add task solution

src/figuresClasses.ts

@@ -1,11 +1,81 @@
-export interface Figure {}
+export type FigureColor = 'red' | 'green' | 'blue';
 
-export class Triangle implements Figure {}
+export interface Figure {
+  shape: 'triangle' | 'circle' | 'rectangle';
+  color: FigureColor;
+  getArea(): number;
+}
+
+function validatePositiveLength(value: number, name: string): void {
+  if (value <= 0) {
+    throw new Error(`${name} must be greater than 0`);
+  }
+}
+
+export class Triangle implements Figure {
+  shape: 'triangle' = 'triangle';
+
+  constructor(
+    public color: FigureColor,
+    public a: number,
+    public b: number,
+    public c: number,
+  ) {
+    validatePositiveLength(a, 'a');
+    validatePositiveLength(b, 'b');
+    validatePositiveLength(c, 'c');
 
-export class Circle implements Figure {}
+    const sortedSides = [a, b, c].sort((x, y) => y - x);
+    const longestSide = sortedSides[0];
+    const sumOfOtherSides = sortedSides[1] + sortedSides[2];
+
+    if (longestSide >= sumOfOtherSides) {
+      throw new Error(`Sides ${a}, ${b} and ${c} can't form a triangle`);
+    }
+  }
+
+  getArea(): number {
+    const s = (this.a + this.b + this.c) / 2;
+    const area = Math.sqrt(s * (s - this.a) * (s - this.b) * (s - this.c));
+
+    return Math.floor(area * 100) / 100;
+  }
+}
 
-export class Rectangle implements Figure {}
+export class Circle implements Figure {
+  shape: 'circle' = 'circle';
+
+  constructor(
+    public color: FigureColor,
+    public radius: number,
+  ) {
+    validatePositiveLength(radius, 'radius');
+  }
+
+  getArea(): number {
+    const area = Math.PI * this.radius * this.radius;
+
+    return Math.floor(area * 100) / 100;
+  }
+}
+
+export class Rectangle implements Figure {
+  shape: 'rectangle' = 'rectangle';
+
+  constructor(
+    public color: FigureColor,
+    public width: number,
+    public height: number,
+  ) {
+    validatePositiveLength(width, 'width');
+    validatePositiveLength(height, 'height');
+  }
+
+  getArea(): number {
+    return Math.floor(this.width * this.height * 100) / 100;
+  }
+}
 
-export function getInfo(figure): string {
-  return typeof figure;
+export function getInfo(figure: Figure): string {
+  return `A ${figure.color} ${figure.shape} - ${figure.getArea()}`;
 }