/**
 * @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
 */
/* tslint:disable:array-type member-access variable-name typedef
 only-arrow-functions directive-class-suffix component-class-suffix
 component-selector no-unnecessary-type-assertion arrow-parens*/
import {PositionStrategy} from './position-strategy';


/**
 * A strategy for positioning overlays. Using this strategy, an overlay is given
 * an explicit position relative to the browser's viewport. We use flexbox,
 * instead of transforms, in order to avoid issues with subpixel rendering which
 * can cause the element to become blurry.
 */
export class GlobalPositionStrategy implements PositionStrategy {
  private _cssPosition = 'static';
  private _topOffset = '';
  private _bottomOffset = '';
  private _leftOffset = '';
  private _rightOffset = '';
  private _alignItems = '';
  private _justifyContent = '';
  private _width = '';
  private _height = '';

  /* A lazily-created wrapper for the overlay element that is used as a flex
   * container.  */
  private _wrapper: HTMLElement|null = null;

  /**
   * Sets the top position of the overlay. Clears any previously set vertical
   * position.
   * @param value New top offset.
   */
  top(value = ''): this {
	this._bottomOffset = '';
	this._topOffset = value;
	this._alignItems = 'flex-start';
	return this;
  }

  /**
   * Sets the left position of the overlay. Clears any previously set horizontal
   * position.
   * @param value New left offset.
   */
  left(value = ''): this {
	this._rightOffset = '';
	this._leftOffset = value;
	this._justifyContent = 'flex-start';
	return this;
  }

  /**
   * Sets the bottom position of the overlay. Clears any previously set vertical
   * position.
   * @param value New bottom offset.
   */
  bottom(value = ''): this {
	this._topOffset = '';
	this._bottomOffset = value;
	this._alignItems = 'flex-end';
	return this;
  }

  /**
   * Sets the right position of the overlay. Clears any previously set
   * horizontal position.
   * @param value New right offset.
   */
  right(value = ''): this {
	this._leftOffset = '';
	this._rightOffset = value;
	this._justifyContent = 'flex-end';
	return this;
  }

  /**
   * Sets the overlay width and clears any previously set width.
   * @param value New width for the overlay
   */
  width(value = ''): this {
	this._width = value;

    // When the width is 100%, we should reset the `left` and the offset,
    // in order to ensure that the element is flush against the viewport edge.
	if (value === '100%') {
		this.left('0px');
	}

	return this;
  }

  /**
   * Sets the overlay height and clears any previously set height.
   * @param value New height for the overlay
   */
  height(value = ''): this {
	this._height = value;

    // When the height is 100%, we should reset the `top` and the offset,
    // in order to ensure that the element is flush against the viewport edge.
	if (value === '100%') {
		this.top('0px');
	}

	return this;
  }

  /**
   * Centers the overlay horizontally with an optional offset.
   * Clears any previously set horizontal position.
   *
   * @param offset Overlay offset from the horizontal center.
   */
  centerHorizontally(offset = ''): this {
	this.left(offset);
	this._justifyContent = 'center';
	return this;
  }

  /**
   * Centers the overlay vertically with an optional offset.
   * Clears any previously set vertical position.
   *
   * @param offset Overlay offset from the vertical center.
   */
  centerVertically(offset = ''): this {
	this.top(offset);
	this._alignItems = 'center';
	return this;
  }

  /**
   * Apply the position to the element.
   * @docs-private
   *
   * @param element Element to which to apply the CSS.
   * @returns Resolved when the styles have been applied.
   */
  apply(element: HTMLElement): void {
	if (!this._wrapper && element.parentNode) {
		this._wrapper = document.createElement('div');
		this._wrapper.classList.add('cdk-global-overlay-wrapper');
		element.parentNode.insertBefore(this._wrapper, element);
		this._wrapper.appendChild(element);
	}

	const styles = element.style;
	const parentStyles = (element.parentNode as HTMLElement).style;

	styles.position = this._cssPosition;
	styles.marginTop = this._topOffset;
	styles.marginLeft = this._leftOffset;
	styles.marginBottom = this._bottomOffset;
	styles.marginRight = this._rightOffset;
	styles.width = this._width;
	styles.height = this._height;

	parentStyles.justifyContent = this._justifyContent;
	parentStyles.alignItems = this._alignItems;
  }

  /**
   * Removes the wrapper element from the DOM.
   */
  dispose(): void {
	if (this._wrapper && this._wrapper.parentNode) {
		this._wrapper.parentNode.removeChild(this._wrapper);
		this._wrapper = null;
	}
  }
}