[nodejs module] Count commits

countCommits.js

const { exec, spawn } = require("child_process");

function execPromise(command) {
  return new Promise((resolve, reject) => {
    exec(command, (err, stdout, stderr) => {
      if (err) reject(err);

      resolve({ stdout, stderr });
    });
  });
}

function pipedExecPromise(command, args, path) {
  return new Promise((resolve, reject) => {
    let stdOut = [];
    let stdErr = [];

    function stdoutAppend(data) {
      stdOut.push(data.toString("utf8"));
    }

    function stderrAppend(data) {
      stdErr.push(data.toString("utf8"));
    }

    let child = spawn(command, args, {
      stdio: ["inherit", "pipe", "pipe"],
      cwd: path,
    });

    child.stdout.on("data", stdoutAppend);
    child.stderr.on("data", stderrAppend);

    child.on("close", () => {
      if (stdErr.length) {
        reject({ stderr: stdErr.join("") });

        return;
      }

      resolve({ stdout: stdOut.join("") });
    });
  });
}

async function getAuthors(path) {
  const { stdout } = await pipedExecPromise(
    "git",
    "shortlog -sne".split(" "),
    path
  );

  const baseEmails = stdout
    .replace(/\n$/, "")
    .split("\n")
    .map((line) => line.replace(/^.+<(.+@.+)>$/, "$1"));

  let emails = [];

  baseEmails.forEach((email) => {
    if (emails.find((e) => e === email)) {
      return;
    }

    emails.push(email);
  });

  return emails;
}

async function countCommits(path, author) {
  const command = `cd "${path}" && git rev-list "HEAD^1" --count ${
    author ? "--author=" + author + " --regexp-ignore-case" : ""
  }`;

  const { stdout } = await execPromise(command);

  return Number(stdout.replace(/\n$/, ""));
}

async function countCommitsByEmail(path) {
  const authors = await getAuthors(path);

  const results = await Promise.all(
    authors.map((author) => countCommits(path, author))
  );

  return results.reduce((prev, curr, index) => {
    prev[authors[index]] = curr;

    return prev;
  }, {});
}

module.exports = {
  execPromise,
  pipedExecPromise,
  getAuthors,
  countCommits,
  countCommitsByEmail,
};

example.js

const path = require("path");

const { countCommitsByEmail } = require("./countCommits");

async function main() {
  return await countCommitsByEmail(
    path.resolve(__dirname, "../a/project")
  );
}

main().then(console.log).catch(console.error);