Implement wc command

Author: anosidium

implement-shell-tools/wc/wc.mjs

@@ -0,0 +1,75 @@
+import { program } from "commander";
+import { promises as fs } from "node:fs";
+
+program.name("wc");
+program.description("simple wc clone");
+program.option("-w, --words", "print word count");
+program.option("-l, --lines", "print line count");
+program.option("-c, --bytes", "print byte count");
+program.argument("[paths...]", "file(s) to process");
+program.parse();
+
+const options = program.opts();
+const paths = program.args;
+
+const noFlags = !options.words && !options.lines && !options.bytes;
+const showWords = options.words || noFlags;
+const showLines = options.lines || noFlags;
+const showBytes = options.bytes || noFlags;
+
+function count(content) {
+  const lines = content.split("\n").length - 1;
+  const words = content.trim().split(/\s+/).filter(Boolean).length;
+  const bytes = Buffer.byteLength(content);
+
+  return { lines, words, bytes };
+}
+
+function formatCounts({ lines, words, bytes }, label = "") {
+  const output = [];
+
+  if (showLines) {
+    output.push(lines.toString().padStart(8));
+  }
+
+  if (showWords) {
+    output.push(words.toString().padStart(8));
+  }
+
+  if (showBytes) {
+    output.push(bytes.toString().padStart(8));
+  }
+
+  if (label) {
+    output.push(label);
+  }
+
+  return output.join(" ");
+}
+
+async function processFile(path) {
+  try {
+    const stat = await fs.stat(path);
+
+    if (stat.isDirectory()) {
+      console.error(`${path}: Is a directory`);
+      return;
+    }
+
+    const content = await fs.readFile(path, { encoding: "utf-8" });
+    const counts = count(content);
+    const output = formatCounts(counts, path);
+
+    console.log(output);
+  } catch (err) {
+    console.error(`${path}: ${err.message}`);
+  }
+}
+
+try {
+  for (const path of paths) {
+    await processFile(path);
+  }
+} catch (err) {
+  console.error(err.message);
+}