import {Injectable, Inject} from '@angular/core';
import {Http, Headers, RequestOptions} from '@angular/http';

import { Storage } from '@ionic/storage';

import {Observable} from 'rxjs/Observable';
import {BehaviorSubject} from 'rxjs/BehaviorSubject';
import 'rxjs/add/observable/throw';
import 'rxjs/add/observable/fromPromise';
import 'rxjs/add/operator/map';
import 'rxjs/add/operator/mergeMap';
import 'rxjs/add/operator/toPromise';
import 'rxjs/add/operator/catch';

import {API_ENDPOINTS, IApiEndpoints} from "../config/API_ENDPOINTS.config";
import {APPLICATION_SETTINGS, IApplicationSettings} from "../config/APPLICATION_SETTINGS.config";

import {User} from './user.model';
import {Roles} from './role.model';

@Injectable()
export class AuthenticationService {

    private STORAGE_IDENTIFIER: string;

    public TOKEN: any;

    private _currentUser: BehaviorSubject<any>;
    public currentUser: Observable<any>;

    private _currentRole: BehaviorSubject<number>;
    public currentRole: Observable<number>;

    constructor(
        @Inject(API_ENDPOINTS) private endpoints: IApiEndpoints,
        @Inject(APPLICATION_SETTINGS) private appSettings: IApplicationSettings,
        private http: Http,
        private storage: Storage
    ) {

        this.STORAGE_IDENTIFIER = appSettings.storageIdentifier + 'AUTH';

        this._currentUser = new BehaviorSubject(null);
        this.currentUser = this._currentUser.asObservable();

        this._currentRole = new BehaviorSubject(null);
        this.currentRole = this._currentRole.asObservable();

        this.storage.get(this.STORAGE_IDENTIFIER).then(auth => {
            if(auth) {
                this.TOKEN = auth.access_token || undefined;
                this.me().subscribe();
            }
        });

    }

    /**
     * Login, currently only for "front-end" users.
     *
     * @param email {string}
     * @param password {string}
     * @returns {Observable<R>}
     */
    login(email: string, password: string): Observable<any> {

        let url = [
            this.endpoints.root.production,
            this.endpoints.frontendUser.login
        ].join('/');

        let payload = {
            email: email,
            password: password,
            mobile: true
        };

        return this.http.post(url, payload)
            .map(response => {
                let body = response.json();
                return Observable.fromPromise(this._setUser(body.data));
            })
            .catch(this._handleError.bind(this));

    }

    /**
     * Logout
     */
    logout(): void {
        this._clearUser();
    }

    resetPassword(email: string) {

        let url = [
            this.endpoints.root.production,
            this.endpoints.frontendUser.resetPassword
        ].join('/');

        let payload = {email: email};

        return this.http.post(url, payload)
            .map(response => {

                let body = response.json();

                return body.data;

            })
            .catch(this._handleError.bind(this));

    }

    /**
     * Get logged in "front-end" user information
     * @returns {Observable<R>}
     */
    me(): Observable<any> {

        if(!this.TOKEN) {return}

        let url = [
            this.endpoints.root.production,
            this.endpoints.frontendUser.me
        ].join('/');

        return this.http.get(url)
            .map(response => {

                let body = response.json();

                return Observable.fromPromise(this._setUser(body.data));
            })
            .catch(this._handleError.bind(this));

    }

    updateMe(user: User) {

        if(!this.TOKEN) {return}

        let url = [
            this.endpoints.root.production,
            this.endpoints.frontendUser.editUser
        ].join('/');

        let headers = new Headers({'X-Authorization': this.TOKEN});
        let options = new RequestOptions({headers: headers});

        return this.http.post(url, user, options)
            .map(response => {

                let body = response.json();

                return Observable.fromPromise(this._setUser(body.data));
            })
            .catch(this._handleError.bind(this));

    }

    /**
     * Sets the current users role - must be a Role from the Roles Enum
     * @param role {Role}
     * @returns {any}
     */
    setRole(role): void {
        this.currentRole = role;
        return this._currentRole.next(role);
    }

    /**
     * Check if the user is authenticated based on their auth token being present in Storage
     * @returns {Promise<boolean>|PromiseLike<boolean>}
     */
    isAuthenticated(): Promise<any> {
        return this.storage.get(this.STORAGE_IDENTIFIER)
            .then((auth) => {
                return !!auth;
            });
    }

    /**
     * Helper method for updating user and authentication state
     * @param data
     * @returns {Observable<T>}
     * @private
     */
    private _setUser(data) {
        let user = Object.assign(new User(), data);

        let role = user.is_buyer ? Roles.BUYER : Roles.SELLER;

        let authStore = {
            access_token: user.access_token,
            access_token_expire: user.access_token_expire
        };

        this.TOKEN = authStore.access_token;


        this._currentRole.next(role);
        this._currentUser.next(user);

        return this.storage.set(this.STORAGE_IDENTIFIER, authStore);

    }

    /**
     * Helper method for clearing user and authentication state
     * @private
     */
    private _clearUser() {

        this.TOKEN = undefined;
        this.storage.remove(this.STORAGE_IDENTIFIER);
        this._currentUser.next(null);

    }

    /**
     * Helper method for handling error responses
     * @param error
     * @returns {ErrorObservable}
     * @private
     */
    private _handleError(error) {

        let body = error.json();

        let response = body.data.errors || {};

        console.error(response);

        return Observable.throw(response);

    }
}