import { Base64UrlString } from '@digitalpersona/core';
import { AuthenticationData, IAuthenticationClient, AuthenticationHandle } from '@digitalpersona/services';
import { Handler, MultiCastEventSource } from '../../private';
import { Command, Request, Channel } from '../websdk';
import { Event, CommunicationEventSource, CommunicationFailed } from '../../common';
import { Method } from './messages';
import { IWAData } from './data';

/**
 * Integrated Windows Authentication API.
 * An instance of this class allows internet browsers to authenticate in DigitalPersona servers
 * using Integrated Windows Authentication.
 * The IWA API uses DigitalPersona WebSDK to communicate with Windwows operating system and extract
 * Windows account data for authentication.
 */
export class WindowsAuthClient
    extends MultiCastEventSource
    implements IAuthenticationClient // , CommunicationEventSource
{
    /** A WebSdk channel. */
    private channel: Channel;

    /**
     * Constructs a new IWA API object.
     * @param options - options for the `WebSdk` channel.
     */
    constructor(options?: WebSdk.WebChannelOptions) {
        super();
        this.channel = new Channel("wia", options);
        this.channel.onCommunicationError = this.onConnectionFailed.bind(this);
    }

    /** A uni-cast event handler for the {@link CommunicationFailed} event. */
    public onCommunicationFailed: Handler<CommunicationFailed>;

    /**
     * Adds an event handler for the event.
     * This is a multicast subscription, i.e. many handlers can be registered at once.
     *
     * @param event - a name of the event to subscribe, e.g. "CommunicationFailed"
     * @param handler - an event handler.
     * @returns an event handler reference.
     * Store the reference and pass it to the {@link WindowsAuthClient.off} to unsubscribe from the event.
     *
     * @example
     * ```
     * class IntegratedWindowsAuthComponent
     * {
     *     private client: WindowsAuthClient;
     *
     *     private onCommunicationFailed = (event: CommunicationFailed) => { ... }
     *
     *     public $onInit() {
     *         this.client = new WindowsAuthClient();
     *         this.client.on("CommunicationFailed", this.onCommunicationFailed);
     *     }
     *     public $onDestroy() {
     *         this.client.off("CommunicationFailed", this.onCommunicationFailed);
     *         // alternatively, call this.reader.off() to unsubscribe from all events at once.
     *         delete this.client;
     *     }
     * }
     * ```
     */
    public on<E extends Event>(event: string, handler: Handler<E>): Handler<E> { return this._on(event, handler); }

    /** Deletes an event handler for the event.
     * @param event - a name of the event to subscribe.
     * @param handler - an event handler added with the {@link WindowsAuthClient.on} method.
     */
    public off<E extends Event>(event?: string, handler?: Handler<E>): this { return this._off(event, handler); }

    /** Used internally. Do not call this method. */
    public init(): Promise<AuthenticationData> {
        return this.channel.send(new Request(new Command(
            Method.Init,
        )), 3000)
        .then(response => {
            const data: IWAData = JSON.parse(response.Data || "{}");
            return { handle: data.Handle, data: data.Data };
        });
    }

    /** Used internally. Do not call this method. */
    public continue(handle: AuthenticationHandle, data: string): Promise<Base64UrlString> {
        return this.channel.send(new Request(new Command(
            Method.Continue,
            JSON.stringify({ Handle: handle, Data: data}),
        )))
        .then(response => {
            const d: IWAData = JSON.parse(response.Data || "{}");
            return d.Data;
        });
    }

    /** Used internally. Do not call this method. */
    public term(handle: AuthenticationHandle): Promise<void> {
        return this.channel.send(new Request(new Command(
            Method.Term,
            JSON.stringify({ Handle: handle }),
        )))
        .then();
    }

    /** Converts WebSdk connectivity error to an IWA API event. */
    private onConnectionFailed(): void {
        this.emit(new CommunicationFailed());
    }

}