feat: implement line counter as node console app in typescript

.gitignore

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+dist/
+node_modules/

LICENSE.md

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+# The MIT License (MIT)
+C
+opyright (c) 2025 Stevan Freeborn
+
+Permission is hereby granted, free of charge, to any person obtaining a copy
+of this software and associated documentation files (the "Software"), to deal
+in the Software without restriction, including without limitation the rights
+to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+copies of the Software, and to permit persons to whom the Software is
+furnished to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in all
+copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+SOFTWARE.

README.md

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+# Line Counter
+
+This is a console app that monitors a git repository and reports on the number of lines changed in the repository while it is running. The results are displayed in the console and are written to a file.
+
+## Installation
+
+```pwsh
+npm install -g @stevanfreeborn/line-counter
+```
+
+## Usage
+
+```pwsh
+line-counter <path-to-repo> <path-to-output-dir> [polling-interval-in-seconds]
+```
+

package-lock.json

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+{
+  "name": "@stevanfreeborn/line-counter",
+  "version": "0.0.0",
+  "lockfileVersion": 3,
+  "requires": true,
+  "packages": {
+    "": {
+      "name": "@stevanfreeborn/line-counter",
+      "version": "0.0.0",
+      "license": "MIT",
+      "bin": {
+        "line-counter": "dist/index.js"
+      },
+      "devDependencies": {
+        "@types/node": "^22.14.1",
+        "typescript": "^5.8.3"
+      }
+    },
+    "node_modules/@types/node": {
+      "version": "22.14.1",
+      "resolved": "https://registry.npmjs.org/@types/node/-/node-22.14.1.tgz",
+      "integrity": "sha512-u0HuPQwe/dHrItgHHpmw3N2fYCR6x4ivMNbPHRkBVP4CvN+kiRrKHWk3i8tXiO/joPwXLMYvF9TTF0eqgHIuOw==",
+      "dev": true,
+      "license": "MIT",
+      "dependencies": {
+        "undici-types": "~6.21.0"
+      }
+    },
+    "node_modules/typescript": {
+      "version": "5.8.3",
+      "resolved": "https://registry.npmjs.org/typescript/-/typescript-5.8.3.tgz",
+      "integrity": "sha512-p1diW6TqL9L07nNxvRMM7hMMw4c5XOo/1ibL4aAIGmSAt9slTE1Xgw5KWuof2uTOvCg9BY7ZRi+GaF+7sfgPeQ==",
+      "dev": true,
+      "license": "Apache-2.0",
+      "bin": {
+        "tsc": "bin/tsc",
+        "tsserver": "bin/tsserver"
+      },
+      "engines": {
+        "node": ">=14.17"
+      }
+    },
+    "node_modules/undici-types": {
+      "version": "6.21.0",
+      "resolved": "https://registry.npmjs.org/undici-types/-/undici-types-6.21.0.tgz",
+      "integrity": "sha512-iwDZqg0QAGrg9Rav5H4n0M64c3mkR59cJ6wQp+7C4nI0gsmExaedaYLNO44eT4AtBBwjbTiGPMlt2Md0T9H9JQ==",
+      "dev": true,
+      "license": "MIT"
+    }
+  }
+}

package.json

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+{
+  "name": "@stevanfreeborn/line-counter",
+  "version": "0.0.1",
+  "description": "A simple line counter for reporting the number of lines changed in committed and uncommitted files.",
+  "main": "dist/index.js",
+  "bin": {
+    "line-counter": "dist/index.js"
+  },
+  "scripts": {
+    "build": "tsc",
+    "dev": "tsc --watch",
+    "start": "node dist/index.js",
+    "prepare": "npm run build"
+  },
+  "keywords": [
+    "line",
+    "counter",
+    "git",
+    "commit",
+    "uncommitted"
+  ],
+  "author": "Stevan Freeborn",
+  "license": "MIT",
+  "type": "module",
+  "files": [
+    "dist",
+    "README.md",
+    "LICENSE.md"
+  ],
+  "devDependencies": {
+    "@types/node": "^22.14.1",
+    "typescript": "^5.8.3"
+  }
+}

src/index.ts

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+#!/usr/bin/env node
+
+import { execSync } from "child_process";
+import readline from "readline";
+import fs from "fs";
+import { changeToRepoDirectory, ensureGitInstalled, getCommitDiff, parseArgs, wait } from "./utils.js";
+
+ensureGitInstalled();
+
+const args = parseArgs(process);
+
+let exitRequested = false;
+
+readline.emitKeypressEvents(process.stdin);
+
+if (process.stdin.isTTY) {
+  process.stdin.setRawMode(true);
+}
+
+process.stdin.on("keypress", (_, key) => {
+  if (key.name === "c" && key.ctrl) {
+    console.log("Ctrl+C pressed. Exiting and restoring original directory...");
+    process.chdir(args.originalLocation);
+    exitRequested = true;
+    process.exit(0);
+  }
+});
+
+changeToRepoDirectory(args.repoPath);
+
+const startCommit = execSync("git rev-parse HEAD", {
+  encoding: "utf-8",
+}).trim();
+
+try {
+  while (exitRequested === false) {
+    const committedDiff = getCommitDiff(startCommit);
+    const uncommittedDiff = getCommitDiff();
+
+    const totalAdded = committedDiff.added + uncommittedDiff.added;
+    const totalRemoved = committedDiff.removed + uncommittedDiff.removed;
+    const totalChanged = totalAdded + totalRemoved;
+
+    const output = `Total lines changed: ${totalChanged} (Committed: +${committedDiff.added}/-${committedDiff.removed}, Uncommitted: +${uncommittedDiff.added}/-${uncommittedDiff.removed})`;
+
+    console.clear();
+    console.log(output);
+
+    fs.writeFileSync(args.outputPath, output, { encoding: "utf-8" });
+
+    await wait(args.pollIntervalSeconds);
+  }
+} catch (error) {
+  console.error("An error occurred: ", error);
+  process.exit(1);
+} finally {
+  process.chdir(args.originalLocation);
+}

src/utils.ts

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+import { execSync } from "child_process";
+import fs from "fs";
+
+export function parseArgs(process: NodeJS.Process) {
+  const repoPath = process.argv[2];
+  const outputPath = process.argv[3];
+  const pollInterval = process.argv[4];
+
+  const usageMessage = `
+Usage: line-counter <path-to-repo> <output-path> [poll-interval]
+
+Arguments:
+  path-to-repo    Path to the repository to monitor.
+  output-path     Path to the output directory where the results will be saved.
+  poll-interval   Interval in seconds to poll for changes (default: 10s).
+`;
+
+  if (process.argv[2] === "--help") {
+    console.log(usageMessage);
+    process.exit(0);
+  }
+
+  if (repoPath === undefined) {
+    console.error("Please provide a path to the repository.");
+    console.error(usageMessage);
+    process.exit(1);
+  }
+
+  const repoPathExists = fs.existsSync(repoPath);
+
+  if (!repoPathExists) {
+    console.error(`The specified repository path does not exist: ${repoPath}`);
+    process.exit(1);
+  }
+
+  if (outputPath === undefined) {
+    console.error("Please provide a path to the output directory.");
+    console.error(usageMessage);
+    process.exit(1);
+  }
+
+  const outputPathExists = fs.existsSync(outputPath);
+
+  if (!outputPathExists) {
+    console.error(`The specified output path does not exist: ${outputPath}`);
+    process.exit(1);
+  }
+
+  const outputPathIsDirectory = fs.lstatSync(outputPath).isDirectory();
+
+  if (outputPathIsDirectory === false) {
+    console.error(
+      `The specified output path is not a directory: ${outputPath}`,
+    );
+    process.exit(1);
+  }
+
+  const pollIntervalString = pollInterval || "10";
+  const pollIntervalSeconds = parseInt(pollIntervalString, 10);
+  const originalLocation = process.cwd();
+
+  return {
+    repoPath,
+    outputPath: `${outputPath}/line-counter-output.txt`,
+    pollIntervalSeconds,
+    originalLocation,
+  };
+}
+
+export function ensureGitInstalled() {
+  try {
+    const gitVersion = execSync("git --version", { encoding: "utf-8" });
+    const gitVersionRegex = /git version .+/;
+
+    if (!gitVersionRegex.test(gitVersion)) {
+      console.error(
+        "Git is not installed or not found in PATH. Please install Git and try again.",
+      );
+      process.exit(1);
+    }
+  } catch (error) {
+    console.error("Unable to detect if Git is installed.");
+    process.exit(1);
+  }
+}
+
+export function changeToRepoDirectory(repoPath: string) {
+  try {
+    process.chdir(repoPath);
+  } catch (error) {
+    console.error(`Failed to change directory to ${repoPath}: `, error);
+    process.exit(1);
+  }
+}
+
+export function getCommitDiff(startCommit?: string) {
+  try {
+    const command = startCommit
+      ? `git diff --shortstat ${startCommit} HEAD`
+      : "git diff --shortstat";
+
+    const diff = execSync(command, {
+      encoding: "utf-8",
+    });
+
+    const addMatch = diff.match(/(\d+) insertion/);
+    const removeMatch = diff.match(/(\d+) deletion/);
+
+    let added = 0;
+    let removed = 0;
+
+    if (addMatch && addMatch[1]) {
+      added = parseInt(addMatch[1], 10);
+    }
+
+    if (removeMatch && removeMatch[1]) {
+      removed = parseInt(removeMatch[1], 10);
+    }
+
+    return { added, removed };
+  } catch (error) {
+    console.error("Error executing git diff: ", error);
+    process.exit(1);
+  }
+}
+
+export async function wait(seconds: number) {
+  return new Promise((resolve) => setTimeout(resolve, seconds * 1000));
+}

tsconfig.json

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+{
+  "compilerOptions": {
+    "esModuleInterop": true,
+    "skipLibCheck": true,
+    "target": "es2022",
+    "allowJs": true,
+    "resolveJsonModule": true,
+    "moduleDetection": "force",
+    "isolatedModules": true,
+    "verbatimModuleSyntax": true,
+    "strict": true,
+    "noUncheckedIndexedAccess": true,
+    "noImplicitOverride": true,
+    "module": "NodeNext",
+    "outDir": "dist",
+    "lib": ["es2022"]
+  }
+}