core/src/index.ts

import VueChartwerkPodMixin from './VueChartwerkPodMixin';
import { Grid } from './components/grid';

import { PodState } from './models/state';
import { CoreSeries, CORE_SERIE_DEFAULTS } from './models/series';
import { CoreOptions, CORE_DEFAULT_OPTIONS } from './models/options';

import styles from './css/style.css';

import {
  Margin,
  Serie,
  Options,
  TimeFormat,
  BrushOrientation,
  AxisFormat,
  CrosshairOrientation,
  SvgElementAttributes,
  KeyEvent,
  PanOrientation,
  yAxisOrientation,
  ScrollPanOrientation,
  ScrollPanDirection,
  AxisOption,
  AxesOptions,
  RenderComponent,
} from './types';
import { uid } from './utils';
import { palette } from './colors';

import * as d3 from 'd3';

import debounce from 'lodash/debounce';


const DEFAULT_TICK_SIZE = 2;
const MILISECONDS_IN_MINUTE = 60 * 1000;

abstract class ChartwerkPod<T extends Serie, O extends Options> {

  protected series: CoreSeries<T>;
  protected options: CoreOptions<O>;

  protected d3Node?: d3.Selection<HTMLElement, unknown, null, undefined>;
  protected overlay?: d3.Selection<SVGRectElement, unknown, null, undefined>;
  protected crosshair?: d3.Selection<SVGGElement, unknown, null, undefined>;
  protected brush?: d3.BrushBehavior<unknown>;
  protected zoom?: any;
  protected svg?: d3.Selection<SVGElement, unknown, null, undefined>;
  protected state: PodState<T, O>;
  protected pan?: d3.ZoomBehavior<Element, unknown>;
  protected clipPath?: any;
  protected isPanning = false;
  protected isBrushing = false;
  protected brushStartSelection: [number, number] | null = null;
  protected initScaleX?: d3.ScaleLinear<any, any>;
  protected initScaleY?: d3.ScaleLinear<any, any>;
  protected initScaleY1?: d3.ScaleLinear<any, any>;
  protected xAxisElement?: d3.Selection<SVGGElement, unknown, null, undefined>;
  protected yAxisElement?: d3.Selection<SVGGElement, unknown, null, undefined>;
  protected y1AxisElement?: d3.Selection<SVGGElement, unknown, null, undefined>;
  protected yAxisTicksColors?: string[] = [];
  private _clipPathUID = '';

  protected readonly d3: typeof d3;
  protected deltaYTransform = 0;
  // TODO: forceRerender is a hack, it will be remove someday. But we need to update state on resize
  protected debouncedRender = debounce(this.forceRerender.bind(this), 100);
  // containers
  // TODO: add better names
  protected chartContainer: d3.Selection<SVGGElement, unknown, null, undefined>;
  protected metricContainer: d3.Selection<SVGGElement, unknown, null, undefined>;
  // components
  protected grid: Grid;

  constructor(
    protected readonly el: HTMLElement,
    _series: T[] = [],
    _options: O
  ) {
    // TODO: test if it's necessary
    styles.use();

    this.options = new CoreOptions(_options);
    this.series = new CoreSeries(_series);
    this.d3Node = d3.select(this.el);
    this.addEventListeners();

    this.createSvg();
    this.initPodState();
    this.initComponents();
  }

  protected addEventListeners(): void {
    window.addEventListener('resize', this.debouncedRender);
  }

  protected removeEventListeners(): void {
    window.removeEventListener('resize', this.debouncedRender);
  }

  public render(): void {
    this.options.callbackRenderStart();

    this.renderClipPath();
    this.addEvents();

    this.renderAxes();
    this.renderGrid();

    this.renderCrosshair();
    this.renderMetricsContainer();
    this.renderMetrics();

    this.renderLegend();
    this.renderYLabel();
    this.renderXLabel();

    this.options.callbackRenderEnd();
  }

  public updateData(series?: T[], options?: O, shouldRerender = true): void {
    this.updateSeries(series);
    this.updateOptions(options);
    if(shouldRerender) {
      this.forceRerender();
    }
  }

  public forceRerender(): void {
    // TODO: it is a hack. It is not nessesary to recreate svg.
    // the only purpose for this action, to clear d3.zoom.transform (see https://gitlab.com/chartwerk/core/-/issues/10)
    this.createSvg();
    this.initPodState();
    this.initComponents();
    this.render();
  }

  protected updateOptions(newOptions: O): void {
    if(newOptions === undefined) {
      return;
    }
    this.options.updateOptions(newOptions);
  }

  protected updateSeries(newSeries: T[]): void {
    if(newSeries === undefined) {
      return;
    }
    this.series.updateSeries(newSeries);
  }

  protected abstract renderMetrics(): void;
  protected abstract onMouseOver(): void;
  protected abstract onMouseOut(): void;
  protected abstract onMouseMove(): void;
  protected abstract onMouseClick(): void;
  public abstract renderSharedCrosshair(values: { x?: number, y?: number }): void;
  public abstract hideSharedCrosshair(): void;

  protected initPodState(): void {
    const boxPararms = {
      height: this.height,
      width: this.width,
    }
    this.state = new PodState(boxPararms, this.series, this.options);
  }

  protected initComponents(): void {
    // TODO: make chartContainer a separate class with SvgElParams inside to avoid duplication
    // TODO: bad connection between State and Grid
    const svgElParams = {
      height: this.height,
      width: this.width,
      xScale: this.state.xScale,
      yScale: this.state.yScale,
    }

    this.grid = new Grid(this.chartContainer, svgElParams, this.options.grid);
  }

  protected renderMetricsContainer(): void {
    this.chartContainer.select('.metrics-container').remove();

    // TODO: it should be a class with svgElParams as fields
    // container for clip path
    const clipContatiner = this.chartContainer
      .append('g')
      .attr('clip-path', `url(#${this.rectClipId})`)
      .attr('class', 'metrics-container');

    // container for panning
    this.metricContainer = clipContatiner
      .append('g')
      .attr('class', 'metrics-rect');
      this.options.callbackComponentRenderEnd(RenderComponent.METRICS_CONTAINER);
  }

  protected createSvg(): void {
    this.d3Node.select('svg').remove();
    this.svg = this.d3Node
      .append('svg')
      .style('width', '100%')
      .style('height', '100%')
      .style('backface-visibility', 'hidden');
    this.chartContainer = this.svg
      .append('g')
        .attr('transform', `translate(${this.margin.left},${this.margin.top})`);
  }

  protected renderGrid(): void {
    this.grid.render();
    this.options.callbackComponentRenderEnd(RenderComponent.GRID);
  }

  protected renderAxes(): void {
    // TODO: remove duplicates
    this.renderXAxis();
    this.renderYAxis();
    this.renderY1Axis();
    this.options.callbackComponentRenderEnd(RenderComponent.AXES);
  }

  protected renderXAxis(): void {
    if(this.options.axis.x.isActive === false) {
      return;
    }
    this.chartContainer.select('#x-axis-container').remove();
    this.xAxisElement = this.chartContainer
      .append('g')
      .attr('transform', `translate(0,${this.height})`)
      .attr('id', 'x-axis-container')
      .style('pointer-events', 'none')
      .call(
        d3.axisBottom(this.state.xScale)
          .ticks(this.options.axis.x.ticksCount)
          .tickSize(DEFAULT_TICK_SIZE)
          .tickFormat(this.getAxisTicksFormatter(this.options.axis.x))
      );
  }

  protected renderYAxis(): void {
    if(this.options.axis.y.isActive === false) {
      return;
    }
    this.chartContainer.select('#y-axis-container').remove();
    this.yAxisTicksColors = [];
    this.yAxisElement = this.chartContainer
      .append('g')
      .attr('id', 'y-axis-container')
      .style('pointer-events', 'none')
      // TODO: number of ticks shouldn't be hardcoded
      .call(
        d3.axisLeft(this.state.yScale)
          .ticks(this.options.axis.y.ticksCount)
          .tickSize(DEFAULT_TICK_SIZE)
          .tickFormat(this.getAxisTicksFormatter(this.options.axis.y))
      );
    const ticks = this.yAxisElement.selectAll(`.tick`).select('text').nodes();
    this.yAxisTicksColors.map((color, index) => {
      if(ticks === undefined || ticks[index] === undefined) {
        return;
      }
      d3.select(ticks[index]).attr('color', color);
    });
  }

  protected renderY1Axis(): void {
    if(this.options.axis.y1.isActive === false) {
      return;
    }
    this.chartContainer.select('#y1-axis-container').remove();
    this.y1AxisElement = this.chartContainer
      .append('g')
      .attr('id', 'y1-axis-container')
      .attr('transform', `translate(${this.width},0)`)
      .style('pointer-events', 'none')
      // TODO: number of ticks shouldn't be hardcoded
      .call(
        d3.axisRight(this.state.y1Scale)
          .ticks(this.options.axis.y1.ticksCount)
          .tickSize(DEFAULT_TICK_SIZE)
          .tickFormat(this.getAxisTicksFormatter(this.options.axis.y1))
      );
  }

  protected renderCrosshair(): void {
    this.chartContainer.select('#crosshair-container').remove();

    this.crosshair = this.chartContainer.append('g')
      .attr('id', 'crosshair-container')
      .style('display', 'none');

    if(
      this.options.crosshair.orientation === CrosshairOrientation.VERTICAL ||
      this.options.crosshair.orientation === CrosshairOrientation.BOTH
    ) {
      this.crosshair.append('line')
        .attr('class', 'crosshair-line')
        .attr('id', 'crosshair-line-x')
        .attr('fill', this.options.crosshair.color)
        .attr('stroke', this.options.crosshair.color)
        .attr('stroke-width', '1px')
        .attr('y1', 0)
        .attr('y2', this.height)
        .style('pointer-events', 'none');
    }
    if(
      this.options.crosshair.orientation === CrosshairOrientation.HORIZONTAL ||
      this.options.crosshair.orientation === CrosshairOrientation.BOTH
    ) {
      this.crosshair.append('line')
        .attr('class', 'crosshair-line')
        .attr('id', 'crosshair-line-y')
        .attr('fill', this.options.crosshair.color)
        .attr('stroke', this.options.crosshair.color)
        .attr('stroke-width', '1px')
        .attr('x1', 0)
        .attr('x2', this.width)
        .style('pointer-events', 'none');
    }
    this.options.callbackComponentRenderEnd(RenderComponent.CROSSHAIR);
  }

  protected addEvents(): void {
    // TODO: refactor for a new mouse/scroll events
    const panKeyEvent = this.options.mousePanEvent.keyEvent;
    const isPanActive = this.options.mousePanEvent.isActive;
    const isBrushActive = this.options.mouseZoomEvent.isActive;
    if(panKeyEvent === KeyEvent.MAIN) {
      if(isPanActive) {
        this.initPan();
      }
      if(isBrushActive) {
        this.initBrush();
      }
    } else {
      if(isBrushActive) {
        this.initBrush();
      }
      if(isPanActive) {
        this.initPan();
      }
    }
    this.ensureOverlayExisting();

    setTimeout(() => {
      this.overlay
        .on('mouseover', this.onMouseOver.bind(this))
        .on('mouseout', this.onMouseOut.bind(this))
        .on('mousemove', this.onMouseMove.bind(this))
        .on('click', this.onMouseClick.bind(this))
        .on('dblclick', () => {
          d3.event.stopPropagation();
          // TODO: add the same check as we have in line-pod
          this.zoomOut();
        })
        .on('dblclick.zoom', () => {
          d3.event.stopPropagation();
          // TODO: add the same check as we have in line-pod
          this.zoomOut();
        });
    }, 0);
  }

  protected ensureOverlayExisting(): void {
    this.overlay = this.chartContainer.select('.overlay');
    // init cumstom overlay to handle all events
    if(this.overlay.empty()) {
      this.overlay = this.chartContainer.append('rect')
        .attr('class', 'overlay')
        .attr('width', this.width)
        .attr('height', this.height)
        .attr('x', 0)
        .attr('y', 0)
        .attr('pointer-events', 'all')
        .attr('cursor', 'crosshair')
        .attr('fill', 'none');
    }
    this.options.callbackComponentRenderEnd(RenderComponent.OVERLAY);
  }

  protected initBrush(): void {
    switch(this.options.mouseZoomEvent.orientation) {
      case BrushOrientation.VERTICAL:
        this.brush = d3.brushY();
        break;
      case BrushOrientation.HORIZONTAL:
        this.brush = d3.brushX();
        break;
      case BrushOrientation.SQUARE:
      case BrushOrientation.RECTANGLE:
        this.brush = d3.brush();
        break;
      default:
        this.brush = d3.brushX();
    }
    const keyEvent = this.options.mouseZoomEvent.keyEvent;
    this.brush.extent([
        [0, 0],
        [this.width, this.height]
      ])
      .handleSize(20)
      // TODO: brush selection is hidden if keyEvent is shift
      .filter(this.filterByKeyEvent(keyEvent))
      .on('start', this.onBrushStart.bind(this))
      .on('brush', this.onBrush.bind(this))
      .on('end', this.onBrushEnd.bind(this));

    this.chartContainer.call(this.brush);
  }

  protected filterByKeyEvent(key: KeyEvent): () => boolean {
    // TODO: refactor
    switch(key) {
      case KeyEvent.MAIN:
        return () => !d3.event.shiftKey && !d3.event.button;
      case KeyEvent.SHIFT:
        return () => d3.event.shiftKey && !d3.event.button;
      default:
        throw new Error(`Unknown type of KeyEvent: ${key}`);
    }
  }

  protected isD3EventKeyEqualOption(event: d3.D3ZoomEvent<any, any>, optionsKeyEvent: KeyEvent): boolean {
    if(!event || !event.sourceEvent) {
      return false;
    }
    const isShiftKey = event.sourceEvent.shiftKey;
    const isOptionShift = optionsKeyEvent === KeyEvent.SHIFT;
    return isShiftKey === isOptionShift;
  }

  protected initPan(): void {
    if(
      this.options.mousePanEvent.isActive === false &&
      this.options.scrollPanEvent.isActive === false &&
      this.options.scrollZoomEvent.isActive === false
    ) {
      return;
    }

    this.initScaleX = this.state.xScale.copy();
    this.initScaleY = this.state.yScale.copy();
    if(this.options.axis.y1.isActive) {
      this.initScaleY1 = this.state.y1Scale.copy();
    }
    this.pan = d3.zoom()
      .on('zoom', this.onPanning.bind(this))
      .on('end', this.onPanningEnd.bind(this));

    this.chartContainer.call(this.pan);
  }

  protected renderClipPath(): void {
    this.clipPath = this.chartContainer.append('defs').append('SVG:clipPath')
      .attr('id', this.rectClipId)
      .append('SVG:rect')
      .attr('width', this.width)
      .attr('height', this.height)
      .attr('x', 0)
      .attr('y', 0);
    this.options.callbackComponentRenderEnd(RenderComponent.CLIP_PATH);
  }

  protected renderLegend(): void {
    if(this.options.allOptions.renderLegend === false) {
      return;
    }
    if(!this.series.isSeriesAvailable) {
      return;
    }
    let legendRow = this.chartContainer
      .append('g')
      .attr('class', 'legend-row');
    const series = this.series.allSeries;
    for(let idx = 0; idx < series.length; idx++) {
      let node = legendRow.selectAll('text').node();
      let rowWidth = 0;
      if(node !== null) {
        rowWidth = legendRow.node().getBBox().width + 25;
      }

      const isChecked = series[idx].visible !== false;
      legendRow.append('foreignObject')
        .attr('x', rowWidth)
        .attr('y', this.legendRowPositionY - 12)
        .attr('width', 13)
        .attr('height', 15)
        .html(`<form><input type=checkbox ${isChecked? 'checked' : ''} /></form>`)
        .on('click', () => this.options.callbackLegendClick(idx));

      legendRow.append('text')
        .attr('x', rowWidth + 20)
        .attr('y', this.legendRowPositionY)
        .attr('class', `metric-legend-${idx}`)
        .style('font-size', '12px')
        .style('fill', series[idx].color)
        .text(series[idx].target)
        .on('click', () => this.options.callbackLegendLabelClick(idx));
    }
    this.options.callbackComponentRenderEnd(RenderComponent.LEGEND);
  }

  protected renderYLabel(): void {
    if(this.options.axis.y.label === undefined) {
      return;
    }
    this.chartContainer.append('text')
      .attr('y', 0 - this.margin.left)
      .attr('x', 0 - (this.height / 2))
      .attr('dy', '1em')
      .attr('class', 'y-axis-label')
      .attr('transform', 'rotate(-90)')
      .style('text-anchor', 'middle')
      .style('font-size', '14px')
      .style('fill', 'currentColor')
      .text(this.options.axis.y.label);
  }

  protected renderXLabel(): void {
    if(this.options.axis.x.label === undefined) {
      return;
    }
    let yPosition = this.height + this.margin.top + this.margin.bottom - 35;
    if(!this.series.isSeriesAvailable) {
      yPosition += 20;
    }
    this.chartContainer.append('text')
      .attr('class', 'x-axis-label')
      .attr('x', this.width / 2)
      .attr('y', yPosition)
      .style('text-anchor', 'middle')
      .style('font-size', '14px')
      .style('fill', 'currentColor')
      .text(this.options.axis.x.label);
  }

  protected renderNoDataPointsMessage(): void {
    this.chartContainer.append('text')
      .attr('class', 'alert-text')
      .attr('x', this.width / 2)
      .attr('y', this.height / 2)
      .style('text-anchor', 'middle')
      .style('font-size', '14px')
      .style('fill', 'currentColor')
      .text('No data points');
  }

  private disableScrollForward(event: any): boolean {
    return event.sourceEvent.wheelDelta > 0
        && this.options.scrollPanEvent.direction === ScrollPanDirection.FORWARD;
  }

  private disableScrollBackward(event: any): boolean {
    return event.sourceEvent.wheelDelta < 0
        && this.options.scrollPanEvent.direction === ScrollPanDirection.BACKWARD;
  }

  protected onPanning(): void {
    const event = d3.event;
    if(event.sourceEvent === null || event.sourceEvent === undefined) {
      return;
    }
    if (event.sourceEvent.type === 'wheel'
        && (this.disableScrollBackward(event) || this.disableScrollForward(event))) {
      return;
    }
    this.rescaleMetricAndAxis(event);

    this.options.callbackPanning({
      ranges: [this.state.xValueRange, this.state.yValueRange, this.state.y1ValueRange],
      d3Event: event
    });
  }

  public rescaleMetricAndAxis(event: d3.D3ZoomEvent<any, any>): void {
    this.isPanning = true;
    this.onMouseOut();
    this.onPanningRescale(event);

    // TODO: check clear state for necessity
    this.renderYAxis();
    this.renderXAxis();
    // metrics-rect wrapper is required for panning and any rescaling
    this.chartContainer.select('.metrics-rect')
      .attr('transform', `translate(${this.state.transform.x},${this.state.transform.y}), scale(${this.state.transform.k})`);
  }

  protected onPanningRescale(event: d3.D3ZoomEvent<any, any>): void {
    // rescale metrics and axis on mouse and scroll panning
    const eventType = event.sourceEvent.type; // 'wheel' or 'mousemove'
    const scrollPanOptions = this.options.scrollPanEvent;
    const scrollZoomOptions = this.options.scrollZoomEvent;
    // TODO: maybe use switch and move it to onPanning
    if(eventType === 'wheel') {
      if(scrollPanOptions.isActive === true && this.isD3EventKeyEqualOption(event, scrollPanOptions.keyEvent)) {
        this.onScrollPanningRescale(event);
        return;
      }
      if(scrollZoomOptions.isActive === true && this.isD3EventKeyEqualOption(event, scrollZoomOptions.keyEvent)) {
        const orientation = scrollZoomOptions.orientation;
        let k;
        switch(orientation) {
          case PanOrientation.HORIZONTAL:
            k = `${event.transform.k},1`;
            this.rescaleAxisX(event.transform.x);
            break;
          case PanOrientation.VERTICAL:
            k = `1,${event.transform.k}`;
            this.rescaleAxisY(event.transform.y);
            break;
          case PanOrientation.BOTH:
            k = event.transform.k;
            this.rescaleAxisX(event.transform.x);
            this.rescaleAxisY(event.transform.y);
            break;
          default:
            throw new Error(`Unknown type of PanOrientation: ${orientation}`);
        }
        this.state.transform.k = k;
        return;
      }
      return;
    }

    const panOrientation = this.options.mousePanEvent.orientation;
    if(panOrientation === PanOrientation.HORIZONTAL || panOrientation === PanOrientation.BOTH) {
      this.rescaleAxisX(event.transform.x);
    }
    if(panOrientation === PanOrientation.VERTICAL || panOrientation === PanOrientation.BOTH) {
      this.rescaleAxisY(event.transform.y);
    }
  }

  // TODO: refactor, divide between classes
  rescaleAxisX(transformX: number): void {
    this.state.transform = { x: transformX };
    const rescaleX = d3.event.transform.rescaleX(this.initScaleX);
    this.xAxisElement.call(d3.axisBottom(this.state.xScale).scale(rescaleX));
    this.state.xValueRange = [rescaleX.invert(0), rescaleX.invert(this.width)];
  }

  rescaleAxisY(transformY: number): void {
    this.state.transform = { y: transformY };
    const rescaleY = d3.event.transform.rescaleY(this.initScaleY);
    this.yAxisElement.call(d3.axisLeft(this.state.yScale).scale(rescaleY));
    this.state.yValueRange = [rescaleY.invert(0), rescaleY.invert(this.height)];
    if(this.y1AxisElement) {
      const rescaleY1 = d3.event.transform.rescaleY(this.initScaleY1);
      this.y1AxisElement.call(d3.axisLeft(this.state.y1Scale).scale(rescaleY1));
      this.state.y1ValueRange = [rescaleY1.invert(0), rescaleY1.invert(this.height)];
      // TODO: y1 axis jumps on panning
      this.y1AxisElement.selectAll('line').attr('x2', 2);
      this.y1AxisElement.selectAll('text').attr('x', 5);
    }
  }

  protected onScrollPanningRescale(event: d3.D3ZoomEvent<any, any>): void {
    const scrollPanOptions = this.options.scrollPanEvent;
    // TODO: event.transform.y / x depends on mouse position, so we use hardcoded const, which should be removed
    const transformStep = scrollPanOptions.panStep;
    const scrollPanOrientation = scrollPanOptions.orientation;
    switch(scrollPanOrientation) {
      case ScrollPanOrientation.HORIZONTAL:
        // @ts-ignore
        const signX = Math.sign(event.transform.x);
        const transformX = this.state.absXScale.invert(Math.abs(transformStep));
        let rangeX = this.state.xValueRange;
        this.state.xValueRange = [rangeX[0] + signX * transformX, rangeX[1] + signX * transformX];
        const translateX = this.state.transform.x + signX * transformStep;
        this.state.transform = { x: translateX };
        break;
      case ScrollPanOrientation.VERTICAL:
        // @ts-ignore
        let signY = Math.sign(event.transform.y);
        if(this.options.axis.y.invert === true) {
          signY = -signY;
        }
        let rangeY = this.state.yValueRange;
        const transformY = this.state.absYScale.invert(transformStep);
        this.deltaYTransform = this.deltaYTransform + transformStep;
        // TODO: not hardcoded bounds
        if(this.deltaYTransform > this.height * 0.9) {
          return;
        }
        this.state.yValueRange = [rangeY[0] - signY * transformY, rangeY[1] - signY * transformY];
        const translateY = this.state.transform.y + signY * transformStep;
        this.state.transform = { y: translateY };
        // TODO: add y1 rescale
        break;
      default:
        throw new Error(`Unknown type of scroll pan orientation: ${scrollPanOrientation}`);
    }
  }

  protected onPanningEnd(): void {
    this.isPanning = false;
    this.deltaYTransform = 0;
    this.onMouseOut();
    this.options.callbackPanningEnd([this.state.xValueRange, this.state.yValueRange, this.state.y1ValueRange]);
  }

  protected onBrush(): void {
    const selection = d3.event.selection;
    if(this.options.mouseZoomEvent.orientation !== BrushOrientation.SQUARE || selection === null) {
      return;
    }
    const selectionAtts = this.getSelectionAttrs(selection);
    if(selectionAtts === undefined) {
      return;
    }
    this.chartContainer.select('.selection')
      .attr('x', selectionAtts.x)
      .attr('y', selectionAtts.y)
      .attr('width', selectionAtts.width)
      .attr('height', selectionAtts.height);
  }

  protected getSelectionAttrs(selection: number[][]): SvgElementAttributes | undefined {
    if(this.brushStartSelection === null || selection === undefined || selection === null) {
      return undefined;
    }
    const startX = this.brushStartSelection[0];
    const startY = this.brushStartSelection[1];
    const x0 = selection[0][0];
    const x1 = selection[1][0];
    const y0 = selection[0][1];
    const y1 = selection[1][1];
    const xRange = x1 - x0;
    const yRange = y1 - y0;
    const minWH = Math.min(xRange, yRange);
    const x = x0 === startX ? startX : startX - minWH;
    const y = y0 === startY ? startY : startY - minWH;
    return {
      x, y, width: minWH, height: minWH
    }
  }

  protected onBrushStart(): void {
    // TODO: move to state
    this.isBrushing === true;
    const selection = d3.event.selection;
    if(selection !== null && selection.length > 0) {
      this.brushStartSelection = d3.event.selection[0];
    }
    this.onMouseOut();
  }

  protected onBrushEnd(): void {
    const extent = d3.event.selection;
    this.isBrushing === false;
    if(extent === undefined || extent === null || extent.length < 2) {
      console.warn('Chartwerk Core: skip brush end (no extent)');
      return;
    }
    this.chartContainer
      .call(this.brush.move, null);

    let xRange: [number, number];
    let yRange: [number, number];
    switch(this.options.mouseZoomEvent.orientation) {
      case BrushOrientation.HORIZONTAL:
        const startTimestamp = this.state.xScale.invert(extent[0]);
        const endTimestamp = this.state.xScale.invert(extent[1]);
        xRange = [startTimestamp, endTimestamp];
        this.state.xValueRange = xRange;
        break;
      case BrushOrientation.VERTICAL:
        const upperY = this.state.yScale.invert(extent[0]);
        const bottomY = this.state.yScale.invert(extent[1]);
        // TODO: add min zoom y
        yRange = [upperY, bottomY];
        this.state.yValueRange = yRange;
        break;
      case BrushOrientation.RECTANGLE:
        const bothStartTimestamp = this.state.xScale.invert(extent[0][0]);
        const bothEndTimestamp = this.state.xScale.invert(extent[1][0]);
        const bothUpperY = this.state.yScale.invert(extent[0][1]);
        const bothBottomY = this.state.yScale.invert(extent[1][1]);
        xRange = [bothStartTimestamp, bothEndTimestamp];
        yRange = [bothUpperY, bothBottomY];
        this.state.xValueRange = xRange;
        this.state.yValueRange = yRange;
        break;
      case BrushOrientation.SQUARE:
        const selectionAtts = this.getSelectionAttrs(extent);
        if(selectionAtts === undefined) {
          break;
        }
        const scaledX0 = this.state.xScale.invert(selectionAtts.x);
        const scaledX1 = this.state.xScale.invert(selectionAtts.x + selectionAtts.width);
        const scaledY0 = this.state.yScale.invert(selectionAtts.y);
        const scaledY1 = this.state.yScale.invert(selectionAtts.y + selectionAtts.height);
        xRange = [scaledX0, scaledX1];
        yRange = [scaledY0, scaledY1];
        this.state.xValueRange = xRange;
        this.state.yValueRange = yRange;
        this.brushStartSelection = null;
    }

    this.options.callbackZoomIn([xRange, yRange]);
  }

  protected zoomOut(): void {
    let xAxisMiddleValue: number = this.state.xScale.invert(this.width / 2);
    let yAxisMiddleValue: number = this.state.yScale.invert(this.height / 2);
    const centers = {
      x: xAxisMiddleValue,
      y: yAxisMiddleValue
    }
    this.options.callbackZoomOut(centers);
  }

  getAxisTicksFormatter(axisOptions: AxisOption): (d: any, i: number) => any {
    // TODO: ticksCount === 0 -> suspicious option
    if(axisOptions.ticksCount === 0) {
      return (d) => '';
    }
    switch(axisOptions.format) {
      case AxisFormat.TIME:
        // TODO: customize time format?
        return d3.timeFormat('%m/%d %H:%M');
      case AxisFormat.NUMERIC:
        return (d) => d;
      case AxisFormat.STRING:
        // TODO: add string/symbol format
        throw new Error(`Not supported AxisFormat type ${axisOptions.format} yet`);
      case AxisFormat.CUSTOM:
        if(axisOptions.valueFormatter === undefined) {
          console.warn(`Value formatter for axis is not defined. Path options.axis.{?}.valueFormatter`);
          return (d) => d;
        }
        return (d, i) => {
          if(axisOptions.colorFormatter !== undefined) {
            this.yAxisTicksColors.push(axisOptions.colorFormatter(d, i))
          }
          return axisOptions.valueFormatter(d, i)
        };
      default:
        throw new Error(`Unknown time format for axis: ${axisOptions.format}`);
    }
  }

  get width(): number {
    return this.d3Node.node().clientWidth - this.margin.left - this.margin.right;
  }

  get height(): number {
    return this.d3Node.node().clientHeight - this.margin.top - this.margin.bottom;
  }

  get legendRowPositionY(): number {
    return this.height + this.margin.bottom - 5;
  }

  get margin(): Margin {
    return this.options.margin;
  }

  protected clearState(): void {
    this.state.clearState();
  }

  protected get rectClipId(): string {
    if(this._clipPathUID.length === 0) {
      this._clipPathUID = uid();
    }
    return this._clipPathUID;
  }
}

export {
  ChartwerkPod, VueChartwerkPodMixin,
  PodState, CoreSeries, CoreOptions, CORE_SERIE_DEFAULTS, CORE_DEFAULT_OPTIONS,
  Margin, Serie, Options, TimeFormat, BrushOrientation, PanOrientation,
  AxesOptions, AxisOption, RenderComponent,
  AxisFormat, yAxisOrientation, CrosshairOrientation, ScrollPanOrientation, ScrollPanDirection, KeyEvent,
  palette
};