From 85eb28a5dc0ae3399e4a4c148a3f79060c31c217 Mon Sep 17 00:00:00 2001
From: robonen <robonenandrew@gmail.com>
Date: Thu, 24 Oct 2024 07:28:24 +0700
Subject: [PATCH] feat(packages/stdlib): add sum arrays util

---
 packages/stdlib/src/arrays/sum/index.test.ts | 39 ++++++++++++++++++++
 packages/stdlib/src/arrays/sum/index.ts      | 26 +++++++++++++
 2 files changed, 65 insertions(+)
 create mode 100644 packages/stdlib/src/arrays/sum/index.test.ts
 create mode 100644 packages/stdlib/src/arrays/sum/index.ts

diff --git a/packages/stdlib/src/arrays/sum/index.test.ts b/packages/stdlib/src/arrays/sum/index.test.ts
new file mode 100644
index 0000000..a007487
--- /dev/null
+++ b/packages/stdlib/src/arrays/sum/index.test.ts
@@ -0,0 +1,39 @@
+import { describe, it, expect } from 'vitest';
+import { sum } from '.';
+
+describe('sum', () => {
+  it('return the sum of all elements in a number array', () => {
+    const result = sum([1, 2, 3, 4, 5]);
+    expect(result).toBe(15);
+  });
+
+  it('return 0 for an empty array', () => {
+    const result = sum([]);
+    expect(result).toBe(0);
+  });
+
+  it('return the sum of all elements using a getValue function', () => {
+    const result = sum([{ value: 1 }, { value: 2 }, { value: 3 }], (item) => item.value);
+    expect(result).toBe(6);
+  });
+
+  it('handle arrays with negative numbers', () => {
+    const result = sum([-1, -2, -3, -4, -5]);
+    expect(result).toBe(-15);
+  });
+
+  it('handle arrays with mixed positive and negative numbers', () => {
+    const result = sum([1, -2, 3, -4, 5]);
+    expect(result).toBe(3);
+  });
+
+  it('handle arrays with floating point numbers', () => {
+    const result = sum([1.5, 2.5, 3.5]);
+    expect(result).toBe(7.5);
+  });
+
+  it('handle arrays with a getValue function returning floating point numbers', () => {
+    const result = sum([{ value: 1.5 }, { value: 2.5 }, { value: 3.5 }], (item) => item.value);
+    expect(result).toBe(7.5);
+  });
+});
\ No newline at end of file
diff --git a/packages/stdlib/src/arrays/sum/index.ts b/packages/stdlib/src/arrays/sum/index.ts
new file mode 100644
index 0000000..4a82850
--- /dev/null
+++ b/packages/stdlib/src/arrays/sum/index.ts
@@ -0,0 +1,26 @@
+/**
+ * @name sum
+ * @category Arrays
+ * @description Returns the sum of all the elements in an array
+ * 
+ * @param {Value[]} array - The array to sum
+ * @param {(item: Value) => number} [getValue] - A function that returns the value to sum from each element in the array
+ * @returns {number} The sum of all the elements in the array
+ * 
+ * @example
+ * sum([1, 2, 3, 4, 5]) // => 15
+ * 
+ * sum([{ value: 1 }, { value: 2 }, { value: 3 }], (item) => item.value) // => 6
+ * 
+ * @since 0.0.3
+ */
+export function sum<Value extends number>(array: Value[]): number;
+export function sum<Value>(array: Value[], getValue: (item: Value) => number): number;
+export function sum<Value>(array: Value[], getValue?: (item: Value) => number): number {
+  // This check is necessary because the overload without the getValue argument
+  // makes tree-shaking based on argument types possible
+  if (!getValue)
+    return array.reduce((acc, item) => acc + (item as number), 0);
+
+  return array.reduce((acc, item) => acc + getValue(item), 0);
+}