import { DOCUMENT, ViewportScroller } from '@angular/common';
import {
  afterNextRender,
  ChangeDetectionStrategy,
  Component,
  computed,
  inject,
  Injector,
  signal,
} from '@angular/core';
import { takeUntilDestroyed } from '@angular/core/rxjs-interop';
import { NavigationEnd, Router, RouterLink, RouterLinkActive, RouterOutlet } from '@angular/router';
import { filter } from 'rxjs';
import { DotBackground } from './components/dot-background/dot-background';
import { SHELL_COPY } from './core/content/shell-copy';
import { SITE_CONFIG } from './core/content/site-config';
import { LOCALE_HTML_LANG, otherLocale } from './core/i18n/locale';
import { LocaleService } from './core/i18n/locale.service';
import { NavigationService } from './core/navigation/navigation.service';
import { isBrowserPlatform, viewportMatches } from './core/platform/browser';
import { TerminalDock } from './shared/terminal/terminal-dock';

/** Matches `md` in `src/_breakpoints.scss` (48rem). */
export const WIDE_NAV_QUERY = '(min-width: 48rem)';

@Component({
  selector: 'app-root',
  changeDetection: ChangeDetectionStrategy.OnPush,
  imports: [RouterOutlet, RouterLink, RouterLinkActive, DotBackground, TerminalDock],
  templateUrl: './app.html',
  styleUrl: './app.scss',
})
export class App {
  protected readonly navigation = inject(NavigationService);
  protected readonly localeService = inject(LocaleService);
  private readonly router = inject(Router);
  private readonly injector = inject(Injector);
  private readonly document = inject(DOCUMENT);
  private readonly viewportScroller = inject(ViewportScroller);
  private readonly isBrowser = isBrowserPlatform();
  private readonly wideNav = viewportMatches(WIDE_NAV_QUERY);
  protected readonly siteConfig = SITE_CONFIG;
  protected readonly navOpen = signal(true);

  protected readonly shell = computed(() => SHELL_COPY[this.localeService.locale()]);
  protected readonly otherLocale = computed(() => otherLocale(this.localeService.locale()));
  protected readonly otherHtmlLang = computed(() => LOCALE_HTML_LANG[this.otherLocale()]);
  protected readonly menuLabel = computed(() =>
    this.navOpen() ? this.shell().menuClose : this.shell().menuOpen,
  );

  constructor() {
    afterNextRender(
      () => {
        this.collapseNavIfNarrow();
        this.bindHeaderScrollOffset();
      },
      { injector: this.injector },
    );

    this.router.events
      .pipe(
        filter((event): event is NavigationEnd => event instanceof NavigationEnd),
        takeUntilDestroyed(),
      )
      .subscribe(() => this.collapseNavIfNarrow());
  }

  protected toggleNav(): void {
    this.navOpen.update((open) => !open);
  }

  private collapseNavIfNarrow(): void {
    if (!this.isBrowser || this.wideNav) {
      return;
    }

    this.navOpen.set(false);
  }

  private bindHeaderScrollOffset(): void {
    if (!this.isBrowser) {
      return;
    }

    this.viewportScroller.setOffset(() => [0, this.headerOffsetPx()]);
  }

  private headerOffsetPx(): number {
    const view = this.document.defaultView;
    if (!view) {
      return 0;
    }

    const styles = view.getComputedStyle(this.document.documentElement);
    const raw = styles.getPropertyValue('--header-offset').trim();
    const numeric = Number.parseFloat(raw);
    if (!Number.isFinite(numeric)) {
      return 0;
    }

    if (raw.endsWith('rem')) {
      const rootSize = Number.parseFloat(styles.fontSize);
      return numeric * (Number.isFinite(rootSize) ? rootSize : 16);
    }

    return numeric;
  }
}