import {Component} from '@angular/core';
import {FormControl} from '@angular/forms';
import {Observable} from 'rxjs/Observable';
import {startWith} from 'rxjs/operators/startWith';
import {map} from 'rxjs/operators/map';

export class User {
  constructor(public name: string) { }
}

/**
 * @title Display value autocomplete
 */
@Component({
  selector: 'autocomplete-display-example',
  templateUrl: 'autocomplete-display-example.html',
  styleUrls: ['autocomplete-display-example.css']
})
export class AutocompleteDisplayExample {

  myControl = new FormControl();

  options = [
    new User('Mary'),
    new User('Shelley'),
    new User('Igor')
  ];

  filteredOptions: Observable<User[]>;

  ngOnInit() {
    this.filteredOptions = this.myControl.valueChanges
      .pipe(
        startWith({} as User),
        map(user => user && typeof user === 'object' ? user.name : user),
        map(name => name ? this.filter(name) : this.options.slice())
      );
  }

  filter(name: string): User[] {
    return this.options.filter(option =>
      option.name.toLowerCase().indexOf(name.toLowerCase()) === 0);
  }

  displayFn(user: User): string {
    return user ? user.name : user;
  }

}