Add -n flag support to cat using commander

Author: zohrehKazemianpour

implement-shell-tools/cat/cat.js

@@ -1,17 +1,44 @@
-import process from "node:process"
+import {program} from "commander";
 import {promises as fs} from "node:fs"
 
-const argv = process.argv.slice(2)
 
-if (argv.length != 1) {
-  console.error(
-    `Expected exactly 1 argument (a path) to be passed but got ${argv.length}.`
-  );
-  process.exit(1);
-}
+//here we Configure the program: what flags and arguments it accepts
+// .option("short, long", "description")
+//The < > brackets mean "required"
+
+program
+  .name("cat")
+  .description("concatenate and print files")
+  .option("-n, --number", "Number all output lines")
+  .argument("<path>", "The file path to process");
+
+// here Parse command line arguments (reads process.argv and interprets it)
+program.parse();
 
-const path = argv[0]
 
+// Get the parsed values
+const path = program.args[0]; // The filename user provided
+const hasNumberFlag = program.opts().number;    // True if user used -n flag
 
+//read the file
 const content = await fs.readFile(path, "utf-8")
-console.log(content)
+
+// Output with or without line numbers
+if (hasNumberFlag) {
+  // Add line numbers to each line
+  const lines = content.split("\n"); // Split into array of lines
+  const numberedLines = lines.map((line, index) => {
+    const numberOfLine = index + 1; // Convert 0-based index to 1-based line number
+    return `${numberOfLine} ${line}`; // Format: "     1  Hello"
+  });
+  console.log(numberedLines.join("\n")); // Join back with newlines
+} else {
+  // Just print the file as-is
+  console.log(content);
+}
+
+
+
+
+
+