Implement 'ls' command alternative with directory listing options

Author: Geraldine-Edwards

implement-shell-tools/ls/ls.js

@@ -0,0 +1,83 @@
+import { program } from "commander";
+import { promises as fs } from "node:fs";
+import process from "node:process";
+
+// configure the CLI program with its name, description, arguments, options, and actions (the help instructions)
+program
+    .name("ls")
+    .description("An alternative to the 'ls' command")
+    .argument("[directory]", "The directory to list")
+    // Commander stores -1 as a string key that is accessed using options['1']
+    .option("-1", "List all files, one per line")
+    .option("-a, --all", "Include hidden files (those starting with .) in the listing")
+    .action(async (directory, options) => {
+      if (program.args.length > 1) {
+          console.error(`Expected no more than 1 argument (sample-files) but got ${program.args.length}.`);
+          process.exit(1);
+      }
+
+      // default directory to current folder
+      directory = directory || ".";
+
+      await newLs(directory, options['1'], options.all);
+    });
+
+program.parse(process.argv);
+
+
+async function newLs(directory, oneFlag, allFlag) {
+    try {
+        // check if the path exists
+        const stats = await fs.stat(directory);
+
+        // if it’s a file, just print its name
+        if (stats.isFile()) {
+            console.log(directory);
+            return;
+        } 
+
+        // read directory contents
+        let entries = await fs.readdir(directory);
+
+        let finalEntries;
+
+        // organize -a output ('.' and '..' first, then visible files, then hidden (starts with a .) files)
+        if (allFlag) {
+            const dotEntries = ['.', '..'];
+            const visibleFiles = entries.filter(name => !name.startsWith('.'));
+            const hiddenFiles = entries.filter(name => name.startsWith('.') && name !== '.' && name !== '..');
+
+            // localeCompare = take into account rules of system language/region for ordering 
+            // undefined = uses the system default, numeric = regular number sorting, base = ignore case & accents            
+            visibleFiles.sort((a, b) => a.localeCompare(b, undefined, { numeric: true, sensitivity: 'base' }));
+            hiddenFiles.sort((a, b) => a.localeCompare(b, undefined, { numeric: true, sensitivity: 'base' }));
+
+            // combine to a single new array
+            finalEntries = dotEntries.concat(visibleFiles, hiddenFiles);
+        } else {
+            // sort just visible files
+            finalEntries = entries
+                .filter(name => !name.startsWith('.'))
+                .sort((a, b) => a.localeCompare(b, undefined, { numeric: true, sensitivity: 'base' }));
+        }
+
+        // organize -1 output
+        if (oneFlag) {
+            for (const entry of finalEntries) {
+                console.log(entry);
+            }
+        } else {
+            //no flags (separated by 2 spaces)
+            console.log(finalEntries.join('  '));
+        }
+
+    } catch (err) {
+        console.error(`ls: cannot access '${directory}': No such file or directory`);
+    }
+}
+
+
+
+    
+    
+