wc: support multiple files and print grand total (no flags)

Author: Pezhman-Azizi

implement-shell-tools/wc/wc.js

@@ -1,53 +1,75 @@
 #!/usr/bin/env node
-// wc.js — ESM: single file, no flags
-// Prints: lines words bytes  filename
+// wc.js — ESM: multiple files + total (no flags)
+// Prints per-file: lines words bytes  filename
+// If given >1 files, also prints a "total" line.
 
 import fs from "node:fs";
 import { pathToFileURL } from "node:url";
 
 async function main() {
-  const args = process.argv.slice(2);
-
-  // This commit supports exactly ONE file (no flags yet)
-  if (args.length !== 1) {
-    console.error("Usage (this commit): node wc.js <single-file>");
+  const files = process.argv.slice(2);
+  if (files.length === 0) {
+    console.error("Usage (this commit): node wc.js <file...>");
     process.exit(1);
   }
 
-  const file = args[0];
-
-  try {
-    const buf = await fs.promises.readFile(file); // Buffer
-    const bytes = buf.length;
+  let hadError = false;
+  let totalLines = 0, totalWords = 0, totalBytes = 0;
+  const results = [];
 
-    // Count lines: number of newline characters '\n'
-    let lines = 0;
-    for (let i = 0; i < buf.length; i++) {
-      if (buf[i] === 0x0a) lines++; // '\n'
+  for (const file of files) {
+    try {
+      const st = await fs.promises.lstat(file);
+      if (st.isDirectory()) {
+        console.error(`wc: ${file}: Is a directory`);
+        hadError = true;
+        continue;
+      }
+      const { lines, words, bytes } = await countFile(file);
+      results.push({ file, lines, words, bytes });
+      totalLines += lines; totalWords += words; totalBytes += bytes;
+    } catch (err) {
+      if (err?.code === "ENOENT") {
+        console.error(`wc: ${file}: No such file or directory`);
+      } else if (err?.code === "EACCES") {
+        console.error(`wc: ${file}: Permission denied`);
+      } else {
+        console.error(`wc: ${file}: ${err?.message || "Error"}`);
+      }
+      hadError = true;
     }
+  }
 
-    // Count words: sequences of non-whitespace
-    const text = buf.toString("utf8");
-    const words = (text.match(/\S+/g) || []).length;
-
-    console.log(`${pad(lines)} ${pad(words)} ${pad(bytes)} ${file}`);
-  } catch (err) {
-    if (err?.code === "ENOENT") {
-      console.error(`wc: ${file}: No such file or directory`);
-    } else if (err?.code === "EACCES") {
-      console.error(`wc: ${file}: Permission denied`);
-    } else {
-      console.error(`wc: ${file}: ${err?.message || "Error"}`);
-    }
-    process.exitCode = 1;
+  for (const r of results) {
+    console.log(`${pad(r.lines)} ${pad(r.words)} ${pad(r.bytes)} ${r.file}`);
+  }
+  if (results.length > 1) {
+    console.log(`${pad(totalLines)} ${pad(totalWords)} ${pad(totalBytes)} total`);
   }
+
+  if (hadError) process.exitCode = 1;
+}
+
+async function countFile(file) {
+  const buf = await fs.promises.readFile(file); // Buffer
+  const bytes = buf.length;
+
+  // lines: count '\n' bytes
+  let lines = 0;
+  for (let i = 0; i < buf.length; i++) if (buf[i] === 0x0a) lines++;
+
+  // words: sequences of non-whitespace (on UTF-8 text)
+  const text = buf.toString("utf8");
+  const words = (text.match(/\S+/g) || []).length;
+
+  return { lines, words, bytes };
 }
 
 function pad(n) {
-  // Right-align like wc (fixed width helps match spacing)
+  // Right-align like `wc` (fixed width works well for visual parity)
   return String(n).padStart(7, " ");
 }
 
-// Run only when executed directly
+// run only when executed directly
 const isDirect = import.meta.url === pathToFileURL(process.argv[1]).href;
 if (isDirect) await main();