import { computed, inject, Injectable, signal } from '@angular/core';
import { takeUntilDestroyed } from '@angular/core/rxjs-interop';
import { NavigationEnd, Router } from '@angular/router';
import { filter } from 'rxjs';
import { SITE_CONFIG } from '../content/site-config';
import { otherLocale, type AppLocale } from '../i18n/locale';
import { LocaleService } from '../i18n/locale.service';
import { isAppRouteData } from '../routing/app-route-data';
import { type RouteId } from '../routing/route-ids';
import { routeCommands } from '../routing/route-paths';
import { FOOTER_NAV, PRIMARY_NAV, type NavItem } from './navigation';

export interface ResolvedNavItem {
  readonly routeId: RouteId;
  readonly label: string;
  readonly link: unknown[];
  readonly children?: readonly ResolvedNavItem[];
}

@Injectable({ providedIn: 'root' })
export class NavigationService {
  private readonly localeService = inject(LocaleService);
  private readonly router = inject(Router);
  private readonly activeRouteIdSignal = signal<RouteId>('home');

  readonly activeRouteId = this.activeRouteIdSignal.asReadonly();
  readonly cvHref = SITE_CONFIG.cvAssetPath;
  readonly contactLink = computed(() => this.link('contact'));
  readonly primaryNav = computed(() => this.resolveItems(PRIMARY_NAV, this.localeService.locale()));
  readonly footerNav = computed(() => this.resolveItems(FOOTER_NAV, this.localeService.locale()));

  constructor() {
    this.router.events
      .pipe(
        filter((event): event is NavigationEnd => event instanceof NavigationEnd),
        takeUntilDestroyed(),
      )
      .subscribe(() => this.syncFromRouter());

    this.syncFromRouter();
  }

  link(routeId: RouteId, locale?: AppLocale): unknown[] {
    return routeCommands(routeId, locale ?? this.localeService.locale());
  }

  alternateLocaleLink(): unknown[] {
    const targetLocale = otherLocale(this.localeService.locale());
    const current = this.activeRouteId();
    const routeId = current === 'notFound' ? 'home' : current;
    return routeCommands(routeId, targetLocale);
  }

  private resolveItems(items: readonly NavItem[], locale: AppLocale): ResolvedNavItem[] {
    return items.map((item) => ({
      routeId: item.routeId,
      label: item.label[locale],
      link: routeCommands(item.routeId, locale),
      children: item.children ? this.resolveItems(item.children, locale) : undefined,
    }));
  }

  private syncFromRouter(): void {
    let snapshot = this.router.routerState.snapshot.root;

    while (snapshot.firstChild) {
      snapshot = snapshot.firstChild;
    }

    if (!isAppRouteData(snapshot.data)) {
      return;
    }

    this.localeService.setLocale(snapshot.data.locale);
    this.activeRouteIdSignal.set(snapshot.data.routeId);
  }
}