import { ChangeDetectionStrategy, Component, ElementRef, QueryList, ViewChild, ViewChildren, inject, signal, effect, OnInit, OnDestroy } from '@angular/core';
import { CommonModule } from '@angular/common';
import { Router, NavigationEnd, ActivatedRoute } from '@angular/router';
import { ThemesService } from '../../services/themes.service';
import { TranslatePipe } from '../../pipes/translate.pipe';

const THEMES_BAR_COLLAPSED_KEY = 'newtube.themesBarCollapsed';

@Component({
  selector: 'app-themes-nav',
  standalone: true,
  changeDetection: ChangeDetectionStrategy.OnPush,
  imports: [CommonModule, TranslatePipe],
  templateUrl: './themes-nav.component.html'
})
export class ThemesNavComponent implements OnDestroy {
  private router = inject(Router);
  private route = inject(ActivatedRoute);
  themesSvc = inject(ThemesService);

  themes = () => this.themesSvc.themes();
  activeSlug = this.themesSvc.activeSlug;
  displayedThemes = () => this.themes();

  /** Bande repliée/dépliée (persistée) : la barre reste masquable en permanence. */
  collapsed = signal<boolean>((() => {
    try { return localStorage.getItem(THEMES_BAR_COLLAPSED_KEY) === '1'; } catch { return false; }
  })());

  toggleCollapsed(): void {
    const next = !this.collapsed();
    this.collapsed.set(next);
    try { localStorage.setItem(THEMES_BAR_COLLAPSED_KEY, next ? '1' : '0'); } catch {}
  }

  activeThemeLabel(): string {
    try {
      const slug = this.activeSlug();
      const found = this.themes().find((t) => t.slug === slug);
      if (found) return this.themesSvc.i18nLabel(found);
    } catch {}
    return '';
  }

  @ViewChildren('pill', { read: ElementRef }) pills!: QueryList<ElementRef<HTMLButtonElement>>;
  @ViewChild('scroll', { static: false }) scrollRef?: ElementRef<HTMLDivElement>;

  // Signal to force re-evaluation when data-theme changes
  private themeChanged = signal<number>(0);

  constructor() {
    // Reflect current URL into active slug
    this.router.events.subscribe((e) => {
      if (e instanceof NavigationEnd) this.syncFromUrl();
    });
    // Also on init
    setTimeout(() => this.syncFromUrl(), 0);

    // Effect to listen for theme changes on document.documentElement
    effect(() => {
      const currentTheme = document.documentElement.getAttribute('data-theme') || 'system';
      // Trigger re-evaluation when theme changes
      this.themeChanged.update(n => n + 1);
    });
  }

  ngOnDestroy() {
    // Nothing to cleanup
  }

  private syncFromUrl() {
    const url = this.router.url || '';
    const m = url.match(/#?\/?(?:p\/[^/]+\/)?t\/([^/?#]+)/i);
    if (m && m[1]) this.activeSlug.set(m[1]);
  }

  goToTheme(slug: string) {
    this.activeSlug.set(slug);
    this.router.navigate(['/t', slug]);
  }

  onKeydown(ev: KeyboardEvent, index: number) {
    const list = this.pills?.toArray() || [];
    if (!list.length) return;
    if (ev.key === 'ArrowRight') {
      ev.preventDefault();
      const next = list[(index + 1) % list.length];
      next?.nativeElement?.focus();
      next?.nativeElement?.scrollIntoView({ inline: 'center', behavior: 'smooth', block: 'nearest' });
    } else if (ev.key === 'ArrowLeft') {
      ev.preventDefault();
      const prev = list[(index - 1 + list.length) % list.length];
      prev?.nativeElement?.focus();
      prev?.nativeElement?.scrollIntoView({ inline: 'center', behavior: 'smooth', block: 'nearest' });
    }
  }

  scrollBy(px: number) {
    const el = this.scrollRef?.nativeElement;
    if (!el) return;
    el.scrollBy({ left: px, behavior: 'smooth' });
  }

  onWheel(ev: WheelEvent) {
    const el = this.scrollRef?.nativeElement;
    if (!el) return;
    // Horizontal scroll with mouse wheel while hovering the bar
    if (Math.abs(ev.deltaY) > Math.abs(ev.deltaX)) {
      ev.preventDefault();
      el.scrollLeft += ev.deltaY;
    }
  }

  // Theme helpers (read from document attribute/localStorage)
  private getCurrentTheme(): 'light' | 'dark' | 'black' | 'blue' | 'system' {
    try {
      const fromAttr = document.documentElement.getAttribute('data-theme');
      if (fromAttr) return fromAttr as any;
      const fromStorage = localStorage.getItem('newtube.theme');
      return (fromStorage as any) || 'system';
    } catch {
      return 'system';
    }
  }

  private resolveThemeSlug(): 'light' | 'dark' | 'black' | 'blue' {
    const cur = this.getCurrentTheme();
    if (cur === 'system') {
      const prefersDark = typeof window !== 'undefined' && window.matchMedia?.('(prefers-color-scheme: dark)').matches;
      return prefersDark ? 'dark' : 'light';
    }
    return cur as any;
  }

  isLightTheme(): boolean {
    this.themeChanged(); // Trigger re-evaluation
    return this.resolveThemeSlug() === 'light';
  }
  isDarkTheme(): boolean {
    this.themeChanged(); // Trigger re-evaluation
    return this.resolveThemeSlug() === 'dark';
  }
  isBlackTheme(): boolean {
    this.themeChanged(); // Trigger re-evaluation
    return this.resolveThemeSlug() === 'black';
  }
  isBlueTheme(): boolean {
    this.themeChanged(); // Trigger re-evaluation
    return this.resolveThemeSlug() === 'blue';
  }
}