import { DOCUMENT, isPlatformBrowser } from '@angular/common';
import {
  afterNextRender,
  DestroyRef,
  inject,
  Injectable,
  Injector,
  PLATFORM_ID,
  signal,
} from '@angular/core';

export type TerminalDockState = 'collapsed' | 'expanded' | 'maximized';

@Injectable({ providedIn: 'root' })
export class TerminalDockService {
  private readonly document = inject(DOCUMENT);
  private readonly destroyRef = inject(DestroyRef);
  private readonly injector = inject(Injector);
  private readonly isBrowser = isPlatformBrowser(inject(PLATFORM_ID));

  readonly state = signal<TerminalDockState>('collapsed');
  readonly panelId = 'terminal-dock-panel';
  readonly inputId = 'terminal-dock-input';
  readonly logId = 'terminal-dock-log';

  private trigger: HTMLElement | null = null;

  constructor() {
    afterNextRender(
      () => {
        if (!this.isBrowser) {
          return;
        }

        this.document.addEventListener('keydown', this.onDocumentKeydown);
      },
      { injector: this.injector },
    );

    this.destroyRef.onDestroy(() => this.teardown());
  }

  registerTrigger(element: HTMLElement | null): void {
    this.trigger = element;
  }

  open(opener?: HTMLElement | null): void {
    if (this.state() !== 'collapsed') {
      return;
    }

    if (opener instanceof HTMLElement) {
      this.trigger = opener;
    }

    this.state.set('expanded');
  }

  collapse(): void {
    if (this.state() === 'collapsed') {
      return;
    }

    this.state.set('collapsed');
    this.restoreFocus();
  }

  toggle(opener?: HTMLElement | null): void {
    if (this.state() === 'collapsed') {
      this.open(opener);
      return;
    }

    this.collapse();
  }

  toggleMaximized(): void {
    if (this.state() === 'collapsed') {
      this.open();
      this.state.set('maximized');
      return;
    }

    this.state.update((current) => (current === 'maximized' ? 'expanded' : 'maximized'));
  }

  private restoreFocus(): void {
    const trigger = this.trigger;

    afterNextRender(
      () => {
        if (trigger instanceof HTMLElement && trigger.isConnected) {
          trigger.focus();
        }
      },
      { injector: this.injector },
    );
  }

  private teardown(): void {
    this.document.removeEventListener('keydown', this.onDocumentKeydown);
    this.state.set('collapsed');
    this.trigger = null;
  }

  private readonly onDocumentKeydown = (event: KeyboardEvent): void => {
    if (
      event.key.toLowerCase() !== 'k' ||
      !(event.ctrlKey || event.metaKey) ||
      event.altKey ||
      event.shiftKey
    ) {
      return;
    }

    event.preventDefault();
    this.toggle();
  };
}