import { Injectable } from '@angular/core';
import { HttpClient, HttpErrorResponse } from '@angular/common/http';
import { Observable, BehaviorSubject, AsyncSubject, throwError as observableThrowError,  of, EMPTY } from 'rxjs';
import { map, catchError, combineLatest, tap } from 'rxjs/operators';

import { CookieService } from 'ngx-cookie-service';
import { StompConfig, StompRService } from '@stomp/ng2-stompjs';
import { Message } from '@stomp/stompjs';

import { SnackBarService } from './snackbar.service';
import { PreferencesService, Prefs } from './preferences/preferences.service';

import {
  VO, User, Update, State, Deployment, DeploymentState, SSHKey, NewSSHKey, IdP, Service, Site, JSONObject, IdPInfo
} from './types/types.module';

// TODO terrible name
export interface Combination {
  user: User;
  prefs: Prefs;
}

@Injectable()
export class UserService {
  private initialized = false;
  private loggedIn = false;

  private idpInfo: AsyncSubject<IdPInfo> = new AsyncSubject();

  private observerDebugging = false;

  // relogin on failed XHR calls
  // is turned off when the user is deactivated
  private autoReLogin = true;

  private user: User;
  private user$: BehaviorSubject<User> = new BehaviorSubject(undefined);
  private userEmissions: number = 0;

  private sshKeys: Map<number, SSHKey> = new Map([]);
  private sshKeys$ = new BehaviorSubject<SSHKey[]>([]);

  private deploymentStates: Map<number, DeploymentState> = new Map([]);
  private deploymentStates$ = new BehaviorSubject<DeploymentState[]>([]);

  private deployments: Map<number, Deployment> = new Map([]);
  private deployments$ = new BehaviorSubject<Deployment[]>([]);

  public voSelector = (user: User) => user ? user.vos : [];
  public serviceSelector = (user: User) => user ? user.services : [];

  constructor(
    private cookieService: CookieService,
    private http: HttpClient,
    private snackBar: SnackBarService,
    private stompService: StompRService,
    private prefs: PreferencesService,
  ) {
    this.connect();
  }

  // PRIVATE API
  private connect(): void {
    this.fetch();
    this.fetchIdPInfo();

    this.userSrc().subscribe(
      (newUser: User) => {
        if (newUser == undefined || newUser == null) {
          // LOGGED OUT
          // show the logout to the user
          if (this.loggedIn) {
            this.snackBar.open('Logged out');

            // purge all values
            this.stompService.disconnect();
            this.user = undefined;
            this.deployments = new Map([]);
            this.deployments$.next([]);
            this.sshKeys = new Map([]);
            this.sshKeys$.next([]);
          }

          this.loggedIn =  false;
        } else {
          // LOGGED IN
          // show the login to the user
          if (!this.loggedIn) {
            this.snackBar.open('Logged in');
          }

          if (newUser.id) {
            this.connectLiveUpdates(newUser.id);
          }
          if (newUser.ssh_keys) {
            this.sshKeys = new Map([]);
            newUser.ssh_keys.forEach(
              (key: SSHKey) => this.sshKeys.set(key.id, key),
            );
            this.sshKeys$.next(Array.from(this.sshKeys.values()));
          }
          if (newUser.deployments) {
            newUser.deployments.forEach(
              (newDep: Deployment) => {
                this.deployments.set(newDep.id,  newDep);
              }
            );
            this.deployments$.next(Array.from(this.deployments.values()));
          }

          if (newUser.states) {
            newUser.states.forEach((state: DeploymentState) => {
              this.deploymentStates.set(state.id, state)
            });
            this.deploymentStates$.next(Array.from(this.deploymentStates.values()));
          }

          this.loggedIn = true;
          this.initialized = true;
        }
      },
      this.handleError(true),
      () => console.log('user$ is complete'),
    );
  }

  private connectLiveUpdates(userID: number): void {
    // handle with care
    const login = userID
    const passcode = this.cookieService.get('sessionid');
    const stompConfig: StompConfig = {
      // Which server?
      url: 'wss://'+window.location.host+'/ws',

      // Headers
      // Typical keys: login, passcode, host
      headers: {
        login: 'webpage-client:' + login,
        passcode: passcode,
      },

      // How often to heartbeat?
      // Interval in milliseconds, set to 0 to disable
      heartbeat_in: 0, // Typical value 0 - disabled
      heartbeat_out: 20000, // Typical value 20000 - every 20 seconds
      // Wait in milliseconds before attempting auto reconnect
      // Set to 0 to disable
      // Typical value 15000 (15 seconds)
      reconnect_delay: 15000,

      // Will log diagnostics on console
      debug: false,
    };

    this.stompService.config = stompConfig;
    this.stompService.initAndConnect();

    const subscription = this.stompService.subscribe(
      '/exchange/users/' + userID.toString()
    );

    subscription.subscribe(
      (message: Message) => {
        let update: Update = JSON.parse(message.body);
        console.log('update:', update);

        // TODO rename error to msg
        if (update.error && update.error != '') {
          this.snackBar.open(update.error);
        }

        if (update.deployment_state) {
          this.updateDeploymentState(update.deployment_state);
        }

        if (update.deployment) {
          this.updateDeployment(update.deployment);
        }
      },
      this.logErrorAndFetch,
    );
  }

  private updateDeployment(dep: Deployment): void {
    if (dep != undefined && dep != null) {
      dep.states.forEach((state: DeploymentState) => this.updateDeploymentState(state),
      );
      this.deployments.set(dep.id, dep);
      this.deployments$.next(Array.from(this.deployments.values()));
    }
  }

  private updateDeploymentState(ds: DeploymentState): void {
    if (ds != undefined && ds != null) {
      this.deploymentStates.set(ds.id, ds);
      this.deploymentStates$.next(Array.from(this.deploymentStates.values()));
    }
  }

  private updateState(update: State): void {
    if (update) {
      // report an occured error
      if (update.msg) {
        this.snackBar.open(update.msg);
      }
      if (update.session) {
        if (update.session.deactivated) {
          this.autoReLogin = false;
        }
        if (update.session.auth_error && update.session.auth_error !== 'Not authenticated') {
          this.snackBar.open(update.session.auth_error);
        }
      }

      this.user = update.user;
      this.user$.next(this.user);

    } else {
      this.user$.next(undefined);
    }
  }

  private fetch(): void {
    this.http.get<State>('/backend/api/state').subscribe(
      (state: State) => this.updateState(state),
      this.handleError(false, 'Error fetching state. Try again later'),
    );
  }

  private handleError(fetch: boolean, msg?: string) {
    return (error: any) => {
      if (error.status === 403 && this.autoReLogin) {
        this.login();
        return
      }

      if (msg) {
        this.snackBar.open(msg);
      }
      console.log('fetch:', error);
      if (fetch) {
        this.fetch();
      }
      return EMPTY
    }
  }

  private logErrorAndFetch(error: any)  {
    if (error.status === 403 && this.autoReLogin) {
      this.login();
    }

    console.log(error);
    this.snackBar.open('Error');
    this.fetch();
    return observableThrowError(error);
  }

  private tapLogger(name: string): (e: any) => void {
    return e => {
      if (this.observerDebugging) {
        if (name === 'userSrc') {
          this.userEmissions++;
          console.log(name, this.userEmissions, e);
        } else {
          console.log(name, e);
        }
      }
    }
  }

  private fetchIdPInfo(): void {
      this.http.get<IdPInfo>('/backend/auth/v1/info').subscribe(
        idpInfo => {
          this.idpInfo.next(idpInfo);
          this.idpInfo.complete();
        }
      );
  }

  // PUBLIC API
  public connectIdPInfo(): Observable<IdPInfo> {
      return this.idpInfo.asObservable().pipe(
        combineLatest(
          this.prefs.connect(),
          (authInfo, prefs) => {
            const defaultIdP: IdP = authInfo.idps.find((idp: IdP) => idp.id === authInfo.default);

            if (prefs != undefined && prefs.preferredIdP != undefined) {
              authInfo.selectedIdP = prefs.preferredIdP;
            } else if (defaultIdP) {
              authInfo.selectedIdP = defaultIdP;
            } else if (authInfo.idps.length > 0) {
              authInfo.selectedIdP = authInfo.idps[0];
            } else {
              console.log("No IdPs available. Unable to login");
            }
            return authInfo;
          },
        ),
      );
  }


  public login(idp?: IdP): void {
    const redirect = (idp: IdP) => {
      window.location.href = '/?idphint=' + encodeURIComponent(idp.issuer_uri);
    };

    if (idp != undefined) {
      this.prefs.setPreferredIdP(idp);
      redirect(idp);
    } else {
      this.prefs.connect().subscribe(
        prefs => {
          if (prefs.preferredIdP != undefined) {
            redirect(prefs.preferredIdP);
          }
        }
      )
    }

    console.log('Unable to login: No IdP');
  }

  public logout(): void {
    this.http.post<State>('/backend/auth/v1/logout', undefined).subscribe(
      (state: State) => this.updateState(state),
      (err: HttpErrorResponse) => {
        this.updateState(undefined);
      }
    );
  }

  public deleteUser() {
    return this.http.delete('/rest/user').pipe(
      catchError(this.handleError(true, "Error deleting user")),
    ).subscribe(
      _ => {
          this.user$.next(undefined);
          this.snackBar.open('Deleted user from server');
      },
      this.logErrorAndFetch,
    );
  }

  public uploadSshKey(name: string, key: string | ArrayBuffer): void {
    this.http.post<SSHKey>(
      '/rest/ssh-keys',
      {'name': name, 'key': key},
    ).pipe(
      catchError(this.handleError(true, "Error changing deployment")),
    ).subscribe(
      (newKey: SSHKey) => {
        this.sshKeys.set(newKey.id, newKey);
        this.sshKeys$.next(Array.from(this.sshKeys.values()));
      },
      this.logErrorAndFetch,
    );
  }

  public removeSshKey(key: SSHKey) {
    console.log('Deleting key:', key);
    return this.http.delete(
      `/rest/ssh-key/${ key.id.toString() }`,
    ).pipe(
      catchError(this.handleError(true, "Error changing deployment")),
    ).subscribe(
      _ => {
        this.sshKeys.delete(key.id);
        this.sshKeys$.next(Array.from(this.sshKeys.values()));
      },
      this.logErrorAndFetch,
    );
  }

  public patchDeployment(depType: string, stateTarget: string, id: number): void {
    this.http.patch<Deployment>(
      `/rest/deployment/${ depType }/${ id.toString() }`,
      {'state_target': stateTarget},
    ).pipe(
      catchError(this.handleError(true, "Error changing deployment")),
    ).subscribe(
      (dep: Deployment) => this.updateDeployment(dep),
    );
  }

  public sentQuestionnaire(stateItemID: number, answers: JSONObject) {
    return this.http.patch<DeploymentState>(
      `/rest/state/${ stateItemID }`,
      {'answers': answers},
    ).pipe(
      catchError(this.handleError(true, "Error submitting answers")),
    ).subscribe(
      (state: DeploymentState) => this.updateDeploymentState(state),
      this.logErrorAndFetch,
    );
  }

  // DATA SERVICE API
  //
  public subscribeSpecific<T>(selector: (user: User) => T): Observable<T> {
    return this.userSrc().pipe(
      map(selector),
      tap(this.tapLogger('subscribeSpecific')),
    );
  }

  public sshKeysSrc(): Observable<SSHKey[]> {
    return this.sshKeys$.asObservable().pipe(
      tap(this.tapLogger('sshKeysSrc')),
    );
  }

  public userSrc(): Observable<User> {
    return this.user$.asObservable().pipe(
      tap(this.tapLogger('userSrc')),
    );
  }

  public combiSrc(): Observable<Combination> {
    return this.user$.asObservable().pipe(
      combineLatest(
        this.prefs.connect(),
        (u, p) => {
          return {user: u, prefs: p};
        },
      ),
      tap(this.tapLogger('userSrc')),
    );
  }

  public deploymentsSrc(): Observable<Deployment[]> {
    return this.deployments$.asObservable().pipe(
      tap(this.tapLogger('deploymentsSrc')),
    );
  }

  public depStatesSrc(): Observable<DeploymentState[]> {
    return this.deploymentStates$.asObservable().pipe(
      tap(this.tapLogger('depStatesSrc')),
    );
  }

  public subscribeStateFor(service: Service): Observable<DeploymentState> {
    return this.deploymentStates$.asObservable().pipe(
      map((states: DeploymentState[]) => states.find(
          (dsi: DeploymentState) => dsi.service.id == service.id,
      )),
      tap(this.tapLogger('subscribeStateFor')),
    );
  }

  public subscribeDeployment(selector: (dep: Deployment) => boolean): Observable<Deployment> {
    return this.deploymentsSrc().pipe(
      map((deployments: Deployment[]) => {
          return deployments.find(
            (dep: Deployment) => selector(dep),
          );
        }
      ),
      tap(this.tapLogger('subscribeDeployment')),
    );
  }

  public servicesSrc(): Observable<Service[]> {
    return this.subscribeSpecific(this.serviceSelector).pipe(
      tap(this.tapLogger('servicesSrc')),
    );
  }

  public extractVOs(combi: Combination): VO[] {
    if (combi.prefs.showEmptyVOs) {
      return combi.user.vos;
    }

    // filter out VOs that have no services
    return combi.user.vos.filter(
      (vo: VO) => combi.user.services.some(
        (s: Service) => s.vos.some(
          svo => svo.id === vo.id,
        ),
      ),
    );
  }
}