import { omit, sumBy } from 'lodash';
import moment from 'moment';
import { Inject, Service } from 'typedi';
import {
  EventDispatcher,
  EventDispatcherInterface,
} from 'decorators/eventDispatcher';
import events from 'subscribers/events';
import JournalPoster from 'services/Accounting/JournalPoster';
import AccountsService from 'services/Accounts/AccountsService';
import InventoryService from 'services/Inventory/Inventory';
import SalesInvoicesCost from 'services/Sales/SalesInvoicesCost';
import TenancyService from 'services/Tenancy/TenancyService';
import DynamicListingService from 'services/DynamicListing/DynamicListService';
import { formatDateFields } from 'utils';
import {
  IBillDTO,
  IBill,
  ISystemUser,
  IBillEditDTO,
  IPaginationMeta,
  IFilterMeta,
  IBillsFilter,
} from 'interfaces';
import { ServiceError } from 'exceptions';
import ItemsService from 'services/Items/ItemsService';
import ItemsEntriesService from 'services/Items/ItemsEntriesService';
import JournalCommands from 'services/Accounting/JournalCommands';
import JournalPosterService from 'services/Sales/JournalPosterService';

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',
};

/**
 * Vendor bills services.
 * @service
 */
@Service()
export default class BillsService extends SalesInvoicesCost {
  @Inject()
  inventoryService: InventoryService;

  @Inject()
  accountsService: AccountsService;

  @Inject()
  itemsService: ItemsService;

  @Inject()
  tenancy: TenancyService;
  
  @EventDispatcher()
  eventDispatcher: EventDispatcherInterface;

  @Inject('logger')
  logger: any;

  @Inject()
  dynamicListService: DynamicListingService;

  @Inject()
  itemsEntriesService: ItemsEntriesService;

  @Inject()
  journalPosterService: JournalPosterService;

  /**
   * Validates whether the vendor is exist.
   * @async
   * @param {Request} req
   * @param {Response} res
   * @param {Function} next
   */
  private async getVendorOrThrowError(tenantId: number, vendorId: number) {
    const { vendorRepository } = this.tenancy.repositories(tenantId);

    this.logger.info('[bill] trying to get vendor.', { tenantId, vendorId });
    const foundVendor = await vendorRepository.findOneById(vendorId);

    if (!foundVendor) {
      this.logger.info('[bill] the given vendor not found.', {
        tenantId,
        vendorId,
      });
      throw new ServiceError(ERRORS.BILL_VENDOR_NOT_FOUND);
    }
    return foundVendor;
  }

  /**
   * Validates the given bill existance.
   * @async
   * @param {number} tenantId -
   * @param {number} billId -
   */
  private async getBillOrThrowError(tenantId: number, billId: number) {
    const { Bill } = this.tenancy.models(tenantId);

    this.logger.info('[bill] trying to get bill.', { tenantId, billId });
    const foundBill = await Bill.query()
      .findById(billId)
      .withGraphFetched('entries');

    if (!foundBill) {
      this.logger.info('[bill] the given bill not found.', {
        tenantId,
        billId,
      });
      throw new ServiceError(ERRORS.BILL_NOT_FOUND);
    }
    return foundBill;
  }

  /**
   * Validates the bill number existance.
   * @async
   * @param {Request} req
   * @param {Response} res
   * @param {Function} next
   */
  private async validateBillNumberExists(
    tenantId: number,
    billNumber: string,
    notBillId?: number
  ) {
    const { Bill } = this.tenancy.models(tenantId);
    const foundBills = await Bill.query()
      .where('bill_number', billNumber)
      .onBuild((builder) => {
        if (notBillId) {
          builder.whereNot('id', notBillId);
        }
      });

    if (foundBills.length > 0) {
      throw new ServiceError(ERRORS.BILL_NUMBER_EXISTS);
    }
  }

  /**
   * Converts bill DTO to model.
   * @param {number} tenantId
   * @param {IBillDTO} billDTO
   * @param {IBill} oldBill
   *
   * @returns {IBill}
   */
  private async billDTOToModel(
    tenantId: number,
    billDTO: IBillDTO | IBillEditDTO,
    authorizedUser: ISystemUser,
    oldBill?: IBill
  ) {
    const { ItemEntry } = this.tenancy.models(tenantId);

    const entries = billDTO.entries.map((entry) => ({
      ...entry,
      amount: ItemEntry.calcAmount(entry),
    }));
    const amount = sumBy(entries, 'amount');

    return {
      ...formatDateFields(omit(billDTO, ['open', 'entries']), [
        'billDate',
        'dueDate',
      ]),
      amount,
      entries: entries.map((entry) => ({
        reference_type: 'Bill',
        ...omit(entry, ['amount', 'id']),
      })),
      // Avoid rewrite the open date in edit mode when already opened.
      ...(billDTO.open &&
        !oldBill?.openedAt && {
          openedAt: moment().toMySqlDateTime(),
        }),
      userId: authorizedUser.id,
    };
  }

  /**
   * 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  {number} tenantId - The given tenant id.
   * @param  {IBillDTO} billDTO -
   * @return {Promise<IBill>}
   */
  public async createBill(
    tenantId: number,
    billDTO: IBillDTO,
    authorizedUser: ISystemUser
  ): Promise<IBill> {
    const { billRepository } = this.tenancy.repositories(tenantId);

    this.logger.info('[bill] trying to create a new bill', {
      tenantId,
      billDTO,
    });
    const billObj = await this.billDTOToModel(
      tenantId,
      billDTO,
      authorizedUser,
      null
    );
    // Retrieve vendor or throw not found service error.
    await this.getVendorOrThrowError(tenantId, billDTO.vendorId);

    // Validate the bill number uniqiness on the storage.
    if (billDTO.billNumber) {
      await this.validateBillNumberExists(tenantId, billDTO.billNumber);
    }
    // Validate items IDs existance.
    await this.itemsEntriesService.validateItemsIdsExistance(
      tenantId,
      billDTO.entries
    );
    // Validate non-purchasable items.
    await this.itemsEntriesService.validateNonPurchasableEntriesItems(
      tenantId,
      billDTO.entries
    );
    // Inserts the bill graph object to the storage.
    const bill = await billRepository.upsertGraph({ ...billObj });

    // Triggers `onBillCreated` event.
    await this.eventDispatcher.dispatch(events.bill.onCreated, {
      tenantId,
      bill,
      billId: bill.id,
    });
    this.logger.info('[bill] bill inserted successfully.', {
      tenantId,
      billId: bill.id,
    });

    return bill;
  }

  /**
   * 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 {number} tenantId - The given tenant id.
   * @param {Integer} billId - The given bill id.
   * @param {IBillEditDTO} billDTO - The given new bill details.
   * @return {Promise<IBill>}
   */
  public async editBill(
    tenantId: number,
    billId: number,
    billDTO: IBillEditDTO,
    authorizedUser: ISystemUser
  ): Promise<IBill> {
    const { billRepository } = this.tenancy.repositories(tenantId);

    this.logger.info('[bill] trying to edit bill.', { tenantId, billId });
    const oldBill = await this.getBillOrThrowError(tenantId, billId);

    // Transforms the bill DTO object to model object.
    const billObj = await this.billDTOToModel(
      tenantId,
      billDTO,
      authorizedUser,
      oldBill
    );

    // Retrieve vendor details or throw not found service error.
    await this.getVendorOrThrowError(tenantId, billDTO.vendorId);

    // Validate bill number uniqiness on the storage.
    if (billDTO.billNumber) {
      await this.validateBillNumberExists(tenantId, billDTO.billNumber, billId);
    }
    // Validate the entries ids existance.
    await this.itemsEntriesService.validateEntriesIdsExistance(
      tenantId,
      billId,
      'Bill',
      billDTO.entries
    );

    // Validate the items ids existance on the storage.
    await this.itemsEntriesService.validateItemsIdsExistance(
      tenantId,
      billDTO.entries
    );
    // Accept the purchasable items only.
    await this.itemsEntriesService.validateNonPurchasableEntriesItems(
      tenantId,
      billDTO.entries
    );
    // Update the bill transaction.
    const bill = await billRepository.upsertGraph({
      id: billId,
      ...billObj,
    });
    // Triggers event `onBillEdited`.
    await this.eventDispatcher.dispatch(events.bill.onEdited, {
      tenantId,
      billId,
      oldBill,
      bill,
    });
    this.logger.info('[bill] bill upserted successfully.', {
      tenantId,
      billId,
    });

    return bill;
  }

  /**
   * Deletes the bill with associated entries.
   * @param {Integer} billId
   * @return {void}
   */
  public async deleteBill(tenantId: number, billId: number) {
    const { ItemEntry } = this.tenancy.models(tenantId);
    const { billRepository } = this.tenancy.repositories(tenantId);

    // Retrieve the given bill or throw not found error.
    const oldBill = await this.getBillOrThrowError(tenantId, billId);

    // Delete all associated bill entries.
    const deleteBillEntriesOper = ItemEntry.query()
      .where('reference_type', 'Bill')
      .where('reference_id', billId)
      .delete();

    // Delete the bill transaction.
    const deleteBillOper = billRepository.deleteById(billId);

    await Promise.all([deleteBillEntriesOper, deleteBillOper]);

    // Triggers `onBillDeleted` event.
    await this.eventDispatcher.dispatch(events.bill.onDeleted, {
      tenantId,
      billId,
      oldBill,
    });
  }

  /**
   * Retrieve bills data table list.
   * @param {number} tenantId -
   * @param {IBillsFilter} billsFilter -
   */
  public async getBills(
    tenantId: number,
    billsFilter: IBillsFilter
  ): Promise<{
    bills: IBill;
    pagination: IPaginationMeta;
    filterMeta: IFilterMeta;
  }> {
    const { Bill } = this.tenancy.models(tenantId);
    const dynamicFilter = await this.dynamicListService.dynamicList(
      tenantId,
      Bill,
      billsFilter
    );
    this.logger.info('[bills] trying to get bills data table.', {
      tenantId,
      billsFilter,
    });
    const { results, pagination } = await Bill.query()
      .onBuild((builder) => {
        builder.withGraphFetched('vendor');
        dynamicFilter.buildQuery()(builder);
      })
      .pagination(billsFilter.page - 1, billsFilter.pageSize);

    return {
      bills: results,
      pagination,
      filterMeta: dynamicFilter.getResponseMeta(),
    };
  }

  /**
   * Retrieve all due bills or for specific given vendor id.
   * @param {number} tenantId -
   * @param {number} vendorId -
   */
  public async getDueBills(
    tenantId: number,
    vendorId?: number
  ): Promise<IBill[]> {
    const { Bill } = this.tenancy.models(tenantId);

    const dueBills = await Bill.query().onBuild((query) => {
      query.orderBy('bill_date', 'DESC');
      query.modify('dueBills');

      if (vendorId) {
        query.where('vendor_id', vendorId);
      }
    });
    return dueBills;
  }

  /**
   * Retrieve the given bill details with associated items entries.
   * @param {Integer} billId - Specific bill.
   * @returns {Promise<IBill>}
   */
  public async getBill(tenantId: number, billId: number): Promise<IBill> {
    const { Bill } = this.tenancy.models(tenantId);

    this.logger.info('[bills] trying to fetch specific bill with metadata.', {
      tenantId,
      billId,
    });
    const bill = await Bill.query()
      .findById(billId)
      .withGraphFetched('vendor')
      .withGraphFetched('entries');

    if (!bill) {
      throw new ServiceError(ERRORS.BILL_NOT_FOUND);
    }
    return bill;
  }

  /**
   * Mark the bill as open.
   * @param {number} tenantId
   * @param {number} billId
   */
  public async openBill(tenantId: number, billId: number): Promise<void> {
    const { Bill } = this.tenancy.models(tenantId);

    // Retrieve the given bill or throw not found error.
    const oldBill = await this.getBillOrThrowError(tenantId, billId);

    if (oldBill.isOpen) {
      throw new ServiceError(ERRORS.BILL_ALREADY_OPEN);
    }
    // Record the bill opened at on the storage.
    await Bill.query().findById(billId).patch({
      openedAt: moment().toMySqlDateTime(),
    });
  }

  /**
   * Records the inventory transactions from the given bill input.
   * @param {Bill} bill - Bill model object.
   * @param {number} billId - Bill id.
   * @return {Promise<void>}
   */
  public async recordInventoryTransactions(
    tenantId: number,
    bill: IBill,
    override?: boolean
  ): Promise<void> {
    await this.inventoryService.recordInventoryTransactionsFromItemsEntries(
      tenantId,
      bill.id,
      'Bill',
      bill.billDate,
      'IN',
      override
    );
    // Triggers `onInventoryTransactionsCreated` event.
    this.eventDispatcher.dispatch(events.bill.onInventoryTransactionsCreated, {
      tenantId,
      bill,
    });
  }

  /**
   * 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(tenantId: number, billId: number) {
    // Deletes the inventory transactions by the given reference id and type.
    await this.inventoryService.deleteInventoryTransactions(
      tenantId,
      billId,
      'Bill'
    );
  }

  /**
   * Records the bill journal transactions.
   * @async
   * @param {IBill} bill
   * @param {Integer} billId
   */
  public async recordJournalTransactions(
    tenantId: number,
    bill: IBill,
    override: boolean = false
  ) {
    const journal = new JournalPoster(tenantId);
    const journalCommands = new JournalCommands(journal);

    await journalCommands.bill(bill, override);

    return Promise.all([
      journal.deleteEntries(),
      journal.saveEntries(),
      journal.saveBalance(),
    ]);
  }

  /**
   * Reverts the bill journal entries.
   * @param {number} tenantId
   * @param {number} billId
   */
  public async revertJournalEntries(
    tenantId: number,
    billId: number
  ): Promise<void> {
    await this.journalPosterService.revertJournalTransactions(
      tenantId,
      billId,
      'Bill'
    );
  }
}