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

export interface Toast {
  id: number;
  kind: 'error' | 'info' | 'success';
  text: string;
  ttlMs: number;
}

@Injectable({ providedIn: 'root' })
export class ToastService {
  readonly toasts = signal<Toast[]>([]);
  private nextId = 1;
  private readonly timers = new Map<
    number,
    { timer: ReturnType<typeof setTimeout>; expiresAt: number; remaining: number }
  >();

  error(text: string) {
    this.show('error', text, 6000);
  }

  info(text: string) {
    this.show('info', text, 3000);
  }

  success(text: string) {
    this.show('success', text, 3000);
  }

  dismiss(id: number) {
    const entry = this.timers.get(id);
    if (entry) clearTimeout(entry.timer);
    this.timers.delete(id);
    this.toasts.update((list) => list.filter((t) => t.id !== id));
  }

  /** Freeze the auto-dismiss countdown (hover). */
  pause(id: number) {
    const entry = this.timers.get(id);
    if (!entry) return;
    clearTimeout(entry.timer);
    entry.remaining = Math.max(0, entry.expiresAt - Date.now());
  }

  /** Resume the countdown with whatever time was left when paused. */
  resume(id: number) {
    const entry = this.timers.get(id);
    if (!entry) return;
    entry.expiresAt = Date.now() + entry.remaining;
    entry.timer = setTimeout(() => this.dismiss(id), entry.remaining);
  }

  private show(kind: Toast['kind'], text: string, ttlMs: number) {
    const toast = { id: this.nextId++, kind, text, ttlMs };
    this.toasts.update((list) => [...list, toast]);
    this.timers.set(toast.id, {
      timer: setTimeout(() => this.dismiss(toast.id), ttlMs),
      expiresAt: Date.now() + ttlMs,
      remaining: ttlMs,
    });
  }
}