import {Inject, Injectable, Optional} from '@angular/core';
import {HttpClient} from "@angular/common/http";
import {BehaviorSubject, of} from 'rxjs';

import {Request} from 'express';
import {REQUEST} from '@nguniversal/express-engine/tokens';

import {EnvProperties} from './env-properties';
import {properties} from "../../../../environments/environment";

@Injectable()
export class EnvironmentSpecificService {
  
  public envSpecific: EnvProperties;
  public domain: string;
  private envSpecificSubject: BehaviorSubject<EnvProperties> = new BehaviorSubject<EnvProperties>(null);
  private propertiesPath = "/assets/env-properties.json?v=2";
  
  constructor(private http: HttpClient, @Optional() @Inject(REQUEST) private request: Request) {
    properties.domain = "https://" + this.getDomain();
  }
  
  public loadEnvironment() {
    this.envSpecific = properties;
    return Promise.resolve(this.envSpecific);
  }
  
  public subscribeEnvironment() {
    // Only want to do this once - if root page is revisited, it calls this again.
    if (this.envSpecific === null || this.envSpecific === undefined) {
      this.envSpecific = properties;
    }
    // console.log('subscribeEnvironment: already loaded  ');
    return of(this.envSpecific);
  }
  
  getDomain() {
    var domain = "";
    if (typeof document == 'undefined') {
      domain = this.request.get('host').split(":")[0];
    } else {
      domain = document.location.hostname;
    }
    return domain;
  }
  
  public setEnvProperties(es: EnvProperties) {
    // This has already been set so bail out.
    if (es === null || es === undefined) {
      return;
    }
    this.envSpecific = es;
    if (this.envSpecificSubject) {
      this.envSpecificSubject.next(this.envSpecific);
    }
  }
  
  /*
    Call this if you want to know when EnvProperties is set.
  */
  public subscribe(caller: any, callback: (caller: any, es: EnvProperties) => void) {
    this.envSpecificSubject
      .subscribe((es) => {
        if (es === null) {
          return;
        }
        callback(caller, es);
      });
  }
}