import { SelectionModel } from '@angular/cdk/collections';
import { Injectable } from '@angular/core';
import { MatDialog } from '@angular/material/dialog';
import { BehaviorSubject, throwError } from 'rxjs';
import { Observable } from 'rxjs';
import { tap } from 'rxjs/operators';

import { BillViewItem } from '../core/bill-view-item';
import { ModifierCategory } from '../core/modifier-category';
import { Product } from '../core/product';
import { ReceivePaymentItem } from '../core/receive-payment-item';
import { SaleCategory } from '../core/sale-category';
import { Table } from '../core/table';
import { ToasterService } from '../core/toaster.service';
import { ModifierCategoryService } from '../modifier-categories/modifier-category.service';
import { MathService } from '../shared/math.service';

import { Bill } from './bills/bill';
import { Inventory } from './bills/inventory';
import { Kot } from './bills/kot';
import { VoucherType } from './bills/voucher-type';
import { VoucherService } from './bills/voucher.service';
import { ModifiersComponent } from './modifiers/modifiers.component';

@Injectable()
export class BillService {
  public dataObs: BehaviorSubject<BillViewItem[]>;
  public bill: Bill = new Bill();
  public grossAmount: BehaviorSubject<number>;
  public discountAmount: BehaviorSubject<number>;
  public hhAmount: BehaviorSubject<number>;
  public taxAmount: BehaviorSubject<number>;
  public amount: Observable<number>;
  public amountVal: number;
  public selection = new SelectionModel<string>(true, []);
  private amountBs: BehaviorSubject<number>;
  private updateTable: boolean;
  private allowDeactivate: boolean; // To disable Deactivate Guard on navigation after printing bill or kot.

  constructor(
    private dialog: MatDialog,
    private toaster: ToasterService,
    private math: MathService,
    private ser: VoucherService,
    private modifierCategoryService: ModifierCategoryService,
  ) {
    this.dataObs = new BehaviorSubject<BillViewItem[]>([]);
    this.grossAmount = new BehaviorSubject(0);
    this.discountAmount = new BehaviorSubject(0);
    this.hhAmount = new BehaviorSubject(0);
    this.taxAmount = new BehaviorSubject(0);
    this.amountBs = new BehaviorSubject(0);
    this.amountVal = 0;
    this.updateTable = true;
    this.allowDeactivate = false;
    this.amount = this.amountBs.pipe(tap((x) => (this.amountVal = x)));
  }

  displayBill(): void {
    this.allowDeactivate = false;
    const data = this.transformBillToView(this.bill);
    this.dataObs.next(data);
    this.updateAmounts();
  }

  transformBillToView(bill: Bill): BillViewItem[] {
    return bill.kots
      .map((k: Kot) => [
        new BillViewItem({
          kotId: k.id,
          isKot: true,
          info: k.id ? `Kot: ${k.code} / ${k.date} (${k.user.name})` : '== New Kot ==',
        }),
        ...k.inventories.map(
          (i) =>
            new BillViewItem({
              id: i.id,
              kotId: k.id,
              isKot: false,
              productId: i.product.id,
              isHappyHour: i.isHappyHour,
              isPrinted: !!k.id,
              info: `${i.product.name} @ ${i.price} - ${this.math.halfRoundEven(i.discount * 100, 2)}%`,
              quantity: i.quantity,
              modifiers: i.modifiers,
            }),
        ),
      ])
      .reduce((a, c) => a.concat(c), []);
  }

  loadData(bill: Bill, updateTable: boolean): void {
    this.updateTable = updateTable;
    bill.kots.push(new Kot());
    this.bill = bill;
    this.selection.clear();
    this.displayBill();
  }

  minimum(productId: string, happyHour: boolean): number {
    return this.bill.kots.reduce(
      (t, k) =>
        k.inventories.reduce(
          (a, c) => (c.product.id === productId && c.isHappyHour === happyHour ? a + c.quantity : a),
          0,
        ) + t,
      0,
    );
  }

  addProduct(product: Product, quantity: number, discount: number): void {
    const newKot = this.bill.kots.find((k) => k.id === undefined) as Kot;
    const old = newKot.inventories.find((x) => x.product.id === product.id && x.isHappyHour === product.hasHappyHour);
    if (quantity < 0) {
      const minimum = this.minimum(product.id as string, product.hasHappyHour) + quantity;
      if (minimum + quantity < 0) {
        this.toaster.show('Error', 'Total quantity cannot be negative!');
        return;
      }
    }
    if (old !== undefined) {
      old.quantity += quantity;
    } else {
      const item = new Inventory({
        product,
        quantity,
        price: product.price,
        isHappyHour: product.hasHappyHour,
        taxRate: product.tax.rate,
        tax: product.tax,
        discount,
        modifiers: [],
      });
      newKot.inventories.push(item);
      this.modifierCategoryService.listForProduct(product.id as string).subscribe((result) => {
        if (result.reduce((a: number, c: ModifierCategory) => a + c.minimum, 0)) {
          this.showModifier(item);
        }
      });
    }
    this.displayBill();
  }

  showModifier(item: Inventory): void {
    // [routerLink]="['/sales', 'modifiers', item.id]"
    const dialogRef = this.dialog.open(ModifiersComponent, {
      position: {
        top: '10vh',
      },
      data: {
        list: this.modifierCategoryService.listForProduct(item.product.id as string),
        selected: item.modifiers,
      },
    });

    dialogRef.afterClosed().subscribe((result) => {
      if (result !== undefined) {
        item.modifiers = result;
      }
    });
    this.displayBill();
  }

  addOne(item: BillViewItem): void {
    const newKot = this.bill.kots.find((k) => k.id === undefined) as Kot;
    const old = newKot.inventories.find(
      (x) => x.product.id === item.productId && x.isHappyHour === item.isHappyHour,
    ) as Inventory;
    old.quantity += 1;
    this.displayBill();
  }

  quantity(item: BillViewItem, quantity: number): void {
    const newKot = this.bill.kots.find((k) => k.id === undefined) as Kot;
    const old = newKot.inventories.find(
      (x) => x.product.id === item.productId && x.isHappyHour === item.isHappyHour,
    ) as Inventory;
    old.quantity = quantity;
    this.displayBill();
  }

  subtractOne(item: BillViewItem, canEdit: boolean): void {
    const newKot = this.bill.kots.find((k) => k.id === undefined) as Kot;
    const old = newKot.inventories.find(
      (x) => x.product.id === item.productId && x.isHappyHour === item.isHappyHour,
    ) as Inventory;
    if (item.quantity >= 1 || (canEdit && this.minimum(item.productId as string, item.isHappyHour) >= 1)) {
      old.quantity -= 1;
    } else if (item.quantity === 0) {
      newKot.inventories.splice(newKot.inventories.indexOf(old), 1);
    }
    this.displayBill();
  }

  removeItem(item: BillViewItem): void {
    const newKot = this.bill.kots.find((k) => k.id === undefined) as Kot;
    const old = newKot.inventories.find(
      (x) => x.product.id === item.productId && x.isHappyHour === item.isHappyHour,
    ) as Inventory;
    newKot.inventories.splice(newKot.inventories.indexOf(old), 1);
    this.displayBill();
  }

  modifier(item: BillViewItem): void {
    const newKot = this.bill.kots.find((k) => k.id === undefined) as Kot;
    const old = newKot.inventories.find(
      (x) => x.product.id === item.productId && x.isHappyHour === item.isHappyHour,
    ) as Inventory;
    this.showModifier(old);
  }

  discount(discounts: { id: string; name: string; discount: number }[]): void {
    for (const kot of this.bill.kots) {
      const noDiscount = kot.inventories.filter((x) => x.isHappyHour).map((x) => x.product.id as string);
      for (const inventory of kot.inventories) {
        const e = discounts.find((d) => d.id === (inventory.product.saleCategory as SaleCategory).id);
        if (e === undefined || noDiscount.indexOf(inventory.product.id as string) !== -1) {
          continue;
        }
        inventory.discount = e.discount;
      }
    }
    this.displayBill();
  }

  printKot(guestBookId: string | null): Observable<boolean> {
    const item = JSON.parse(JSON.stringify(this.bill));
    const newKot = this.bill.kots.find((k) => k.id === undefined) as Kot;
    if (newKot.inventories.filter((x) => x.quantity !== 0).length === 0) {
      return throwError('Cannot print a blank KOT\nPlease add some products!');
    }
    if (!this.happyHourItemsBalanced() || this.happyHourItemsMoreThanRegular()) {
      return throwError('Happy hour products are not balanced.');
    }
    return this.ser
      .saveOrUpdate(item, VoucherType.Kot, guestBookId, this.updateTable)
      .pipe(tap(() => (this.allowDeactivate = true)));
  }

  printBill(guest_book_id: string | null, voucherType: VoucherType): Observable<boolean> {
    const item = JSON.parse(JSON.stringify(this.bill));
    const newKot = this.bill.kots.find((k) => k.id === undefined) as Kot;
    if (item.kots.length === 1 && newKot.inventories.length === 0) {
      return throwError('Cannot print a blank Bill\nPlease add some products!');
    }
    if (!this.happyHourItemsBalanced() || this.happyHourItemsMoreThanRegular()) {
      return throwError('Happy hour products are not balanced.');
    }
    return this.ser
      .saveOrUpdate(item, voucherType, guest_book_id, this.updateTable)
      .pipe(tap(() => (this.allowDeactivate = true)));
  }

  receivePayment(value: { choices: ReceivePaymentItem[]; reason: string }): Observable<boolean> {
    return this.ser.receivePayment(this.bill.id as string, value.choices, value.reason, this.updateTable);
  }

  moveTable(table: Table): Observable<boolean> {
    return this.ser.moveTable(this.bill.id as string, table);
  }

  mergeTable(table: Table): Observable<boolean> {
    return this.ser.mergeTable(this.bill.id as string, table);
  }

  moveKot(kotId: string, table: Table): Observable<boolean> {
    return this.ser.moveKotToNewTable(this.bill.id as string, kotId, table);
  }

  mergeKot(kotId: string, table: Table): Observable<boolean> {
    return this.ser.mergeKotWithOldBill(this.bill.id as string, kotId, table);
  }

  cancelBill(reason: string): Observable<boolean> {
    return this.ser.cancelBill(this.bill.id as string, reason, this.updateTable);
  }

  updateAmounts() {
    this.grossAmount.next(
      this.math.halfRoundEven(
        this.bill.kots.reduce((t, k) => k.inventories.reduce((a, c) => a + c.price * c.quantity, 0) + t, 0),
      ),
    );
    this.hhAmount.next(
      this.math.halfRoundEven(
        this.bill.kots.reduce(
          (t, k) => k.inventories.reduce((a, c) => a + (c.isHappyHour ? c.price : 0) * c.quantity, 0) + t,
          0,
        ),
      ),
    );
    this.discountAmount.next(
      this.math.halfRoundEven(
        this.bill.kots.reduce(
          (t, k) => k.inventories.reduce((a, c) => a + (c.isHappyHour ? 0 : c.price) * c.quantity * c.discount, 0) + t,
          0,
        ),
      ),
    );
    this.taxAmount.next(
      this.math.halfRoundEven(
        this.bill.kots.reduce(
          (t, k) =>
            k.inventories.reduce(
              (a, c) => a + (c.isHappyHour ? 0 : c.price) * c.quantity * (1 - c.discount) * c.taxRate,
              0,
            ) + t,
          0,
        ),
      ),
    );
    this.amountBs.next(
      this.math.halfRoundEven(
        this.bill.kots.reduce(
          (t, k) =>
            k.inventories.reduce(
              (a, c) =>
                a +
                this.math.halfRoundEven(
                  (c.isHappyHour ? 0 : c.price) * c.quantity * (1 - c.discount) * (1 + c.taxRate),
                  2,
                ),
              0,
            ) + t,
          0,
        ),
      ),
    );
  }

  splitBill(inventories: string[], table: Table): Observable<boolean> {
    return this.ser.splitBill(this.bill.id as string, inventories, table, this.updateTable);
  }

  public getInventories(saleCategories: string[]): { move: string[]; keep: string[] } {
    const data: { move: string[]; keep: string[] } = { move: [], keep: [] };
    for (const kot of this.bill.kots) {
      for (const inv of kot.inventories) {
        if (saleCategories.indexOf(inv.product.saleCategory?.id as string) === -1) {
          data.keep.push(inv.id as string);
        } else {
          data.move.push(inv.id as string);
        }
      }
    }
    return data;
  }

  private happyHourItemsBalanced(): boolean {
    for (const kot of this.bill.kots) {
      const happyHourItems = kot.inventories
        .filter((x) => x.isHappyHour)
        .map((x) => ({ id: x.product.id as string, quantity: x.quantity }));
      for (const item of happyHourItems) {
        const q = kot.inventories.find(
          (x) => !x.isHappyHour && x.product.id === item.id && x.quantity === item.quantity,
        );
        if (q === undefined) {
          return false;
        }
      }
    }
    return true;
  }

  private happyHourItemsMoreThanRegular(): boolean {
    const invs: { [id: string]: { normal: number; happy: number } } = {};
    for (const kot of this.bill.kots) {
      for (const inventory of kot.inventories) {
        const pid = inventory.product.id as string;
        if (invs[pid] === undefined) {
          invs[pid] = { normal: 0, happy: 0 };
        }
        if (inventory.isHappyHour) {
          invs[pid].happy += inventory.quantity;
        } else {
          invs[pid].normal += inventory.quantity;
        }
      }
    }
    for (const [, value] of Object.entries(invs)) {
      if (value.happy > value.normal) {
        return true;
      }
    }
    return false;
  }

  public canDeactivate(): boolean {
    if (this.allowDeactivate) {
      return true;
    }
    const newKot = this.bill.kots.find((k) => k.id === undefined) as Kot;
    return newKot.inventories.length === 0;
  }
}