got store working. now working on product-dimension switcher.

lib/__tests__/product-test.ts

@@ -0,0 +1,24 @@
+import { length } from "enheter";
+import { AreaProduct, LengthProduct, price } from "../product";
+
+describe("Product tests", () => {
+
+  it(`Length product gives correct price for a shorter length`, () => {
+    const standard = new LengthProduct(price("USD", 20), length("foot", 4));
+    const comparison = standard.priceFor(length("foot", 2));
+    expect(comparison.value).toEqual(10);
+  });
+
+  it(`Length product gives correct price for a longer length`, () => {
+    const standard = new LengthProduct(price("USD", 20), length("foot", 4));
+    const comparison = standard.priceFor(length("foot", 8));
+    expect(comparison.value).toEqual(40);
+  });
+
+  it(`Length product gives correct price if different units`, () => {
+    const standard = new LengthProduct(price("USD", 10), length("foot", 1));
+    const comparison = standard.priceFor(length("inch", 24));
+    expect(comparison.value).toEqual(20);
+  });
+
+});

lib/product.ts

@@ -0,0 +1,63 @@
+import {length as en_length, area as en_area} from "enheter"
+import {Measure, LengthUnit, AreaUnit, } from "enheter"
+export type Id = string;
+
+export type Currency = "USD";
+
+export class Price<C extends Currency> {
+    constructor(public value : number) {}
+}
+
+export function price(c : Currency, value : number) {
+    return new Price<typeof c>(value);
+}
+
+export type ProductAttributes = {
+    name?: string,
+    image?: string,
+    description?: string,
+    depth?: string,
+    [key:string]: any,
+}
+
+
+export abstract class Product {
+    id?: Id
+    constructor(public pricePerUnit : Price<Currency>, public attributes : ProductAttributes = {}) {}
+    public abstract priceFor(measure : Measure<"length"> | Measure<"area">) : Price<Currency>;
+}
+
+
+interface ILength {
+    length : Measure<"length">
+}
+
+interface IArea {
+    area: Measure<"area">
+}
+
+export class LengthProduct extends Product implements ILength {
+    constructor(public pricePerUnit : Price<Currency>, public length: Measure<"length">, public attributes : ProductAttributes = {}) {
+        super(pricePerUnit, attributes);
+    }
+
+    public priceFor(length : Measure<"length">): Price<Currency> {
+        const ratio = length.convertTo(this.length.unit).divideBy(this.length).value;
+        return {
+            value: this.pricePerUnit.value * ratio,
+        };
+    }
+}
+
+export class AreaProduct extends Product implements IArea {
+    constructor(public pricePerUnit : Price<Currency>, public area : Measure<"area">, public attributes : ProductAttributes = {}) {
+        super(pricePerUnit, attributes);
+    }
+
+    public priceFor(area : Measure<"area">): Price<Currency> {
+        const ratio = area.convertTo(this.area.unit).divideBy(this.area).value;
+        return {
+            value: this.pricePerUnit.value * ratio,
+        };
+    }
+}