import { Injectable, signal } from '@angular/core';
import { Observable } from 'rxjs';

export interface DialogRequest {
  title: string;
  message?: string;
  confirmLabel?: string;
  danger?: boolean;
  /** Set — the dialog asks for a text (prompt); the value is the initial text. */
  input?: string;
  inputLabel?: string;
  required?: boolean;
}

interface OpenDialog extends DialogRequest { resolve: (value: string | null) => void; }

/** One glass dialog at a time: confirm (resolves '' or null) and prompt (the text or null). */
@Injectable({ providedIn: 'root' })
export class DialogService {
  readonly current = signal<OpenDialog | null>(null);

  ask(request: DialogRequest): Observable<string | null> {
    return new Observable<string | null>(subscriber => {
      this.current()?.resolve(null);
      this.current.set({
        ...request,
        resolve: value => {
          this.current.set(null);
          subscriber.next(value);
          subscriber.complete();
        }
      });
    });
  }

  confirm(title: string, message: string, confirmLabel = 'Confirm', danger = false): Observable<string | null> {
    return this.ask({ title, message, confirmLabel, danger });
  }

  prompt(title: string, inputLabel: string, value = '', confirmLabel = 'Save'): Observable<string | null> {
    return this.ask({ title, inputLabel, input: value, confirmLabel, required: true });
  }
}