/**
 * Copyright since 2025 Mifos Initiative
 *
 * This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this
 * file, You can obtain one at http://mozilla.org/MPL/2.0/.
 */

import { Component, OnInit, inject } from '@angular/core';
import { CommonModule } from '@angular/common';
import { FormsModule } from '@angular/forms';
import { MatIconModule } from '@angular/material/icon';
import { MatSnackBar, MatSnackBarModule } from '@angular/material/snack-bar';
import { MatDialog, MatDialogModule } from '@angular/material/dialog';
import { forkJoin, of } from 'rxjs';
import { catchError } from 'rxjs/operators';
import { CashierService } from '../cashier.service';
import { ClientsService } from 'app/clients/clients.service';
import {
  CustomerSearchDialogComponent,
  CustomerSearchResult
} from 'app/shared/customer-search-dialog/customer-search-dialog.component';
import { businessToday } from 'app/core/utils/business-today';

interface Denom {
  id: number;
  value: number;
  kind: 'note' | 'coin';
  label: string;
}

/** An existing client picked through Customer Search, with what the counter needs to identify them. */
interface SelectedCustomer {
  clientId: number;
  displayName: string;
  cifNumber: string | null;
  mobileNo: string | null;
  officeName: string | null;
  accountNo: string | null;
  accountType: string | null;
  /** PAN on the client's KYC record, if any. */
  kycPan: string | null;
  panVerified: boolean;
  kycStatus: string;
}

/** The cashier at the counter: the one who takes the customer's notes and hands over the change. */
interface CashierInfo {
  cashierId: number;
  name: string;
  tellerName: string | null;
  officeName: string | null;
  /** Cash the vault allocated to them for the day, once known. */
  allocatedAmount: number | null;
  /** Cash they hold now. */
  totalAmount: number;
}

/** Same rule as ClientKycApiConstants.PAN_REGEX on the server: 5 letters, 4 digits, 1 letter. */
const PAN_PATTERN = /^[A-Z]{5}[0-9]{4}[A-Z]$/;

/** Income Tax Rule 114B / RBI: a cash exchange above this needs the customer's PAN. */
const PAN_MANDATORY_ABOVE = 50000;

const KYC_STATUS: Record<number, string> = {
  100: 'Pending',
  200: 'In Progress',
  300: 'Verified',
  400: 'Rejected',
  500: 'Expired'
};

/** Cashier cash-exchange entry: customer gives some denominations and takes equal-value change (net 0). */
@Component({
  selector: 'mifosx-cash-exchange-entry',
  templateUrl: './cash-exchange-entry.component.html',
  styleUrls: ['./cash-exchange-entry.component.scss'],
  standalone: true,
  imports: [
    CommonModule,
    FormsModule,
    MatIconModule,
    MatSnackBarModule,
    MatDialogModule
  ]
})
export class CashExchangeEntryComponent implements OnInit {
  private service = inject(CashierService);
  private clientsService = inject(ClientsService);
  private dialog = inject(MatDialog);
  private snackBar = inject(MatSnackBar);

  notes: Denom[] = [];
  coins: Denom[] = [];
  receivedCounts: Record<number, number> = {};
  givenCounts: Record<number, number> = {};
  exchangeDate = '';
  note = '';
  saving = false;

  // ── Customer info ──
  /** An existing client found through Customer Search, or a walk-in identified at the counter. */
  customerMode: 'existing' | 'walkin' = 'walkin';
  selectedCustomer: SelectedCustomer | null = null;
  loadingCustomer = false;
  walkInName = '';
  walkInMobile = '';
  panNumber = '';

  // ── Cashier at the counter, and their position (for the denomination overdraft check) ──
  /** The cashier linked to the logged-in user; null when the login is not a cashier's. */
  cashier: CashierInfo | null = null;
  private availableMap = new Map<number, number>();
  positionLoaded = false;

  /** All denominations (notes then coins) */
  get denoms(): Denom[] {
    return [
      ...this.notes,
      ...this.coins
    ];
  }

  ngOnInit(): void {
    const d = businessToday();
    this.exchangeDate = `${d.getFullYear()}-${String(d.getMonth() + 1).padStart(2, '0')}-${String(d.getDate()).padStart(2, '0')}`;
    this.service.getActiveDenominations().subscribe({
      next: (list) => {
        const rows: Denom[] = (list || []).map((x: any) => ({
          id: x.id,
          value: x.denomination,
          kind: x.kind,
          label: '₹' + x.denomination
        }));
        this.notes = rows.filter((r) => r.kind === 'note').sort((a, b) => b.value - a.value);
        this.coins = rows.filter((r) => r.kind === 'coin').sort((a, b) => b.value - a.value);
      },
      error: () => {
        this.notes = [];
        this.coins = [];
      }
    });
    this.service.getCashierPositionForMe().subscribe({
      next: (res: any) => {
        this.availableMap.clear();
        ((res?.denominations || []) as any[]).forEach((d: any) => {
          if (d.denominationId) this.availableMap.set(Number(d.denominationId), Number(d.count ?? 0));
        });
        const cashierId = res?.cashierId ? Number(res.cashierId) : null;
        this.cashier = cashierId
          ? {
              cashierId,
              name: res.cashierName || '',
              tellerName: null,
              officeName: null,
              allocatedAmount: null,
              totalAmount: Number(res.totalAmount ?? 0)
            }
          : null;
        this.positionLoaded = true;
        if (cashierId) this.loadCashierDetails(cashierId);
      },
      error: () => {
        this.positionLoaded = true;
      }
    });
  }

  /** The counter, branch and today's allocation; the card still shows name and cash in hand without them. */
  private loadCashierDetails(cashierId: number): void {
    this.service
      .getInterCashierCashierSummary(cashierId, this.exchangeDate)
      .pipe(catchError(() => of(null)))
      .subscribe((r: any) => {
        if (!r || this.cashier?.cashierId !== cashierId) return;
        this.cashier = {
          ...this.cashier,
          tellerName: r.tellerName || null,
          officeName: r.officeName || null,
          allocatedAmount: Number(r.allocatedAmount ?? 0)
        };
      });
  }

  /** Up to two letters for the cashier's avatar. */
  get cashierInitials(): string {
    const words = (this.cashier?.name || '').trim().split(/\s+/).filter(Boolean);
    if (words.length === 0) return '?';
    const first = words[0].charAt(0);
    const last = words.length > 1 ? words[words.length - 1].charAt(0) : '';
    return (first + last).toUpperCase();
  }

  countFor(side: 'r' | 'g', d: Denom): number {
    return (side === 'r' ? this.receivedCounts : this.givenCounts)[d.id] || 0;
  }

  subtotal(side: 'r' | 'g', d: Denom): number {
    return this.countFor(side, d) * d.value;
  }

  onChange(side: 'r' | 'g', d: Denom, raw: any): void {
    (side === 'r' ? this.receivedCounts : this.givenCounts)[d.id] = Math.max(0, Math.floor(Number(raw) || 0));
  }

  bump(side: 'r' | 'g', d: Denom, delta: number): void {
    const map = side === 'r' ? this.receivedCounts : this.givenCounts;
    map[d.id] = Math.max(0, (map[d.id] || 0) + delta);
  }

  get receivedTotal(): number {
    return this.denoms.reduce((s, d) => s + this.subtotal('r', d), 0);
  }

  get givenTotal(): number {
    return this.denoms.reduce((s, d) => s + this.subtotal('g', d), 0);
  }

  get difference(): number {
    return this.receivedTotal - this.givenTotal;
  }

  get matches(): boolean {
    return this.receivedTotal > 0 && this.receivedTotal === this.givenTotal;
  }

  /** Above ₹50,000 the customer's PAN is mandatory (Income Tax Rule 114B, followed under RBI guidelines). */
  get needsPan(): boolean {
    return this.receivedTotal > PAN_MANDATORY_ABOVE;
  }

  /** Up to two letters for the avatar: first and last word of the customer's name. */
  get customerInitials(): string {
    const words = (this.selectedCustomer?.displayName || '').trim().split(/\s+/).filter(Boolean);
    if (words.length === 0) return '?';
    const first = words[0].charAt(0);
    const last = words.length > 1 ? words[words.length - 1].charAt(0) : '';
    return (first + last).toUpperCase();
  }

  get panValue(): string {
    return this.panNumber.trim().toUpperCase();
  }

  /** A PAN that is entered must be well-formed, required or not. */
  get panFormatInvalid(): boolean {
    return !!this.panValue && !PAN_PATTERN.test(this.panValue);
  }

  get panMissing(): boolean {
    return this.needsPan && !this.panValue;
  }

  /** The PAN comes from the client's KYC record, so the cashier confirms it rather than types it. */
  get panFromKyc(): boolean {
    return !!this.selectedCustomer?.kycPan && this.panValue === this.selectedCustomer.kycPan.toUpperCase();
  }

  /** Who the customer is has to be known: a picked client, or a walk-in's name once PAN is required. */
  get customerIdentified(): boolean {
    if (this.customerMode === 'existing') return !!this.selectedCustomer;
    return !this.needsPan || this.walkInName.trim().length > 0;
  }

  /** A login with no cashier behind it has no drawer to take notes into or give change from. */
  get noCashier(): boolean {
    return this.positionLoaded && !this.cashier;
  }

  /** How many of the denomination the cashier holds, or null while that is not known (loading, or no cashier). */
  availableFor(d: Denom): number | null {
    if (!this.positionLoaded || !this.cashier) return null;
    return this.availableMap.get(d.id) ?? 0;
  }

  /** The cashier is giving more of this denomination than they hold. */
  exceedsAvailable(d: Denom): boolean {
    const available = this.availableFor(d);
    return available !== null && this.countFor('g', d) > available;
  }

  /** The + on the given side stops at what the cashier holds; a larger typed number is still caught and shown. */
  canGiveMore(d: Denom): boolean {
    const available = this.availableFor(d);
    return available === null || this.countFor('g', d) < available;
  }

  /** What this exchange does to the cashier's count of the denomination: notes taken in less notes given out. */
  netFor(d: Denom): number {
    return this.countFor('r', d) - this.countFor('g', d);
  }

  /** The cashier's count of the denomination once this exchange is recorded, or null while it is not known. */
  drawerAfter(d: Denom): number | null {
    const available = this.availableFor(d);
    return available === null ? null : available + this.netFor(d);
  }

  /**
   * The denominations this exchange changes, with the drawer's count before and after, so the effect shows
   * while the counts are being typed. The branch's total for each denomination moves by the same amount, as
   * the customer's notes go into the drawer and the change comes out of it; the vault is not involved.
   */
  get impactRows(): Array<{ id: number; label: string; kind: string; net: number; before: number; after: number }> {
    if (!this.positionLoaded || !this.cashier) return [];
    return this.denoms
      .filter((d) => this.netFor(d) !== 0)
      .map((d) => ({
        id: d.id,
        label: d.label,
        kind: d.kind,
        net: this.netFor(d),
        before: this.availableFor(d) ?? 0,
        after: this.drawerAfter(d) ?? 0
      }));
  }

  /** Denominations where cashier is giving more than currently available. */
  get givenOverdraftItems(): Array<{ label: string; available: number; requested: number }> {
    // Without a cashier every denomination would read as "0 available"; the missing cashier is the
    // thing to tell the user, not a stock shortage.
    if (!this.positionLoaded || !this.cashier) return [];
    return this.denoms
      .map((d) => ({ label: d.label, available: this.availableMap.get(d.id) ?? 0, requested: this.countFor('g', d) }))
      .filter((item) => item.requested > 0 && item.requested > item.available);
  }

  get hasGivenOverdraft(): boolean {
    return this.givenOverdraftItems.length > 0;
  }

  get valid(): boolean {
    return (
      this.matches &&
      !!this.cashier &&
      !this.hasGivenOverdraft &&
      !this.panFormatInvalid &&
      !this.panMissing &&
      this.customerIdentified &&
      !this.loadingCustomer
    );
  }

  setCustomerMode(mode: 'existing' | 'walkin'): void {
    if (this.customerMode === mode) return;
    this.customerMode = mode;
    this.selectedCustomer = null;
    this.walkInName = '';
    this.walkInMobile = '';
    this.panNumber = '';
  }

  /** Pick an existing client through Customer Search, then load their details and KYC (PAN). */
  openCustomerSearch(): void {
    this.dialog
      // An existing customer without an account is still a known customer, so the account is not required.
      .open(CustomerSearchDialogComponent, { width: '960px', maxWidth: '95vw', data: { requireAccount: false } })
      .afterClosed()
      .subscribe((result: CustomerSearchResult | undefined) => {
        if (!result?.clientId) return;
        this.loadCustomer(result);
      });
  }

  private loadCustomer(result: CustomerSearchResult): void {
    this.loadingCustomer = true;
    const id = String(result.clientId);
    forkJoin({
      client: this.clientsService.getClientData(id, true).pipe(catchError(() => of(null))),
      kyc: this.clientsService.getClientKyc(id, true).pipe(catchError(() => of(null)))
    }).subscribe(({ client, kyc }: { client: any; kyc: any }) => {
      const kycPan: string | null = kyc?.panNumber || result.panNumber || null;
      this.selectedCustomer = {
        clientId: result.clientId,
        displayName: client?.displayName || result.displayName,
        cifNumber: client?.cifNumber || null,
        mobileNo: client?.mobileNo || result.mobileNo || null,
        officeName: client?.officeName || result.officeName || null,
        accountNo: result.accountNo || null,
        accountType: result.accountType || null,
        kycPan,
        panVerified: !!kyc?.panVerified,
        kycStatus: KYC_STATUS[Number(kyc?.kycStatus?.id ?? kyc?.kycStatus)] || 'Not on record'
      };
      this.panNumber = kycPan ? kycPan.toUpperCase() : '';
      this.loadingCustomer = false;
    });
  }

  clearCustomer(): void {
    this.selectedCustomer = null;
    this.panNumber = '';
  }

  clear(): void {
    this.receivedCounts = {};
    this.givenCounts = {};
    this.note = '';
    this.customerMode = 'walkin';
    this.selectedCustomer = null;
    this.walkInName = '';
    this.walkInMobile = '';
    this.panNumber = '';
  }

  submit(): void {
    if (!this.valid || this.saving) return;
    this.saving = true;
    const build = (side: 'r' | 'g') =>
      this.denoms
        .filter((d) => this.countFor(side, d) > 0)
        .map((d) => ({ denominationId: d.id, denominationValue: d.value, count: this.countFor(side, d) }));
    const customer = this.customerMode === 'existing' ? this.selectedCustomer : null;
    const pan = this.panValue || null;
    const payload: any = {
      exchangeDate: this.exchangeDate,
      note: this.note || null,
      clientId: customer?.clientId ?? null,
      accountNo: customer?.accountNo ?? null,
      customerName: customer ? customer.displayName : this.walkInName.trim() || null,
      customerMobile: customer ? customer.mobileNo : this.walkInMobile.trim() || null,
      panNumber: pan,
      customerIdProof: pan,
      received: build('r'),
      given: build('g')
    };
    this.service.createCashExchange(payload).subscribe({
      next: () => {
        this.snackBar.open('Cash exchange recorded', 'Close', { duration: 3000 });
        this.clear();
        this.saving = false;
      },
      error: () => {
        this.saving = false;
      }
    });
  }
}