///
/// 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 {
  AfterContentInit,
  Component,
  ContentChildren,
  EventEmitter,
  inject,
  Input,
  OnDestroy,
  Output,
  QueryList,
} from '@angular/core';
import { Subject } from 'rxjs';
import { takeUntil } from 'rxjs/operators';
import { SelectionService } from '../../directives/selection/selection.service';
import { SelectListItemComponent } from './select-list-item/select-list-item.component';
import { MultipleSelectListStrategy } from './strategies/multiple-select-list.strategy';
import { SingleSelectListStrategy } from './strategies/single-select-list.strategy';

@Component({
  selector: 'ux-select-list',
  templateUrl: './select-list.component.html',
  providers: [SelectionService],
  host: {
    role: 'list',
  },
})
export class SelectListComponent<T> implements AfterContentInit, OnDestroy {
  private readonly _selection = inject<SelectionService<T>>(SelectionService);

  /** Determine if we allow multiple items to be selected */
  @Input() set multiple(multiple: boolean) {
    this._selection.strategy.deselectAll();
    this._selection.setStrategy(
      multiple ? new MultipleSelectListStrategy<T>() : new SingleSelectListStrategy<T>()
    );
  }

  /** Set the selected items */
  @Input() set selected(selected: T | ReadonlyArray<T>) {
    // if the selection entered is the same as the current selection then do nothing
    if (this._selection.selection$.value === selected) {
      return;
    }

    // if selected is an array and has not items and there are no items currently selected also do nothing
    if (
      Array.isArray(selected) &&
      selected.length === 0 &&
      this._selection.selection$.value.length === 0
    ) {
      return;
    }

    // select only the specified items
    if (Array.isArray(selected)) {
      this._selection.selectOnly(...selected);
    } else {
      this._selection.selectOnly(selected as T);
    }
  }

  /** Emit when the selection changes */
  @Output() selectedChange = new EventEmitter<ReadonlyArray<T>>();

  /** Find all select list items */
  @ContentChildren(SelectListItemComponent) items: QueryList<SelectListItemComponent<T>>;

  /** Automatically unsubscribe all observables */
  private readonly _onDestroy = new Subject<void>();

  constructor() {
    // set the selection strategy to single by default
    this._selection.setStrategy(new SingleSelectListStrategy<T>());

    // emit the selection changes when they occur
    this._selection.selection$
      .pipe(takeUntil(this._onDestroy))
      .subscribe(selection => this.selectedChange.emit(selection));
  }

  ngAfterContentInit(): void {
    // supply the initial item set
    this._selection.dataset = this.items.map(item => item.data);

    // if the item set changes update the list
    this.items.changes
      .pipe(takeUntil(this._onDestroy))
      .subscribe(() => (this._selection.dataset = this.items.map(item => item.data)));
  }

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