add grid as a separate class

src/components/grid.ts

@@ -0,0 +1,100 @@
+import { GridOptions } from '../types';
+
+
+// we import only d3 types here
+import * as d3 from 'd3';
+
+import defaultsDeep from 'lodash/defaultsDeep';
+
+const DEFAULT_GRID_TICK_COUNT = 5;
+const DEFAULT_GRID_OPTIONS = {
+  x: {
+    isActive: true,
+    ticksCount: DEFAULT_GRID_TICK_COUNT,
+  },
+  y: {
+    isActive: true,
+    ticksCount: DEFAULT_GRID_TICK_COUNT,
+  },
+}
+export type SvgElOptions = {
+  height: number,
+  width: number,
+  xScale: d3.ScaleLinear<number, number>,
+  yScale: d3.ScaleLinear<number, number>,
+}
+
+
+// Grid Class - is a core component, which can be a separate Pod in the future. (but not in current Pod terminology)
+// All components have construcor with required args: svg element which will be filled with this component and options for it.
+// All compoтents have a reqiured method "render", which will be called in core costructor. <- this solution is temporary.
+// svgElement should be a separate class with its own height, width, xScale, yScale params to avoid SvgElOptions as argument.
+// We have a general problem with passing d3 as argument everywhere. Fix it, and remove from arg in constructor here.
+export class Grid {
+  _gridOptions: GridOptions;
+
+  constructor(
+    private _d3: typeof d3,
+    private _svgEl: d3.Selection<SVGElement, unknown, null, undefined>,
+    private _svgElOptions: SvgElOptions,
+    gridOptions: GridOptions,
+  ) {
+    this._gridOptions = this.setOptionDefaults(gridOptions);
+  
+    this.render();
+  }
+
+  protected setOptionDefaults(gridOptions: GridOptions): GridOptions {
+    return defaultsDeep(gridOptions, DEFAULT_GRID_OPTIONS);
+  }
+
+  render(): void {
+    // TODO: temporary. Move out of here
+    this._svgEl.selectAll('.grid').remove();
+  
+    this.renderGridLinesX();
+    this.renderGridLinesY();
+    this.updateStylesOfTicks();
+  }
+
+  renderGridLinesX(): void {
+    if(!this._gridOptions.x.isActive) {
+      return;
+    }
+    this._svgEl
+      .append('g')
+      .attr('transform', `translate(0,${this._svgElOptions.height})`)
+      .attr('class', 'grid x-grid')
+      .style('pointer-events', 'none')
+      .call(
+        this._d3.axisBottom(this._svgElOptions.xScale)
+          .ticks(this._gridOptions.x.ticksCount)
+          .tickSize(-this._svgElOptions.height)
+          .tickFormat(() => '')
+      );
+  }
+
+  renderGridLinesY(): void {
+    if(!this._gridOptions.y.isActive) {
+      return;
+    }
+    this._svgEl
+      .append('g')
+      .attr('class', 'grid y-grid')
+      .style('pointer-events', 'none')
+      .call(
+        this._d3.axisLeft(this._svgElOptions.yScale)
+          .ticks(this._gridOptions.y.ticksCount)
+          .tickSize(-this._svgElOptions)
+          .tickFormat(() => '')
+      );
+  }
+
+  updateStylesOfTicks(): void {
+    // TODO: add options for these actions
+    this._svgEl.selectAll('.grid').selectAll('.tick')
+      .attr('opacity', '0.5');
+    this._svgEl.selectAll('.grid').select('.domain')
+      .style('pointer-events', 'none');
+  }
+}

src/types.ts

@@ -30,16 +30,7 @@ export type Options = {
     y?: AxisOption,
     y1?: AxisOption
   };
-  grid?: {
-    x?: {
-      isActive?: boolean;
-      ticksCount?: number;
-    },
-    y?: {
-      isActive?: boolean;
-      ticksCount?: number;
-    },
-  };
+  grid?: GridOptions;
   crosshair?: {
     orientation?: CrosshairOrientation;
     color?: string;
@@ -93,6 +84,16 @@ export type Options = {
   renderTicksfromTimestamps?: boolean;
   renderLegend?: boolean;
 };
+export type GridOptions = {
+  x?: {
+    isActive?: boolean;
+    ticksCount?: number;
+  },
+  y?: {
+    isActive?: boolean;
+    ticksCount?: number;
+  },
+}
 export type AxisOption = {
   isActive?: boolean;
   ticksCount?: number;