added code for the wc exercise

Author: Luke-Manyamazi

implement-shell-tools/wc/wc.mjs

@@ -0,0 +1,89 @@
+import { program } from "commander";
+import process from "node:process";
+import { readFileSync, existsSync } from "node:fs";
+
+program
+  .name("wc")
+  .description("Count lines, words, and characters in files")
+  .argument("[files...]", "Files to process")
+  .option("-l, --lines", "Count lines")
+  .option("-w, --words", "Count words")
+  .option("-c, --chars", "Count characters (bytes)")
+program.parse(process.argv);
+
+const options = program.opts();
+const files = program.args.length ? program.args : ["/dev/stdin"];
+
+function countFile(filePath, options) {
+  let content = "";
+  try {
+    if (filePath === "/dev/stdin") {
+      content = readFileSync(process.stdin.fd, "utf8");
+    } else {
+      if (!existsSync(filePath)) {
+        console.error(`wc: ${filePath}: No such file or directory`);
+        return null;
+      }
+      content = readFileSync(filePath, "utf8");
+    }
+  } catch (error) {
+    console.error(`wc: ${filePath}: ${error.message}`);
+    return null;
+  }
+
+  if (typeof content !== 'string') {
+    content = "";
+  }
+
+  const lineCount = (content.match(/\n/g) || []).length;
+
+  const wordCount = content.trim().split(/\s+/).filter(Boolean).length;
+
+  const charCount = Buffer.byteLength(content, "utf8");
+
+  return {
+    file: filePath,
+    lines: options.lines || (!options.words && !options.chars) ? lineCount : null,
+    words: options.words || (!options.lines && !options.chars) ? wordCount : null,
+    chars: options.chars || (!options.lines && !options.words) ? charCount : null,
+  };
+}
+
+const results = [];
+let totalLines = 0;
+let totalWords = 0;
+let totalChars = 0;
+const hasMultipleFiles = files.length > 1;
+
+files.forEach(file => {
+  const result = countFile(file, options);
+  if (result) {
+    results.push(result);
+
+    if (result.lines !== null) totalLines += result.lines;
+    if (result.words !== null) totalWords += result.words;
+    if (result.chars !== null) totalChars += result.chars;
+  }
+});
+
+results.forEach(result => {
+  const output = [];
+  if (result.lines !== null) output.push(result.lines.toString().padStart(8));
+  if (result.words !== null) output.push(result.words.toString().padStart(8));
+  if (result.chars !== null) output.push(result.chars.toString().padStart(8));
+  console.log(output.join(" "), result.file);
+});
+
+if (hasMultipleFiles && results.length > 0) {
+  const totalOutput = [];
+  if (options.lines || (!options.words && !options.chars)) {
+    totalOutput.push(totalLines.toString().padStart(8));
+  }
+  if (options.words || (!options.lines && !options.chars)) {
+    totalOutput.push(totalWords.toString().padStart(8));
+  }
+  if (options.chars || (!options.lines && !options.words)) {
+    totalOutput.push(totalChars.toString().padStart(8));
+  }
+  console.log(totalOutput.join(" "), "total");
+}