import { Observable, ReplaySubject, Subject, throwError as observableThrowError } from 'rxjs'
import { catchError, map, mergeMap, share, tap } from 'rxjs/operators'
import { HttpClient, HttpHeaders, HttpParams } from '@angular/common/http'
import { Injectable } from '@angular/core'
import { Router } from '@angular/router'
import { NotificationsService } from 'angular2-notifications'
import { OAuthClientLocal, User as UserServerModel, UserRefreshToken } from '../../../../../shared'
import { User } from '../../../../../shared/models/users'
import { UserLogin } from '../../../../../shared/models/users/user-login.model'
import { environment } from '../../../environments/environment'
import { RestExtractor } from '../../shared/rest'
import { AuthStatus } from './auth-status.model'
import { AuthUser } from './auth-user.model'
import { objectToUrlEncoded } from '@app/shared/misc/utils'
import { peertubeLocalStorage } from '@app/shared/misc/peertube-local-storage'
import { I18n } from '@ngx-translate/i18n-polyfill'

interface UserLoginWithUsername extends UserLogin {
  access_token: string
  refresh_token: string
  token_type: string
  username: string
}

type UserLoginWithUserInformation = UserLoginWithUsername & User

@Injectable()
export class AuthService {
  private static BASE_CLIENT_URL = environment.apiUrl + '/api/v1/oauth-clients/local'
  private static BASE_TOKEN_URL = environment.apiUrl + '/api/v1/users/token'
  private static BASE_USER_INFORMATION_URL = environment.apiUrl + '/api/v1/users/me'
  private static LOCAL_STORAGE_OAUTH_CLIENT_KEYS = {
    CLIENT_ID: 'client_id',
    CLIENT_SECRET: 'client_secret'
  }

  loginChangedSource: Observable<AuthStatus>
  userInformationLoaded = new ReplaySubject<boolean>(1)

  private clientId: string = peertubeLocalStorage.getItem(AuthService.LOCAL_STORAGE_OAUTH_CLIENT_KEYS.CLIENT_ID)
  private clientSecret: string = peertubeLocalStorage.getItem(AuthService.LOCAL_STORAGE_OAUTH_CLIENT_KEYS.CLIENT_SECRET)
  private loginChanged: Subject<AuthStatus>
  private user: AuthUser = null
  private refreshingTokenObservable: Observable<any>

  constructor (
    private http: HttpClient,
    private notificationsService: NotificationsService,
    private restExtractor: RestExtractor,
    private router: Router,
    private i18n: I18n
  ) {
    this.loginChanged = new Subject<AuthStatus>()
    this.loginChangedSource = this.loginChanged.asObservable()

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

  loadClientCredentials () {
    // Fetch the client_id/client_secret
    this.http.get<OAuthClientLocal>(AuthService.BASE_CLIENT_URL)
        .pipe(catchError(res => this.restExtractor.handleError(res)))
        .subscribe(
          res => {
            this.clientId = res.client_id
            this.clientSecret = res.client_secret

            peertubeLocalStorage.setItem(AuthService.LOCAL_STORAGE_OAUTH_CLIENT_KEYS.CLIENT_ID, this.clientId)
            peertubeLocalStorage.setItem(AuthService.LOCAL_STORAGE_OAUTH_CLIENT_KEYS.CLIENT_SECRET, this.clientSecret)

            console.log('Client credentials loaded.')
          },

          error => {
            let errorMessage = error.message

            if (error.status === 403) {
              errorMessage = this.i18n('Cannot retrieve OAuth Client credentials: {{errorText}}.\n', { errorText: error.text })
              errorMessage += this.i18n(
                '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(this.i18n('Error'), errorMessage, { timeOut: 7000 })
          }
        )
  }

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

    return this.user.getRefreshToken()
  }

  getRequestHeaderValue () {
    const accessToken = this.getAccessToken()

    if (accessToken === null) return null

    return `${this.getTokenType()} ${accessToken}`
  }

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

    return this.user.getAccessToken()
  }

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

    return this.user.getTokenType()
  }

  getUser () {
    return this.user
  }

  isLoggedIn () {
    return !!this.getAccessToken()
  }

  login (username: string, password: string) {
    // Form url encoded
    const body = {
      client_id: this.clientId,
      client_secret: this.clientSecret,
      response_type: 'code',
      grant_type: 'password',
      scope: 'upload',
      username,
      password
    }

    const headers = new HttpHeaders().set('Content-Type', 'application/x-www-form-urlencoded')
    return this.http.post<UserLogin>(AuthService.BASE_TOKEN_URL, objectToUrlEncoded(body), { headers })
               .pipe(
                 map(res => Object.assign(res, { username })),
                 mergeMap(res => this.mergeUserInformation(res)),
                 map(res => this.handleLogin(res)),
                 catchError(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 () {
    if (this.refreshingTokenObservable) return this.refreshingTokenObservable

    console.log('Refreshing token...')

    const refreshToken = this.getRefreshToken()

    // Form url encoded
    const body = new HttpParams().set('refresh_token', refreshToken)
                                 .set('client_id', this.clientId)
                                 .set('client_secret', this.clientSecret)
                                 .set('response_type', 'code')
                                 .set('grant_type', 'refresh_token')

    const headers = new HttpHeaders().set('Content-Type', 'application/x-www-form-urlencoded')

    this.refreshingTokenObservable = this.http.post<UserRefreshToken>(AuthService.BASE_TOKEN_URL, body, { headers })
                                         .pipe(
                                           map(res => this.handleRefreshToken(res)),
                                           tap(() => this.refreshingTokenObservable = null),
                                           catchError(err => {
                                             this.refreshingTokenObservable = null

                                             console.error(err)
                                             console.log('Cannot refresh token -> logout...')
                                             this.logout()
                                             this.router.navigate([ '/login' ])

                                             return observableThrowError({
                                               error: this.i18n('You need to reconnect.')
                                             })
                                           }),
                                           share()
                                         )

    return this.refreshingTokenObservable
  }

  refreshUserInformation () {
    const obj = {
      access_token: this.user.getAccessToken(),
      refresh_token: null,
      token_type: this.user.getTokenType(),
      username: this.user.username
    }

    this.mergeUserInformation(obj)
        .subscribe(
          res => {
            this.user.patch(res)
            this.user.save()

            this.userInformationLoaded.next(true)
          }
        )
  }

  private mergeUserInformation (obj: UserLoginWithUsername): Observable<UserLoginWithUserInformation> {
    // User is not loaded yet, set manually auth header
    const headers = new HttpHeaders().set('Authorization', `${obj.token_type} ${obj.access_token}`)

    return this.http.get<UserServerModel>(AuthService.BASE_USER_INFORMATION_URL, { headers })
               .pipe(map(res => Object.assign(obj, res)))
  }

  private handleLogin (obj: UserLoginWithUserInformation) {
    const hashTokens = {
      accessToken: obj.access_token,
      tokenType: obj.token_type,
      refreshToken: obj.refresh_token
    }

    this.user = new AuthUser(obj, hashTokens)
    this.user.save()

    this.setStatus(AuthStatus.LoggedIn)
    this.userInformationLoaded.next(true)
  }

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

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