/**
 * @license
 * Copyright Google Inc. All Rights Reserved.
 *
 * Use of this source code is governed by an MIT-style license that can be
 * found in the LICENSE file at https://angular.io/license
 */

import {Injectable} from '@angular/core';

import {AsyncValidatorFn, ValidatorFn} from './directives/validators';
import {StringMapWrapper} from './facade/collection';
import {isArray, isPresent} from './facade/lang';
import {AbstractControl, FormArray, FormControl, FormGroup} from './model';



/**
 * Creates a form object from a user-specified configuration.
 *
 * ```typescript
 * @Component({
 *   selector: 'my-app',
 *   template: `
 *     <form [formGroup]="loginForm">
 *       <p>Login <input formControlName="login"></p>
 *       <div formGroupName="passwordRetry">
 *         <p>Password <input type="password" formControlName="password"></p>
 *         <p>Confirm password <input type="password" formControlName="passwordConfirmation"></p>
 *       </div>
 *     </form>
 *     <h3>Form value:</h3>
 *     <pre>{{value}}</pre>
 *   `,
 *   directives: [REACTIVE_FORM_DIRECTIVES]
 * })
 * export class App {
 *   loginForm: FormGroup;
 *
 *   constructor(builder: FormBuilder) {
 *     this.loginForm = builder.group({
 *       login: ["", Validators.required],
 *       passwordRetry: builder.group({
 *         password: ["", Validators.required],
 *         passwordConfirmation: ["", Validators.required, asyncValidator]
 *       })
 *     });
 *   }
 *
 *   get value(): string {
 *     return JSON.stringify(this.loginForm.value, null, 2);
 *   }
 * }
 * ```
 *
 * @stable
 */
@Injectable()
export class FormBuilder {
  /**
   * Construct a new {@link FormGroup} with the given map of configuration.
   * Valid keys for the `extra` parameter map are `optionals` and `validator`.
   *
   * See the {@link FormGroup} constructor for more details.
   */
  group(controlsConfig: {[key: string]: any}, extra: {[key: string]: any} = null): FormGroup {
    const controls = this._reduceControls(controlsConfig);
    const validator: ValidatorFn =
        isPresent(extra) ? StringMapWrapper.get(extra, 'validator') : null;
    const asyncValidator: AsyncValidatorFn =
        isPresent(extra) ? StringMapWrapper.get(extra, 'asyncValidator') : null;
    return new FormGroup(controls, validator, asyncValidator);
  }
  /**
   * Construct a new {@link FormControl} with the given `formState`,`validator`, and
   * `asyncValidator`.
   */
  control(
      formState: Object, validator: ValidatorFn|ValidatorFn[] = null,
      asyncValidator: AsyncValidatorFn|AsyncValidatorFn[] = null): FormControl {
    return new FormControl(formState, validator, asyncValidator);
  }

  /**
   * Construct an array of {@link FormControl}s from the given `controlsConfig` array of
   * configuration, with the given optional `validator` and `asyncValidator`.
   */
  array(
      controlsConfig: any[], validator: ValidatorFn = null,
      asyncValidator: AsyncValidatorFn = null): FormArray {
    var controls = controlsConfig.map(c => this._createControl(c));
    return new FormArray(controls, validator, asyncValidator);
  }

  /** @internal */
  _reduceControls(controlsConfig: {[k: string]: any}): {[key: string]: AbstractControl} {
    var controls: {[key: string]: AbstractControl} = {};
    StringMapWrapper.forEach(controlsConfig, (controlConfig: any, controlName: string) => {
      controls[controlName] = this._createControl(controlConfig);
    });
    return controls;
  }

  /** @internal */
  _createControl(controlConfig: any): AbstractControl {
    if (controlConfig instanceof FormControl || controlConfig instanceof FormGroup ||
        controlConfig instanceof FormArray) {
      return controlConfig;

    } else if (isArray(controlConfig)) {
      var value = controlConfig[0];
      var validator: ValidatorFn = controlConfig.length > 1 ? controlConfig[1] : null;
      var asyncValidator: AsyncValidatorFn = controlConfig.length > 2 ? controlConfig[2] : null;
      return this.control(value, validator, asyncValidator);

    } else {
      return this.control(controlConfig);
    }
  }
}