean {
+    return this.dueAmount !== this.total && this.dueAmount > 0;
+  }
+
+  /**
+   * Deetarmine whether the bill paid fully.
+   * @return {boolean}
+   */
+  get isFullyPaid(): boolean {
+    return this.dueAmount === 0;
+  }
+
+  /**
+   * Detarmines whether the bill paid fully or partially.
+   * @return {boolean}
+   */
+  get isPaid(): boolean {
+    return this.isPartiallyPaid || this.isFullyPaid;
+  }
+
+  /**
+   * Retrieve the remaining days in number
+   * @return {number|null}
+   */
+  get remainingDays(): number | null {
+    const currentMoment = moment();
+    const dueDateMoment = moment(this.dueDate);
+
+    return Math.max(dueDateMoment.diff(currentMoment, 'days'), 0);
+  }
+
+  /**
+   * Retrieve the overdue days in number.
+   * @return {number|null}
+   */
+  get overdueDays(): number | null {
+    const currentMoment = moment();
+    const dueDateMoment = moment(this.dueDate);
+
+    return Math.max(currentMoment.diff(dueDateMoment, 'days'), 0);
+  }
+
+  /**
+   * Detarmines the due date is over.
+   * @return {boolean}
+   */
+  get isOverdue(): boolean {
+    return this.overdueDays > 0;
+  }
+
+  /**
+   * Retrieve the unallocated cost amount.
+   * @return {number}
+   */
+  get unallocatedCostAmount(): number {
+    return Math.max(this.landedCostAmount - this.allocatedCostAmount, 0);
+  }
+
+  /**
+   * Retrieves the calculated amount which have not been invoiced.
+   */
+  get billableAmount(): number {
+    return Math.max(this.total - this.invoicedAmount, 0);
+  }
+
+  /**
+   * Table name
+   */
+  static get tableName() {
+    return 'bills';
+  }
+
+  /**
+   * Model modifiers.
+   */
+  static get modifiers() {
+    return {
+      /**
+       * Filters the bills in draft status.
+       */
+      draft(query) {
+        query.where('opened_at', null);
+      },
+
+      /**
+       * Filters the opened bills.
+       */
+      published(query) {
+        query.whereNot('openedAt', null);
+      },
+
+      /**
+       * Filters the opened bills.
+       */
+      opened(query) {
+        query.whereNot('opened_at', null);
+      },
+      /**
+       * Filters the unpaid bills.
+       */
+      unpaid(query) {
+        query.where('payment_amount', 0);
+      },
+      /**
+       * Filters the due bills.
+       */
+      dueBills(query) {
+        query.where(
+          raw(`COALESCE(AMOUNT, 0) -
+            COALESCE(PAYMENT_AMOUNT, 0) -
+            COALESCE(CREDITED_AMOUNT, 0) > 0
+          `),
+        );
+      },
+      /**
+       * Filters the overdue bills.
+       */
+      overdue(query) {
+        query.where('due_date', '<', moment().format('YYYY-MM-DD'));
+      },
+      /**
+       * Filters the not overdue invoices.
+       */
+      notOverdue(query, asDate = moment().format('YYYY-MM-DD')) {
+        query.where('due_date', '>=', asDate);
+      },
+      /**
+       * Filters the partially paid bills.
+       */
+      partiallyPaid(query) {
+        query.whereNot('payment_amount', 0);
+        query.whereNot(raw('`PAYMENT_AMOUNT` = `AMOUNT`'));
+      },
+      /**
+       * Filters the paid bills.
+       */
+      paid(query) {
+        query.where(raw('`PAYMENT_AMOUNT` = `AMOUNT`'));
+      },
+      /**
+       * Filters the bills from the given date.
+       */
+      fromDate(query, fromDate) {
+        query.where('bill_date', '<=', fromDate);
+      },
+
+      /**
+       * Sort the bills by full-payment bills.
+       */
+      sortByStatus(query, order) {
+        query.orderByRaw(`PAYMENT_AMOUNT = AMOUNT ${order}`);
+      },
+
+      /**
+       * Status filter.
+       */
+      statusFilter(query, filterType) {
+        switch (filterType) {
+          case 'draft':
+            query.modify('draft');
+            break;
+          case 'delivered':
+            query.modify('delivered');
+            break;
+          case 'unpaid':
+            query.modify('unpaid');
+            break;
+          case 'overdue':
+          default:
+            query.modify('overdue');
+            break;
+          case 'partially-paid':
+            query.modify('partiallyPaid');
+            break;
+          case 'paid':
+            query.modify('paid');
+            break;
+        }
+      },
+
+      /**
+       * Filters by branches.
+       */
+      filterByBranches(query, branchesIds) {
+        const formattedBranchesIds = castArray(branchesIds);
+
+        query.whereIn('branchId', formattedBranchesIds);
+      },
+
+      dueBillsFromDate(query, asDate = moment().format('YYYY-MM-DD')) {
+        query.modify('dueBills');
+        query.modify('notOverdue');
+        query.modify('fromDate', asDate);
+      },
+
+      overdueBillsFromDate(query, asDate = moment().format('YYYY-MM-DD')) {
+        query.modify('dueBills');
+        query.modify('overdue', asDate);
+        query.modify('fromDate', asDate);
+      },
+
+      /**
+       *
+       */
+      billable(query) {
+        query.where(raw('AMOUNT > INVOICED_AMOUNT'));
+      },
+    };
+  }
+
+  /**
+   * Bill model settings.
+   */
+  // static get meta() {
+  //   return BillSettings;
+  // }
+
+  /**
+   * Relationship mapping.
+   */
+  static get relationMappings() {
+    const { Vendor } = require('../../Vendors/models/Vendor');
+    const {
+      ItemEntry,
+    } = require('../../TransactionItemEntry/models/ItemEntry');
+    const {
+      BillLandedCost,
+    } = require('../../BillLandedCosts/models/BillLandedCost');
+    const { Branch } = require('../../Branches/models/Branch.model');
+    const { Warehouse } = require('../../Warehouses/models/Warehouse.model');
+    const { TaxRateModel } = require('../../TaxRates/models/TaxRate.model');
+    const {
+      TaxRateTransaction,
+    } = require('../../TaxRates/models/TaxRateTransaction.model');
+    const { Document } = require('../../ChromiumlyTenancy/models/Document');
+    // const { MatchedBankTransaction } = require('models/MatchedBankTransaction');
+
+    return {
+      vendor: {
+        relation: Model.BelongsToOneRelation,
+        modelClass: Vendor,
+        join: {
+          from: 'bills.vendorId',
+          to: 'contacts.id',
+        },
+        filter(query) {
+          query.where('contact_service', 'vendor');
+        },
+      },
+
+      entries: {
+        relation: Model.HasManyRelation,
+        modelClass: ItemEntry,
+        join: {
+          from: 'bills.id',
+          to: 'items_entries.referenceId',
+        },
+        filter(builder) {
+          builder.where('reference_type', 'Bill');
+          builder.orderBy('index', 'ASC');
+        },
+      },
+
+      locatedLandedCosts: {
+        relation: Model.HasManyRelation,
+        modelClass: BillLandedCost,
+        join: {
+          from: 'bills.id',
+          to: 'bill_located_costs.billId',
+        },
+      },
+
+      /**
+       * Bill may belongs to associated branch.
+       */
+      branch: {
+        relation: Model.BelongsToOneRelation,
+        modelClass: Branch,
+        join: {
+          from: 'bills.branchId',
+          to: 'branches.id',
+        },
+      },
+
+      /**
+       * Bill may has associated warehouse.
+       */
+      warehouse: {
+        relation: Model.BelongsToOneRelation,
+        modelClass: Warehouse,
+        join: {
+          from: 'bills.warehouseId',
+          to: 'warehouses.id',
+        },
+      },
+
+      /**
+       * Bill may has associated tax rate transactions.
+       */
+      taxes: {
+        relation: Model.HasManyRelation,
+        modelClass: TaxRateTransaction,
+        join: {
+          from: 'bills.id',
+          to: 'tax_rate_transactions.referenceId',
+        },
+        filter(builder) {
+          builder.where('reference_type', 'Bill');
+        },
+      },
+
+      /**
+       * Bill may has many attached attachments.
+       */
+      attachments: {
+        relation: Model.ManyToManyRelation,
+        modelClass: Document,
+        join: {
+          from: 'bills.id',
+          through: {
+            from: 'document_links.modelId',
+            to: 'document_links.documentId',
+          },
+          to: 'documents.id',
+        },
+        filter(query) {
+          query.where('model_ref', 'Bill');
+        },
+      },
+
+      /**
+       * Bill may belongs to matched bank transaction.
+       */
+      // matchedBankTransaction: {
+      //   relation: Model.HasManyRelation,
+      //   modelClass: MatchedBankTransaction,
+      //   join: {
+      //     from: 'bills.id',
+      //     to: 'matched_bank_transactions.referenceId',
+      //   },
+      //   filter(query) {
+      //     query.where('reference_type', 'Bill');
+      //   },
+      // },
+    };
+  }
+
+  /**
+   * Retrieve the not found bills ids as array that associated to the given vendor.
+   * @param {Array} billsIds
+   * @param {number} vendorId -
+   * @return {Array}
+   */
+  static async getNotFoundBills(billsIds, vendorId) {
+    const storedBills = await this.query().onBuild((builder) => {
+      builder.whereIn('id', billsIds);
+
+      if (vendorId) {
+        builder.where('vendor_id', vendorId);
+      }
+    });
+
+    const storedBillsIds = storedBills.map((t) => t.id);
+
+    const notFoundBillsIds = difference(billsIds, storedBillsIds);
+    return notFoundBillsIds;
+  }
+
+  static changePaymentAmount(
+    billId: number,
+    amount: number,
+    trx: Knex.Transaction,
+  ) {
+    const changeMethod = amount > 0 ? 'increment' : 'decrement';
+
+    return this.query(trx)
+      .where('id', billId)
+      [changeMethod]('payment_amount', Math.abs(amount));
+  }
+
+  /**
+   * Retrieve the default custom views, roles and columns.
+   */
+  // static get defaultViews() {
+  //   return DEFAULT_VIEWS;
+  // }
+
+  /**
+   * Model search attributes.
+   */
+  static get searchRoles() {
+    return [
+      { fieldKey: 'bill_number', comparator: 'contains' },
+      { condition: 'or', fieldKey: 'reference_no', comparator: 'contains' },
+      { condition: 'or', fieldKey: 'amount', comparator: 'equals' },
+    ];
+  }
+
+  /**
+   * Prevents mutate base currency since the model is not empty.
+   */
+  static get preventMutateBaseCurrency() {
+    return true;
+  }
+}

packages/server/src/modules/Bills/queries/Bill.transformer.ts

@@ -0,0 +1,217 @@
+import { Transformer } from '@/modules/Transformer/Transformer';
+import { Bill } from '../models/Bill';
+import { AttachmentTransformer } from '@/modules/Attachments/Attachment.transformer';
+import { ItemEntryTransformer } from '@/modules/TransactionItemEntry/ItemEntry.transformer';
+import { SaleInvoiceTaxEntryTransformer } from '@/modules/SaleInvoices/queries/SaleInvoiceTaxEntry.transformer';
+
+export class BillTransformer extends Transformer {
+  /**
+   * Include these attributes to sale bill object.
+   * @returns {Array}
+   */
+  public includeAttributes = (): string[] => {
+    return [
+      'formattedBillDate',
+      'formattedDueDate',
+      'formattedCreatedAt',
+      'formattedAmount',
+      'formattedPaymentAmount',
+      'formattedBalance',
+      'formattedDueAmount',
+      'formattedExchangeRate',
+      'subtotalFormatted',
+      'subtotalLocalFormatted',
+      'subtotalExcludingTaxFormatted',
+      'taxAmountWithheldLocalFormatted',
+      'totalFormatted',
+      'totalLocalFormatted',
+      'taxes',
+      'entries',
+      'attachments',
+    ];
+  };
+
+  /**
+   * Excluded attributes.
+   * @returns {string[]}
+   */
+  public excludeAttributes = (): string[] => {
+    return ['amount', 'amountLocal', 'localAmount'];
+  };
+
+  /**
+   * Retrieve formatted bill date.
+   * @param {IBill} bill
+   * @returns {String}
+   */
+  protected formattedBillDate = (bill: Bill): string => {
+    return this.formatDate(bill.billDate);
+  };
+
+  /**
+   * Retrieve formatted bill date.
+   * @param {IBill} bill
+   * @returns {String}
+   */
+  protected formattedDueDate = (bill: Bill): string => {
+    return this.formatDate(bill.dueDate);
+  };
+
+  /**
+   * Retrieve the formatted created at date.
+   * @param {IBill} bill
+   * @returns {string}
+   */
+  protected formattedCreatedAt = (bill: Bill): string => {
+    return this.formatDate(bill.createdAt);
+  };
+
+  /**
+   * Retrieve formatted bill amount.
+   * @param {IBill} bill
+   * @returns {string}
+   */
+  protected formattedAmount = (bill: Bill): string => {
+    return this.formatNumber(bill.amount, { currencyCode: bill.currencyCode });
+  };
+
+  /**
+   * Retrieve formatted bill amount.
+   * @param {IBill} bill
+   * @returns {string}
+   */
+  protected formattedPaymentAmount = (bill: Bill): string => {
+    return this.formatNumber(bill.paymentAmount, {
+      currencyCode: bill.currencyCode,
+    });
+  };
+
+  /**
+   * Retrieve formatted bill amount.
+   * @param {IBill} bill
+   * @returns {string}
+   */
+  protected formattedDueAmount = (bill: Bill): string => {
+    return this.formatNumber(bill.dueAmount, {
+      currencyCode: bill.currencyCode,
+    });
+  };
+
+  /**
+   * Retrieve formatted bill balance.
+   * @param {IBill} bill
+   * @returns {string}
+   */
+  protected formattedBalance = (bill: Bill): string => {
+    return this.formatNumber(bill.balance, { currencyCode: bill.currencyCode });
+  };
+
+  /**
+   * Retrieve the formatted exchange rate.
+   * @param {IBill} bill
+   * @returns {string}
+   */
+  protected formattedExchangeRate = (bill: Bill): string => {
+    return this.formatNumber(bill.exchangeRate, {
+      currencyCode: this.context.organization.baseCurrency,
+    });
+  };
+
+  /**
+   * Retrieves the formatted subtotal.
+   * @param {IBill} bill
+   * @returns {string}
+   */
+  protected subtotalFormatted = (bill: Bill): string => {
+    return this.formatNumber(bill.subtotal, {
+      currencyCode: bill.currencyCode,
+    });
+  };
+
+  /**
+   * Retrieves the local subtotal formatted.
+   * @param {IBill} bill
+   * @returns {string}
+   */
+  protected subtotalLocalFormatted = (bill: Bill): string => {
+    return this.formatNumber(bill.subtotalLocal, {
+      currencyCode: this.context.organization.baseCurrency,
+    });
+  };
+
+  /**
+   * Retrieves the formatted subtotal tax excluded.
+   * @param {IBill} bill
+   * @returns {string}
+   */
+  protected subtotalExcludingTaxFormatted = (bill: Bill): string => {
+    return this.formatNumber(bill.subtotalExcludingTax, {
+      currencyCode: bill.currencyCode,
+    });
+  };
+
+  /**
+   * Retrieves the local formatted tax amount withheld
+   * @param {IBill} bill
+   * @returns {string}
+   */
+  protected taxAmountWithheldLocalFormatted = (bill: Bill): string => {
+    return this.formatNumber(bill.taxAmountWithheldLocal, {
+      currencyCode: this.context.organization.baseCurrency,
+    });
+  };
+
+  /**
+   * Retrieves the total formatted.
+   * @param {IBill} bill
+   * @returns {string}
+   */
+  protected totalFormatted = (bill: Bill): string => {
+    return this.formatNumber(bill.total, {
+      currencyCode: bill.currencyCode,
+    });
+  };
+
+  /**
+   * Retrieves the local total formatted.
+   * @param {IBill} bill
+   * @returns {string}
+   */
+  protected totalLocalFormatted = (bill: Bill): string => {
+    return this.formatNumber(bill.totalLocal, {
+      currencyCode: this.context.organization.baseCurrency,
+    });
+  };
+
+  /**
+   * Retrieve the taxes lines of bill.
+   * @param {Bill} bill
+   */
+  // protected taxes = (bill: Bill) => {
+  //   return this.item(bill.taxes, new SaleInvoiceTaxEntryTransformer(), {
+  //     subtotal: bill.subtotal,
+  //     isInclusiveTax: bill.isInclusiveTax,
+  //     currencyCode: bill.currencyCode,
+  //   });
+  // };
+
+  /**
+   * Retrieves the entries of the bill.
+   * @param {Bill} credit
+   * @returns {}
+   */
+  // protected entries = (bill: Bill) => {
+  //   return this.item(bill.entries, new ItemEntryTransformer(), {
+  //     currencyCode: bill.currencyCode,
+  //   });
+  // };
+
+  /**
+   * Retrieves the bill attachments.
+   * @param {ISaleInvoice} invoice
+   * @returns
+   */
+  // protected attachments = (bill: Bill) => {
+  //   return this.item(bill.attachments, new AttachmentTransformer());
+  // };
+}

packages/server/src/modules/Bills/queries/GetBill.ts

@@ -0,0 +1,37 @@
+import { Inject, Injectable } from '@nestjs/common';
+import { BillsValidators } from '../commands/BillsValidators.service';
+import { BillTransformer } from './Bill.transformer';
+import { Bill } from '../models/Bill';
+import { TransformerInjectable } from '@/modules/Transformer/TransformerInjectable.service';
+import { TenantModelProxy } from '@/modules/System/models/TenantBaseModel';
+
+@Injectable()
+export class GetBill {
+  constructor(
+    @Inject(Bill.name) private billModel: TenantModelProxy<typeof Bill>,
+
+    private transformer: TransformerInjectable,
+    private validators: BillsValidators,
+  ) {}
+
+  /**
+   * Retrieve the given bill details with associated items entries.
+   * @param {Integer} billId - Specific bill.
+   * @returns {Promise<IBill>}
+   */
+  public async getBill(billId: number): Promise<Bill> {
+    const bill = await this.billModel()
+      .query()
+      .findById(billId)
+      .withGraphFetched('vendor')
+      .withGraphFetched('entries.item')
+      .withGraphFetched('branch')
+      .withGraphFetched('taxes.taxRate')
+      .withGraphFetched('attachments');
+
+    // Validates the bill existence.
+    this.validators.validateBillExistance(bill);
+
+    return this.transformer.transform(bill, new BillTransformer());
+  }
+}

packages/server/src/modules/Bills/queries/GetBillPayments.ts

@@ -0,0 +1,32 @@
+import { Inject, Injectable } from '@nestjs/common';
+import { BillPaymentEntry } from '@/modules/BillPayments/models/BillPaymentEntry';
+import { BillPaymentTransactionTransformer } from '@/modules/BillPayments/queries/BillPaymentTransactionTransformer';
+import { TransformerInjectable } from '@/modules/Transformer/TransformerInjectable.service';
+
+@Injectable()
+export class GetBillPayments {
+  constructor(
+    @Inject(BillPaymentEntry.name)
+    private billPaymentEntryModel: typeof BillPaymentEntry,
+    private transformer: TransformerInjectable,
+  ) {}
+
+  /**
+   * Retrieve the specific bill associated payment transactions.
+   * @param {number} billId
+   * @returns {}
+   */
+  public getBillPayments = async (billId: number) => {
+    const billsEntries = await this.billPaymentEntryModel
+      .query()
+      .where('billId', billId)
+      .withGraphJoined('payment.paymentAccount')
+      .withGraphJoined('bill')
+      .orderBy('payment:paymentDate', 'ASC');
+
+    return this.transformer.transform(
+      billsEntries,
+      new BillPaymentTransactionTransformer(),
+    );
+  };
+}

packages/server/src/modules/Bills/queries/GetBills.service.ts

@@ -0,0 +1,68 @@
+import { Inject, Injectable } from '@nestjs/common';
+import * as R from 'ramda';
+import { TransformerInjectable } from '@/modules/Transformer/TransformerInjectable.service';
+import { DynamicListService } from '@/modules/DynamicListing/DynamicList.service';
+import { Bill } from '../models/Bill';
+import { IFilterMeta, IPaginationMeta } from '@/interfaces/Model';
+import { BillTransformer } from './Bill.transformer';
+import { IBillsFilter } from '../Bills.types';
+import { TenantModelProxy } from '@/modules/System/models/TenantBaseModel';
+
+@Injectable()
+export class GetBillsService {
+  constructor(
+    private transformer: TransformerInjectable,
+    private dynamicListService: DynamicListService,
+
+    @Inject(Bill.name) private billModel: TenantModelProxy<typeof Bill>,
+  ) {}
+
+  /**
+   * Retrieve bills data table list.
+   * @param {IBillsFilter} billsFilter -
+   */
+  public async getBills(filterDTO: IBillsFilter): Promise<{
+    bills: Bill;
+    pagination: IPaginationMeta;
+    filterMeta: IFilterMeta;
+  }> {
+    // Parses bills list filter DTO.
+    const filter = this.parseListFilterDTO(filterDTO);
+
+    // Dynamic list service.
+    const dynamicFilter = await this.dynamicListService.dynamicList(
+      this.billModel(),
+      filter,
+    );
+    const { results, pagination } = await this.billModel()
+      .query()
+      .onBuild((builder) => {
+        builder.withGraphFetched('vendor');
+        builder.withGraphFetched('entries.item');
+        dynamicFilter.buildQuery()(builder);
+
+        // Filter query.
+        filterDTO?.filterQuery && filterDTO?.filterQuery(builder);
+      })
+      .pagination(filter.page - 1, filter.pageSize);
+
+    // Tranform the bills to POJO.
+    const bills = await this.transformer.transform(
+      results,
+      new BillTransformer(),
+    );
+    return {
+      bills,
+      pagination,
+      filterMeta: dynamicFilter.getResponseMeta(),
+    };
+  }
+
+  /**
+   * Parses bills list filter DTO.
+   * @param filterDTO -
+   */
+  private parseListFilterDTO(filterDTO) {
+    return R.compose(this.dynamicListService.parseStringifiedFilter)(filterDTO);
+  }
+}

packages/server/src/modules/Bills/queries/GetDueBills.service.ts

@@ -0,0 +1,28 @@
+import { Inject, Injectable } from '@nestjs/common';
+import { Bill } from '../models/Bill';
+import { TenantModelProxy } from '@/modules/System/models/TenantBaseModel';
+
+@Injectable()
+export class GetDueBills {
+  constructor(
+    @Inject(Bill.name) private billModel: TenantModelProxy<typeof Bill>,
+  ) {}
+
+  /**
+   * Retrieve all due bills or for specific given vendor id.
+   * @param {number} vendorId -
+   */
+  public async getDueBills(vendorId?: number): Promise<Bill[]> {
+    const dueBills = await this.billModel()
+      .query()
+      .onBuild((query) => {
+        query.orderBy('bill_date', 'DESC');
+        query.modify('dueBills');
+
+        if (vendorId) {
+          query.where('vendor_id', vendorId);
+        }
+      });
+    return dueBills;
+  }
+}

packages/server/src/modules/Bills/subscribers/BillGLEntriesSubscriber.ts

@@ -0,0 +1,59 @@
+import { Injectable } from '@nestjs/common';
+import {
+  IBillCreatedPayload,
+  IBillEditedPayload,
+  IBIllEventDeletedPayload,
+  IBillOpenedPayload,
+} from '../Bills.types';
+import { BillGLEntries } from '../commands/BillsGLEntries';
+import { events } from '@/common/events/events';
+import { OnEvent } from '@nestjs/event-emitter';
+
+@Injectable()
+export class BillGLEntriesSubscriber {
+  /**
+   * @param {BillGLEntries} billGLEntries - Bill GL entries command.
+   */
+  constructor(private billGLEntries: BillGLEntries) {}
+
+  /**
+   * Handles writing journal entries once bill created.
+   * @param {IBillCreatedPayload} payload -
+   */
+  @OnEvent(events.bill.onCreated)
+  @OnEvent(events.bill.onOpened)
+  public async handlerWriteJournalEntriesOnCreate({
+    bill,
+    trx,
+  }: IBillCreatedPayload | IBillOpenedPayload) {
+    if (!bill.openedAt) return null;
+
+    await this.billGLEntries.writeBillGLEntries(bill.id, trx);
+  };
+
+  /**
+   * Handles the overwriting journal entries once bill edited.
+   * @param {IBillEditedPayload} payload -
+   */
+  @OnEvent(events.bill.onEdited)
+  public async handleOverwriteJournalEntriesOnEdit({
+    bill,
+    trx,
+  }: IBillEditedPayload) {
+    if (!bill.openedAt) return null;
+
+    await this.billGLEntries.rewriteBillGLEntries(bill.id, trx);
+  };
+
+  /**
+   * Handles revert journal entries on bill deleted.
+   * @param {IBIllEventDeletedPayload} payload -
+   */
+  @OnEvent(events.bill.onDeleted)
+  public async handlerDeleteJournalEntries({
+    oldBill,
+    trx,
+  }: IBIllEventDeletedPayload) {
+    await this.billGLEntries.revertBillGLEntries(oldBill.id, trx);
+  };
+}

packages/server/src/modules/Bills/subscribers/BillWriteInventoryTransactionsSubscriber.ts

@@ -0,0 +1,58 @@
+import { Injectable } from '@nestjs/common';
+import {
+  IBillCreatedPayload,
+  IBillEditedPayload,
+  IBIllEventDeletedPayload,
+  IBillOpenedPayload,
+} from '../Bills.types';
+import { BillInventoryTransactions } from '../commands/BillInventoryTransactions';
+import { events } from '@/common/events/events';
+import { OnEvent } from '@nestjs/event-emitter';
+
+@Injectable()
+export class BillWriteInventoryTransactionsSubscriber {
+  constructor(private readonly billsInventory: BillInventoryTransactions) {}
+
+  /**
+   * Handles writing the inventory transactions once bill created.
+   * @param {IBillCreatedPayload | IBillOpenedPayload} payload -
+   */
+  @OnEvent(events.bill.onCreated)
+  @OnEvent(events.bill.onOpened)
+  public async handleWritingInventoryTransactions({
+    bill,
+    trx,
+  }: IBillCreatedPayload | IBillOpenedPayload) {
+    // Can't continue if the bill is not opened yet.
+    if (!bill.openedAt) return null;
+
+    await this.billsInventory.recordInventoryTransactions(bill.id, false, trx);
+  }
+
+  /**
+   * Handles the overwriting the inventory transactions once bill edited.
+   * @param {IBillEditedPayload} payload -
+   */
+  @OnEvent(events.bill.onEdited)
+  public async handleOverwritingInventoryTransactions({
+    bill,
+    trx,
+  }: IBillEditedPayload) {
+    // Can't continue if the bill is not opened yet.
+    if (!bill.openedAt) return null;
+
+    await this.billsInventory.recordInventoryTransactions(bill.id, true, trx);
+  };
+
+  /**
+   * Handles the reverting the inventory transactions once the bill deleted.
+   * @param {IBIllEventDeletedPayload} payload -
+   */
+  @OnEvent(events.bill.onDeleted)
+  public async handleRevertInventoryTransactions({
+    billId,
+    trx,
+  }: IBIllEventDeletedPayload) {
+    await this.billsInventory.revertInventoryTransactions(billId, trx);
+  }
+}