import {Injectable} from '@angular/core';
import {Toast} from './toast';
import {Observable} from 'rxjs/Observable';
import 'rxjs/add/operator/share';
import {Observer} from 'rxjs/Observer';
import {Subject} from 'rxjs/Subject';


@Injectable()
export class ToasterService {
    addToast: Observable<Toast>;
    private _addToast: Observer<Toast>;

    clearToasts: Observable<IClearWrapper>;
    private _clearToasts: Observer<IClearWrapper>;

    removeToast: Observable<IClearWrapper>;
    /** @internal */
    _removeToastSubject: Subject<IClearWrapper>

    /**
     * Creates an instance of ToasterService.
     */
    constructor() {
        this.addToast = new Observable<Toast>((observer: any) => this._addToast = observer).share();
        this.clearToasts = new Observable<IClearWrapper>((observer: any) => this._clearToasts = observer).share();
        this._removeToastSubject = new Subject<IClearWrapper>()
        this.removeToast = this._removeToastSubject.share();
    }

    /**
     * Synchronously create and show a new toast instance.
     *
     * @param {(string | Toast)} type The type of the toast, or a Toast object.
     * @param {string=} title The toast title.
     * @param {string=} body The toast body.
     * @returns {Toast}
     *          The newly created Toast instance with a randomly generated GUID Id.
     */
    pop(type: string | Toast, title?: string, body?: string): Toast {
        const toast = typeof type === 'string' ? { type: type, title: title, body: body } : type;

        toast.toastId = Guid.newGuid();

        if (!this._addToast) {
            throw new Error('No Toaster Containers have been initialized to receive toasts.');
        }

        this._addToast.next(toast);
        return toast;
    }


    /**
     * Asynchronously create and show a new toast instance.
     *
     * @param {(string | Toast)} type The type of the toast, or a Toast object.
     * @param {string=} title The toast title.
     * @param {string=} body The toast body.
     * @returns {Observable<Toast>}
     *          A hot Observable that can be subscribed to in order to receive the Toast instance
     *          with a randomly generated GUID Id.
     */
    popAsync(type: string | Toast, title?: string, body?: string): Observable<Toast> {
        setTimeout(() => {
            this.pop(type, title, body);
        }, 0);

        return this.addToast;
    }


    /**
     * Clears a toast by toastId and/or toastContainerId.
     *
     * @param {string} toastId The toastId to clear.
     * @param {number=} toastContainerId
     *        The toastContainerId of the container to remove toasts from.
     */
    clear(toastId?: string, toastContainerId?: number) {
        const clearWrapper: IClearWrapper = {
            toastId: toastId, toastContainerId: toastContainerId
        };

        this._clearToasts.next(clearWrapper)
    }
}

export interface IClearWrapper {
    toastId?: string;
    toastContainerId?: number;
}

// http://stackoverflow.com/questions/26501688/a-typescript-guid-class
class Guid {
    static newGuid() {
        return 'xxxxxxxx-xxxx-4xxx-yxxx-xxxxxxxxxxxx'.replace(/[xy]/g, function(c) {
            const r = Math.random() * 16 | 0, v = c === 'x' ? r : ( r & 0x3 | 0x8 );
            return v.toString(16);
        });
    }
}