From 8e9b3168edd4fec2dd1c314e1961a4540a0b80f6 Mon Sep 17 00:00:00 2001
From: Timur Demin <me@tdem.in>
Date: Sun, 26 Jan 2020 14:43:30 +0500
Subject: [PATCH] Add a sort helper

---
 src/helpers/sort.test.ts | 52 ++++++++++++++++++++++++++++++++++++++++
 src/helpers/sort.ts      | 27 +++++++++++++++++++++
 2 files changed, 79 insertions(+)
 create mode 100644 src/helpers/sort.test.ts
 create mode 100644 src/helpers/sort.ts

diff --git a/src/helpers/sort.test.ts b/src/helpers/sort.test.ts
new file mode 100644
index 0000000..4a8c5c0
--- /dev/null
+++ b/src/helpers/sort.test.ts
@@ -0,0 +1,52 @@
+import { sortByAttrs } from "./sort";
+
+type Record = {
+    id: number;
+    name: string;
+};
+
+const testData: Record[] = [
+    { id: 1, name: "Beth" },
+    { id: 2, name: "Anna" },
+    { id: 3, name: "Roy" },
+    { id: 4, name: "Amy" },
+];
+const sortedByName: Record[] = [
+    { id: 2, name: "Anna" },
+    { id: 4, name: "Amy" },
+    { id: 1, name: "Beth" },
+    { id: 3, name: "Roy" },
+];
+const sortedByID: Record[] = [
+    { id: 1, name: "Beth" },
+    { id: 2, name: "Anna" },
+    { id: 3, name: "Roy" },
+    { id: 4, name: "Amy" },
+];
+const testDataWithMultipleProps: Record[] = [
+    { id: 2, name: "Beth" },
+    { id: 1, name: "Beth" },
+    { id: 3, name: "Roy" },
+    { id: 3, name: "Amy" },
+];
+const sortedByMultipleProps: Record[] = [
+    { id: 1, name: "Beth" },
+    { id: 2, name: "Beth" },
+    { id: 3, name: "Amy" },
+    { id: 3, name: "Roy" },
+];
+
+describe("sort helpers on strict types", () => {
+    it("generates an empty array in response to an empty array", () => {
+        expect(sortByAttrs([])).toEqual([]);
+    });
+    it("sorts an array by a single property", () => {
+        expect(sortByAttrs(testData, "name")).toEqual(sortedByName);
+        expect(sortByAttrs(testData, "id")).toEqual(sortedByID);
+    });
+    it("sorts an array by multiple props", () => {
+        expect(sortByAttrs(testDataWithMultipleProps, "name", "id")).toEqual(
+            sortedByMultipleProps
+        );
+    });
+});
diff --git a/src/helpers/sort.ts b/src/helpers/sort.ts
new file mode 100644
index 0000000..7985c60
--- /dev/null
+++ b/src/helpers/sort.ts
@@ -0,0 +1,27 @@
+type Map = { [key: string]: any };
+
+/**
+ * Sorts any array given the list of attributes in order of descending priority.
+ * Uses bubble sort algorithm to sort the array. Returns a new array.
+ * @param a The array of things to sort
+ * @param attrs The attributes in order of descending priority
+ */
+export const sortByAttrs = <T extends Map>(a: T[], ...attrs: (keyof T)[]) => {
+    // the single edge case
+    if (a.length === 0) {
+        return [];
+    }
+    const arr = [...a];
+    for (let i = 0; i < arr.length; i++) {
+        for (let j = i; j < arr.length - 1; j++) {
+            attrs.forEach((attr) => {
+                if (arr[j][attr] > arr[j + 1][attr]) {
+                    let temp = arr[j];
+                    arr[j] = arr[j + 1];
+                    arr[j + 1] = temp;
+                }
+            });
+        }
+    }
+    return arr;
+};