import {FocusMonitor} from '@angular/cdk/a11y';
import {coerceBooleanProperty} from '@angular/cdk/coercion';
import {Component, ElementRef, Input, OnDestroy} from '@angular/core';
import {FormBuilder, FormGroup} from '@angular/forms';
import {MatFormFieldControl} from '@angular/material/form-field';
import {Subject} from 'rxjs/Subject';


/** Data structure for holding telephone number. */
export class MyTel {
  constructor(public area: string, public exchange: string, public subscriber: string) {}
}


/** Custom `MatFormFieldControl` for telephone number input. */
@Component({
  selector: 'my-tel-input',
  templateUrl: 'form-field-custom-control-example.html',
  styleUrls: ['form-field-custom-control-example.css'],
  providers: [{provide: MatFormFieldControl, useExisting: MyTelInput}],
  host: {
    '[class.floating]': 'shouldLabelFloat',
    '[id]': 'id',
    '[attr.aria-describedby]': 'describedBy',
  }
})
export class MyTelInput implements MatFormFieldControl<MyTel>, OnDestroy {
  static nextId = 0;

  parts: FormGroup;

  stateChanges = new Subject<void>();

  focused = false;

  ngControl = null;

  errorState = false;

  controlType = 'my-tel-input';

  get empty() {
    let n = this.parts.value;
    return !n.area && !n.exchange && !n.subscriber;
  }

  get shouldLabelFloat() {
    return this.focused || !this.empty;
  }

  id = `my-tel-input-${MyTelInput.nextId++}`;

  describedBy = '';

  @Input()
  get placeholder() {
    return this._placeholder;
  }
  set placeholder(plh) {
    this._placeholder = plh;
    this.stateChanges.next();
  }
  private _placeholder: string;

  @Input()
  get required() {
    return this._required;
  }
  set required(req) {
    this._required = coerceBooleanProperty(req);
    this.stateChanges.next();
  }
  private _required = false;

  @Input()
  get disabled() {
    return this._disabled;
  }
  set disabled(dis) {
    this._disabled = coerceBooleanProperty(dis);
    this.stateChanges.next();
  }
  private _disabled = false;

  @Input()
  get value(): MyTel | null {
    let n = this.parts.value;
    if (n.area.length == 3 && n.exchange.length == 3 && n.subscriber.length == 4) {
      return new MyTel(n.area, n.exchange, n.subscriber);
    }
    return null;
  }
  set value(tel: MyTel | null) {
    tel = tel || new MyTel('', '', '');
    this.parts.setValue({area: tel.area, exchange: tel.exchange, subscriber: tel.subscriber});
    this.stateChanges.next();
  }

  constructor(fb: FormBuilder, private fm: FocusMonitor, private elRef: ElementRef) {
    this.parts =  fb.group({
      'area': '',
      'exchange': '',
      'subscriber': '',
    });

    fm.monitor(elRef.nativeElement, true).subscribe((origin) => {
      this.focused = !!origin;
      this.stateChanges.next();
    });
  }

  ngOnDestroy() {
    this.stateChanges.complete();
    this.fm.stopMonitoring(this.elRef.nativeElement);
  }

  setDescribedByIds(ids: string[]) {
    this.describedBy = ids.join(' ');
  }

  onContainerClick(event: MouseEvent) {
    if ((event.target as Element).tagName.toLowerCase() != 'input') {
      this.elRef.nativeElement.querySelector('input').focus();
    }
  }
}


/** @title Form field with custom telephone number input control. */
@Component({
  selector: 'form-field-custom-control-example',
  template: `
    <mat-form-field>
      <my-tel-input placeholder="Phone number" required></my-tel-input>
      <mat-icon matSuffix>phone</mat-icon>
      <mat-hint>Include area code</mat-hint>
    </mat-form-field>
  `
})
export class FormFieldCustomControlExample {}