import {
    OnInit,
} from '@angular/core';

import {
    MemoizedSelector,
    Store,
} from '@ngrx/store';

import {
    of,
} from 'rxjs';

/**
 * Often our components (mostly organisms) use a similar structure when we
 * initialize them. This is provides an easy way to test a component that
 * just pulls data from the store when running ngOnInit.
 *
 * An example of how this might be useful if is a component has an ngOnInit
 * function that looks like this:
 * public ngOnInit() {
 *  this.isCurrentSidebarTabEdit$ =
 *      this._store.select(selectIsCurrentSidebarTabEdit);
 * }
 *
 * In which case we could easily test that the store select is called and that
 * the property is set to the matching value.
 *
 * An example of this would be:
 * storeConnectOnInitTests<
 *  MyComponentClass,
 *  StateInterface,
 * >({
 *  initComponentFunction: (store) => new MyComponentClass(store),
 *  initStoreFunction: initMockStore,
 *  propertyName: 'isCurrentSidebarTabEdit$',
 *  selector: selectIsCurrentSidebarTabEdit,
 * });
 *
 * Which would test that isCurrentSidebarTabEdit$ is set to the value from the
 * store and that the store is called with the selectIsCurrentSidebarTabEdit
 * selector.
 */
export const storeConnectOnInitTests = <
    ComponentType extends OnInit,
    State
>({
    initComponentFunction,
    initStoreFunction,
    propertyName,
    selector,
}: {
    initComponentFunction: (store: Store<State>) => ComponentType,
    initStoreFunction: () => Store<State>,
    propertyName: keyof ComponentType,
    selector: MemoizedSelector<object, any>,
}) => {
    const initData = () => {
        const mockReturnValue = of('some value');
        const store = initStoreFunction();
        store.select = jest.fn((arg) => arg === selector
            ? mockReturnValue
            : of(null),
        );
        const component = initComponentFunction(store);

        return {
            component,
            mockReturnValue,
            store,
        };
    };

    test(`Calls store.select with ${selector.name}`, () => {
        const {
            component,
            store,
        } = initData();

        component.ngOnInit();

        expect(store.select).toHaveBeenCalledWith(selector);
    });

    test(`Sets ${propertyName} to the value from the store`, () => {
        const {
            component,
            mockReturnValue,
        } = initData();

        component.ngOnInit();

        expect(component[propertyName]).toBe(mockReturnValue);
    });
};