nagi1 / hill-chart

import { Selection } from 'd3-selection';

import {

  event,

  select,

  scaleLinear,

  axisBottom,

  line,

  drag,

  range,

} from './d3';

import {

  hillFn,

  hillFnInverse,

  textOutRange,

  calculateTextPositionForX,

  calculateTextMarginForY,

  uId,

} from './helpers';

import './styles.css';

import {

  Config,

  ConfigInternal,

  Data,

  DataPointInternal,

  IHillChartClass,

} from './types';

const DEFAULT_SIZE = 10;

const defaults: ConfigInternal = {

  target: 'svg',

  width: 900,

  height: 300,

  preview: false,

  darkMode: false,

  backgroundColor: 'transparent',

  footerText: {

    show: true,

    fontSize: 0.75,

  },

  margin: {

    top: 20,

    right: 20,

    bottom: 40,

    left: 20,

  },

};

export default class HillChart extends EventEmitter implements IHillChartClass {

  /**

   * ### Public Variables ###

   */

  data: IHillChartClass['data'] = [];

  target = defaults.target;

  width = defaults.width;

  height = defaults.height;

  preview = defaults.preview;

  darkMode = defaults.darkMode;

  backgroundColor = defaults.backgroundColor;

  footerText = defaults.footerText;

  margin = defaults.margin;

  /**

   * ### Private Variables ###

   */

  chartWidth = 0;

  chartHeight = 0;

  colorScheme: IHillChartClass['colorScheme'] = 'hill-chart-light';

  svg: IHillChartClass['svg'] = select<SVGGElement, DataPointInternal>('svg');

  xScale: IHillChartClass['xScale'] = scaleLinear();

  yScale: IHillChartClass['yScale'] = scaleLinear();

  bottomLine: IHillChartClass['bottomLine'] = axisBottom(this.xScale);

  mainLineCurvePoints: IHillChartClass['mainLineCurvePoints'] = [];

  line: IHillChartClass['line'] = line<Pick<DataPointInternal, 'x' | 'y'>>()

    .x(0)

    .y(0);

  constructor(data: Data, config: Config) {

    super();

    Object.assign(this, defaults, { data }, config);

    this.init();

  }

  init() {

    const { width, height, margin, target } = this;

    // Calculate real chart dimensions without the margins

    this.chartWidth = width - margin.left - margin.right;

    this.chartHeight = height - margin.top - margin.bottom;

    // Render the svg and center chart according to margins

    this.colorScheme = this.darkMode ? 'hill-chart-dark' : 'hill-chart-light';

    const defaultBg = this.darkMode ? '#2f3437' : '#ffffff';

    const bgColor = this.backgroundColor;

    const useDefaultBg = bgColor === true || bgColor === undefined;

    const useTransparentBg = this.backgroundColor === false;

    const suppliedBgColor = useDefaultBg ? defaultBg : this.backgroundColor;

    this.backgroundColor = useTransparentBg ? 'transparent' : suppliedBgColor;

    this.svg = select<SVGGElement, DataPointInternal>(target)

      .attr('class', this.colorScheme)

      .attr('width', width)

      .attr('height', height)

      .attr(

        'style',

        `stroke-width: 0; background-color: ${this.backgroundColor};`

      )

      .append('g')

      .attr('transform', `translate(${margin.left}, ${margin.top})`);

    // Set X and Y axis scale values, it used to determine the center of the chart

    // when calling this.xScale(50), it also flip the y axis to start from the

    // lowest point and scale up like claiming a hill from the ground.

    this.xScale = scaleLinear().domain([0, 100]).range([0, this.chartWidth]);

    this.yScale = scaleLinear().domain([0, 100]).range([this.chartHeight, 0]);

    // Normalize data on the y axis

    this.normalizeData();

  }

  normalizeData() {

    this.data = this.data.map((point) => {

      return {

        id: point.id ? point.id : uId(),

        color: point.color,

        description: point.description,

        link: point.link,

        x: point.x ? point.x : 0,

        y: point.y ? point.y : hillFn(point.x ? point.x : 0),

        size: point.size ? point.size : DEFAULT_SIZE,

      };

    });

  }

  // Replace the data points

  replaceData(data: Partial<DataPointInternal>[]) {

    // Update and normalize the data

    Object.assign(this, { data });

    this.normalizeData();

  }

  // Replace the data points, and re-render the group

  replaceAndUpdate(data: Data) {

    // Update and normalize the data

    this.replaceData(data);

    // Remove the existing points

    this.svg.selectAll('.hill-chart-group').remove();

    // Render group of points

    this.renderGroup();

  }

  undraggablePoint() {

    return this.svg

      .selectAll('.hill-chart-group')

      .data(this.data)

      .enter()

      .append('a')

      .attr('href', (data) => {

        return data.link ? data.link : '#';

      })

      .append('g')

      .attr('class', 'hill-chart-group')

      .style('cursor', 'pointer')

      .attr('transform', (data) => {

        data.x = this.xScale(data.x);

        data.y = this.yScale(data.y);

        return `translate(${data.x}, ${data.y})`;

      });

  }

  render() {

    // Render the horizontal bottom line on X axis

    this.renderBottomLine(5);

    // Render the main curve line

    this.renderMainCurve();

    // Render the line in the middle

    this.renderMiddleLine();

    if (this.footerText.show) {

      // Render the text on the footer

      this.renderFooterText();

    }

    // Render the group on the chart

    this.renderGroup();

  }

  renderGroup() {

    const self = this;

    // Handle dragging

    const dragPoint = drag<SVGGElement, DataPointInternal>()

      .on('drag', function (data) {

        let { x } = event;

        // Check point movement, preventing it from wondering outside the main curve

        if (!x || x < 0) {

          x = 0;

          self.emit('home', {

            ...data,

            y: hillFnInverse(self.yScale.invert(data.y)),

          });

        } else if (x > self.chartWidth) {

          x = self.chartWidth;

          self.emit('end', {

            ...data,

            x: self.xScale.invert(self.chartWidth),

            y: hillFnInverse(self.yScale.invert(data.y)),

          });

        }

        // Convert current point coordinates back to the original

        // between 0 and 100 to set it in the data attribute

        const invertedX = self.xScale.invert(x);

        data.x = x;

        data.y = self.yScale(hillFn(invertedX));

        const invertedY = hillFnInverse(self.yScale.invert(data.y));

        const newInvertedCoordinates = {

          x: invertedX,

          y: invertedY,

        };

        // click event

        select<SVGGElement, DataPointInternal>(this).on('click', () => {

          self.emit('pointClick', { ...data, ...newInvertedCoordinates });

        });

        if (!self.preview) {

          const selectedPoint = select<SVGGElement, DataPointInternal>(

            this

          ).attr('transform', `translate(${data.x}, ${data.y})`);

          selectedPoint

            .select('text')

            .style('text-anchor', () => {

              if (textOutRange(invertedX)) {

                return 'end';

              }

              return 'start';

            })

            .attr('x', (point) =>

              calculateTextPositionForX(point.size, invertedX)

            );

          self.emit('move', invertedX, invertedY);

        }

      })

      .on('end', (data) => {

        if (this.preview) {

          return;

        }

        let { x } = event;

        // Check point movement, preventing it from wondering outside the main curve

        if (!x || x < 0) {

          x = 0;

        } else if (x > this.chartWidth) {

          x = this.chartWidth;

        }

        // Convert current point coordinates back to the original

        const invertedX = this.xScale.invert(x);

        data.y = this.yScale(hillFn(invertedX));

        const invertedY = hillFnInverse(this.yScale.invert(data.y));

        const newInvertedCoordinates = {

          x: invertedX,

          y: invertedY,

        };

        this.emit('moved', { ...data, ...newInvertedCoordinates });

      });

    let group:

      | Selection<SVGGElement, DataPointInternal, SVGGElement, unknown>

      | undefined;

    if (this.preview) {

      group = this.undraggablePoint();

    } else {

      // Create group consisted of a circle and a description text, where

      // the data attributes determine the position of them on the curve

      group = this.svg

        .selectAll('.hill-chart-group')

        .data(this.data)

        .enter()

        .append('g')

        .attr('class', 'hill-chart-group')

        .attr('transform', (data) => {

          data.x = this.xScale(data.x);

          data.y = this.yScale(data.y);

          return `translate(${data.x}, ${data.y})`;

        })

        .call(dragPoint);

    }

    group

      .append('circle')

      .attr('class', 'hill-chart-circle')

      .attr('fill', (data) => data.color)

      .attr('cx', 0)

      .attr('cy', 0)

      .attr('r', (data) => data.size || DEFAULT_SIZE);

    group

      .append('text')

      .text((data) => data.description)

      .attr('x', (data) =>

        calculateTextPositionForX(

          data.size || DEFAULT_SIZE,

          this.xScale.invert(data.x)

        )

      )

      .style('text-anchor', (data) => {

        if (textOutRange(this.xScale.invert(data.x))) {

          return 'end';

        }

        return 'start';

      })

      .attr('y', calculateTextMarginForY());

  }

  renderMainCurve() {

    // Generate the main line curve points

    this.mainLineCurvePoints = range(0, 100, 0.1).map((i) => ({

      x: i,

      y: hillFn(i),

    }));

    // Map main line curve points to <svg> d attribute

    this.line = line<Pick<DataPointInternal, 'x' | 'y'>>()

      .x((d) => this.xScale(d.x))

      .y((d) => this.yScale(d.y));

    // Render the actual main line curve

    this.svg

      .append('path')

      .attr('class', 'chart-hill-main-curve')

      .datum(this.mainLineCurvePoints)

      .attr('d', this.line);

  }

  renderBottomLine(marginTop = 5) {

    // Generate the horizontal bottom line on the X axis

    this.bottomLine = axisBottom(this.xScale).ticks(0).tickSize(0);

    // Render the acutal svg

    this.svg

      .append('g')

      .attr('class', 'hill-chart-bottom-line')

      .attr('transform', `translate(0, ${this.chartHeight + marginTop})`)

      .call(this.bottomLine);

  }

  renderMiddleLine() {

    this.svg

      .append('line')

      .attr('class', 'hill-chart-middle-line')

      .attr('y1', this.yScale(0))

      .attr('y2', this.yScale(100))

      .attr('x2', this.xScale(50))

      .attr('x1', this.xScale(50));

  }

}