import { Component, OnInit } from '@angular/core';
import { FormGroup, FormArray, FormBuilder, FormBuilder, Validators } from '@angular/forms';
import { Customer } from './customer.interface';

@Component({
  moduleId: module.id,
  selector: 'my-app',
  templateUrl: 'app.component.html',
})
export class AppComponent implements OnInit {
    public myForm: FormGroup; // our model driven form
    
    // standing data
    public PAYMENT_METHOD_TYPE = {
      BANK: 'bank',
      CARD: 'card'
    };

    constructor(private _fb: FormBuilder) { } // form builder simplify form initialization

    ngOnInit() {
        // we will initialize our form model here
        this.myForm = this._fb.group({
            name: ['Jane Doe'],
            paymentMethod: this.initPaymentMethodFormGroup()
        });
        
        this.subscribePaymentTypeChanges();
        
        this.setPaymentMethodType(this.PAYMENT_METHOD_TYPE.BANK);
    }

    initPaymentMethodFormGroup() {
      // initialize payment method form group
      const group = this._fb.group({
            type: [''],
            card: this._fb.group(this.initPaymentMethodCardModel()),
            bank: this._fb.group(this.initPaymentMethodBankModel()),
        });
      
      return group;
    }
    
    subscribePaymentTypeChanges() {
      
      // controls
      const pmCtrl = (<any>this.myForm).controls.paymentMethod;
      const bankCtrl = pmCtrl.controls.bank;
      const cardCtrl = pmCtrl.controls.card;
      
      // initialize value changes stream
      const changes$ = pmCtrl.controls.type.valueChanges;
      
      // subscribe to the stream
      changes$.subscribe(paymentMethodType => {
        if (paymentMethodType === this.PAYMENT_METHOD_TYPE.BANK) {
          Object.keys(bankCtrl.controls).forEach(key => {
            bankCtrl.controls[key].setValidators(this.initPaymentMethodBankModel()[key][1]);
            bankCtrl.controls[key].updateValueAndValidity();
          });
          
          Object.keys(cardCtrl.controls).forEach(key => {
            cardCtrl.controls[key].setValidators(null);
            cardCtrl.controls[key].updateValueAndValidity();
          });
        }
        
        if (paymentMethodType === this.PAYMENT_METHOD_TYPE.CARD) {
          Object.keys(bankCtrl.controls).forEach(key => {
            bankCtrl.controls[key].setValidators(null);
            bankCtrl.controls[key].updateValueAndValidity();
          });
          
          Object.keys(cardCtrl.controls).forEach(key => {
            cardCtrl.controls[key].setValidators(this.initPaymentMethodCardModel()[key][1]);
            cardCtrl.controls[key].updateValueAndValidity();
          });
        }
        
      });
    }
    
    initPaymentMethodCardModel() {
      // you get valid testing credit card from http://www.getcreditcardnumbers.com/
      const cardNoRegex = `^(?:4[0-9]{12}(?:[0-9]{3})?|5[1-5][0-9]{14}|6(?:011|5[0-9][0-9])[0-9]{12}|3[47][0-9]{13}|3(?:0[0-5]|[68][0-9])[0-9]{11}|(?:2131|1800|35\d{3})\d{11})$`;
      const expiryRegex = `^(0[1-9]|1[0-2])\/?([0-9]{4}|[0-9]{2})$`;
      
      
      // initialize card model
      const model = {
        cardNo: ['', [Validators.required, Validators.pattern(cardNoRegex)]],
        cardHolder: ['', Validators.required],
        expiry: ['', [Validators.required, Validators.pattern(expiryRegex)]]
      };
      
      return model;
    }
    
    initPaymentMethodBankModel() {
      // initialize bank model
      const model = {
        accountNo: ['', Validators.required],
        accountHolder: ['', Validators.required],
        routingNo: ['', Validators.required]
      };
      
      return model;
    }
    
    setPaymentMethodType(type: string) {
      // update payment method type value
      const ctrl: FormControl = (<any>this.myForm).controls.paymentMethod.controls.type;
      ctrl.setValue(type);
    }

    save(model: Customer, isValid: boolean) {
        // call API to save
        // ...
        console.log(model, isValid);
    }
}
import { NgModule }      from '@angular/core';
import { BrowserModule } from '@angular/platform-browser';
import { FormsModule, ReactiveFormsModule } from '@angular/forms';

import { AppComponent }   from './app.component';

@NgModule({
  imports:      [ BrowserModule, ReactiveFormsModule ],
  declarations: [ AppComponent ],
  bootstrap:    [ AppComponent ]
})

export class AppModule { }
import { platformBrowserDynamic } from '@angular/platform-browser-dynamic';

import { AppModule } from './app.module';

const platform = platformBrowserDynamic();
platform.bootstrapModule(AppModule);

<!DOCTYPE html>
<html>
  <head>
    <title>Handle different form controls</title>
    <!--optional bootstrap for faster styling-->
    <link rel="stylesheet" href="https://maxcdn.bootstrapcdn.com/bootstrap/3.3.6/css/bootstrap.min.css" integrity="sha384-1q8mTJOASx8j1Au+a5WDVnPi2lkFfwwEAa8hDDdjZlpLegxhjVME1fgjWPGmkzs7" crossorigin="anonymous">

    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1">

    <!-- 1. Load libraries -->
     <!-- Polyfill(s) for older browsers -->
    <script src="https://unpkg.com/core-js/client/shim.min.js"></script>

    <script src="https://unpkg.com/zone.js@0.6.23?main=browser"></script>
    <script src="https://unpkg.com/reflect-metadata@0.1.3"></script>
    <script src="https://unpkg.com/systemjs@0.19.27/dist/system.src.js"></script>

    <!-- 2. Configure SystemJS -->
    <script src="systemjs.config.js"></script>
    <script>
      System.import('app').catch(function(err){ console.error(err); });
    </script>
  </head>

  <!-- 3. Display the application -->
  <body>
    <my-app>Loading...</my-app>
  </body>
</html>

/**
 * PLUNKER VERSION
 * (based on systemjs.config.js in angular.io)
 * System configuration for Angular 2 samples
 * Adjust as necessary for your application needs.
 */
(function (global) {
  System.config({
    // DEMO ONLY! REAL CODE SHOULD NOT TRANSPILE IN THE BROWSER
    transpiler: 'ts',
    typescriptOptions: {
      tsconfig: true
    },
    meta: {
      'typescript': {
        "exports": "ts"
      }
    },
    paths: {
      // paths serve as alias
      'npm:': 'https://unpkg.com/'
    },
    // map tells the System loader where to look for things
    map: {
      // our app is within the app folder
      app: 'app',

      // angular bundles
      '@angular/core': 'npm:@angular/core/bundles/core.umd.js',
      '@angular/common': 'npm:@angular/common/bundles/common.umd.js',
      '@angular/compiler': 'npm:@angular/compiler/bundles/compiler.umd.js',
      '@angular/platform-browser': 'npm:@angular/platform-browser/bundles/platform-browser.umd.js',
      '@angular/platform-browser-dynamic': 'npm:@angular/platform-browser-dynamic/bundles/platform-browser-dynamic.umd.js',
      '@angular/http': 'npm:@angular/http/bundles/http.umd.js',
      '@angular/router': 'npm:@angular/router/bundles/router.umd.js',
      '@angular/forms': 'npm:@angular/forms/bundles/forms.umd.js',
      '@angular/upgrade': 'npm:@angular/upgrade/bundles/upgrade.umd.js',

      // other libraries
      'rxjs':                       'npm:rxjs',
      'angular2-in-memory-web-api': 'npm:angular2-in-memory-web-api',
      'ts':                         'npm:plugin-typescript@4.0.10/lib/plugin.js',
      'typescript':                 'npm:typescript@2.0.2/lib/typescript.js',

    },
    // packages tells the System loader how to load when no filename and/or no extension
    packages: {
      app: {
        main: './main.ts',
        defaultExtension: 'ts'
      },
      rxjs: {
        defaultExtension: 'js'
      },
      'angular2-in-memory-web-api': {
        main: './index.js',
        defaultExtension: 'js'
      }
    }
  });
})(this);

{
  "compilerOptions": {
    "target": "es5",
    "module": "commonjs",
    "moduleResolution": "node",
    "sourceMap": true,
    "emitDecoratorMetadata": true,
    "experimentalDecorators": true,
    "removeComments": false,
    "noImplicitAny": true,
    "suppressImplicitAnyIndexErrors": true
  }
}
export interface Customer {
  name: stirng;
  paymentMethod: {
    type: string; // must be either 'bank' or 'card'
    card: {
      cardNo: string; // must be visa, master, amex
      cardHolder: string;
      expiry: string; // must be format MM/YY
    },
    bank: {
      accountNo: string;
      accountHolder: string;
      routingNo: string;
    }
  }
}
<div class="container">
  <div class="row">
    <div class="col-xs-12">
      <div class="margin-20">
        <h4>Add customer</h4>
      </div>
      <form [formGroup]="myForm" novalidate (ngSubmit)="save(myForm.value, myForm.valid)">
        <div class="form-group">
          <label>Name</label>
          <input type="text" class="form-control" formControlName="name">
        </div>
        <!--payment method-->
        <div class="form-group">
          <label>Payment Method</label>
        </div>
        <div formGroupName="paymentMethod">
          
          <div class="row">
            <div class="col-xs-6">
              <button type="button" (click)="setPaymentMethodType(PAYMENT_METHOD_TYPE.BANK)" 
                class="btn btn-block text-capitalize"
                [class.btn-default]="myForm.controls.paymentMethod.controls.type.value !== PAYMENT_METHOD_TYPE.BANK" 
                [class.btn-primary]="myForm.controls.paymentMethod.controls.type.value === PAYMENT_METHOD_TYPE.BANK">
                {{ PAYMENT_METHOD_TYPE.BANK }}
              </button>
            </div>
            <div class="col-xs-6">
              <button type="button" (click)="setPaymentMethodType(PAYMENT_METHOD_TYPE.CARD)" 
                class="btn btn-block text-capitalize"
                [class.btn-default]="myForm.controls.paymentMethod.controls.type.value !== PAYMENT_METHOD_TYPE.CARD" 
                [class.btn-primary]="myForm.controls.paymentMethod.controls.type.value === PAYMENT_METHOD_TYPE.CARD">
                {{ PAYMENT_METHOD_TYPE.CARD }}
              </button>
            </div>
          </div>

          <div class="panel panel-default margin-20" 
            *ngIf="myForm.controls.paymentMethod.controls.type.value === PAYMENT_METHOD_TYPE.BANK">
            <div class="panel-body">
              <div class="form-group col-xs-8" formGroupName="bank">
                <label>Account no.</label>
                <input type="text" class="form-control" formControlName="accountNo">
                <small *ngIf="!myForm.controls.paymentMethod.controls.bank.controls.accountNo.valid" 
                  class="text-danger">
                 Required.
                </small>
              </div>
              <div class="form-group col-xs-4" formGroupName="bank">
                <label>Routing no.</label>
                <input type="text" class="form-control" formControlName="routingNo">
                <small *ngIf="!myForm.controls.paymentMethod.controls.bank.controls.routingNo.valid" 
                  class="text-danger">
                 Required.
                </small>
              </div>
              <div class="form-group col-xs-12" formGroupName="bank">
                <label>Name</label>
                <input type="text" class="form-control" formControlName="accountHolder">
                <small *ngIf="!myForm.controls.paymentMethod.controls.bank.controls.accountHolder.valid" 
                  class="text-danger">
                 Required.
                </small>
              </div>
            </div>
          </div>
          <div class="panel panel-default margin-20" 
            *ngIf="myForm.controls.paymentMethod.controls.type.value === PAYMENT_METHOD_TYPE.CARD">
            <div class="panel-body">
              <div class="form-group col-xs-8" formGroupName="card">
                <label>Card no.</label>
                <input type="text" class="form-control" formControlName="cardNo">
                <small *ngIf="!myForm.controls.paymentMethod.controls.card.controls.cardNo.valid" 
                  class="text-danger">
                 Required (Must be valid card number).
                </small>
              </div>
              <div class="form-group col-xs-4" formGroupName="card">
                <label>Expiry</label>
                <input type="text" formControlName="expiry"
                  placeholder="MM/YY" class="form-control">
                <small *ngIf="!myForm.controls.paymentMethod.controls.card.controls.expiry.valid" 
                  class="text-danger">
                 Required (Must be in format MM/YY).
                </small>
              </div>
              <div class="form-group col-xs-12" formGroupName="card">
                <label>Name</label>
                <input type="text" class="form-control" formControlName="cardHolder">
                <small *ngIf="!myForm.controls.paymentMethod.controls.card.controls.cardHolder.valid" 
                  class="text-danger">
                 Required.
                </small>
              </div>
            </div>
          </div>
        </div>
        
        <div class="margin-20">
          <button type="submit" class="btn btn-primary pull-right" [disabled]="!myForm.valid">Submit</button>
        </div>
        <div class="clearfix"></div>

        <div class="margin-20">
          <div>myForm details:-</div>
          <pre>Is myForm valid?: <br>{{myForm.valid | json}}</pre>
          <pre>form value: <br>{{myForm.value | json}}</pre>
        </div>
      </form>
    </div>
  </div>
</div>