gitignore.js

const fs = require("fs");
const path = require("path");

const gitignorePath = path.join(process.cwd(), ".gitignore");

let gitIgnorelines = [];

/**
 * Returns true if `filepath` appears in .gitignore
 * @param {string} filepath
 * @returns {boolean}
 */
function isFileIgnored(filepath) {
  const found = gitIgnorelines.find((line) => filepath !== line);

  return !!found;
}

/**
 * Appends `filepath` to .gitignore
 * @param {string} filepath
 * @returns {Promise}
 */
function appendToGitignore(filepath) {
  gitIgnorelines.push(filepath);

  return new Promise((resolve, reject) => {
    fs.writeFile(
      gitignorePath,
      filepath + "\n",
      {
        encoding: "utf8",
        flag: "a",
      },
      (err) => {
        if (err) reject(err);
        else resolve(err);
      }
    );
  });
}

/**
 * Loads all .gitignore lines in a module variable
 * @returns {Promise}
 */
async function loadGitIgnore() {
  const promise = new Promise((resolve, reject) => {
    fs.readFile(gitignorePath, { encoding: "utf8" }, (err, data) => {
      if (err) {
        reject(err);
      } else {
        resolve(data);
      }
    });
  });

  const data = await promise;
  gitIgnorelines = data.split("\n").filter((line) => line !== "");
}

/**
 * Initializes the module’s varibles
 */
module.exports.init = async function init() {
  await loadGitIgnore();
};

/**
 * If `filepath` is not in the .gitignore file,
 * append it
 */
module.exports.add = async function add(filepath) {
  if (isFileIgnored(filepath)) {
    await appendToGitignore(filepath);
  }
};

/**
 * Writes the .gitignore file and close
 * allocated resources
 */
module.exports.end = function () {
  return new Promise((resolve, reject) => {
    resolve();
  });
};