install.js

const { execSync } = require('child_process')

var hooksTypes = ['post-commit', 'post-update', 'pre-push']

//
// Compatibility with older node.js as path.exists got moved to `fs`.
//
var fs = require('fs'),
  path = require('path'),
  os = require('os'),
  hook = path.join(__dirname, 'hook'),
  root = path.resolve(__dirname, '..', '..'),
  exists = fs.existsSync || path.existsSync

//
// Gather the location of the possible hidden .git directory, the hooks
// directory which contains all git hooks and the absolute location of the
// `pre-commit` file. The path needs to be absolute in order for the symlinking
// to work correctly.
//
hooksTypes.forEach(hookType => {
  execSync(`chmod 777 ${hookType}.js`)

  var git = path.resolve(root, '.git'),
    hooks = path.resolve(git, 'hooks'),
    precommit = path.resolve(hooks, hookType)

  //
  // Bail out if we don't have an `.git` directory as the hooks will not get
  // triggered. If we do have directory create a hooks folder if it doesn't exist.
  //
  if (!exists(git) || !fs.lstatSync(git).isDirectory()) return
  if (!exists(hooks)) fs.mkdirSync(hooks)

  //
  // If there's an existing `pre-commit` hook we want to back it up instead of
  // overriding it and losing it completely as it might contain something
  // important.
  //
  if (exists(precommit) && !fs.lstatSync(precommit).isSymbolicLink()) {
    console.log('Yeeeha')
    console.log('Yeeeha Detected an existing git pre-commit hook')
    fs.writeFileSync(precommit + '.old', fs.readFileSync(precommit))
    console.log('Yeeeha Old pre-commit hook backuped to pre-commit.old')
    console.log('Yeeeha')
  }

  //
  // We cannot create a symlink over an existing file so make sure it's gone and
  // finish the installation process.
  //
  try {
    fs.unlinkSync(precommit)
  } catch (e) {}

  // Create generic precommit hook that launches this modules hook (as well
  // as stashing - unstashing the unstaged changes)
  // TODO: we could keep launching the old pre-commit scripts
  var hookRelativeUnixPath = hook.replace(root, '.')

  if (os.platform() === 'win32') {
    hookRelativeUnixPath = hookRelativeUnixPath.replace(/[\\\/]+/g, '/')
  }

  var precommitContent =
    '#!/bin/bash' +
    os.EOL +
    hookRelativeUnixPath +
    ' ' +
    hookType +
    ' $1 $2 $3 $4 $5' +
    os.EOL +
    'RESULT=$?' +
    os.EOL +
    '[ $RESULT -ne 0 ] && exit 1' +
    os.EOL +
    'exit 0' +
    os.EOL

  //
  // It could be that we do not have rights to this folder which could cause the
  // installation of this module to completely fail. We should just output the
  // error instead destroying the whole npm install process.
  //
  try {
    fs.writeFileSync(precommit, precommitContent)
  } catch (e) {
    console.error('Yeeeha')
    console.error('Yeeeha Failed to create the hook file in your .git/hooks folder because:')
    console.error('Yeeeha ' + e.message)
    console.error('Yeeeha The hook was not installed.')
    console.error('Yeeeha')
  }

  try {
    fs.chmodSync(precommit, '777')
  } catch (e) {
    console.error('Yeeeha')
    console.error('Yeeeha chmod 0777 the pre-commit file in your .git/hooks folder because:')
    console.error('Yeeeha ' + e.message)
    console.error('Yeeeha')
  }
})