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// (C) Copyright 2015 Moodle Pty Ltd.
//
// 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 { CoreItemsManagerSource } from './items-manager-source';
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/**
* Listeners.
*/
export interface CoreItemsanagerListener<Item> {
onSelectedItemUpdated?(item: Item): void;
}
/**
* Helper to manage a collection of items in a page.
*/
export abstract class CoreItemsManager<
Item = unknown,
Source extends CoreItemsManagerSource<Item> = CoreItemsManagerSource<Item>,
> {
protected source?: { instance: Source; unsubscribe: () => void };
protected itemsMap: Record<string, Item> | null = null;
protected selectedItem: Item | null = null;
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protected listeners: CoreItemsanagerListener<Item>[] = [];
constructor(source: Source) {
this.setSource(source);
}
/**
* Get source.
*
* @returns Source.
*/
getSource(): Source {
if (!this.source) {
throw new Error('Source is missing from items manager');
}
return this.source.instance;
}
/**
* Set source.
*
* @param newSource New source.
*/
setSource(newSource: Source | null): void {
if (this.source) {
this.source.unsubscribe();
delete this.source;
this.onSourceReset();
}
if (newSource) {
this.source = {
instance: newSource,
unsubscribe: newSource.addListener({
onItemsUpdated: items => this.onSourceItemsUpdated(items),
onReset: () => this.onSourceReset(),
}),
};
const items = newSource.getItems();
if (items) {
this.onSourceItemsUpdated(items);
}
}
}
/**
* Process page destroyed operations.
*/
destroy(): void {
this.setSource(null);
}
/**
* Get selected item.
*
* @return Selected item, null if none.
*/
getSelectedItem(): Item | null {
return this.selectedItem;
}
/**
* Set selected item.
*
* @param item Item, null if none.
*/
setSelectedItem(item: Item | null): void {
this.selectedItem = item;
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this.listeners.forEach(listener => listener.onSelectedItemUpdated?.call(listener, item));
}
/**
* Register a listener.
*
* @param listener Listener.
* @returns Unsubscribe function.
*/
addListener(listener: CoreItemsanagerListener<Item>): () => void {
this.listeners.push(listener);
return () => this.removeListener(listener);
}
/**
* Remove a listener.
*
* @param listener Listener.
*/
removeListener(listener: CoreItemsanagerListener<Item>): void {
const index = this.listeners.indexOf(listener);
if (index === -1) {
return;
}
this.listeners.splice(index, 1);
}
/**
* Called when source items have been updated.
*
* @param items New items.
*/
protected onSourceItemsUpdated(items: Item[]): void {
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this.itemsMap = items.reduce((map, item) => {
map[this.getItemId(item)] = item;
return map;
}, {});
}
/**
* Called when source has been updated.
*/
protected onSourceReset(): void {
this.itemsMap = null;
this.selectedItem = null;
}
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/**
* Get item by ID.
*
* @param id ID
* @return Item, null if not found.
*/
getItemById(id: string | number): Item | null {
return this.itemsMap?.[id] ?? null;
}
/**
* Get an ID to identify an item.
*
* @param item Data about the item.
* @return Item ID.
*/
abstract getItemId(item: Item): string | number;
}