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selection_service.ts
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selection_service.ts
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/**
* @license
* Copyright 2020 Google LLC
*
* 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.
*/
// tslint:disable:no-new-decorators
import {action, computed, observable} from 'mobx';
import {IndexedInput, ServiceUser} from '../lib/types';
import {LitService} from './lit_service';
import {SelectionObservedByUrlService} from './url_service';
/**
* The AppState interface for working with the SelectionService
*/
export interface AppState {
currentInputData: IndexedInput[];
getCurrentInputDataById: (id: string) => IndexedInput | null;
getExamplesById: (ids: string[]) => IndexedInput[];
}
/**
* A singleton service for managing App selections of input data.
*/
export class SelectionService extends LitService implements
SelectionObservedByUrlService {
// Service linking helper methods (to be called after construction)
private appState!: AppState;
setAppState(appState: AppState) {
this.appState = appState;
}
@observable private readonly selectedIdsSet = new Set<string>();
@observable private primarySelectedIdInternal: string|null = null;
// Track the last user, so components can avoid resetting on selections they
// triggered.
@observable private lastUserInternal: ServiceUser = null;
@computed
get lastUser() {
return this.lastUserInternal;
}
@computed
get primarySelectedId() {
return this.primarySelectedIdInternal;
}
@computed
get selectedIds(): string[] {
return [...this.selectedIdsSet.values()];
}
@computed
get selectedInputData(): IndexedInput[] {
if (this.selectedIds.length === 0) {
return [];
}
return this.appState.currentInputData.filter((inputData) => {
return this.selectedIdsSet.has(inputData.id);
});
}
@computed
get primarySelectedInputData(): IndexedInput|null {
if (this.primarySelectedId !== null) {
return this.appState.getCurrentInputDataById(this.primarySelectedId);
}
return null;
}
@action
setLastUser(user: ServiceUser) {
this.lastUserInternal = user;
}
@action
setPrimarySelection(id: string|null, user: ServiceUser = null) {
if (id === null || this.selectedIdsSet.has(id)) {
// Primary id is within the selected set, or we're clearing selection.
this.primarySelectedIdInternal = id;
this.setLastUser(user);
} else {
// Not in main selection, so update that.
this.selectIds([id], user);
}
}
@action
selectIds(ids: string[], user: ServiceUser = null) {
this.selectedIdsSet.clear();
ids.forEach(id => {
this.selectedIdsSet.add(id);
});
if (this.primarySelectedId !== null &&
this.selectedIdsSet.has(this.primarySelectedId)) {
// Don't change primary selected id.
} else if (this.selectedIdsSet.size === 0) {
// Clear primary if selection is empty.
this.primarySelectedIdInternal = null;
} else {
// Default to first point.
this.primarySelectedIdInternal = ids[0];
}
this.setLastUser(user);
}
/**
* Sync state from another selection service.
* Atomic, so we only trigger a single set of reactions.
*/
@action
syncFrom(other: SelectionService) {
this.selectIds(other.selectedIds);
this.setPrimarySelection(other.primarySelectedId);
}
isIdSelected(id: string) {
return this.selectedIdsSet.has(id);
}
/**
* Gets the selected input data if any selected, otherwise all input data.
*/
@computed
get selectedOrAllInputData(): IndexedInput[] {
return this.selectedInputData.length > 0 ? this.selectedInputData :
this.appState.currentInputData;
}
}