// Copyright (c) 2017 VMware, Inc. All Rights Reserved.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//    http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
import { Directive, OnChanges, Input, SimpleChanges } from "@angular/core";
import {
  NG_VALIDATORS,
  Validator,
  Validators,
  ValidatorFn,
  AbstractControl
} from "@angular/forms";

@Directive({
  selector: "[dateValidator]",
  providers: [
    { provide: NG_VALIDATORS, useExisting: DateValidatorDirective, multi: true }
  ]
})
export class DateValidatorDirective implements Validator, OnChanges {
  @Input() dateValidator: string;
  private valFn = Validators.nullValidator;

  ngOnChanges(changes: SimpleChanges): void {
    const change = changes["dateValidator"];
    if (change) {
      this.valFn = dateValidator();
    } else {
      this.valFn = Validators.nullValidator;
    }
  }
  validate(control: AbstractControl): { [key: string]: any } {
    return this.valFn(control) || Validators.nullValidator;
  }
}

export function dateValidator(): ValidatorFn {
  return (control: AbstractControl): { [key: string]: any } => {
    let controlValue = control.value;
    let valid = true;
    if (controlValue) {
      const regYMD = /^(19|20)\d\d([- /.])(0[1-9]|1[012])\2(0[1-9]|[12][0-9]|3[01])$/g;
      const regDMY = /^(0[1-9]|[12][0-9]|3[01])[- /.](0[1-9]|1[012])[- /.](19|20)\d\d$/g;
      valid = regYMD.test(controlValue) || regDMY.test(controlValue);
    }
    return valid
      ? Validators.nullValidator
      : { dateValidator: { value: controlValue } };
  };
}