import { Component, ChangeDetectionStrategy, inject, signal, computed, effect, OnDestroy } from '@angular/core';
import { AuthService } from '../../services/auth.service';
import { CartService } from '../../services/cart.service';
import { TranslatePipe } from '../../i18n/translate.pipe';
import { getDiscountedPrice } from '../../utils/item.utils';

@Component({
  selector: 'app-telegram-login',
  imports: [TranslatePipe],
  templateUrl: './telegram-login.component.html',
  styleUrls: ['./telegram-login.component.scss'],
  changeDetection: ChangeDetectionStrategy.OnPush
})
export class TelegramLoginComponent implements OnDestroy {
  private authService = inject(AuthService);
  private cartService = inject(CartService);

  showDialog = this.authService.showLoginDialog;
  status = this.authService.status;

  loginUrl = signal('');
  qrToken = signal('');
  qrStatus = signal<'loading' | 'ready' | 'expired' | 'error'>('loading');
  encodedQrUrl = computed(() => encodeURIComponent(this.loginUrl()));

  private pollTimer?: ReturnType<typeof setInterval>;

  constructor() {
    effect(() => {
      if (this.showDialog()) {
        this.initQrLogin();
      } else {
        this.stopPolling();
      }
    });
  }

  ngOnDestroy(): void {
    this.stopPolling();
  }

  close(): void {
    this.authService.hideLogin();
    this.stopPolling();
  }

  openTelegramLogin(): void {
    window.open(this.loginUrl(), '_blank');
    if (!this.pollTimer) {
      if (this.qrToken()) {
        this.startPolling(this.qrToken());
      } else {
        this.startSessionPolling();
      }
    }
  }

  refreshQr(): void {
    this.stopPolling();
    this.initQrLogin();
  }

  private initQrLogin(): void {
    this.qrStatus.set('loading');
    this.authService.createQrToken().subscribe({
      next: (res) => {
        this.loginUrl.set(res.url);
        this.qrToken.set(res.token);
        this.qrStatus.set('ready');
        this.startPolling(res.token);
      },
      error: () => {
        this.loginUrl.set(this.authService.getTelegramLoginUrl());
        this.qrStatus.set('error');
        this.startSessionPolling();
      }
    });
  }

  private startSessionPolling(): void {
    this.stopPolling();
    let checks = 0;
    this.pollTimer = setInterval(() => {
      checks++;
      if (checks > 100) {
        this.stopPolling();
        this.qrStatus.set('expired');
        return;
      }
      this.authService.checkSessionOnce().subscribe(session => {
        if (session && session.active) {
          this.stopPolling();
          this.syncCartAndComplete(session.sessionId);
        }
      });
    }, 3000);
  }

  private startPolling(token: string): void {
    this.stopPolling();
    if (!token) return;

    let checks = 0;
    this.pollTimer = setInterval(() => {
      checks++;
      if (checks > 100) {
        this.stopPolling();
        this.qrStatus.set('expired');
        return;
      }

      this.authService.pollQrToken(token).subscribe({
        next: (res) => {
          switch (res.status) {
            case 'confirmed':
              this.stopPolling();
              if (res.session) {
                this.syncCartAndComplete(res.session.sessionId);
              } else {
                this.authService.onTelegramLoginComplete();
              }
              break;
            case 'expired':
              this.stopPolling();
              this.qrStatus.set('expired');
              break;
          }
        },
        error: () => {
          // Network error — keep polling
        }
      });
    }, 3000);
  }

  private syncCartAndComplete(sessionId: string): void {
    const cartItems = this.cartService.items().map(item => ({
      itemID: item.itemID,
      quantity: item.quantity,
      colour: item.colour || '',
      size: item.size || '',
      price: item.discount > 0
        ? item.price * (1 - item.discount / 100)
        : item.price,
    }));

    this.authService.syncCart(sessionId, cartItems).subscribe(() => {
      this.authService.onTelegramLoginComplete();
    });
  }

  private stopPolling(): void {
    if (this.pollTimer) {
      clearInterval(this.pollTimer);
      this.pollTimer = undefined;
    }
  }
}