import {
    BaseExtensionMessage,
    ExtensionMesssage,
    MessageResponse,
    NotificationMessage,
    WatchQueryFetchPolicy,
} from '@vendure/common/lib/extension-host-types';
import { Observable } from 'rxjs';
import { take } from 'rxjs/operators';

let targetOrigin = 'http://localhost:3000';

/**
 * @description
 * Set the [window.postMessage API](https://developer.mozilla.org/en-US/docs/Web/API/Window/postMessage)
 * `targetOrigin`. The Vendure ui-devkit uses the postMessage API to
 * enable cross-frame and cross-origin communication between the ui extension code and the Admin UI
 * app. The `targetOrigin` is a security feature intended to provide control over where messages are sent.
 */
export function setTargetOrigin(value: string) {
    targetOrigin = value;
}

/**
 * @description
 * Perform a GraphQL query and returns either an Observable or a Promise of the result.
 */
export function graphQlQuery<T, V extends { [key: string]: any }>(
    document: string,
    variables?: { [key: string]: any },
    fetchPolicy?: WatchQueryFetchPolicy,
): {
    then: Promise<T>['then'];
    stream: Observable<T>;
} {
    const result$ = sendMessage('graphql-query', { document, variables, fetchPolicy });
    return {
        then: (...args: any[]) =>
            result$
                .pipe(take(1))
                .toPromise()
                .then(...args),
        stream: result$,
    };
}

/**
 * @description
 * Perform a GraphQL mutation and returns either an Observable or a Promise of the result.
 */
export function graphQlMutation<T, V extends { [key: string]: any }>(
    document: string,
    variables?: { [key: string]: any },
): {
    then: Promise<T>['then'];
    stream: Observable<T>;
} {
    const result$ = sendMessage('graphql-mutation', { document, variables });
    return {
        then: (...args: any[]) =>
            result$
                .pipe(take(1))
                .toPromise()
                .then(...args),
        stream: result$,
    };
}

/**
 * @description
 * Display a toast notification.
 */
export function notify(options: NotificationMessage['data']) {
    sendMessage('notification', options).toPromise();
}

function sendMessage<T extends ExtensionMesssage>(type: T['type'], data: T['data']): Observable<any> {
    const requestId =
        type +
        '__' +
        Math.random()
            .toString(36)
            .substr(3);
    const message: BaseExtensionMessage = {
        requestId,
        type,
        data,
    };

    return new Observable<any>(subscriber => {
        const handleReply = (event: MessageEvent) => {
            const response: MessageResponse = event.data;
            if (response && response.requestId === requestId) {
                if (response.complete) {
                    subscriber.complete();
                    tearDown();
                    return;
                }
                if (response.error) {
                    subscriber.error(response.data);
                    tearDown();
                    return;
                }
                subscriber.next(response.data);
            }
        };
        const tearDown = () => {
            window.parent.postMessage({ requestId, type: 'cancellation', data: null }, targetOrigin);
        };
        window.addEventListener('message', handleReply);
        window.parent.postMessage(message, targetOrigin);

        return tearDown;
    });
}