From c480eca0290315905e7485470e29c66065705fff Mon Sep 17 00:00:00 2001
From: joshuaboud <joshuaboud@hotmail.com>
Date: Tue, 21 Jun 2022 17:22:29 -0300
Subject: [PATCH] add function to get common abs path and list of relative
 paths from list of abs paths

---
 navigator/src/functions/commonPath.js      | 25 ++++++++++
 navigator/src/functions/commonPath.test.js | 54 ++++++++++++++++++++++
 2 files changed, 79 insertions(+)
 create mode 100644 navigator/src/functions/commonPath.js
 create mode 100644 navigator/src/functions/commonPath.test.js

diff --git a/navigator/src/functions/commonPath.js b/navigator/src/functions/commonPath.js
new file mode 100644
index 0000000..390ef75
--- /dev/null
+++ b/navigator/src/functions/commonPath.js
@@ -0,0 +1,25 @@
+/**
+ * Get greatest common denomincator path of an array of input paths
+ * @param {string[]} paths - Full paths from which to get common denominator
+ * @returns {CommonPathObj}
+ */
+export function commonPath(paths) {
+	const pathArrs = paths.map(str => str.split('/'));
+	let commonArr = [...pathArrs[0]];
+	for (let i = 0; i < pathArrs.length; i++) {
+		const iDiffer = pathArrs[i].findIndex((segment, index) => segment !== commonArr[index]);
+		if (iDiffer !== -1)
+			commonArr = commonArr.slice(0, iDiffer);
+		if (commonArr.length <= 1)
+			break;
+	}
+	const common = commonArr.join('/').replace(/^(?!\/)/, '/');
+	const relativePaths = pathArrs.map(fullArr => fullArr.slice(commonArr.length).join('/') || '.');
+	return { common, relativePaths };
+}
+
+/**
+ * @typedef {Object} CommonPathObj
+ * @property {string} common - The common denominator of all paths provided
+ * @property {string[]} relativePaths - the input paths made relative to the common path
+ */
diff --git a/navigator/src/functions/commonPath.test.js b/navigator/src/functions/commonPath.test.js
new file mode 100644
index 0000000..e1f05e4
--- /dev/null
+++ b/navigator/src/functions/commonPath.test.js
@@ -0,0 +1,54 @@
+import { commonPath } from "./commonPath";
+
+describe('The commonPath function', () => {
+	const filesInTmpTest = [
+		'/tmp/test/file1',
+		'/tmp/test/file2',
+		'/tmp/test/subdir/file3',
+	];
+	const filesInTmpHello = [
+		'/tmp/hello/file1',
+		'/tmp/hello/file2',
+		'/tmp/hello/subdir/file3',
+	];
+	const filesInTmp = [
+		...filesInTmpTest,
+		...filesInTmpHello,
+	];
+	const filesInHome = [
+		'/home/jboudreau/test1',
+		'/home/jboudreau/test2',
+		'/home/jboudreau/test3',
+		'/home/jboudreau/test/1/2/3/4',
+		'/home/mhooper/1/2/3/4',
+	]
+	const allFiles = [
+		...filesInTmp,
+		...filesInHome,
+		'/file',
+		'/',
+	]
+	it('can get the expected common denominator path from a list of inputs', () => {
+		expect(commonPath(filesInTmpTest).common).toEqual('/tmp/test');
+		expect(commonPath(filesInTmpHello).common).toEqual('/tmp/hello');
+		expect(commonPath(filesInTmp).common).toEqual('/tmp');
+		expect(commonPath(filesInHome).common).toEqual('/home');
+		expect(commonPath(allFiles).common).toEqual('/');
+	});
+
+	it('can properly generate relative paths s.t. common + / + relativePath === path', () => {
+		const testPaths = (paths) => {
+			const { common, relativePaths } = commonPath(paths);
+			for (let i = 0; i < relativePaths.length; i++) {
+				expect(relativePaths[i][0]).not.toEqual('/');
+				expect(relativePaths[i].length).toBeGreaterThanOrEqual(1);
+				expect(`${common}/${relativePaths[i]}`.replace(/\/+/g, '/').replace(/(?<=\/)\.$/, '')).toEqual(paths[i]);
+			}
+		}
+		testPaths(filesInTmpTest);
+		testPaths(filesInTmpHello);
+		testPaths(filesInTmp);
+		testPaths(filesInHome);
+		testPaths(allFiles);
+	});
+})