import { AsyncPipe } from "@angular/common";
import { Component } from "@angular/core";
import { takeUntilDestroyed, toObservable } from "@angular/core/rxjs-interop";
import { injectNetwork } from "ngxtension/inject-network";
import {
  distinctUntilChanged,
  map,
  skipWhile,
  startWith,
  switchMap,
  timer,
} from "rxjs";

const INDICATOR_TIMEOUT_MS = 2 * 1000;
const INDICATOR_TRANSITION_MS = 300;

@Component({
  standalone: true,
  selector: "app-network-indicator",
  imports: [AsyncPipe],
  template: `
    @let isOnline = isOnline$ | async;
    <div
      class="indicator"
      [class.visible]="isVisible$ | async"
      [style.background]="isOnline ? 'green' : 'red'"
    >
      {{ isOnline ? "Online" : "Offline" }}
    </div>
  `,
  styles: `
  .indicator {
    text-align: center;

    display: none;
    opacity: 0;
    transition: opacity ${INDICATOR_TRANSITION_MS}ms ease,
      display ${INDICATOR_TRANSITION_MS}ms ease allow-discrete;

    &.visible {
      opacity: 1;
      display: block;
    }
  }

  @starting-style {
    .indicator.visible {
      opacity: 0;
    }
  }
  `,
})
export class NetworkIndicatorComponent {
  private readonly network = injectNetwork();
  protected readonly isOnline$ = toObservable(this.network.online).pipe(
    skipWhile(Boolean),
    distinctUntilChanged(),
    takeUntilDestroyed()
  );
  protected readonly isVisible$ = this.isOnline$.pipe(
    switchMap(() =>
      timer(INDICATOR_TIMEOUT_MS).pipe(
        map(() => false),
        startWith(true)
      )
    )
  );
}