import { Injectable } from '@angular/core';
import { Headers, Http, Response, URLSearchParams } from '@angular/http';
import { Router } from '@angular/router';
import { Observable } from 'rxjs/Observable';
import { Subject } from 'rxjs/Subject';
import 'rxjs/add/operator/map';
import 'rxjs/add/operator/mergeMap';
import 'rxjs/add/observable/throw';

import { NotificationsService } from 'angular2-notifications';

import { AuthStatus } from './auth-status.model';
import { AuthUser } from './auth-user.model';
// Do not use the barrel (dependency loop)
import { RestExtractor } from '../../shared/rest';

@Injectable()
export class AuthService {
  private static BASE_CLIENT_URL = '/api/v1/clients/local';
  private static BASE_TOKEN_URL = '/api/v1/users/token';
  private static BASE_USER_INFORMATIONS_URL = '/api/v1/users/me';

  loginChangedSource: Observable<AuthStatus>;

  private clientId: string;
  private clientSecret: string;
  private loginChanged: Subject<AuthStatus>;
  private user: AuthUser = null;

  constructor(
    private http: Http,
    private notificationsService: NotificationsService,
    private restExtractor: RestExtractor,
    private router: Router
   ) {
    this.loginChanged = new Subject<AuthStatus>();
    this.loginChangedSource = this.loginChanged.asObservable();

    // Fetch the client_id/client_secret
    // FIXME: save in local storage?
    this.http.get(AuthService.BASE_CLIENT_URL)
      .map(this.restExtractor.extractDataGet)
      .catch((res) => this.restExtractor.handleError(res))
      .subscribe(
        result => {
          this.clientId = result.client_id;
          this.clientSecret = result.client_secret;
          console.log('Client credentials loaded.');
        },

        error => {
          let errorMessage = `Cannot retrieve OAuth Client credentials: ${error.text}. \n`;
          errorMessage += 'Ensure you have correctly configured PeerTube (config/ directory), in particular the "webserver" section.';

          // We put a bigger timeout
          // This is an important message
          this.notificationsService.error('Error', errorMessage, { timeOut: 7000 });
        }
      );

    // Return null if there is nothing to load
    this.user = AuthUser.load();
  }

  getRefreshToken() {
    if (this.user === null) return null;

    return this.user.getRefreshToken();
  }

  getRequestHeaderValue() {
    return `${this.getTokenType()} ${this.getAccessToken()}`;
  }

  getAccessToken() {
    if (this.user === null) return null;

    return this.user.getAccessToken();
  }

  getTokenType() {
    if (this.user === null) return null;

    return this.user.getTokenType();
  }

  getUser(): AuthUser {
    return this.user;
  }

  isAdmin() {
    if (this.user === null) return false;

    return this.user.isAdmin();
  }

  isLoggedIn() {
    if (this.getAccessToken()) {
      return true;
    } else {
      return false;
    }
  }

  login(username: string, password: string) {
    let body = new URLSearchParams();
    body.set('client_id', this.clientId);
    body.set('client_secret', this.clientSecret);
    body.set('response_type', 'code');
    body.set('grant_type', 'password');
    body.set('scope', 'upload');
    body.set('username', username);
    body.set('password', password);

    let headers = new Headers();
    headers.append('Content-Type', 'application/x-www-form-urlencoded');

    let options = {
      headers: headers
    };

    return this.http.post(AuthService.BASE_TOKEN_URL, body.toString(), options)
                    .map(this.restExtractor.extractDataGet)
                    .map(res => {
                      res.username = username;
                      return res;
                    })
                    .flatMap(res => this.mergeUserInformations(res))
                    .map(res => this.handleLogin(res))
                    .catch((res) => this.restExtractor.handleError(res));
  }

  logout() {
    // TODO: make an HTTP request to revoke the tokens
    this.user = null;

    AuthUser.flush();

    this.setStatus(AuthStatus.LoggedOut);
  }

  refreshAccessToken() {
    console.log('Refreshing token...');

    const refreshToken = this.getRefreshToken();

    let body = new URLSearchParams();
    body.set('refresh_token', refreshToken);
    body.set('client_id', this.clientId);
    body.set('client_secret', this.clientSecret);
    body.set('response_type', 'code');
    body.set('grant_type', 'refresh_token');

    let headers = new Headers();
    headers.append('Content-Type', 'application/x-www-form-urlencoded');

    let options = {
      headers: headers
    };

    return this.http.post(AuthService.BASE_TOKEN_URL, body.toString(), options)
                    .map(this.restExtractor.extractDataGet)
                    .map(res => this.handleRefreshToken(res))
                    .catch((res: Response) => {
                      // The refresh token is invalid?
                      if (res.status === 400 && res.json() && res.json().error === 'invalid_grant') {
                        console.error('Cannot refresh token -> logout...');
                        this.logout();
                        this.router.navigate(['/login']);

                        return Observable.throw({
                          json: () => '',
                          text: () => 'You need to reconnect.'
                        });
                      }

                      return this.restExtractor.handleError(res);
                    });
  }

  refreshUserInformations() {
    const obj = {
      access_token: this.user.getAccessToken()
    };

    this.mergeUserInformations(obj)
        .subscribe(
          res => {
            this.user.displayNSFW = res.displayNSFW;
            this.user.role = res.role;

            this.user.save();
          }
        );
  }

  private mergeUserInformations(obj: { access_token: string }) {
    // Do not call authHttp here to avoid circular dependencies headaches

    const headers = new Headers();
    headers.set('Authorization', `Bearer ${obj.access_token}`);

    return this.http.get(AuthService.BASE_USER_INFORMATIONS_URL, { headers })
             .map(res => res.json())
             .map(res => {
               const newProperties = {
                 id: res.id,
                 role: res.role,
                 displayNSFW: res.displayNSFW
               };

               return Object.assign(obj, newProperties);
             }
    );
  }

  private handleLogin (obj: any) {
    const id = obj.id;
    const username = obj.username;
    const role = obj.role;
    const displayNSFW = obj.displayNSFW;
    const hashTokens = {
      access_token: obj.access_token,
      token_type: obj.token_type,
      refresh_token: obj.refresh_token
    };

    this.user = new AuthUser({ id, username, role, displayNSFW }, hashTokens);
    this.user.save();

    this.setStatus(AuthStatus.LoggedIn);
  }

  private handleRefreshToken (obj: any) {
    this.user.refreshTokens(obj.access_token, obj.refresh_token);
    this.user.save();
  }

  private setStatus(status: AuthStatus) {
    this.loginChanged.next(status);
  }

}