/*---------------------------------------------------------------------------------------------
 *  Copyright (c) Microsoft Corporation. All rights reserved.
 *  Licensed under the MIT License. See License.txt in the project root for license information.
 *--------------------------------------------------------------------------------------------*/

import { StandardWheelEvent } from '../../../../../vs/base/browser/mouseEvent';
import {
  AbstractScrollbar,
  ISimplifiedMouseEvent,
  ScrollbarHost,
} from '../../../../../vs/base/browser/ui/scrollbar/abstractScrollbar';
import { ScrollableElementResolvedOptions } from '../../../../../vs/base/browser/ui/scrollbar/scrollableElementOptions';
import { ARROW_IMG_SIZE } from '../../../../../vs/base/browser/ui/scrollbar/scrollbarArrow';
import { ScrollbarState } from '../../../../../vs/base/browser/ui/scrollbar/scrollbarState';
import {
  INewScrollPosition,
  ScrollEvent,
  Scrollable,
  ScrollbarVisibility,
} from '../../../../../vs/base/common/scrollable';
import {
  Codicon,
  registerCodicon,
} from '../../../../../vs/base/common/codicons';

const scrollbarButtonUpIcon = registerCodicon(
  'scrollbar-button-up',
  Codicon.triangleUp
);
const scrollbarButtonDownIcon = registerCodicon(
  'scrollbar-button-down',
  Codicon.triangleDown
);

export class VerticalScrollbar extends AbstractScrollbar {
  constructor(
    scrollable: Scrollable,
    options: ScrollableElementResolvedOptions,
    host: ScrollbarHost
  ) {
    const scrollDimensions = scrollable.getScrollDimensions();
    const scrollPosition = scrollable.getCurrentScrollPosition();
    super({
      lazyRender: options.lazyRender,
      host: host,
      scrollbarState: new ScrollbarState(
        options.verticalHasArrows ? options.arrowSize : 0,
        options.vertical === ScrollbarVisibility.Hidden
          ? 0
          : options.verticalScrollbarSize,
        // give priority to vertical scroll bar over horizontal and let it scroll all the way to the bottom
        0,
        scrollDimensions.height,
        scrollDimensions.scrollHeight,
        scrollPosition.scrollTop
      ),
      visibility: options.vertical,
      extraScrollbarClassName: 'vertical',
      scrollable: scrollable,
      scrollByPage: options.scrollByPage,
    });

    if (options.verticalHasArrows) {
      const arrowDelta = (options.arrowSize - ARROW_IMG_SIZE) / 2;
      const scrollbarDelta =
        (options.verticalScrollbarSize - ARROW_IMG_SIZE) / 2;

      this._createArrow({
        className: 'scra',
        icon: scrollbarButtonUpIcon,
        top: arrowDelta,
        left: scrollbarDelta,
        bottom: undefined,
        right: undefined,
        bgWidth: options.verticalScrollbarSize,
        bgHeight: options.arrowSize,
        onActivate: () =>
          this._host.onMouseWheel(new StandardWheelEvent(null, 0, 1)),
      });

      this._createArrow({
        className: 'scra',
        icon: scrollbarButtonDownIcon,
        top: undefined,
        left: scrollbarDelta,
        bottom: arrowDelta,
        right: undefined,
        bgWidth: options.verticalScrollbarSize,
        bgHeight: options.arrowSize,
        onActivate: () =>
          this._host.onMouseWheel(new StandardWheelEvent(null, 0, -1)),
      });
    }

    this._createSlider(
      0,
      Math.floor(
        (options.verticalScrollbarSize - options.verticalSliderSize) / 2
      ),
      options.verticalSliderSize,
      undefined
    );
  }

  protected _updateSlider(sliderSize: number, sliderPosition: number): void {
    this.slider.setHeight(sliderSize);
    this.slider.setTop(sliderPosition);
  }

  protected _renderDomNode(largeSize: number, smallSize: number): void {
    this.domNode.setWidth(smallSize);
    this.domNode.setHeight(largeSize);
    this.domNode.setRight(0);
    this.domNode.setTop(0);
  }

  public onDidScroll(e: ScrollEvent): boolean {
    this._shouldRender =
      this._onElementScrollSize(e.scrollHeight) || this._shouldRender;
    this._shouldRender =
      this._onElementScrollPosition(e.scrollTop) || this._shouldRender;
    this._shouldRender = this._onElementSize(e.height) || this._shouldRender;
    return this._shouldRender;
  }

  protected _mouseDownRelativePosition(
    offsetX: number,
    offsetY: number
  ): number {
    return offsetY;
  }

  protected _sliderMousePosition(e: ISimplifiedMouseEvent): number {
    return e.posy;
  }

  protected _sliderOrthogonalMousePosition(e: ISimplifiedMouseEvent): number {
    return e.posx;
  }

  protected _updateScrollbarSize(size: number): void {
    this.slider.setWidth(size);
  }

  public writeScrollPosition(
    target: INewScrollPosition,
    scrollPosition: number
  ): void {
    target.scrollTop = scrollPosition;
  }
}