///
/// Copyright 2015-2026 Micro Focus or one of its affiliates.
///
/// Licensed under the Apache License, Version 2.0 (the "License");
/// you may not use this file except in compliance with the License.
/// You may obtain a copy of the License at
///
///      http://www.apache.org/licenses/LICENSE-2.0
///
/// Unless required by applicable law or agreed to in writing, software
/// distributed under the License is distributed on an "AS IS" BASIS,
/// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
/// See the License for the specific language governing permissions and
/// limitations under the License.
///

import {
  AfterViewInit,
  Directive,
  ElementRef,
  EventEmitter,
  inject,
  OnDestroy,
  Output,
} from '@angular/core';
import { fromEvent, Subject } from 'rxjs';
import { takeUntil } from 'rxjs/operators';

@Directive({ selector: '[segmentFocus],[segmentBlur]' })
export class PartitionMapSegmentEventsDirective implements AfterViewInit, OnDestroy {
  private readonly _elementRef = inject(ElementRef);

  /** Emit when the segment receives focus */
  @Output() segmentFocus = new EventEmitter<FocusEvent>();

  /** Emit when the segment is blurred */
  @Output() segmentBlur = new EventEmitter<FocusEvent>();

  /** Unsubscribe from observables */
  private readonly _onDestroy = new Subject<void>();

  ngAfterViewInit(): void {
    // Get the parent segment element
    // Note we cannot use DI to get the element as this is a template
    // and the context has no knowledge of the partition map template
    const segment = this.getSegmentElement();

    if (segment) {
      fromEvent<FocusEvent>(segment, 'focus')
        .pipe(takeUntil(this._onDestroy))
        .subscribe(event => this.segmentFocus.emit(event));

      fromEvent<FocusEvent>(segment, 'blur')
        .pipe(takeUntil(this._onDestroy))
        .subscribe(event => this.segmentBlur.emit(event));
    }
  }

  ngOnDestroy(): void {
    this._onDestroy.next();
    this._onDestroy.complete();
  }

  /**
   * Find the parent element that is a partition map segment
   */
  private getSegmentElement(): HTMLElement {
    let ancestor = (this._elementRef.nativeElement as HTMLElement).parentElement;

    while (ancestor !== null) {
      if (ancestor.classList.contains('partition-map-segment')) {
        return ancestor;
      }
      ancestor = ancestor.parentElement;
    }
  }
}