implement wc with -l -w -c flags

Author: Konvaly

implement-shell-tools/wc/wc.js

@@ -0,0 +1,82 @@
+import { promises as fs } from "node:fs";
+import process from "node:process";
+
+const args = process.argv.slice(2);
+
+const showLines = args.includes("-l");
+const showWords = args.includes("-w");
+const showBytes = args.includes("-c");
+
+const noSpecificFlag = !showLines && !showWords && !showBytes;
+
+const filePaths = args.filter((arg) => !arg.startsWith("-"));
+
+if (filePaths.length === 0) {
+  console.error("Usage: node wc.js [-l] [-w] [-c] <file...>");
+  process.exit(1);
+}
+
+const results = [];
+
+for (const filePath of filePaths) {
+  const content = await fs.readFile(filePath, "utf-8");
+
+  const lines = content.endsWith("\n")
+    ? content.split("\n").length - 1
+    : content.split("\n").length;
+
+  const words = content.split(/\s+/).filter((w) => w.length > 0).length;
+
+  const bytes = Buffer.byteLength(content, "utf-8");
+
+  results.push({ filePath, lines, words, bytes });
+}
+
+const totalLines = results.reduce((sum, r) => sum + r.lines, 0);
+const totalWords = results.reduce((sum, r) => sum + r.words, 0);
+const totalBytes = results.reduce((sum, r) => sum + r.bytes, 0);
+
+let maxNumber;
+
+if (noSpecificFlag) {
+  maxNumber = Math.max(totalLines, totalWords, totalBytes);
+} else if (showLines) {
+  maxNumber = totalLines;
+} else if (showWords) {
+  maxNumber = totalWords;
+} else {
+  maxNumber = totalBytes;
+}
+
+const width = String(maxNumber).length + 2;
+
+function formatLine(counts, label) {
+  const parts = counts.map((n) => String(n).padStart(width, " "));
+  return parts.join("") + " " + label;
+}
+
+for (const { filePath, lines, words, bytes } of results) {
+  if (noSpecificFlag) {
+    process.stdout.write(formatLine([lines, words, bytes], filePath) + "\n");
+  } else if (showLines) {
+    process.stdout.write(formatLine([lines], filePath) + "\n");
+  } else if (showWords) {
+    process.stdout.write(formatLine([words], filePath) + "\n");
+  } else if (showBytes) {
+    process.stdout.write(formatLine([bytes], filePath) + "\n");
+  }
+}
+
+if (results.length > 1) {
+  if (noSpecificFlag) {
+    process.stdout.write(
+      formatLine([totalLines, totalWords, totalBytes], "total") + "\n",
+    );
+  } else if (showLines) {
+    process.stdout.write(formatLine([totalLines], "total") + "\n");
+  } else if (showWords) {
+    process.stdout.write(formatLine([totalWords], "total") + "\n");
+  } else if (showBytes) {
+    process.stdout.write(formatLine([totalBytes], "total") + "\n");
+  }
+}