import {Injectable, NgZone} from 'angular2/angular2';

import {Config} from '../config/config';


/**
 * The Input component is used to focus text input elements.
 *
 * @usage
 * ```html
 * <ion-input>
 *   <ion-label>Name</ion-label>
 *   <input value="Name" type="text">
 * </ion-input>
 * ```
 */
 @Injectable()
export class Form {

  constructor(config: Config, zone: NgZone) {
    this._config = config;
    this._zone = zone;

    this._inputs = [];
    this._focused = null;

    zone.runOutsideAngular(() => {
      this.focusCtrl(document);
    });
  }

  register(input) {
    this._inputs.push(input);
  }

  deregister(input) {
    let index = this._inputs.indexOf(input);
    if (index > -1) {
      this._inputs.splice(index, 1);
    }
    if (input === this._focused) {
      this._focused = null;
    }
  }

  focusCtrl(document) {
    let scrollAssist = this._config.get('scrollAssist');

    // raw DOM fun
    let focusCtrl = document.createElement('focus-ctrl');
    focusCtrl.setAttribute('aria-hidden', true);

    if (scrollAssist) {
      this._tmp = document.createElement('input');
      this._tmp.tabIndex = -1;
      focusCtrl.appendChild(this._tmp);
    }

    this._blur = document.createElement('button');
    this._blur.tabIndex = -1;
    focusCtrl.appendChild(this._blur);

    document.body.appendChild(focusCtrl);

    if (scrollAssist) {
      this._tmp.addEventListener('keydown', (ev) => {
        ev.preventDefault();
        ev.stopPropagation();
      });
    }

  }

  focusOut() {
    console.debug('focusOut');
    this._blur.focus();
  }

  setFocusHolder(type) {
    if (this._tmp && this._config.get('scrollAssist')) {
      this._tmp.type = type;
      console.debug('setFocusHolder', this._tmp.type);
      this._tmp.focus();
    }
  }

  setAsFocused(input) {
    this._focused = input;
  }

  /**
   * Focuses the next input element, if it exists.
   */
  focusNext(currentInput) {
    console.debug('focusNext');

    let index = this._inputs.indexOf(currentInput);
    if (index > -1 && (index + 1) < this._inputs.length) {
      let nextInput = this._inputs[index + 1];
      if (nextInput !== this._focused) {
        return nextInput.initFocus();
      }
    }

    index = this._inputs.indexOf(this._focused);
    if (index > 0) {
      let previousInput = this._inputs[index - 1];
      if (previousInput) {
        previousInput.initFocus();
      }
    }
  }

}