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'
import { OAuthClientLocal } from '../../../../../shared'
// Do not use the barrel (dependency loop)
import { RestExtractor } from '../../shared/rest'

@Injectable()
export class AuthService {
  private static BASE_CLIENT_URL = API_URL + '/api/v1/oauth-clients/local'
  private static BASE_TOKEN_URL = API_URL + '/api/v1/users/token'
  private static BASE_USER_INFORMATIONS_URL = API_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: OAuthClientLocal) => {
          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 () {
    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 email = obj.email
    const displayNSFW = obj.displayNSFW
    const hashTokens = {
      accessToken: obj.access_token,
      tokenType: obj.token_type,
      refreshToken: obj.refresh_token
    }

    this.user = new AuthUser({ id, username, role, displayNSFW, email }, 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)
  }

}